LTE DIMENSIONING

LTE DIMENSIONING Ericsson

Context • Reasons behind the 3GPP Long Term Evolution (LTE) strategy for UMTS. • Perform calculations on the radio interface capacity • Explain how the LTE downlink and uplink data rates are achieved and calculated. • List the LTE UE category capabilities. • Explain radio wave propagation and typical channel models

• Describe the different types of traffic carried by LTE networks. • Protocols that support the various LTE traffic types. • Operation of TCP, UDP, HTTP and FTP Internet Protocols. • Explain the issues surrounding Voice over LTE.

Context Cont.. • • • •

Perform Tracking Area planning Perform Paging Capacity calculations Tools are used in radio network dimensioning Apply subscriber and traffic growth scenarios and perform dimensioning exercise • Recommend sites for LTE deployment to meet coverage and capacity requirements set by the customer • List the Ericsson products in the RBS 6000 family. – Explain the hardware structure and capabilities of the RBS 6101, 6102, 6201, 6202, and 6601.

> Delta GSM, wcdma/ hspa & lte

2G/3G/LTE topology delta • RBS (eNodeB) in the RAN

RBS BSC RNC

• No CS core network – IP based

• Upgrades/New nodes

SGSN-MME

– SGSN  MME – GGSN  P/S-GW

– HLR functionality HSS

Converged Packet GW (P/S-GW & GGSN)

HSS

Basic Principles of EUL & HSDPA UL Interference

• EUL

Shared Uu load time

• HSDPA

SF=1 SF=2 SF=4

Channelization codes allocated

SF=8 SF=16 2 ms Shared channelization codes time User #1

User #2

User #3

LTE Radio Interface (Downlink) User #1 scheduled

User #2 scheduled

User #3 scheduled 180 kHz

frequency

LTE Advantages Faster scheduling

Simplicity IP transport SON

Shorter TTI, 1ms

Flexible bandwidth

Multi-Antennas TX

RX 1.4

3

5

FDD and TDD FDD-only

Half-duplex FDD

fDL

fDL

fUL

fUL

TDD-only fDL/UL

10

15

20 MHz

LTE & HSPA Limitations • Modulation technique: 64QAM

• Reduced Latency • 100 MHz bandwidth

100 MHz

...

...

TX

...

• MIMO

RX

Delta GSM, WCDMA/HSPA & LTE • Time & Frequency • Flexibility – Scheduler – Bandwidth

• MIMO • Higher throughput • All IP

frequency

ROADMAP

HOW THE LTE DOWNLINK AND UPLINK DATA RATES ARE ACHIEVED AND CALCULATED.

LTE DL peak rate 20 MHz and 4x4 MIMO AND 64 QAM 14 OFDM symbols per 1.0 ms subframe 64QAM = 6 bits per symbol 6 x 14 = 84 bits per 1.0 ms subframe 84bits/1.0ms = 84kbps per subcarrier 12 x 84kbps = 1.008Mbps per Scheduling Block 100 Scheduling Blocks in 20MHz 100 x 1.008Mbps = 100.8Mbps per antenna

4 x 4 MIMO: 403.2Mbps ! BUT in reality approx. 300Mbps

…and UL no MIMO 75Mbps

LTE 3GPP Rel. 10 Higher Peak Rates 20 MHz

• Carrier aggregation 100 MHz total bandwidth 20 MHz

• Spectrum aggregation

20 MHz

40 MHz total bandwidth

8

• DL/UL Multi-Antenna transmission

Peak rates: 3Gbps/1.5Gbps !

