Lte Coverage and Capacity Dimensioning

Ministry of Higher Education National Telecommunication Institute Electronics and Communications Department

Long Term Evolution (LTE) Access Network Coverage and Capacity Dimensioning This thesis submitted in partial fulfilment of the requirements for the degree of high diploma in telecommunication and information engineering. Submitted by

● Amr Abdel-Magid Kassab ● Amr Mahmoud Morsy ● Mohammed Mahmoud Mohammed Saad ● Mohamed Mahmoud Mohamed Tantawy ● Mohamed Morsy Mohamed ● Hanaa Abdelmoety Kamel ● Walaa Abd-Elhamid Elawam Supervised By Dr.Hamed Abdel Fatah El Shenawy Cairo 2013

Acknowledgements First of all, we are grateful to ALLAHALMIGHTY, the most merciful, the most beneficent, who gave us strength, guidance and abilities to complete this thesis in a successful manner. We are thankful to our parents and our teachers that guided us throughout our career path especially in building up our base in education and enhance our knowledge. We are indebted to our supervisor Dr. Hamed Abd El Fattah ElShenawy for his supervision and his co-operation and support really helped us completing our project.

Abstract Long Term Evolution (LTE) is set of enhancement to the current cellular system in use. LTE is designed to have scalable channel bandwidth up to 20MHz, with low latency and packet optimized radio access technology. The peak data rate of LTE is 100 Mbps in downlink and 50 Mbps in the uplink. LTE support both FDD and TDD duplexing. LTE with OFDM technology in the down link, which provides higher spectral efficiency and more robustness against multipath fading LTE with SC-FDMA in the uplink LTE LTE with different MIMO configurations Dimensioning is initial phase of network planning. It provides estimate of the network elements count as well as the capacity of those elements. The purpose of our project to estimate the required number of eNodeBs needed to support users with certain traffic load with a desired level of quality of service (QOS) and cover the area of interest. This estimate fulfills coverage requirements and verified for capacity requirements . Coverage dimensioning occurs via radio link budget (RLB), maximum allowable propagation path loss (MAPL) is obtained. MAPL is converted into cell radius by using appropriate propagation models. The radius of the cell is used to calculate the number of sites required to cover the area of interest. The cell size and the site count are obtained. Capacity planning deals with the ability of the network to provide services to certain numbers of users with a desired level of quality of service (QOS). Capacity based site count is compared with coverage based site count. The greater one is selected as the final site count.

Project objectives  Overview of LTE system architecture and specifications  Dimensioning of LTE Network  Coverage dimensioning via radio link budget and propagation models  Capacity dimensioning  Numerical results using Visual Studio and basic language  Conclusions and suggestions for future work.

List of Contents Item

Page

1.0

Chapter One: Overview of LTE

1-1

1.1

Introduction

1-2

2.2

IMT-Advanced

1-2

1.3

LTE specifications

1-4

LTE Architecture

1-15

2.0

Chapter Two: LTE network dimensioning

2-1

2.1

Introduction

2-2

2.2

LTE network dimensioning

2-2

2.3

LTE network dimensioning inputs

2-6

2.4

Coverage planning inputs

2-7

2.5

Capacity planning inputs

2-8

2.6

LTE network dimensioning outputs

2-8

2.7

Comparison among dimensioning, planning, optimization

2-9

3.0

Chapter Three: Coverage dimensioning

3-1

3.1

Introduction

3-2

3.2

Concepts and Terminology

3-4

3.3

Link Budget Definition

3-5

3.4

Why we use Link Budget?

3-6

3.5

What are the types of Link Budget?

3-6

3.6

Up Link Budget (Up Link coverage)

3-7

3.7

Up Link Budget entries

3-7

3.8

Morphologies Classifications

3-28

3.9

Down Link Budget(Down Link coverage)

3-29

3.10

Down Link limited Link Budget

3-35

3.11

propagation models

3-37

3.12

Classifications of propagation models

3-39

i

3.13

Ericsson variant COST 231 Okomara-Hata wave propagation

3-42

model 3.14

Example of coverage dimensioning (Radio Link budget)

3-44

4.0

Chapter Four: Capacity dimensioning

4-1

4.1

Introduction

4-2

4.2

Uplink capacity

4-3

4.3

Downlink capacity

4-6

4.4

Application or service distribution model

4-13

5.0

Chapter Five: numerical results

5-1

5.1

Uplink budget

5-3

5.2

Effects on cell Radius (R)

5-17

5.3

Downlink capacity

5-21

6.0

Chapter Six: conclusion and suggestions for future work

6-1

6.1

Conclusion

6-2

6.2

Suggestions for future work

6-3

ii

List of figures Items

Page

Figure(1-1)

Overview of IMT advanced

1-2

Figure(1-2)

Resource element and resource block

1-14

Figure(1-3)

LTE architecture

1-15

Figure(1-4)

Evolved Packet System

1-15

Figure(2-1)

LTE network planning process

2-2

Figure(2-2)

Dimensioning basic steps

2-3

Figure(2-3)

LTE network dimensioning inputs

2-6

Figure(2-4)

LTE coverage planning

2-7

Figure(2-5)

LTE dimensioning outputs

2-9

Figure(2-6)

LTE optimization process stages

2-10

Figure(2-7)

LTE optimization process

2-11

Figure(2-8)

LTE optimization process

2-16

Figure(3-1)

LTE Dimensioning Process

3-4

Figure(3-2)

Resource Block Definition in Frequency Domain 3-11

Figure(3-3)

Downlink and Uplink User Scheduling in Time

3-12

and Frequency Domain. Figure (4.1)

channel bandwidth partitioning

4-22

Figure (4-2)

subscriber class deployment model

4-29

Figure(5-1)

flowchart of effective isotropic radiated power

5-3

Figure(5-2)

Effective Isotropic Radiated Power

5-3

Figure(5-3)

flowchart of sensitivity of eNodeB

5-5

Figure(5-4)

Sensitivity of Enhanced nodeB

5-5

Figure(5-5)

flowchart of Interference Margin

5-7

Figure(5-6)

flowchart of Log Normal Fading Margin

5-7

Figure(5-7)

flowchart of total margins

5-8

iii

Figure(5-8)

Total margin

5-8

Figure(5-9)

flowchart of total gains

5-10

Figure(5-10)

flowchart of total losses

5-10

Figure(5-11)

total gains and total losses

5-11

Figure(5-12)

flowchart of maximum allowable path loss

5-12

Figure(5-13)

Max. allowable path loss

5-13

Figure(5-14)

flowchart of cell radius using Ericson variant

5-14

Okumara -Hata Figure(5-15)

flowchart of site count

5-15

Figure(5-16)

cell radius and Site Count

5-15

Figure(5-17)

the effect of cell Loading Factor (Q) on the cell

5-17

Radius (R) Omni Figure(5-18)

the effect of cell Loading Factor (Q) on the cell

5-18

Radius (R) 3 sector Figure(5-19)

the effect of morphology on the cell Radius (R)

5-19

omni Figure(5-20)

the effect of morphology on the cell Radius (R) 3 5-20 sector

Figure(5-21)

downlink capacity

5-21

Figure (5-22)

Final Base site count

5-25

iv

List of tables

Item Table(1-1)

Page

Improvement in downlink spectral efficiency going 1-7 from 2G to 4G System

Table (1-2)

Targets for average spectrum efficiency

1-8

Table (3-1)

Bandwidths and number of physical resource 3-16 blocks

Table(3-2)

Channel models specifications 1

3-18

Table (3-3)

Channel models specifications 2

3-18

Table(3-4)

Channel propagation conditions

3-19

Table(3-5)

Maximum Doppler frequency for each channel 3-19 model

Table(3-6)

Semi –empirical parameters for uplink

3-21

Table(3-7)

Examples of F for varying tilt

3-23

Table(3-8)

Lognormal fading margins for varying standard 3-24 deviation of log normal fading

Table(3-9)

Values of penetration loss on different morphology 3-26 classes

Table(3-10)

Summarizes the features of different morphologies

3-28, 3-29

Table(3-11)

Examples of Fc at cell edge for varying tilt

3-33

Table(3-12)

Semi –empirical parameters for downlink

3-33

Table(3-13)

Fixed attenuation A in Ericsson variant COST 231 3-43 Okumara Hata propagation models

Table (3-14) Example of coverage dimensioning (Radio Link budget) Table(4-1)

3-44 3-45

SINR values corresponding to each modulation 4-4 coding scheme (MCS) v

Table(4-2)

semi- empirical parameters for up link

4-5

Table(4-3)

Semi- empirical parameters for downlink

4-11

Table (4.5)

applications or services distribution model

4-14

Table (4.6)

mobile service flows and QoS parameters

4-19

Table (4.7)

subscriber class distribution model

4-28

Table (4.8)

subscriber class traffic model

4-30

Table (5-1)

Default values of User Equipment Effective 5-4 Isotropic Radiated Power(EIRP)

Table(5-2)

Default values of Enhanced NodeB sensitivity

5-6

Table(5-3)

Default values of total margin

5-9

Table(5-4)

Default values of total Gain and losses

5-12

Table(5-5)

Default values of Maximum allowable path loss 5-14 (MAPL)

Table(5-6)

values of Cell Radius and Site count with 5-16 difference Base stations heights

Table(5-7)

The effect of cell Loading Factor (Q) on the cell 5-17 Radius (R) Omni

Table(5-8)

The effect of cell Loading Factor (Q) on the cell 5-18 Radius (R) 3 sector

Table(5-9)

the effect of eNodeB height on the cell Radius (R) 5-19 omni

Table(5-10)

the effect of eNodeB height on the cell Radius (R) 5-20 3 sector

vi

List of Acronyms and Abbreviations 16QAM: 16 point quadrature amplitude modulation 3GPP: Third Generation Partnership 64QAM: 64 point quadrature amplitude modulation 3G: third generation 4G: fourth generation

A ACK: Acknowledgement AGC: Automatic Gain Control AP: Access Point ARQ: Automatic Repeater Request AUC: Authentication center A/D: Analog to digital ADSL: Assymetric Digital Subscriber Line AMPS: Advanced Mobile Phone Services AWGN: Additive White Gaussian Noise

B BCH: Broadcast Channel BPSK: Binary Phase Shift Keying BSC: Base Station Controller BTS: Base Transceiver Station BW: Bandwidth BER: Bit Error Rate vii

