WiMAX 16e Frequency Planning V1.0

WiMAX Wireless Network Frequency Planning (802.16E) Issue 1.0

Contents WiMAX Overview

WiMAX Sub-Carrier Assignment Mode & Frequency Reuse Mode

WiMAX Typical Typical Networking Mode

WiMAX Network Expansion Solution

Contents WiMAX Overview

WiMAX Sub-Carrier Assignment Mode & Frequency Reuse Mode

WiMAX Typical Typical Networking Mode

WiMAX Network Expansion Solution

Evolving Wireless Landscape 1992-2000 TDMA

GSM GSM

PDC

cdmaOne cdmaOne

2004-2008

2000-2004 EGPRS 384kbps

TD-SCDMA (China)

GPRS ~150kbps WCDMA 2Mbps

cdma20001x 144bps

HSDPA 14Mbps(2006)

EVDO Rel.0 2.4Mbps

HSUPA (2008)

EVDO Rev.A 3.1Mbps(2006)

LTE

 AIE

Mobile WiMAX will wil l be available before LTE, AIE! WiMAX 802.16-2004 OFDM

Mobile WiMAX 802.16-2005 SISO/OFDMA

SIMO/MIMO

AAS

What Can WiMAX Do? Mobility High Speed

Cellular Network (GSM, UMTS, HSPDA, …)

  e Suburban-incar    l   c    i    h   e    V

BWA (WiMAX 802.16d, 802.16e, …)

Urban-incar

   k    l   a    W

   d   e   x    i    F

On foot Nomadic

Fixed Network (xDSL, …)

Urban fixed Personal

0,01

0,1

1

10

100

Bandwidth (Mb/s)

Mobile WiMAX can satisfy both Mobility Mobility and  and Broadband Access! Access!

Spectrum by Region Canada 2.3/2.5GHz 3.5/5GHz

USA

Russia Europe 3.5GHz 5GHz

2.3/2.5/3.5GHz 5GHz

1.5/2.3GHz 2.5/5GHz

Asia Pacific

ME & A C & SA

3.5GHz 5GHz

2.3/3.3/3.5GHz 5GHz

2.5/3.5GHz 5GHz

Each geographical region defines and regulates its own set of licensed and license-exempt bands, as shown in the previous figure. WiMAX global applications are mainly used in 2.5GHz, 3.5GHz, and 5.8GHz frequency bands, of which 5.8GHz is a license-exempt band.

Contents WiMAX Overview

WiMAX Sub-Carrier Assignment Mode & Frequency Reuse Mode

WiMAX Typical Networking Mode

WiMAX Network Expansion Solution

What is OFDMA?  s   u  b   c   a r  r  i    e r  1 

 s   u  b   c   a r  r  i    e r  2 

 s   u  b   c   a r  r  i    e r   3 

 s   u  b   c   a r  r  i    e r  N

 s   u  b   c   a r  r  i    e r  4 

Frequency OFDM Slot/Frame

IFFT

SN

S1 S2 S3 S4 S5 S6 S7 IFFT

SN+1SN+ SN+ SN+4 IFFT

Time

2

3

S2N

OFDM Symbol (FTT duration)

Guard Time

Bandwidth

1. OFDM is a multi-carrier system 2. Available bandwidth is divided into many narrow bands. 3. Data is transmitted in parallel on these bands.

OFDMA is the foundation for 4G! OFDMA: Orthogonal Frequency Division Multiplex Access

 OFDMA Frame Structure Power

DL Sub-frame

Last Frame

TTG

UL Sub-frame

RTG

Next Frame Time

  r   e    b   m   u    N    l   a   c    i   g   o    L    l   e   n   n   a    h   c      b   u    S

1

FCH UL

Burst#1

DL Burst#2

MAP

Burst#2 S

  e DL    l    bMAP   m   a   e   r    P

DL Burst#4

DL Burst#1

 ACK

DL Burst#3 DL Burst#5

DL Burst#6

UL MAP

Burst#3

Burst#4 Ran ging

DL Burst#7

Burst#5

N 0

1 2

3

4

5

6

7

……

N

0 Guard

1

Fast Feedback (CQICH) …… 2 3 4

M Symbol

OFDMA frame is a time-frequency two-dimensional structure. The y axis is the sub-channel and the x axis unit is symbol.