4

Throughput • Key factors impact the DL peak throughput – – – – – – –

How to calculate the DL theory peak throughput Example for LTE TDD DL throughput TM2/3/7/8 Example for LTE FDD DL throughput TM2/3 Key factors impact the UL peak throughput How to calculate the UL theory peak throughput Example for LTE TDD UL throughput Example for LTE FDD UL throughput

DL Key factor › Bandwidth › Uplink-Downlink configuration (TDD only) › Special sub-frame configuration (TDD only) › CFI format › UE category › Transmission mode

Bandwidth • LTE support bandwidth: – 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz,20MHz

TDD frame structure

Uplink-Downlink configuration

Special sub-frame configuration • For the special subframe configurations 0 and 5 with normal downlink CP or configurations 0 and 4 with extended downlink CP, there shall be no PDSCH transmission in DwPTS of the special subframe.

CFI

UE category

UE category cont.

Transmission mode

TDD

TDD THROUGHPUT CALCULATION

Peak dl throughput calculation flow

Peak dl throughput calculation step › Step1: Determine PRB number of DL SF – Get the RB number from bandwidth; – Get the DL sub-frame number from Uplink-Downlink configuration;

› Step2: Determine total RE of each DL SF (RE) – SF total RE = PRB * sub carrier per PRB * OFDM symbol per SF – Get the available OFDM symbol of special sub-frame from Special subframe configuration;

› Step3: Deduct common channel/signal overhead – Get the PDCCH overhead from CFI configuration. – Reduce the overhead of common channel/signal: CRS, UERS,PDCCH, PBCH, PSS, SSS. Get the available RE number of each sub-frame.

Peak dl throughput calculation step (CONT) › Step4: Determine the physical bits number – Physical bits = RE number * modulation order

› Step5: Determine TB size – Step 5-1 Use PRB number and MCS index to determine the TB size from ITBS table. (use max MCS index as the initial value) – Step 5-2 If the TB size exceed the UE capacity or channel code rate > 0.93, lower the MCS index, repeat step 5-1 until the TB size fulfill the criteria. • •

The effective channel code rate is defined as the number of downlink information bits (including CRC bits) divided by the number of physical channel bits on PDSCH.(CRC bit = [TB size/6144]*24) The UE may skip decoding a transport block in an initial transmission if the effective channel code rate is higher than 0.930.

› Step6: Peak throughput – Sum all DL sub-frame TB size within one radio frame(10ms), multiply by 100, then we got the peak throughput (bps).

Example (TM2) Precondition

• Assumption: – Bandwidth: 20M - 100 PRB for normal DL subframe

– Uplink-Downlink configuration: 1 (DSUUD DSUUD) - 4 normal DL subframe and 2 special subframe

– Special sub-frame configuration: 7 (10:2:2) - 10 OFDM symbol in each special subframe

– CFI format 1 – UE category 3 – Transmission mode: 2 – Normal CP

Example (TM2) STEP1 Determine prb number of each DL subframe • if the transport block is transmitted in DwPTS of the special subframe in frame structure type 2, then set the – Nprb = Max { N’prb x 0.75, 1}

Example (TM2) STEP2 Determine Total RE number of each subframe • Normal DL subframe: – 14 * 1200 = 16800

• Special subframe: – 10 * 1200 = 12000

Example (TM2) STEP3-1 Determine the overhead OFDM symbol (CRS)

Example (TM2) STEP3-2 Determine the overhead RE (PBCH) • PBCH location: – Time domain: sf0, slot1, first 4 OFDM symbol – Freq. domain: the central 72 subcarrier

• In PBCH RE, there will be CRS punching. – The PBCH resource mapping operation shall assume cell specific reference signals for antenna ports 0-3 being present irrespective of the actual configuration.

Example (TM2) STEP3-2 Determine the overhead RE (PBCH) 4-antenna port CRS RE mapping

Example (TM2) STEP3-2 Determine the overhead RE (PBCH)

• PBCH RE number: – 72 * 4 – 48 = 240

• The 48 CRS RE, in 2-antenna port scenario, 24 really used for CRS transmission while other 24 reserved. – In SF0, the RE occupied by CRS is 1600 + 24(reserved) = 1624

Example (TM2) STEP3-3 Determine the overhead RE (control region) • CFI = 1 mean allocate 1 OFDM symbol to PDCCH, (PHICH and PCFICH also in located in this control region).