C CDMA: Code Division Multiple Access CW: Continuous Wave CPL: Car Penetration Loss COST: Community Collaborative studies in the areas of science and technology

D DL: Downlink DSL: Digital Subscriber Line D/A: Digital to analog DU: Dense Urban

E EDGE: Enhanced Data Rate for GSM Evolution EIR: Equipment Identity Register EIRP: Effective Isotropic Radiated Power eNodeB: Enhanced NodeB (enhanced base station) EPA: extended pedestrian ETU: extended terrestrial EVA: extended vehicular EPC: Evolved Packet Core EPS: Evoved Packet System

F FDD: Frequency Division Duplex FDMA: Frequency Division Multiple Access FTT: Fast Fourier Transform FM: Frequency Modulation FWLL: Fixed Wireless Local Loop viii

FFM: Fast Fading Margin

G GGSN: Gateway GPRS Serving Node GMSC: Gateway Mobile Switching Center GMSK: Gaussian Minimum Shift Keying GSM: Global System for Mobile GPRS: General Packet Radio Service GUI: Graphical User Interface

H HARQ: Hybrid Automatic Repeater Request HLR: Home Location Register HSCSD: High Speed Circuit Switched Data HSDPA: High Speed Downlink Packet Access HSS: Home Subscriber Server HSUPA: High Speed Uplink Packet Access

I IMS: IP Multimedia Subsystem IM: Interference Margin IP: Internet Protocol

K KPI: Key Performance Indicator

L LTE: Long Term Evolution

M MBMS: Multimedia broadcast multicast services MB-SFN: Multicast/broadcast-single frequency network ix

MIMO: Multi Input Multi Output MME: Mobile Mobility Management Entity MRC: Maximal ratio combining MS: mobile Station MSC: Mobile Switching Center MAPL: Maximum Allowable Path Loss

O OFDM: Orthogonal Frequency Division Multiplexing OMC: Operation and Maintenance Center

P PAPR: Peak -to-average power ratio PCRF: Policy and Charging Rules Function PDCCH: Physical downlink control channel PDN: Public Data Network PLMN: Public land Mobile Network PRB: Physical Resource Block PSK: Phase Shift Keying PSTN: Public Switched Telephone Network P-GW: PDN Gateway PUCCH: Physical Uplink Control Channel PDCCH: Physical Downlink Control Channel

Q QAM: Quadrature Amplitude Modulation QPSK: Quadrature phase shift Keying QOS: Quality Of Service

x

R RFPA: Radio Frequency Power Amplifier RNC: Radio Network Controller RLB: Radio Link Budget

S SC-FDMA: Single Carrier-Frequency Division Multiple Access SGSN: Serving GPRS Support Node SIM: Subscriber Identity Module SINR: Signal Interference -to-noise ratio S-GW: Serving Gateway SRVCC: Single Radio Voice Call Continuity SMS: Short Message Service SU: Sub Urban

T TDD: Time Division Duplexing TDMA: Time Division Multiple Access TMA: Tower Mounted Amplifier

U UE: User Equipment UL: Uplink UMTS: Universal Mobile Telecommunication system UTRAN: UMTS Terrestrial Radio Access Network

V VLR: Visitor Location Register VOIP: Voice over IP

xi

W WCDMA: Wideband Code Division Multiple Access WIMAX: Worldwide Interoperability for Microwave Access

xii

Chapter One Overview of Long Term Evolution (LTE)

Chapter 1: Overview of Long Term Evolution (LTE)

Chapter one Overview of Long Term Evolution (LTE) 1.1. Introduction LTE is designed to meet users need for high speed data and media transport as well as high-capacity voice support .The LTE PHY employs some advanced Technologies that are new to mobile applications these include OFDMA -SC-FDMA –MIMO. The LTE PHY uses OFDMA in downlink and SC-FDMA on up link.

Figure (1-1) Overview of IMT Advanced

1.2. IMT-Advanced International Mobile Telecommunications Advanced (IMTAdvanced) is requirements issued by the ITU-R of the International Telecommunication Union (ITU) in 2008 for what is marketed as 4G mobile phone and Internet access service.

1-2

Chapter 1: Overview of Long Term Evolution (LTE) 1.2.1 IMT ADVANCED Requirements Specific requirements of the IMT-Advanced report included: 1- Based on an all-Internet Protocol (IP) packet switched network 2- Interoperability with existing wireless standards 3- A nominal data rate of 100 Mbit/s while the client physically moves at high speeds relative to the station,50 Mbit /s in the uplink and 1 Gbit/s while client and station are in relatively fixed positions. 4- Dynamically share and use the network resources to support more simultaneous users per cell. 5- Scalable channel bandwidth 1.4 MHz, 3 MHz, 5 MHz, 15 MHz and 20 MHz optionally up to 40 6- Peak link spectral efficiency of 15 bit/s/Hz in the downlink, and 6.25bit/s/Hz in the uplink (meaning that 1 Gbit/s in the downlink should be possible over less than 67 MHz bandwidth) 7- System spectral efficiency of up to 3 bit/s/Hz/cell in the downlink and 2.25 bit/s/Hz/cell for indoor usage 8- Seamless connectivity and global roaming across multiple networks with smooth handovers 9- Ability to offer high quality of service for multimedia support 10- support antenna configurations a- Downlink 4×2, 2×2, 1×2, 1×1 b- Uplink 1×2, 1×1 11- coverage a- full performance up to 5 km b-slight degradation 5 km-30 km c-operation up to 100 km should not be precluded by standard

1-3

Chapter 1: Overview of Long Term Evolution (LTE) 12- mobility a- optimized for low speed less than 15 km per hour b-high performance at speeds up to 120 km per hour c-maintain link at speeds up to 350 km per hour 13- LTE support efficient broadcast mode performance :multicast and broadcast 14- broadcast spectral efficiency 1bit /sec/Hz 15- LTE support paired and unpaired frequency band 16- It support FDD and TDD, half duplex TDD 17- Support adaptive modulation technique: High level and low level modulation 18- Support scalable FFT size 19- It support turbo code 20- It support low complexity low cost terminal 21- Support VOIP 60 session /Hz/cell 22- Support of cell sizes from tens of meters of radius (femto and Pico cells) up to over 100 km radius microcells 23- Simplified architecture: The network side of EUTRAN is composed only by the enodeBs. 24- Low data transfer latencies (sub-5ms latency for small IP packets in optimal conditions), lower latencies for handover and connection setup time. 1.3 LTE specifications 1.3.1 Peak Rates and Peak Spectral Efficiency For Data rate many services with lower data rates such as voice services are important and still occupy a large part of a mobile network’s overall capacity, but it is the higher data rate services that drive the design

1-4

Chapter 1: Overview of Long Term Evolution (LTE) of the radio interface. The ever increasing demand for higher data rates for web browsing, streaming and file transfer pushes the peak data rates for mobile systems from kbit/s for 2G, to Mbit/s for 3G and getting close to Gbit/s for 4G (Erik Dahlman, Stefan Parkvall, and Johan Sköld, 2011). For marketing purposes, the first parameter by which different radio access technologies are usually compared is the peak peruser data rate which can be achieved. This peak data rate generally scales according to the amount of spectrum used, and, for MIMO systems, according to the minimum of the number of transmit and receive antennas. The peak data rate can be defined as the maximum throughput per user assuming the whole bandwidth being allocated to a single user with the highest modulation and coding scheme and the maximum number of antennas supported. Typical radio interface overhead (control channels, pilot signals, guard intervals, etc.) is estimated and taken into account for a given operating point. For TDD systems, the peak data rate is generally calculated for the downlink and uplink periods separately. This makes it possible to obtain a single value independent of the uplink/downlink ratio and a fair system comparison that is agnostic of the duplex mode. The maximum spectral efficiency is then obtained simply by dividing the peak rate by the used spectrum allocation. The target peak data rates for downlink and uplink in LTE Release 8 were set at 100 Mbps and 50 Mbps respectively within a 20 MHz bandwidth, 7 corresponding to respective peak spectral efficiencies of 5 and 2.5 bps/Hz. The underlying assumption here is that the terminal has two receive antennas and one transmit antenna. The number of antennas used at the base station is more easily upgradeable by the network

1-5

Chapter 1: Overview of Long Term Evolution (LTE) operator, and the first version of the LTE specifications was therefore designed to support downlink MIMO operation with up to four transmit and receive antennas. When comparing the capabilities of different radio communication technologies, great emphasis is often placed on the peak data rate capabilities. While this is one indicator of how technologically advanced a system is and can be obtained by simple calculations, it may not be a key differentiator in the usage scenarios for a mobile communication system in practical deployment. Moreover, it is relatively easy to design a system that can provide very high peak data rates for users close to the base station, where interference from other cells is low and techniques such as MIMO can be used to their greatest extent. It is much more challenging to provide high data rates with good coverage and mobility, but it is exactly these latter aspects which contribute most strongly to user satisfaction. In typical deployments, individual users are located at varying distances from the base stations, the propagation conditions for radio signals to individual users are rarely ideal, and the available resources must be shared between many users. Consequently, although the claimed peak data rates of a system are genuinely achievable in the right conditions, it is rare for a single user to be able to experience the peak data rates for a sustained period, and the envisaged applications do not usually require this level of performance. A differentiator of the LTE system design compared to some other systems has been the recognition of these „typical deployment constraints‟ from the beginning. During the design process, emphasis was therefore placed not only on providing a competitive peak data rate for use when conditions allow, but also

1-6

Chapter 1: Overview of Long Term Evolution (LTE) importantly on system level performance, which was evaluated during several performance verification steps. System-level evaluations are based on simulations of multicell configurations where data transmission from/to a population of mobiles is considered in a typical deployment scenario. The sections below describe the main metrics used as requirements for system level performance. In order to make these metrics meaningful, parameters such as the deployment scenario, traffic models, channel models and system configuration need to be defined (Stefanie Sesia, Issam Toufik and Matthew Baker, 2011).

Table (1-1): Improvement in downlink spectral efficiency going from 2G to 4G System 1.3.2 Spectrum efficiency In this section, the target for peak spectrum efficiency, the average spectrum efficiency, and cell edge spectrum efficiency are defined. The target for average spectrum efficiency and the cell edge user throughput efficiency should be given a higher priority than the target for peak spectrum efficiency and VoIP capacity. The target for average spectrum

1-7

Chapter 1: Overview of Long Term Evolution (LTE) efficiency and the cell edge spectrum efficiency should be achieved simultaneously. The peak spectrum efficiency is the highest data rate normalized by overall cell bandwidth assuming error-free conditions, when all available radio resources for the corresponding link direction are assigned to a single UE.