Allocation of Sub-carrier Pilot sub-carrier

DC sub-carrier Data sub-carrier Guard sub-carrier

…

…

…

…

…

…

10MHz*(28/25)=10.94KHz*1024

PUSC: Partial used sub-carrier FUSC: Full used sub-carrier Band AMC: Adaptive modulation and coding

Sub-channel

Sub-Carrier Assignment Mode: DL-FUSC Pilot sub-carrier

Data sub-carrier

DC sub-carrier Guard sub-carrier

… …

…

…

…

… 0

86 Sub-carrier

12

36

39

840

848 87 Sub-carrier

1. Determine the positions of 82 pilot sub-carriers. FUSC replacement mode includes two groups of pilots: a group of fixed pilots and a group of variable pilots. Fixed pilots appears in each OFDM symbol. The variable pilots fall into two sub-sets, which occur by alternating parity symbols. The pilot positions of adjacent sector FUSC replacement area are the same. Pilots are transmitted in rated power. 2. Except 173 guard sub-carriers, 1 DC sub-carrier and 82 pilot sub-carriers, assign the rest 768 data sub-carriers to each sub-channel. 3. Divide the rest 768 data sub-carriers into 48 groups. Each group contains 16 consecutive sub-carriers. 4. Obtain a data sub-carrier from each group (the obtain mode is related to DL_Permbase) to form the sub-channel. Therefore, there are 16 sub-channels. Each sub-channel consists of 48 data sub -carrier.

Disadvantages: In the case of single-band networking, there is large interference at the cell edge. Pilot positions of adjacent sector FUSC replacement areas are the same. Pilots are always transmitted in rated power. The pilot signal to interference ratio (SIR) determines the quality evaluated by channels and the terminal demodulation capability. Therefore, it is unavailable to use PUSC to reduce the interference.  Advantages: FUSC resources are used, high spectrum efficiency

Only Downlink

Sub-Carrier Assignment Mode: DL-PUSC DL-PUSC Parameters

Values

System bandwidth (mhz)

1.25

2.5

5

10

20

FFT size (nfft)

128

N/A

512

1024

2048

Number of guard sub-carriers

43

N/A

91

183

367

Number of cluster/sub-channels 

6/3

N/A

30/15

30

120/60

Number of used sub-carriers

85

N/A

421

841

1681

Number of data sub-carriers

72

N/A

360

720

1440

Number of pilot sub-carriers

12

N/A

60

120

240

Even Symbol

Odd Symbol

PUSC protocol specifies that downlink PUSC replacement area is the replacement area that must occur in the frame structure. Detailed assignment mode of PUSC is as follows (take 1024 as an example): 1. Except guard sub-carriers and DC sub-carriers, divide the 840 available sub-carriers into 60 physical clusters. Each physical cluster consists of 14 consecutive sub-carriers, and cross two symbols on time. 2. Convert the physical cluster into logical cluster by certain mapping relation. The conversion mode of local cluster of the first replacement area, PUSC replacement area, fixed conversion mode, and PUSC with all sub-carriers is related to DL_PermBase, which is determined by upper -level management entity. 3. Divide all logical clusters into 6 groups. 4. Allocate pilot sub-carrier in the cluster of each group, and divide the rest data sub-carrier to the sub-channel.

Disadvantage: Although the single-band networking is implemented, each sector can only use 1/3 of all frequency resources, and the system spectrum efficiency is low.  Advantage: Adjacent sectors use conflict-free sub-channel resources to ensure that the SIR in the cell is high. MS can receive signals from multiple adjacent sectors to implement soft switch or quick BTS selection.

Sub-Carrier Assignment Mode: UL-PUSC UL-PUSC Parameters

Values 5

10

Symbol 0

System bandwidth (mhz)

1.25

2.5

20

FFT size (Nfft)

128

N/A 512 1024

2048

Number of guard sub-carriers

31

N/A 103 183

367

Number of tiles

24

N/A 102 210

552

Number of sub-channels

4

N/A 17

35

92

Number of sub-carriers per tile

4

N/A 4

4

3

Number of used sub-carriers

97

N/A 409 841

Symbol 1

Tile

Symbol 2

Data carrier

Pilot carrier

1681

PUSC is shorted for partial used sub-carrier.   A uplink slot includes one sub-channel and three symbols. There are totally 48 data sub-carriers and 24 pilot sub-carriers.   The minimum unit of uplink assignment is tile. Each sub-channel has 6 tiles. Each tile consists of 4 consecutive sub-carriers,

and cross three symbol lengths on time.