• CRS also punching in control region, so the control region overhead need deduct those RE: • 1*1200 – 400 = 800

Example (TM2) STEP3-4 Determine the overhead RE (PSS & SSS) • PSS location: – Time domain: sf1 and sf6, the 3rd OFDM symbol – Freq. domain: the central 72 subcarrier

• PSS overhead OFDM symbol: – 72 * 1 = 72

• SSS location: – Time domain: sf0 and sf5, the last OFDM symbol – Freq. domain: the central 72 subcarrier

• SSS overhead OFDM symbol: – 72 * 1 = 72

Example (TM2) STEP3-5 Determine the overhead RE (result)

Example (TM2) STEP4 Determine the Physical bit rate › For MCS > 17, the modulation is 64QAM. one OFDM symbol can carry 6 bits information. – nPhysicalBit = 6 * nSymbol

Example (TM2) STEP5 Determine the TB size › Step5-1: the TBS is given by the (TBS index, PRB number) entry of Table 7.1.7.2.1-1 Transport block size table (36.213) – TBS index can be determine by MCS index use Table 7.1.7.1-1: Modulation and TBS index table for PDSCH (36.213) • Use highest MCS index first.

– PRB number, can be find in the STEP1 result.

• Step5-2: Calculate the code rate, if the code rate is large than 0.93, lower the MCS index, repeat step1 to get new TB size until the code rate < 0.93. • Step5-2: Compare the TB size with UE category max DL TB size, if TB size > UE category max DL TB size, repeat step5-1 to get new TB size until the criteria is fulfill.

Example (TM2) STEP5 Modulation and TBS index table (partial)

Example (TM2) STEP5 Transport block size table (partial)

Example (TM2) STEP5 Determine the sf0 TB size • SF0: PRB number is 100, TBS index is 26, the TB size is 75376 • Calculate the code rate: – The effective channel code rate is defined as the number of downlink information bits (including CRC bits) divided by the number of physical channel bits on PDSCH. – The UE may skip decoding a transport block in an initial transmission if the effective channel code rate is higher than 0.930. – Sf0 code rate = 75376/84384 = 0.893 < 0.93

• › Compare with category 3 UE max DL TB size: – For there is only one TB in TM2, so we compare with Maximum number of bits of a DL-SCH transport block received within a TTI. – 75376 2000 >4000 Aggregated antenna bandwidth (MHz) 240 480 Scheduling Capacity / TTI 12 24

DIGITAL unit

Auxiliary Multiplexing Unit(XMU) › Provides interoperability between the DBA and RRUS › Receives carrier data from the DBA via 2 HSSL links and transmits it to RRUS via CPRI link

› Synchs and receives O&M data from 1 DUL via CPRI › Supports CDMA not LTE but passes LTE data in multimode configurations.

RADIO The main purpose of the Radio Unit is to send and receive signals, The Radio Unit receives digital data and converts it to analog radio signals. It also receives radio signals and converts these to digital signals. The radio equipment in the RBS 6000 base stations can be of two types: 1. Radio units (RUs) 1. RUS(the multi standard radio unit) 2. RUG(GSM specific radio unit) 3. RUL (LTE specific radio unit) 4. RUW( WCDMA specific radio unit) 2. Remote radios for main-remote configurations. These can be either remote radio units (RRUs) or antenna integrated units (AIR). 1. RRUS (MultiStandard) 2. RRUG ( GSM) 3. RRUW (WCDMA) 4. RRUL (LTE) 5. Antenna Integrated Radio Unit (AIR) 6. Remote Radio Unit A2 (RRUS A2) 7. Micro Remote Radio Unit (mRRUS)