The system target to support downlink peak spectrum

efficiency of 30 bps/Hz and uplink peak spectrum efficiency of 15 bps/Hz. Assumption of antenna configuration is (8x8) or less for DL and( 4x4) or less for UL Average spectrum efficiency is defined as the aggregate throughput of all users (the number of correctly received bits over a certain period of time) normalized by the overall cell bandwidth divided by the number of cells. The average spectrum efficiency is measured in b/s/Hz/cell. Advanced E-UTRA should target the average spectrum efficiency to be as high as possible, given a reasonable system complexity. The expectation at the end of the study item is that the values of all the targets (of the different configurations) will be made available, but currently the evaluation for the blanked out boxes in the table below, are a lower priority. Advanced E-UTRA should target the average spectrum efficiencies in different environments in Table (2-2).

Table (1-2): Targets for average spectrum efficiency

1-8

Chapter 1: Overview of Long Term Evolution (LTE) 1.3.3 Cell edge user throughput The cell edge user throughput is defined as the 5% point of CDF of the user throughput normalized with the overall cell bandwidth. Advanced E-UTRA should target the cell edge user throughput to be as high as possible, given a reasonable system complexity. A more homogeneous distribution of the user experience over the coverage area is highly desirable and therefore a special focus should be put on improving the cell edge performance. The expectation at the end of the study item is that the values of all the targets (of the different configurations) will be made available, but currently the evaluation for the blanked out boxes in the table below, are a lower priority. Advanced E- UTRA should target the cell edge user throughput below in different environments 1.3.4 Voice Capacity (VOIP) VoIP services convert your voice into a digital signal that travels over the Internet. If you are calling a regular phone number, the signal is converted to a regular telephone signal before it reaches the destination. VoIP can allow you to make a call directly from a computer, a special VoIP phone, or a traditional phone connected to a special adapter. In addition, wireless "hot spots" in locations such as airports, parks, and cafes allow you to connect to the Internet and may enable you to use VoIP service wirelessly. Some VoIP providers offer their services for free, normally only for calls to other subscribers to the service. Your VoIP provider may permit you to select an area code different from the area in which you live. It

1-9

Chapter 1: Overview of Long Term Evolution (LTE) also means that people who call you may incur long distance charges depending on their area code and service. Some VoIP providers charge for a long distance call to a number outside your calling area, similar to existing, traditional wire line telephone service. Other VoIP providers permit you to call anywhere at a flat rate for a fixed number of minutes. Depending upon your service, you might be limited only to other subscribers to the service, or you may be able to call anyone who has a telephone number - including local, long distance, mobile, and international numbers. If you are calling someone who has a regular analog phone, that person does not need any special equipment to talk to you. Some VoIP services may allow you to speak with more than one person at a time. Some VoIP services offer features and services that are not available with a traditional phone, or are available but only for an additional fee. You may also be able to avoid paying for both a broadband connection and a traditional telephone line.

If you're

considering replacing your traditional telephone service with VoIP, there are some possible differences. Some VoIP services don't work during power outages and the service provider may not offer backup power. Not all VoIP services connect directly to emergency services through 9-1-1. For additional information VoIP providers may or may not offer directory assistance/white page listings. 1.3.5 Mobility The system shall support mobility across the cellular network for various mobile speeds up to 350km/h (or perhaps even up to 500km/h depending on the frequency band).

1 - 10

System performance shall be

Chapter 1: Overview of Long Term Evolution (LTE) enhanced for 0 to 10km/h and preferably enhanced but at least no worse than E-UTRAand E-UTRAN for higher speeds. 1.3.6 Control Plane and User Plane Latency Control plane deals with signaling and control functions, while user plane deals with actual user data transmission. C-Plane latency is measured as the time required for the UE (User Equipment) to transit from idle state to active state. In idle state, the UE does not have an Reconnection. Once the RRC is setup, the UE transitions to connected state and then to the active state when it enters the dedicated mode. U-Plane latency is defined as one way state when it enters the dedicated mode. U-Plane latency is defined as one-way transmit time between a packet being available at the IP layer in the UE/E-UTRAN (Evolved UMTS Terrestrial Radio Access Network) edge node and the availability of this packet at the IP layer in the EUTRAN/ UE node. U-Plane latency is relevant for the performance of many applications. This tutorial presents in detail the delay budgets of C-Plane and U-Plane procedures that add to overall latency in state transition and packet transmission. Latency calculations are made for both FDD and TDD modes of operation. Technical details of C-Plane and U-Plane latency .This tutorial is organized as follows: Requirements and assumptions in Section This tutorial presents in detail the delay budgets of C- Plane and U-Plane procedures that add to overall latency in state transition and packet transmission. Latency calculations are made for both FDD and TDD modes of operation. Technical details of C-Plane and U-Plane latency are cited in This tutorial is organized as follows: Requirements

1 - 11

Chapter 1: Overview of Long Term Evolution (LTE) and assumptions in Section II, C- Plane latency analysis in Section III and U-Plane latency analysis in Section IV. The conclusions are summarized in Section V. All the values indicated in the tables are in mill seconds (ms). The method of calculating these latencies is illustrated in the appendix. Low latency where5 ms user plane latency for small IP packets (user equipment to radio access network [RAN] edge) .100 ms camped to active. 50 ms dormant to active. Scalable bandwidth where the 4G channel offers four times more bandwidth than current 3G systems and is scalable. So, while 20 MHz channels may not be available everywhere, 4G systems will offer channel sizes down to 5 MHz, in increments of 1.5 MHz. 1.3.7 Spectrum Allocation and Duplex Modes Transmission techniques exist  Simplex One party transmits data and the other party receives data.No simultaneous transmission is possible, the communication is one-way and only one frequency (channel) is used.  Half Duplex Each party can receive and transmit data, but not at the same time. The communication is two-way and only one frequency (channel) is used.  Full Duplex Each party can transmit and receive data simultaneously.

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Chapter 1: Overview of Long Term Evolution (LTE) The communication is two-way and two frequencies. Full duplex main methods used are  Time Division Duplexing (TDD) The communication is done using one frequency, but the time for transmitting and receiving is different. This method emulates full duplex communication using a half-duplex link.  Frequency Division Duplexing (FDD) The communication is done using two frequencies and the transmitting and receiving of data is simultaneous. The advantages of TDD are typically observed in situations uplink and downlink data transmissions are not symmetrical. Transmitting and receiving is done using one frequency, the channel estimations for beam forming (and other smart antenna techniques) apply for both the uplink and the downlink. A typical disadvantage of TDD is the need to use guard periods between the downlink and uplink transmissions. The advantages of FDD are typically observed in situations where the uplink and downlink data transmissions are symmetrical (which is not usually the case when using wireless phones). More importantly, when using FDD, the interference between neighboring Radio Base Stations (RBSs) is lower than when using TDD. Also, the spectral efficiency (which is a function of how well a given spectrum is used by certain access technology) of FDD is greater than TDD.

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Chapter 1: Overview of Long Term Evolution (LTE) Frequency band from 2600MHz to 2.6 GHz. Channel bandwidth up to 20 MHz Channel bandwidth on-demand (1.4 MHz, 3MHz, 5MHz, 10MHz, 15MHz, 20MHz). Charging / volume 1.3.8 Resource element and resource block A resource element is the smallest unit in the physical layer and occupies one OFDM or SC-FDMA symbol in the time domain and one subcarrier in the frequency domain as shown in figure (2-1) . Aresource block (RB) is the smallest unit that can be scheduled for transmission. An RB physically occupies 0.5 ms (1 slot) in the time domain and 180 KHz in the frequency domain .the number of subcarriers per RB and the number of symbols per RB vary as a function of the cyclic prefix length and subcarrier spacing.

Figure (1-2): Resource element and resource block

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Chapter 1: Overview of Long Term Evolution (LTE) 1.4 LTE architecture

Figure (1-3) LTE architecture The combination of the EPC and the evolved RAN ( E-UTRAN) is the evolved packet system (EPS).

Figure (1-4) Evolved Packet System

1 - 15

Chapter 1: Overview of Long Term Evolution (LTE) 1.4.1 Access network E-UTRAN Consists only of enodeBs on the network side. The enodeB performs tasks similar to those performed by the nodeBs and RNC (radio network controller) together in UTRAN. The aim of this simplification is to reduce the latency of all radio interface operations. The eNBs are interconnected with each other by means of the X2 interface. The eNBs are connected by the S1 interface to the EPC (Evolved Packet Core). The eNB connects to the MME (Mobility Management Entity) by means of the S1-MME interface and to the Serving Gateway (S-GW) by means of the S1-U interface. The S1 interface supports a many-to-many relation between MMEs / Serving gateways and eNBs. eNodeB eNB interfaces with the UE and hosts the Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Control Protocol (PDCP) layers. It also hosts Radio Resource Control (RRC) functionality corresponding to the control plane. It performs many functions including radio resource management, admission control, scheduling, enforcement of negotiated UL QoS, cell information broadcast, ciphering/deciphering of user and control plane data, and compression/decompression of DL/UL user plane packet headers. Functions of eNodeB  Transmission & Reception

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Chapter 1: Overview of Long Term Evolution (LTE)  Modulation & Demodulation  Radio resources allocation  Error Detection and Correction  Connectivity to the EPC  Header Compression & packet encryption  Scheduling and transmission of broadcast information 1.4.2 CORE NETWORK ( EPC ) The main logical nodes of the EPC are:  Mobility Management Entity (MME)  PDN Gateway (P-GW)  Policy and Charging Rules Function (PCRF)  Serving Gateway (S-GW).  Home Subscriber Server (HSS) 1- MME Mobility Management Entity is the control node that processes the signaling between the UE and the CN. Manages and stores UE context (for idle state: UE/user identities, UE mobility state, user security parameters). It generates temporary identities and allocates them to UEs.  Security Procedures (by interacting with the HSS).  Idle mode UE Tracking Area update & Paging  Handling QoS

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Chapter 1: Overview of Long Term Evolution (LTE)  Choosing the SGW for a UE at the initial attach and at time of intra-LTE handover involving Core Network node relocation. 2-P-GW The PDN GW provides connectivity to the UE to external packet data networks by being the point of exit and entry of traffic for the UE The Packet data network gateway is responsible for:  IP address allocation for the UE  Charging (according to rules from the PCRF )  Filtering of downlink user IP packets into the different QoS based bearers  mobility anchor for interworking with non-3GPP technologies such as CDMA2000 and WiMAX networks 3-PCRF The Policy and Charging Rules Function is responsible for :  Real time Determination of policy & charging rules 

QoS handling.