UL_PUSC assignment procedure (take 1024 as an example)  Divide the 840 available sub-carriers except for guard sub-carriers and DC sub-carriers into 210 tiles.  Separate all tiles into 6 groups. Each group consists of 35 consecutive tiles.  Obtain one tile from the 6 groups (the obtain method is related to UL_Permbase) to from a sub-channel. 35 sub-

channels can be formed in total. Each sub-channel consists of 6 tiles.

Feature: Tile is the minimum unit in the sub-channel assignment. The minimum collision unit of uplink is tile. If adjacent sectors use a same time, the demodulation performance will be greatly affected.

Sub-Carrier Assignment Mode: DL-PUSC with All SC PUSC is shorted for partial used sub-carrier. PUSC with all sc refers to the PUSC replacement mode of all used bandwidth resources.   In this replacement area, the divisions of logical clusters and

sub-channels in each group are related to the downlink replacement DL-PermBase.   If each cell uses different DL-PermBase, the sub-channels

related to each cell only consists of part of the same sub1 2 3

carriers, thus effectively reducing the co-channel interference.

Feature: For users whose SIR meets certain conditions, use PUSC with all sc can fully use all spectrum resources.

PUSC

PUSC with all SC

Sub-Carrier Assignment Mode: Band AMC Band-AMC Parameters

Values

System Bandwidth (MHz)

1.25

2.5

5

10

20

FFT Size (Nfft)

128

N/A

512

1024 2048

Number of guard sub-carriers

19

N/A

79

159

319

Number of used sub-carriers (Nused)

109

N/A

433

865

1729

Number of pilots (Npilots)

12

N/A

48

96

192

Number of data sub-carriers

96

N/A

384

768

1536

Number of bands

3

N/A

12

24

48

Number of bins per band

4

N/A

4

4

4

Number of sub-carriers per bin (8data+1pilot)

9

N/A

9

9

9

Number of sub-channels

2

N/A

8

16

32

1 pilot tone

8 data tones

BAND AMC BIN structure

  Mobile wimax profile specifies that both uplink and downlink can use t he band AMC assignment mode.   Sub-channels of band AMC are consecutive. No matter uplink or downlink, each sub-channel has

independent pilots.

Sub-Carrier Assignment Mode: Band AMC Band AMC assignment procedure:   Separate all available sub-carriers into groups. Nine consecutive sub-carriers is a unit group, which is called "bin". Each bin

consists of 8 data sub-carriers and a pilot sub -carrier.   Assign each bin into sub-channels. Each assignment slot must have 48 data sub-carriers, namely, 6 bins. The possible

assignment modes are: 1 bin x 6 symbols, 2 bins x 3 symbols, 3 bins x 2 symbols, and 6 bins x 1 symbol. Common MAP can only use the 2 bins x 3 symbols assignment mode.

Independence of wireless channel to different users  Advantage: Sub-carriers of each sub-channel are consecutive. For a user, there must be some sub-channels have better conditions. The channel independence of each user can ensure that each user assigned with AMC can enjoys the best channel condition and obtain the multi-user diversity gain, which is greater than the gain of frequency diversity. Disadvantage: BS needs the channel condition of each user, and assigns resources in a unified way. The channel conditions of a user must be stable. It is not fit for users in high -speed mobility.

Frequency Reuse Mode

N×S×K

Red lines in the figure indicates the interference of a same direction and frequency.

The network is divided into clusters of N cells, S sector per cell, and K different frequency allocations per cell.

When selecting the frequency reuse mode, consider comprehensively the influence of frequency resources and interference.

Scalability of Channel Bandwidth GSM 200KHz

Channel bandwidth can be adjusted in the range from 1M to 20MHz based on the actual requirement. Data 400 chips

CDMA 1.2288MHz 1MHz - 20MHz WCDMA 3.84MHz The scalability of channel bandwidth makes the WIMAX frequency division greatly different from that of the current 2G/3G system.

Network planning solution can select different channel bandwidths according to the customer frequency resources and capacity requirements.

Summary 1.