Remote Radio Unit (RRUS) • • • • •

• •

The remote radio unit (RRUS) is designed to be installed close to the antennas, and can be either wall or pole mounted. Units support multi standard operation. Two standards can operate simultaneously on each unit. Dual band configurations are supported by connecting the RRUS for different frequency bands to the same main unit. The RRUS has support for TMA and remote electrical tilt (RET). RRUS different models:• The RRUS 61 is intended for TD-LTE applications only • RRUS 01/02/11/12 are used for FDD applications (GSM, WCDMA and LTE). RRUS 01/02 support one transmitter branch per unit RRUS 11/12/61 support two transmitter branches (MIMO/Tx div) per unit.

RRUS11

RRUS12

RRUS32

RRUSA2

AIR21

Good to Know • ABW – Aggregated Bandwidth • IBW – Instantaneous Bandwidth

Continue… • One 2.5G CPRI can maximum support 40 Mhz ABW (BW*RX/TX) • Two 2.5 CPRI can maximum support 80 Mhz ABW (BW*RX/TX) • One 10G CPRI can maximum support 160 Mhz ABW (BW*RX/TX). •

NOTE: 10G CPRI is not yet used in the market. This will be used for PCS/AWS RRUS32 to handle 15Mhz x 4 RX using 1 CPRI.

DU CPRI SUPPORT

CONTIGUOUS BAND (Bandwidth Expansion) DUS RU RU A2

1 CPRI Example

1C : 700 2x10

2C: 4x10 or 4x5

DUS RU RU A2

2 CPRI Example

1C : 700 2x10

2C: 4x15 or 4x20

• As the name suggests, in this scope the bandwidth within the band is being increased from 10MHz to 15 MHz (10+5) or to 20mhz (10+10). 2 way receive diversity (2WRD) Condition: • The above can be achieved with configuration changes in the node only • no physical changes needed 4 way receive diversity (4WRD) Condition: • If the site needs to BE defined with 4WRD then this can be achieved With ADDITION OR modification of A2 and AIR Data port 2 separate DU port ALONG WITH CONFIGURATION CHANGES WITHIN THE NODE.

CONTIGUOUS BAND (BWE) CONTIGUOUS BAND (BANDWIDTH EXPANSION - BWE) Radio Type

Bandwidth of CellFDD

RX or TX

2.5G CPRI Support

2.5G CPRI Required

10G CPRI Support 10G CPRI Required

RRUS11

5

2

YES

1

NO

NA

RRUS11

10

2

YES

1

NO

NA

RRUS12

5

2

YES

1

NO

NA

RRUS12

10

2

YES

1

NO

NA

5

4

YES

1

NO

NA

RRUS11+RRUSA2

10

4

YES

1

NO

NA

RRUS11+RRUSA2

15

2

YES

1

NO

NA

15

4

YES

2

NO

NA

RRUS11+RRUSA2

20

2

YES

1

NO

NA

RRUS11+RRUSA2

20

4

YES

2

NO

NA

AIR21

5

2

YES

1

NO

NA

AIR21

10

2

YES

1

NO

NA

AIR21

10

4

YES

1

NO

NA

RRUS32

10

2

YES

1

YES

1

RRUS32

10

4

YES

1

YES

1

RRUS32

15

2

YES

1

YES

1

RRUS32

15

4

YES

2

YES

1

RRUS32

20

2

YES

1

YES

1

RRUS32

20

4

YES

2

YES

1

RRUS11+RRUSA2

RRUS11+RRUSA2

NON CONTIGUOUS BAND(POWERSPLIT) DUS

DUS RU RU A2

1 CPRI Example

1C : 700 2x10

RU RU

2C/3C: 4x10 (5 + 5)

A2

2 CPRI Example

1C : 700 2x10

2C/3C: 4x15 (5+10) or 4x20 (10+10)

1)

Using RRUS11/RRUS12 only

› NO extra CPRI needed › only remote node configuration NEEDED where single RRU power split done. › ready to handle 2 carriers (including 2C and 3C cells).