4-S-GW The SGW routes and forwards user data packets, while also acting as the mobility anchor for the user plane during inter-eNB handovers and as the anchor for mobility between LTE and other 3GPP technologies (terminating S4 interface and relaying the traffic between 2G/3G systems and PDN GW).

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Chapter 1: Overview of Long Term Evolution (LTE) The serving gateway is responsible for:  Routes and forwards user data packets  Mobility anchor for intra E-UTRAN mobility (when the UE moves between eNodeBs)  Mobility anchor with 2G/GSM and 3G/UMTS mobility.

5-HSS  Users subscription data  Information about the PDNs to which the user can connect  The identity of the MME to which the user is currently attached or registered  Authentication information

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Chapter Two LTE Network Dimensioning

Chapter 2: LTE Network Dimensioning Chapter Two LTE Network Dimensioning 2.1 Introduction Dimensioning is a part of the whole planning process, which also includes detailed planning and optimization of the wireless cellular network as shown in figure: (2-1) Planning Dimensioning Requirements and strategy for coverage, capacity and quality

Coverage planning and site selection and acquisition Capacity requirement

Optimization Performance analysis in terms of quality, efficiency and availability

Parameter planning

Figure: (2-1) LTE network planning process

2.2 LTE network dimensioning It is the initial phase of network planning. It provides the first estimate of the network element count as well as the capacity of those elements. The purpose of dimensioning is to estimate the required number of eNodeBs needed to support a specified traffic load in an area. The aim of this whole exercise is to provide a method to design the wireless cellular network such that it meets the requirements set forth by the customer. This process can be modified to fit the needs of any wireless cellular network. This is a very important process in network deployment. Wireless cellular network dimensioning is directly related to the quality and effectiveness of the network. And can deeply affect its development. Wireless cellular network dimensioning follows basic steps shown in figure:

2-2

Chapter 2: LTE Network Dimensioning

Dimensioning steps

Data/Traffic Analysis

Coverage estimation

Capacity Evaluation

Transport Dimensioning

Figure (2-2): Dimensioning basic steps 2.2.1 Data and Traffic analysis This is the first step in LTE dimensioning. It involves gathering of required inputs and their analysis to prepare them for use in LTE dimensioning process. Operator data and requirements are analysed to determine the best system configuration. Wireless cellular dimensioning requires some fundamental data elements. These parameters include subscriber population, traffic distribution, geographical area to be covered, frequency band, allocated bandwidth, and coverage and capacity requirements. Propagation models according to the area and frequency band should be selected and modified if need. This is necessary for coverage estimation. System specific parameters like, transmit power of the antennas, their gains, estimate of system losses, type of antenna system used etc., must be known prior to the start of wireless cellular network dimensioning. Each wireless network has its own set of parameters. Traffic analysis gives an estimate of the traffic to be carried by the system. Different types of traffic that will be carried by the network are modulated. Traffic types may include voice calls, VOIP, PS or CS traffic. Overheads carried by each type of traffic are calculated and included in the model. Time and amount of traffic is also forecasted to evaluate the performance of the network and to determine whether the network can fulfil the requirements set forth.

2-3

Chapter 2: LTE Network Dimensioning 2.2.2 Coverage estimation It is used to determine the coverage area of each eNodeB. Coverage estimation calculates the area where eNodeB can be heard by the users (receivers). It gives the maximum area that can be covered by eNodeB. But it is not necessary that an acceptable connection (e.g a voice call) between eNodeB and receiver can be established in coverage area. However eNodeB can be detected by the receiver in coverage area. Coverage analysis fundamentally remains the most critical step in the design of LTE network as with 3G systems. RLB (Radio Link Budget) is at the heart of coverage planning which allows the testing of path loss model and the required peak data rates against the target coverage levels. The result is the effective cell range to work out the coverage-limited site count. This requires the selection of appropriate propagation model to calculate path loss. LTE RLB with the knowledge of cell size estimates and of the area to be covered is an estimate of the total number of sites is found. This estimate is based on coverage requirements and needs to be verified for the capacity requirements. Coverage planning includes radio link budget and coverage analysis RLB comprises of all the gains and losses in the path of the signal from transmitter to receiver. This includes transmitter and receiver gains as well as losses and the effect of the wireless medium between them. Free space propagation loss, fast fading and slow fading in taken into account. Additionally, parameters that are particular to some systems are also considered. Frequency hopping and antenna diversity margins are two examples. 2.2.3 Capacity evaluation Capacity planning deals with the ability of the network to provide services to the users with a desired level of quality. After the site coverage area is calculated using coverage estimation, capacity relates issues are analyzed. This involves selection of site and system configuration, e.g. channels used channel elements and sectors. These elements are different for each system. Configuration is selected such that it fulfils the traffic requirements. In some wireless cellular systems, coverage and capacity are interrelated, e.g. in WCDMA.

2-4

Chapter 2: LTE Network Dimensioning In this case, data pertaining to user distribution and forecast of subscriber’s growth is of almost importance. Dimensioning team must consider these values as the have direct impact on coverage and capacity, Capacity evaluation gives an estimate of the number of sites required to carry the anticipated traffic over the coverage area. Once the number of sites according to the traffic forecast is determined, the interfaces of the network are dimensioned. Number of interfaces can vary from a few in some systems to many in others. The objective of this step is to perform the allocation of traffic in such a way that no bottle neck is created in the wireless network. All the quality of service requirements are to be met and cost has to be minimized. Good interface dimensioning is very important for smooth performance of the network. With a rough estimate of the cell size and site count, verification of coverage analysis is carried out for the required capacity. It is verified whether with the given site density, the system can carry the specified load or new sites have to be added. In LTE, the main indicator of capacity is SINR distribution in the cell. This distribution is obtained by carrying out system levels simulations. SINR distribution can be directly mapped into system capacity (data rate). LTE cell capacity is impacted by several factors, for example, packet scheduler implementation, supported MCSs, antenna configurations and interference level. Therefore, many sets of simulation results are required for comprehensive analysis. Capacity based site count is then compared with coverage result and greater of the two numbers is selected as the final site count, as already mentioned in the previous section. 2.2.4 Transport Dimensioning Transport dimensioning deals with the dimensioning of interfaces between different network elements. In LTE, S1 (between eNodeB and a GW) and X2 (between two eNodeBs) are the two interfaces to be dimensioned. These interfaces were still in the process of being standardized at the time of this work. Therefore, transport dimensioning is not included in this thesis work.

2-5

Chapter 2: LTE Network Dimensioning An initial sketch of LTE network is obtained by following the above mentioned steps of dimensioning exercise. This initial assessment forms the basis of detailed planning phase. In this thesis, main emphasis is on steps two to four. First step is unnecessary because the data for the test cases is taken from WIMAX scenario, allowing its by pass. Coverage and capacity planning is dealt in detail and resulting site count is calculated to give an estimate of the dimensioned LTE network. Dimensioning of LTE will depend on the operator strategy and business case. The physical side of the task means to find the best possible solution of the network which meets operator requirements and expectations. In detail and resulting site count is calculated to give an estimate if the dimensioned LTE network. Dimensioning of LTE will depend on the operator strategy and business case. The physical side of the task means to find the best possible solution of the network which meets operator requirements and expectative. 2.3 LTE network dimensioning inputs LTE dimensioning inputs used in the development of methods and models for LTE dimensioning. LTE dimension inputs can be broadly divided into three categories; quality, coverage and capacity related inputs. LTE network dimensioning has three main processes shown in figure (2-3).

Dimensioning inputs

Quality inputs

Coverage planning inputs

Capacity planning inputs

Figure (2-3): LTE network dimensioning inputs

2-6

Chapter 2: LTE Network Dimensioning 2.3.1 Quality inputs Quality inputs include average cell throughput and blocking probability. These parameters are the customer requirements to provide a certain level of service to its users. These inputs directly translate into Qos parameters. Besides cell edge coverage probability is used in the dimensioning tool to determine the cell radius and thus the site count. Three methods are employed to determine the cell edge. These include user defined maximum throughput at the cell edge, maximum coverage with respect to lowest MCS (giving the minimum possible site count) and predefined cell radius. With a predefined cell radius, parameters can be varied to check the data rate achieved at this cell size. This option gives the flexibility to optimize transmitted power and determining a suitable data rate corresponding to this power. 2.4 Coverage planning inputs Required coverage probability plays a vital role in determination of call radius. Even a minor change in coverage probability causes a large variation in cell radius as shown in figure (2-4)

Radio Link budget (RLB)

MAPL Propagation model Cell size

Figure (2-4): LTE coverage planning LTE dimensioning inputs for coverage planning exercise are similar to the corresponding inputs for 3G UMTS networks. Radio link budget (RLB) is of central importance to coverage planning in LTE.

2-7

Chapter 2: LTE Network Dimensioning RLB inputs include transmitter and receiver antenna systems, number of antennas used, conventional system gains and losses, cell loading and propagation models. LTE can operate in both the conventional frequency bands of 900 and 1800 MHz as well as extended band of 2600 MHz. Models for all the three possible frequency bands are incorporated in this work. Additionally, channel types (pedestrian, Vehicular) and geographical information is needed to start the coverage dimensioning exercise. Geographical input information consists of area type information (Urban, Rural, etc.) and size of each area type to be covered. Furthermore, required coverage probability plays a vital role in determination of cell radius. Even a minor change in coverage probability causes a large variation in cell radius. 2.5 Capacity planning inputs Capacity planning inputs provides the requirements, to be met by LTE network dimensioning exercise. Capacity planning inputs gives the number of subscribers in the system, their demanded services and subscriber usage level. Available spectrum and channel bandwidth used by the LTE system are also very important for LTE capacity planning. Traffic analysis and data rate to support available services (Speech, Data) are used to determine the number of subscribers supported by a single cell and eventually the cell radius based on capacity evaluation. LTE system level simulation results and LTE link level simulation results are used to carry out capacity planning exercise along with other inputs. These results are obtained from Nokia's internal sources. Subscriber growth forecast is used in this work to predict the growth and cost of the network in years to come. This is a marketing specific input targeting the feasibility of the network over a longer period of time. Forecast data will be provided by the LTE operators. 2.6 LTE network dimensioning outputs Outputs or targets of LTE dimensioning process have already been discussed indirectly in the previous section. Outputs of the dimensioning phase are used to estimate the feasibility and cost of the network. These outputs are further used in detailed network planning. Dimensioning LTE network can help out LTE core network team to plan a suitable network design and to determine the number of backhaul links required in the starting phase of the network as shown in figure (2-5) Cell size is the main output of LTE dimensioning exercise.