DL_PUSC and DL_FUSC assignment modes: A sub-carrier is the minimum unit of sub-channel division. Sub-carriers of a sub-channel are widely distributed in the entire frequency band. Higher frequency diversity gain can be obtained.

2.

UL_PUSC: Although sub-carriers of sub-channels are also distributed in the entire frequency band, the tile consisting of four consecutive sub-carriers with 3 consecutive symbols is the minimum unit. Thus, for UL_PUSC, avoid the conflicts between sub -channels as much as possible.

3.

BAND AMC: Sub-carriers in each sub-channel are consecutive, thus, sub-carriers in a subchannel has similar attenuation. Because the channel of each user is independent, multiple users can get resources with fine channel condition; therefore, the system can get greater multi user diversity gain.

 WiMAX network planning aims at the OFDMA network planning.  For the sub-carrier assignment mode, select FUSC, PUSC, or

FFR. Different sub-carrier assignment mode can respectively get the diversity gain and multi-user gain.  Typical applications of frequency reuse mode include 1*3*3 and

1*3*1. When selecting the frequency reuse mode, consider comprehensively the frequency resources and system interference.

Contents WiMAX Overview

WiMAX Sub-Carrier Assignment Mode & Frequency Reuse Mode

WiMAX Typical Networking Mode

WiMAX Network Expansion Solution

Typical Applications: PUSC 1x3x1 All BTS use one frequency point. Three sectors of a BTS is a reuse cluster. The three sectors use respectively 1/3 sub-channel in a frequency point. The same directional sectors of different BTSs use the same sub-channel.

1 2

1

1 2

2 3

F1

2 3

3

3

•

3

2

2

•

F1 1

1

Uplink

1

Both uplink and downlink use PUSC replacement.

1: logical sub-channel 1-11; 2: logical sub-channel 12-23; 3: logical sub-channel 24-35

Downlink

3 1: Segment 0: 0-9 2: Segment 1: 10-19 3: Segment 2: 20-29

Three sectors of a BTS is a reuse cluster. The three sectors use respectively 1/3 sub-channel in a frequency point. The same directional sectors of different BTSs use the same sub-channel. Ensure that the sub-channels of adjacent sectors in one BTS do not conflict. All sectors use the same PermBase.

Typical Application: PUSC 1x3x1 Advantages:   The entire network enjoys co-channel. Soft handover can be implemented.   Do not need complex scheduling method of sub-carrier replacement mode. The implementation is

easy and the system expense is small.   The system interference is small. There is no sub- channel conflict between adjacent sectors of a BTS.   The coverage range is wide. Cost of initial network construction is low, and the network construction risk is low.   Network construction is fast, the interference is easy to be controlled, and the network planning and optimization are simple.

Disadvantages:   The spectrum utilization is low.   Network capacity is small.

1. Adapt to situations with integrated operator frequency resources and consecutive frequency bands. 2. If the frequency point bandwidth is wide (>=10MHz), it can be used as the initial  Adapt to initial network construction mode of the urban or densely-populated urban areas. Basically network satisfy the phase one capacity requirements. construction 3. Use relatively narrow frequency point bandwidth (=5MHz), it can be used on initial network construction of dense or common urban. If the bandwidth of frequency point is narrow requirements ( FFR 1*3*1 > FUSC 1*3*3 (PUSC with all SC 1*3*3)

FFR 1*3*1

Summary 1.

PUSC 1*3*1, applied to initial network construction, can be expanded to FFR 1*3*1.

2.

FUSC 1*3*3, applied to large-capacity network construction, with enough frequency resources.

3.

FFR 1*3*1, the system frequency reuse is close to 1, is the preferred networking mode in later network construction.

Network planning is more flexible!

Contents WiMAX Overview

WiMAX Sub-Carrier Assignment Mode & Frequency Reuse Mode

WiMAX Typical Networking Mode

WiMAX Network Expansion Solution

Increasing Channel Bandwidth Currently, Huawei can support 5M/10MHz channel bandwidth. In the follow-up procedure, other values specified in protocols, such as 3.5MHz can also be supported. When there are available consecutive frequency bands, you can directly expand the system channel bandwidth from 5MHz to 10MHz, thus doubling the system capacity.

Advantages:   Have no impact on original network. Network re-planning is not required.   The capacity increases with the channel bandwidth.