2)

Using [RRU + A2] or [AIR]

› Extra CPRI fiber needed › needs to be installed before actual work scheduled. › TOWER CREWS NEED TO LAY DOWN THIS CPRI FIBER FROM DATA 2 PORT OF A2 / AIR EXTENDING IT TO DU WITHOUT TERMINATING. › Final du end connection will be terminated by the integrator at the time of activity.

Additional InFO • IBW: It is the maximum edge-to-edge spacing between two carriers. • E.g. two 10 Mhz carriers, the gap between them can be 20 MHz, since 10 + 20 + 10 = 40 MHz • Two carriers are within the 40 MHz edge-to-edge IBW of the RRUS12 and RRUSA2. • Edge-To-Edge Calculation: CarrierA_BW+CarrierB_BW+((CarrierA_CFCarrierB_CF)/10) BW – Bandwidth, CF = EARFCNDL Eg: 10 + 10 + ((2175-2000) / 10) = 37.5 < 40 Mhz 10+10+ ((5780-5760)/10) = 30 < 40Mhz

MULTICARRER NON CONTIGUOUS (Power Split) MULTICARRIER NON CONTIGUOUS BAND (POWER SPLIT) Bandwidth Combination Radio Type of Powersplit 5+5 RRUS11 10+5 RRUS11 10+10 or 5+15 RRUS11 5+5 RRUS12 10+5 RRUS12 10+10 or 5+15 RRUS12 5+5 RRUS11+RRUSA2 5+10 RRUS11+RRUSA2 5+10 RRUS11+RRUSA2 10+10 or 5+15 RRUS11+RRUSA2 10+10 or 5+15 RRUS11+RRUSA2 5+5 RRUS12+RRUSA2 5+10 RRUS12+RRUSA2 5+10 RRUS12+RRUSA2 10+10 or 5+15 RRUS12+RRUSA2 10+10 or 5+15 RRUS12+RRUSA2 5+5 AIR21 5+5 AIR21 5+10 AIR21 10+10 or 5+15 AIR21 5+5 RRUS32 5+5 RRUS32 5+10 RRUS32 5+10 RRUS32 10+10 or 5+15 RRUS32 10+10 or 5+15 RRUS32

Total Bandwidth 10 15 20 10 15 20 10 15 15 20 20 10 15 15 20 20 10 10 15 20 10 10 15 15 20 20

RX or TX 2 2 2 2 2 2 4 2 4 2 4 4 2 4 2 4 2 4 4 4 2 4 2 4 2 4

2.5G CPRI Support YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES YES

2.5G CPRI Required 1 1 1 1 1 1 1 1 2 1 2 1 1 2 1 2 1 1 2 2 1 1 NA NA NA NA

10G CPRI Support NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO YES YES YES YES YES YES

10G CPRI Required NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA 1 1 1 1 1 1

L14B/L15B Capability Maximum configuration with Software Level: [# of cells/# of 4W cells/# of carrier branches/# of radios/ant bandwidth/# of bands/carriers]: [12/6/24/12/300/4]--- (L14B) [12/6/36/24/300/6] --- (L15B)

XMU

2C Add Using XMU with 2 CPRI

Alpha

Beta Gamma

XMU with IDL2

RRU Configuration 2nd carrier 2X5MHz / 1X10 MHz configurations

SECONDARY COMPONENTS

SECONDARY EQUIPMENTS Antenna

• •

Multi Band : 65 degree, 90 degree Single Band: 45 degree, 65 degree, 90 degree

Hybrid Cable

• •

5 sets of DC power (outer ring) 6 sets of fiber optic (inner ring)

Combiners and Filters

• • •

ESMR 800MHz TX Filter Combiner TSBDA

Ancillary

• •

Support Alarm Unit(SAU) Global Positioning System(GPS)

THANK YOU