2-8

Chapter 2: LTE Network Dimensioning Two values of cell radius are obtained, one from coverage evaluation and second from capacity evaluation. The larger of the number is taken as the final output. Cell radius is then used to determine the number of sites. Assuming a hexagonal cell shape, number of sites can be calculated by using simple geometry. This procedure is explained capacities of eNBs are obtained from capacity evaluation, along with the number of subscribers supported by each cell. Interface dimensioning is the last step in LTE access network dimensioning, which is out of scope of this thesis work. The reason is that LTE interfaces (S1 and S2) were still undergoing standardization.

Population statistics Number of subscribes Dimensioning Outputs

Area to be covered by the network Subscriber geographical spread Cell throughput Final site-count

Figure (3-5): LTE dimensioning outputs 2.7 Comparison among dimensioning, planning and optimization. Dimensioning is the initial phase of network planning. It provides the first estimate of the network element count as well as the capacity of these elements. The purpose of dimensioning is t estimate the required number of the radio base stations needed to support a specified traffic load in an area. The radio network planning process is designed to maximize the networks coverage, whilst at the same time providing the desired

2-9

Chapter 2: LTE Network Dimensioning capacity. In order to achieve this, there are number of stages that are typically performed, these include: Initial Planning, Detailed Planning and Optimization. Optimization is probably the most important stage when planning an LTE network. Typically it can be split into pre-launch optimization. There are however a number of different areas that may be optimized, these include.

Figure (2-6) optimization stages of LTE

2.7.1 Planning of LTE The radio network planning process is designed to maximize the networks coverage, whilst at the same time providing the desired capacity. In order to achieve this, there are a number of stages that are typically performed, these include:  Nominal or preliminary planning  Detailed planning  Optimization

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Chapter 2: LTE Network Dimensioning

Figure (2.7) the cellular network planning processes 2.7.1.1 Nominal or preliminary cell planning A nominal or preliminary cell plan can be produced from the data compiled from coverage and traffic analysis. The nominal cell plains a graphical representation of the network and looks like a cell pattern on a map. During nominal cell planning, do not care about the position of the sites taking only in consideration the separation distance between sites. To simplify the network planning, hexagonal shaped cells are adopted although they are artificial or fictitious and do not exist in real world but it have become a widely promoted symbols for cellular structured system. Nominal cell plans are the first cell plans and forms the basis for further planning. In reality, each company has a planning tool which is a work station equipped with a software package based on link budget calculations and using certain propagation model to determine the cell radius and the results are displayed on the map using different colors. An up to date digital three dimensional map with high resolutions for the area where the network is to be planned is used to import the actual environment data that include the terrain fluctuations (height information), clutter distribution, dense degree of the area of interest. The area of interest is

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Chapter 2: LTE Network Dimensioning divided into different sub regions according to different environment definitions. Each sub region has its own characteristics. The classification is based on the dense of buildings and their heights in the sub region. Each sub region is classified into one of the four categories: dense urban (DU), urban (UR), suburban (SU) and rural (RU).The planning tool determines the classification of each sub region. It is possible to import data from site survey files. Data can also be imported from field measurements files to tune the propagation model as will be explained in the following subsections. The area where the network is to be planned to be covered with cellular structured system is used. Two study cases are investigated:  Coverage oriented environment and rural environments.

represent

suburban

 Capacity oriented environment represent dense urban and urban environments. Using the software program developed by us the maximum allowable path loss (MAPL) is calculated using reverse link budget and forward link budget and the link balance was made and the least value was taken as an input to the propagation model. Thus, the cell radius was calculated using coverage criterion. The classification of sub regions according to their building density and heights is determined by us during site survey by observing the area features, landmarks and terrain in each sub region. 2.7.2 Detailed planning 2.7.2.1 Site surveys Once the nominal cell planning has been completed, site surveys can be performed for all the proposed site locations by the site survey team. The site survey includes: site search, candidate sites are chosen, the site survey team check the validity of each location of the sites, contact with the site owner, site location lease agreement, get permission of the new sites, and carry out the construction of the civil works, tower erection, transmission and interconnection between the network entities. Finally site acquisition. The following items must be checked for each site: The space for the equipment including: antennas, cable runs and power facilities. The exact site locations (with some shifts)are fed back to the network planning team to modify the network planning by shifting the

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Chapter 2: LTE Network Dimensioning locations of the sites such that no dead zones were introduced and overlap between sites were reduced as much as possible. 2.7.2.2 Field measurements The purpose of the field measurements is to correct the propagation model to reflect the propagation status of wireless signal in the environment of the area of interest, thus making the model more practical meet the coverage requirement. To conduct field tests, the following steps have to be followed: You have to choose the frequency of the measurement. If there is interference on the frequency point to be used, choose a frequency point without interference. The transmission characteristics are almost the same when frequency difference is 10 MHz or so. Field measurements site choice: You have to choose the field measurements site. The field measurements site should not be too much higher than the surrounding buildings and 10 meters are suitable. To obtain as much data as possible for correcting various clutters, two or three field measurements sites with similar surrounding clutters (building heights, site height, and so on) can be chosen to carry out field measurements and data from several sites can be synthesized to execute the correction of the various clutters. Choose pertinent parameters of the field measurements site i.e. use omnidirectional antenna, choose proper transmission power, no obstruction surrounding the field measurements site, and clean the frequency point. The tools for field measurements includes: transmitter or CW transmitter, scanner or field strength meter and GPS handset. Before field measurements, you have to span antennas, install transmitter, and adjust output power and frequency point to proper values and transmitting signal. After field measurements, the field measurements data is put into a form acceptable for the planning tool load the field measurements file into the planning tool and correct the model. 2.7.2.3 System design (or final cell plan) The actual and the exact site locations are used to produce the final cell planning which is used for network installations, provided that no dead zones and overlap between sites is small as possible 2.5 System diagnosis The test team via the driving test and using test mobile system which is a testing tool. The testing tool includes mobile test units (MTUs) in cars and fixed test units geographically distributed. The testing tool consists of a MS with special software, a portable personal computer (PC) and a

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Chapter 2: LTE Network Dimensioning global positioning system (GPS) receiver and mobile traffic recording (MTR) and cell traffic recording (CTR). The MS is used in active and idle mode. The PC is used for presentation, control and measurement data storage. The GPS receiver provides the exact position of the measurement site by utilizing satellites. When the satellite signals are shadowed, the GPS system switches to dead reckoning. Dead reckoning consists of a speed sensor and a gyro. This provides the position if satellite signals are lost temporarily. The measurement data can be imported to the planning tool and can be displayed on a map to compare the measured handoffs with the predicted cell boundaries for example to check the network performance, to evaluate the customer complaints, to verify that the final cell planning was implemented successfully. 2.7.2.4 System tuning After installation of the network, it is continuously monitored to determine how well it meets the coverage and capacity requirement using the measured data, parameters are changed. Other measurements can be taken if necessary. The parameters to be changed are such as eNodeB transmitted power, eNodeB antenna height, antenna down tilting angle, antenna type (gain, horizontal HPBW, and so on). Change handoff parameters, change, add or decrease channels. 2.7.2.5 System growth Cell planning is an ongoing process. If the network needs to be expanded to extend coverage due to increase in traffic of because or change in the environment Starting with a new capacity or traffic and coverage or power analysis. 2.7.2.6 eNodeB site choice When choosing eNodeB site, the following rules should be obeyed: 1) Antenna height should be higher to some degree than the surroundings. 2) Ensure that there is no obvious obstruction in surrounding environments. 3) Ensure that there is no obstruction surrounding the position of setting the global positioning (GPS) antenna. 4) Meet coverage goal requirement concerning the effective coverage of the eNodeB. 5) Predict traffic distribution in the coverage area and set the eNodeB sites on the places of real traffic need.

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Chapter 2: LTE Network Dimensioning 6) Utilize existent sites such as telecom Egypt centrals in case of rural communication network and use other communication resources as possible such as towers, buildings. 7) Guarantee necessary space separation concerning the interference from other systems. 8) Avoid strong wireless transmitter, radar or other serious interference. 9) Choose places with convenient traffic, reliable electricity plant, if not available use generators or solar cell panels 10) Avoid being near the flammable or explosive buildings. 11) Avoid being near the industrial manufactories with poisonous gas or smoke and dust. 12) Avoid hospitals, educational buildings, military zones, church, mosques, and entertainment areas. 2.7.2.7 Antenna configuration and cell type choice The choice of eNodeB antenna should concern with the following factors: site type, dense degree of eNodeB and relative positions between them and dense degree of the area and so on. The following rules should be obeyed when choosing antennas: 1) In dense urban (DU) and urban (UR) areas i.e. in capacity oriented areas, sectorized cells or directional antennas with narrow power beam width (HPBW) angle can be chosen and large gain can be chosen to reduce the other cell interference and increase the capacity. 2) In suburban areas and rural areas with low capacity where user or population density is low i.e. In coverage oriented areas, Omni cells with omnidirectional antennas with high antenna height can be chosen. 3) In suburban areas and rural areas, when the capacity increases, directional antennas with wide half power beam width (HPBW) angle and large gain value can be chosen to increase coverage. 4) In highways, where there is no need to cover towns along the road, or at border area or at the coast, 2 sector configuration is the optimal solution with two directional antennas with narrower width and higher gain antennas. 5) Three sector cells is the optimum solution to meet both capacity and coverage in all morphologies. 6) Dual polarization is usually used in dense urban (DU) and urban (UR) areas and space diversity is usually used in suburban (SU) rural (RU) areas.

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Chapter 2: LTE Network Dimensioning 2.7.3 LTE optimization Optimization is probably the most important stage when planning LTE network. Typically it can be split into pre-launch optimization and post-launch optimization. There is however a number of different areas that may be optimized these including:    

Capacity Coverage Configuration and parameters Interference

Prelaunching optimization It is done when the sites are on air but not available to users. It is done via drive test to determine gaps and holes for coverage and to ensure optimal operation for the network and to verify coverage, capacity and quality requirements.

Figure (2-8) LTE optimization process

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Chapter Three Coverage Dimensioning

Chapter 3: Coverage Dimensioning

Chapter Three Coverage Dimensioning 3.1 Introduction The link budget calculations estimate the maximum allowed signal Attenuation, called path loss, between the mobile and the base station antenna. The maximum path loss allows the maximum cell range to be estimated with a suitable propagation model, such as Okumura–Hata. The cell range gives the number of base station sites required to cover the target geographical area. The link budget calculation can also be used to compare the relative coverage of the different systems . Network dimensioning requires determination the number or cells (number of sites) to cover a certain region and to determine the radius of each cell and the spacing between them either using traffic or coverage criteria. So, in this chapter we will discuss the coverage analysis using the link budget and certain propagation model. This chapter presents the outline and basic concepts required to dimension coverage in the Long Term Evolution (LTE) network with functions in the current release. The method presented in this document consists of concepts and mathematical calculations that are elements of a general dimensioning process. The detailed order and flow of calculations depends on the required output of and type of input for the specific dimensioning task. The method provides a specific dimensioning process example. By changing the prescribed inputs and outputs and the order of calculations, the dimensioning process can be adapted to other methods.

3-2

Chapter 3: Coverage Dimensioning

Input requirements for the capacity and coverage dimensioning process consist of a bit rate at the cell edge, one for downlink and one for uplink. The required output is site-to-site distance and cell capacity in the uplink and downlink. The method is developed for Frequency Division Duplex (FDD), but can also be used for Time Division Duplex (TDD) .  Limitations Limitations to the calculation method include the following:  Multiple Inputs Multiple Outputs (MIMO) is considered only for the downlink for a maximum of two antennas  Outer loop power control in the uplink is not modelled  The method is adapted and developed primarily as a mobile broadband service that can handle Voice over IP (VoIP) to a limited extent  Quality of Service (QoS) is not handled by the method  Assumptions Calculations for coverage and capacity are based on the following assumptions:  All user equipment is assumed to have two receiving antennas  All resource blocks are transmitted at the same power, including user data, as well as control channels and control signals  The coverage for control channels and control signals equals that of user data at the same power.  Layer 1 overhead for all control channels and control signals is included in the Signal-to-Interference-and-Noise Ratio (SINR) to bit rate relationships. 3-3

Chapter 3: Coverage Dimensioning

Figure (3-1) LTE Dimensioning Process 3.2 Concepts and Terminology The following terms are used in describing capacity and coverage dimensioning: Average user bit rate The bit rate achievable by a single user. When all resources in a cell are used, the average user bit rate can be the average throughput in one cell. It is a measure of average potential in a cell while all interfering cells are loaded to the dimensioned level. Cell edge The geographical location where the path loss between eNodeB and the antenna is at a specific maximum threshold value, as calculated using the quality requirement imposed on the network, guaranteeing the required quality with a probability of 95%, for example. Cell throughput Cell throughput is obtained in one cell when all cells are loaded to the dimensioned level, and the resource use is equal to system load, 3-4

Chapter 3: Coverage Dimensioning

interfering cells as well as interfered cells. It is the average throughput per cell as calculated across the entire network. Coverage (area) The percentage of cell area that can be served according to a defined quality requirement. With an assumed uniform subscriber density (often assumed in a dimensioning exercise), the percentage of served area equals the percentage of served users. Resource block It is the smallest unit in the physical layer and occupies one OFDM or SC-FDMA symbol in the time domain and one subcarrier in the frequency domain. A two-dimensional unit in the time-frequency plane, Consisting of a group of 12 carriers, each with 15 kHz bandwidth, and one slot of 0.5 ms. System load The extent of available air interface resource usage. The system load equals the ratio of used resource blocks as an average over the entire system. 3.3 link Budget Definition Illustrative example: you are planning a vacation .You estimate that you will need 1000 L.E to pay for the hotels, restaurant, food etc.. You start your vacation and watch the money get spent at each stop. When you get home, you pat yourself on the back for a job well done because you still have 50 L.E left in your wallet. We do something similar with communication links, called creating "a link budget" The traveller is the signal and instead of money it starts out with ”power". 3-5

Chapter 3: Coverage Dimensioning

It spends its power (or attenuates, in engineering terminology) as it travels wired or wireless. So you can use a credit card along the way for extra money infusion, the signal can get "margin" extra power infusion along the way from intermediate amplifiers such as microwave repeaters foe telephone links or from satellite transponders for satellite links. The designer hopes that the signal will complete its trip with just enough power to be decoded at the receiver with the desired signal quality. In our example, we started our trip with 1000 LE because we wanted a budget vacation. But what if our goal was a first-class vacation with stays at five stars hotels, best shows and travel by A1000LE budget would not be enough and possibly we will need instead $5000. The quality of the trip desired determines how much money we need to take along. Link budget means to catalog all losses and gains between the two ends of communication i.e. mobile station (MS) and eNodeB to yield the maximum allowable (or available or acceptable) loss in signal strength that can be tolerated between the transmitter and receiver. Link budget traces power expenditures along path from transmitter to receiver to identify or determine the maximum allowable path loss and to determine the maximum feasible cell radius using propagation model. Link budget is defined sometimes as the difference between transmitter effective isotropic radiated power (EIRP) and the minimum signal strength at the receiver i.e. the receiver sensitivity for acceptable quality .Link budget is specified in logarithmic units (decibels) .Link budget output is fed to propagation model to provide the greatest spatial 3-6

Chapter 3: Coverage Dimensioning

distance

between

transmitter

and

receiver

at

which

reliable

communication of the desired quality can still take place. 3.4 Why we use Link Budget? link budget is necessary to determine or calculate the maximum allowable or available, or accepted path loss (MAPL) where communication is achieved reliably or that will provides adequate signal strength at the cell boundary for acceptable voice quality over 90% of the coverage area if it is flat or 75% if it is hilly .Link budget is necessary to determine the radius of the cells, and finally to determine the locations of cell sites as well as the spacing between them to ensure reliable and uninterrupted communication as mobile stations (MSs) move through the coverage area of interest. 3.5 What are the types of link budget? Since communication in mobile cellular phone system between mobile stations (MSs) and eNodeB is bidirectional. Thus it depends on the quality of the both reverse link and forward link. There are two link budgets:  Reverse link budget (up link budget) i.e. as signal is transmitted from mobile station (MS) and received by eNodeB.  Forward link budget (down link budget) i.e. as signal is transmitted from eNodeB and received by mobile station (MS). The reverse link budget has to be considered in system design first then forward link budget and finally link balance will be made. But since coverage is usually reverse link limited, we will focus on reverse link budget (up link budget).

3-7

Chapter 3: Coverage Dimensioning

3.6 Up link Budget (uplink coverage) Most mobile telephony systems are frequently limited by the uplink, so it is useful to start link budget calculations with the uplink coverage requirements. The calculations are performed according to the following stages:  User equipment (UE) effective isotropic radiated or transmitted power per physical resource block (PRB)  The uplink required bit rate per physical resource Block (PRB) (Rrequired, PRB)  The uplink required SINR (  ) given the uplink required bit rate physical resource Block (PRB) (Rrequired, PRB).  ENodeB receiver sensitivity (SeNodeB)  Uplink noise rise or interference margin (IM) (BIUL)  Log normal fading margin (BLNF)  Uplink link budget maximum allowable path loss (MAPLUL) 3.7 Up Link Budget Entries: The following set of definitions is to be read in conjunction with the appended reverse link budget (uplink budget) spread sheet. 3.7.1 Maximum mobile station (MS) transmitted power per traffic channel: It is the power coming out of the radio / amplifier and into the antenna power; the power value is 23 dBm at cellular frequencies .These values are taken from minimum performance standards for a 200 milliwatt mobile station.

3-8

Chapter 3: Coverage Dimensioning

3.7.2 Mobile station (MS) transmitter antenna gain (dBi) : An antenna is a device used to transmit or receive radio frequency (RF). The radio produces an RF signal and the antenna is the transport medium used to direct that signal onto free space for its eventual reception by another antenna attached to a receiver. One of the most important aspects of an antenna is the antenna gain. Mobile station (MS) antenna gain is the measure of strength of the amplification effect of MS antenna directed signal with respect to signal loss. It is the output transmitted power from the mobile station, in a particular direction, compared to that produced in any direction by a perfect reference antenna (isotropic antenna or dipole antenna). An antenna can create an amplification effect depending on its construction. The amplification effect is the result of focusing the transmission signal into a tight beam. Antenna gain works by the same principle. Signal loss simply describes a decrease in signal strength. Gain and loss are very important to antenna and radio performance because they directly affect signal quality and the signal transmission and reception capabilities. Antenna gain has a direct effect on the total power radiated from an antenna. The value of the power transmitted into an antenna will not leave the antenna at the same value. It will be increased by the amount of gain of the antenna. Antenna gain can be expressed in dBi, decibels relative to an idea isotropic radiator or dBd, decibels relative to an idea dipole effective area. A half –wave dipole antenna has an isotropic gain of 2.15 dBi. This means that the dipole, in the direction of maximum radiation, is 2.15dB more intense than that of an isotropic radiator, based on the same input power. 3-9

Chapter 3: Coverage Dimensioning

The value taken for MS antenna gain ranges between 0 dB this is the gain of the mobile station (MS) antenna. At both cellular and personal communication system (PCS) frequencies, this is a dipole whose gain can be taken to be 2.2 dBi. Mobile station (MS) antenna gain is defined either absolute gain or relative gain.  The absolute gain: it is the ratio of maximum radiation intensity in (watts) per unit solid angle to the total input power over 4 .  The relative power antenna gain It is the power gain of the antenna concerned in certain direction to the power gain of a reference antenna assuming the input power is the same for each antenna. The reference antenna may be isotropic antenna or dipole antenna. The isotropic antenna radiates equally in all directions in all planes like point of source. It is fictions or hypothetical antenna and is used as a reference. 3.7.3 Head /Body Losses (dB) Head /body loss refers to the attenuation of the radio signal during both transmission and reception as the mobile station antenna is held to the ear of the mobile station (MS). At personal communication system (PCS) and cellular frequencies, this attenuation is mainly due to the head of the user while at lower frequencies (large wave lengths) the entire human body could distort the radiation pattern of the mobile station antenna. Head/body losses are the amount of power that is absorbed through the head and body of the human being from MS. Typically head /body loss values range from 2 to 5 dB (3dB).Values to be used in the link budget are typically provided by the wireless network operator based on field measurements or prior experience. It is 3 - 10

Chapter 3: Coverage Dimensioning

important to obtain these values from the operator since any design loss raises design cell count.  It worth to mention that in fixed wireless local loop (FWLL), the head /body loss is zero while in mobile cellular mobile has a value. 3.7.4 Physical resource block: A resource element is the smallest unit in the physical layer and occupies one OFDM or OFDMA symbol in the time domain and one subcarrier in the frequency domain. A transmitted OFDMA signal can be carried by a number of parallel subcarriers. Each LTE subcarrier is 15 kHz. Twelve subcarriers (180 kHz) are grouped into a resource block. Depending on the carrier bandwidth, LTE supports a varying number of resource blocks. The downlink has an unused central subcarrier. The following illustration shows resource block definition:

Figure (3-2) Resource Block Definition in Frequency Domain. A resource block is limited in both the frequency and time domains . One resource block is 12 subcarriers during one slot (0.5 ms).

3 - 11

Chapter 3: Coverage Dimensioning

In the downlink, the time-frequency plane of OFDMA structure is used to its full potential. The scheduler can allocate resource blocks anywhere, even non-contiguously. A variant used in the uplink requires the scheduled bandwidth to be contiguous and a single carrier. The method, called SC-FDMA, can be considered a separate multiple access method. A user is scheduled every Transmit Time Interval (TTI) of 1 ms, indicating a minimum of two consecutive resource blocks in time at every scheduling instance. The minimum scheduling in the frequency dimension is the width of one resource block. The scheduler is free to schedule users both in the frequency and time domain. The illustration in shows user scheduling in the time and frequency domain for downlink and uplink:

Figure (3-3) Downlink and Uplink User Scheduling in Time and Frequency Domain.

3 - 12

Chapter 3: Coverage Dimensioning

The bit rate requirement should be based on the service for which the system is dimensioned, and as a compromise between conflicting needs and trends, with the following considerations: ' With a small nPRB the required bit rate can be satisfied with a minimum

of resources. This leaves a maximum amount of space in the timefrequency resource plane for other users to maximize capacity. ' At a large nPRB , the transmitted blocks are spread over a frequency

interval, with less power used per physical resource block. A lower modulation scheme and/or a higher coding rate can be selected. The receiver is capable of decoding the transmissions at lower SINR, to give a higher path loss leading to an increased cell range. Additionally, the user ' equipment can reduce maximum output power when using large nPRB

according to the 3GPP document user equipment (UE) radio transmission and reception. The back-off allowed is not assumed to be used at cell edge. The impact from noise rise on the resulting coverage range when ' varying nPRB in the dimensioning plays a comparatively minor role, unless

the noise rise is very high. All physical resource blocks must be consecutive in the uplink. ' Large nPRB may be less probable if the scheduler operates efficiently.

Using a few different values of for calculating the link budget can be helpful. 3.7.5 User equipment effective isotropic radiated power (EIRP) per physical resource Block (PRB) All allocated resource blocks share the total user equipment output power. 3 - 13

Chapter 3: Coverage Dimensioning

Assuming that all resource blocks are allocated an equal amount of power, the power per physical resource block (PRB )is calculated in the following way:

Equation (3-1) represents power of user equipment per physical resource block

Equation (3-2) represents Effective Isotropic Radiated Power of user equipment Where: GUE is the user equipment transmitting antenna gain [dBi] LHBL is the head body loss [dB ] Gother is the gain due to using MIMO. LHBL is head/ body loss [dB] EIRP means effective or equivalent isotropic radiated power. This refers to the effective isotropically radiated power from the mobile station (MS) at the antenna connector or it is the power radiated within a given geographical. It is the effective input power to hypothetically isotropic antenna that achieves the maximum radiated intensity in any direction. It is a function of the MS transmitted power and the MS transmitter antenna gain and head/body losses. 3.7.6 eNodeB receiver thermal noise density No This simply refers to the thermal noise floor at absolute temperature. No is eNodeB thermal noise density and given by: No = 10log KT 3 - 14

Chapter 3: Coverage Dimensioning

Where: K is Boltzman constant = 1.3806488 × 10-23 Watt/Hertz/Kelvin or joule /Kelvin (J/K) T is temperature in kelvin degree =290 degree Kelvin or degree Celsius (K) =273+17 degree centigrade No =10 log (1.3806488 × 10-23 *290) / 1 mW = -174 dBm/Hz Equation (3-3) represents eNodeB receiver thermal noise density 3.7.7 eNodeB receiver noise figure (NF) (dB) The eNodeB receiver noise figure (NF) is a measure of the signal to noise ratio (SNR) degradation when signal enters receiver till SNR i reach the input of demodulator by the eNodeB front end RF amplifier and filter Noise figure is given by: NF=10 log (SNRi / SNRo) Equation (3-4) eNodeB receiver noise figure. Where: SNR: It is the input signal to noise ratio. SNRo is the output signal to noise ratio. 3.7.8 The uplink required bit rate per physical resource Block (PRB) (Rbrequired, PRB,UL) Dimensioning starts by defining the quality requirement. Quality is expressed as a certain bit rate that can be provided to one individual user at the cell edge with a certain probability. The required bit rate follows the service for which the system is dimensioned. All calculations are performed per physical resource block. Table (3-1) shows how to obtain the required bit rate per physical resource block; the ' required bit rate is divided by the number of physical resource blocks nPRB

3 - 15

Chapter 3: Coverage Dimensioning

that can be allocated to obtain that bit rate. The required bit rate per resource block is given by:

Equation (3-5) represents the required bit rate per physical resource block Where: : Required bit rate : Physical resource block ' In a real system, nPRB is selected by the scheduler on a 1 ms Time

Transmission Interval (TTI) level. In a dimensioning exercise, the ' number nPRB can be selected freely, guided by experience and

understanding of the system within the constraints of total deployed bandwidth, as shown in table (3-1).

Table (3-1) bandwidths and number of physical resource blocks (PRB) specified in 3GPP 3.7.9 The uplink required SINR (  ) given the uplink required bit rate Rrequired, PRB

3 - 16

Chapter 3: Coverage Dimensioning

Similar to High Speed Packet Access (HSPA) in WCDMA, LTE includes a variety of different transport formats with different modulation and coding schemes. Each format has a specified bit rate. The SINR requirement for decoding a particular transport format has been determined by a large set of simulations. The simulation results in a set of tables for different channel models and for different antenna arrangements. As an approximation, the simulation results have been fitted to a semi-empirical parameterized expression. The expression for the dependency between Rrequired,PRB and the SINR  is expressed along with the semi-empirical constants a0, a1, a2 and a3. Using the required bit rate Rrequired,PRB , a SINR  is obtained that represents the requirement on signal quality. For the transport formats in LTE, given the required bit rate per resource block, RPRB, the signal-to-interference-and-noise ratio (SINR), γ, is determined by a set of link simulations. The uplink cases simulated include the following:  Antenna techniques: 2-branch RX diversity  Modulation schemes: QPSK, 16-QAM  Channel models and Doppler frequency EPA 5 Hz, EVA 70 Hz, ETU 300Hz 

Performance analysis of multipath propagation channels: The multipath propagation condition consists of several parts:  A delay profile in the form of a ―tapped delay-line‖, characterized by a number of tapes at fixed positions on a sampling grid. The profile can be further characterized by the r.m.s delay spread and the maximum delay spanned by the taps. 3 - 17

Chapter 3: Coverage Dimensioning

 A combination of channel model parameters that include the Delay profile and Doppler spectrum that characterized by a classical spectrum shape and a maximum Doppler frequency. Both delay profiles and Doppler spectrum for various E-UTRA channel models were considered. The delay profiles are selected to be representative of low, medium and high delay spread environments. The resulting model parameters. Here the Excess tap delay and Relative power were analysed and the mobile radio channels such as Extended Pedestrian A, Extended Vehicular A, Extended typical urban Model and HSTC model performance were compared using the Table (3-2). Model

No. of channels taps

Max. Delay

7

410 ns

Extended Vehicular A(EVA)

9

2510ns

Extended typical urban(ETU)

9

5000ns

Extended Pedestrian A (EPA)

Table (3-2) Channel models specifications EPA Excess tab delay(ns)

EVA Relative power

Excess tab

Relative power (dB)

(dB)

delay(ns)

0

0

0

0

30

-1

-30

-1.5

70

-2

150

-1.4

90

-3

310

-3.6

110

-8

370

-0.6

190

-17.2

710

-9.1

410

-20.8

1090

-7

Table (3-3) Channel model specifications

3 - 18

Chapter 3: Coverage Dimensioning

Extended urban and HSTC model ETU

HSTC model

Excess tap delay (ns)

Excess tap delay (ns)

Excess tap delay (ns)

Excess tap delay (ns)

0

-1

0

-1

50

-1

900

-21

120

-1

1900

-35

200

0

2200

-39

230

0

2700

-39.1

500

0

6100

-43

1600

-3

7100

-21.2

2300

-5

10100

-35

5000

-7

-

-

Table (3-4) channel propagation conditions Table (3-4) shows channel propagation conditions that are used for the performance measurements in multi-path fading environment for low, medium and high Doppler frequencies. In this paper, the combination of channel models that include the Delay profile and the Doppler spectrum are considered for the simulation [5]. Model

Maximum Doppler frequency

EPA

5 Hz

EVA

70 Hz

ETU

300 Hz

HSTC

1340 Hz

Table (3-5) Maximum Doppler frequency channel model Table (4&5) shows multi-path delay profiles that are used for the performance measurements in multi-path fading environment. The Excess tap delay functions can be expressed in terms of Doppler spectrum as mentioned below. S (f) ∝1/((1-(f/fd)2)0.5

Equation (3-6) represents Doppler spectrum 3 - 19

Chapter 3: Coverage Dimensioning

Where: S (f): Doppler spectrum, f: Frequency, fd: It is the Doppler frequency which proportional inversely with Doppler spectrum. 1- Extended Pedestrian A (EPA)

Extended Pedestrian A. A propagation channel model based on the International Telecommunication Union (ITU) Pedestrian A model, extended to a wider bandwidth of 20 MHz. The pedestrian channel model represents a UE speed of 3 km/h. It described by Tau: is a vector of path delays, each specified in nano seconds. Tau: [0 30 70 90 110 190 410]/109 PDB (Power Delayed Bus): is a vector of relative path powers, in dB PDB = [0 -1 -2 -3 -8 -17.2 -20.8] 2- Extended Vehicular A (EVA) • Extended Vehicular A. A propagation channel model based on the International Telecommunication Union (ITU) Vehicular A model, extended to a wider bandwidth of 20 MHz. • The vehicular channel model represents UE speeds of 30, 120 km/h and higher. Tau= [0 30 150 310 370 710 1090 1730 2510]/ (109). PDB= [0 -1.5 -1.4 -3.6 -0.6 -9.1 -7 -12 -16.9]. 3-Extended Terrestrial Urban (ETU) A propagation channel model based on the GSM Typical Urban model, extended to a wider bandwidth of 20 MHz It models a scattering environment which is considered to be typical in a urban area. 3 - 20

Chapter 3: Coverage Dimensioning

Tau=

[0

50

120

200

230

500

1600

2300

5000]/(10^9)

PDB=[-1 -1 -1 0 0 0 -3 -5 -7] 3.7.10 the required signal-to-interference-and-noise ratio SINR  t arget given the required bit rate RPRB The results, including an implementation margin, have been fitted to a semi-empirical parameterized expression for the required signal-tointerference-and-noise ratio SINR  t arget given the required bit rate RPRB is written as follows:

Equation (3-7) represents the required signal-to-interference-and-noise ratio SINR. The semi-empirical parameters for uplink a0, a1,a2 and a3 are given in tables (3.6)

Table (3- 6) semi-empirical parameters for uplink 3.7.11 eNodeB receiver sensitivity (SeNodeB) eNodeB receiver sensitivity SeNodeB is the required signal power at the system reference point when there is no interference contribution from other user equipments. The following relation describes eNodeB receiver sensitivity per physical resource block (PRB): 3 - 21

Chapter 3: Coverage Dimensioning

Equation (3-8) represents eNodeB receiver sensitivity Where Nt is the thermal noise power density and is equal -174 dBm/Hz NfeNodeB is the noise figure of the eNodeB receiver [dB] WPRB is the bandwidth per physical resource block (PRB): 180 kHz  t arg et,UL is SINR requirement for the uplink traffic channel [dB] N PRB,UL is the thermal noise per physical resource block in uplink is

given by:

Equation (3-9) represents the thermal noise per physical resource block in uplink The eNodeB receiver can be assumed to have a noise figure of 2 dB with tower mounted amplifier (TMA) and 3 dB without. 3.7.12 Up link noise rise or interference margin (IM) BIUL : In LTE a user does not interfere with other users in the cell since they are separated in the frequency/time domain. The noise rise in the uplink depends only on interference from adjacent cells. In the link budget, an interference margin compensates for noise rise. The standard case of closed loop power control is shown as a linear ratio. The uplink interference margin is given by:

Equation (3-10) represents Up link noise rise or interference margin. Where: 3 - 22

Chapter 3: Coverage Dimensioning

 t arg et UL is the SINR target for the uplink open loop power control.

QUL is average uplink system load.

CLF is defined as the ratio of actual capacity to pole point capacity. Pole point capacity is defined as the capacity when all user equipment raise their power to infinity this is a hypothetical situation which is taken as a reference. F is the average ratio of path gains for interfering cells to those of the serving cell. F is defined and investigated thoroughly for WCDMA radio network dimensioning. Table (3.7) gives values for F at varying electric tilt with 30 meter antenna height and 3-sector sites. The values are based on system simulations.

Table (3.7) examples of F for varying tilt 3.7.13 Log normal fading margin: Fading is defined as the random variation (change or fluctuation) of the received signal. There are different types of fading: large scale or slow fading and small scale or fast fading. Fading is described using probability density functions: large scale or slow fading is log normal distributed while small scale or fast fading which is Rayleigh or Rican distributed. Rayleigh distribution describes 3 - 23

Chapter 3: Coverage Dimensioning

the received signal is due to only reflection and there is no line of sight (LOS). Log normal distribution describes signal changes due to abstraction in the path between eNodeB and mobile station (MS). Fading margin is an extra margin is included in the link budget. The lognormal fade margin is calculated based on the coverage objective, which is typically specified as a target coverage probability at cell edge. Typical numbers are 90% and 75% edge coverage probability. Achieving 90% edge coverage implies that at 90% of the locations at edge, a cell can be initiated and kept up. Using path loss models, one can relate area coverage probability to edge coverage probability and hence to fade margin requirement. 95% area coverage probability is mapped to 75% edge coverage. These values presume a completely noise limited receiver. The lognormal (or slow fading) margin models the required area coverage probability. By adding this margin, a probability is secured for setting up and maintaining a connection at a given quality. Table (3.8) shows fading margins in dB for varying standard deviation σ of the lognormal fading process and different coverage probabilities:

Table (3.8) log normal fading margins for varying standard deviation of lognormal Fading 3 - 24

Chapter 3: Coverage Dimensioning

Equation (3-11) represents Log normal fading margin Where: 

is the mean of log normal.



is the standard deviation of log normal.

P% is the coverage probability The standard components are given for link analysis in the radio interface. The standard margins for indoor, car penetration loss, body loss, feeder loss, jumper loss, and antenna gain are the same as any mobile network. A fading margin is required to guarantee a certain coverage probability. MAPLUL represents the maximum allowable path loss in uplink link budget, fed into the downlink link budget. 3.7.14 eNodeB receiver cable feeder, jumper and connector losses Feeder cable loss Feeder cable loss is the loss of electrical energy due to the inherent characteristics of the feeder cable. The eNodeB receiver feeder cable is dependent on the feeder type and length of feeder run. The receiver cable and connector losses are nominally taken in the range of 2 dB to 4 dB. When the cable length and diameter (and hence attenuation/feet) are known, the actual cable losses may be substituted in the link budget along with additional margin of 0.5 dB for connector (and duplexer) losses. Radio equipment should be placed as close as possible to the antennas in order to reduce the feeder cable loss. Typically feeder cable diameters used are 7/8" and 15/8" and corresponding attenuations are 6.15 dB/100 meters and 3.84 dB/meters. Jumper loss "Lj" 3 - 25

Chapter 3: Coverage Dimensioning

Jumper loss is the loss of electrical energy due to the connection of the tower top amplifier with the antenna using jumpers. A typical value of the jumper is 11.2 dB/100m.When the used jumper type and length is known, the total jumper loss can be calculated. Connector loss "Lc" It is the loss of electrical energy because of connectors that make the antennas tied with the top of the tower. A typical value of the connector loss is 1 dB. 3.7.15 Building / vehicle penetration loss: This refers to the attenuation of the signal as it passes through one or more walls of the building in the desired coverage area. When a mobile station (MS) is used inside the building and the eNodeB is situated outside, there is a loss when the signal penetrates the building. It is defined as the difference between the average signal strength outside the buildings and the average signal strength over the ground floor of the building. The value of penetration loss must be included when designing link budget. Table (3.9) shows the value of penetration loss on different morphology classes In building dense

In building

urban

suburban

20

18

In building rural

In car

12

9

Table (3-9) values of penetration loss on different morphology classes When the MS is situated in a car without external antenna, an extra margin has to be added to cope with the penetration loss of the car. This extra margin is typically 9 dB.

3 - 26

Chapter 3: Coverage Dimensioning

3.7.16 eNodeB receiver antenna gain (dBi) This refers to the gain of the receiving antenna at eNobeB .While the actual antennas used in the network may vary from site to site, a nominal, representative value is provided in the link budget based on the frequency of operation and sectorization. The nominal antenna gain values for personal communication systems (PCS) and cellular frequencies differ based on the cell Omni or sectorized .The gain units are dBi or gain with respect to an isotropic radiator. The value of antenna gain also can be varied depending to the manufacturer. Typically a value of eNondeB receiver antenna gain is typically 12 dBi for omni cell and 18 dBi for sectorized cell 3.7.17 Uplink link budget maximum allowable path loss (MAPLUL) Finally, the uplink link budget maximum allowable path loss (MAPLUL) Can be calculated as follows:

Equation (3-12) represents Uplink link budget maximum allowable path loss. Where: (MAPLUL) is the maximum allowable path loss due to propagation in the air [dB] BLNF

is the log-normal fading margin [dB]

BIUL

is the uplink interference margin [dB]

LCPL

is the car penetration loss [dB]

LBPL

is the building penetration loss [dB]

GeNodeB is the eNodeB receiver antenna gain [dBi] Gother

is the other gain [dBi]

Lf

is eNode B feeder loss [ dB ] 3 - 27

Chapter 3: Coverage Dimensioning

Lj

is the Jumper loss [dB]

LC

is connector loss [ dB ]

3.8 Morphologies classifications Dense urban (DU): Central business districts with skyscrapers or with buildings with having 10 to 20 stories and above, the building separation (S) less than 10 meters. Clutter height higher than 30 meters. Urban (UR): Residential , office area, hotels, hospitals etc with buildings having 5 to 10 stories and street width less than 5 meters and building separation (S) less than 10 meters. Clutter height higher from 15 to 30 meters. Suburban(SU): Mix of residential and business communications with 2 to 5 stories shops and offices. The building separation is (S) less than 20 meters. Villages or high ways scattered with trees and houses, some obstacles near the MS but not very congested. Rural area: Parks or fields with small trees with height less than 12 meters and 20% house density of residential area of

2 stories with wide roads, The

building separation is (S) less than 20 meters. Clutter height higher than 3o meters. Open areas: Clutter height higher than 3 meters open areas, parks, fields, paved areas. Morphology

Clutter height

class

(meters)

Dense urban

H>30

Building separation

Morphology definition

(meters) S