Disadvantages   Additional spectrum resources are required, and the spectrum resources of new channel

bandwidth must be consecutive.  Relevant channel bandwidth must be supported by products. (simple)  The solution only fits for entire network expansion.

5MHz

10MHz

Adding Carrier (Multi-Carrier Configuration) When there are additional spectrum resources, adopt the multi-carrier configuration mode to increase the system capacity. Multi-carrier configuration refers to that configure multiple different carriers in the sectors of a BTS.

Advantages:  Only require adding devices, which has little impact on the original network. Network re -

planning is not required.  The system capacity increases with the carrier number. The expansion effect is obvious.  One sector supports the multi-carrier networking of different bandwidths.

Disadvantages:  Operators need remaining spectrum resources.  To keep original coverage, adding carriers require additional power.  The same sector can support adjacent carrier configuration. If there is condition, do not

use adjacent carriers to reduce interference.  The expansion is related to the original frequency reuse mode. As the number of carriers increase, the system capacity becomes smaller. Generally, the number of multi-carriers is no less than 4.

 Adopting MIMO Technology Advantages:  Do not need additional carrier resources.  Have little impact on original network. Network re-planning

is not required.  Expansion effect is obvious.

Limitations:  The product needs to support the MIMO function.  Partial devices need be replaced (such as band board

and RF equipment). The cost is high.  The solution only fits for the condition that original existing network device does not support MIMO.

By using the MIMO Matrix_A technology, the link signal quality can be effectively increased. In the same condition, users can use higher-efficiency code modulation mode; thus, increasing the capacity of the entire system. By using the MIMO Matrix_B technology, the original capacity can be doubled theoretically.

 Adopting AAS Technology

Omni Antennas

Smart Antennas

 Through directional transmit signals, suppress the interference of transmitter on users of a same cell or

neighbor.  Through the space signal integration, increase the transmit antenna gain of specified directional MS and reduce the transmit power.  Increase the coverage range and improve the spectrum usage. 1. MAP message are spread in the cell, and transmitted to all users; therefore, DL-MAP cannot obtain gains from AAS. Because MAP messages cannot be reliably tr ansferred in the expand area, AAS expansion area cannot used for cell planning. 2. If AAS is in the complex propagation environment such as urban area, the system gain obtained is less than that of suburban or rural environment. 3. The AAS capacity gain is increased in non-linear way, not similar to MIMO. Four antenna beams add about 50% capacity. 4. AAS design is based on TDD mode. In the WiMAX FDD mode, because the uplink and downlink frequencies are different, the channels are not reliable. 5. The support of AAS to mobility is to be improved. The AAS relies on accurate fast evaluation, in highspeed terminal cases, because the channel environment is complex, AAS is hard to support the mobility.

Sector Splitting Sector splitter indicates that reduce the coverage angle of each sector by half to expand the typical 3sector BTS into 5-sector BTS.

Advantages:  Similar to cell splitting. However, the sector splitting does not need to add new sites to

avoid difficulties in site location obtaining.  New spectrum resources are not required.  The system capacity is increased significantly with the number of BTS sectors.

Limitations:  The sector splitting solution has strict requirements on interference control. The expansion method

of sector splitting is used together with AAS new antenna technology.  The greater the sector splitting is, the less the increasing range of system capacity is. Generally, the number of sectors in a BTS after the sector splitting shall be less than 6.

Adding Site -- Cell Splitting

Advantages:   Do not affect original networking mode. Only need to add sites.   The expansion is easy. Do not need support of enhanced technology.   Expansion does not affect the entire network.

Disadvantages:  This expansion mode gets capacity by adding sites. The expansion cost is high.  If the sites are densely distributed, the interference cannot be controlled, which

brings difficulties to network optimization.

Adding Sites -- Micro-Cell Advantages:  Do not affect original networking mode. Adding sites

in high-traffic area is used to attract most traffics. The original macro-cell ensures the consecutive coverage.  The expansion implementation is easy. Do not need the support of enhanced technology.

Macro-cell consecutive coverage

Disadvantages:  Need to add sites. The expansion cost is high.  Require the seamless handover between hot-spot

Macro-cell consecutive coverage

area and macro-cell. Micro-cell/in-door coverage

This expansion mode fits for various networking modes. It reduces the original network load by adding indoor coverage in hot-spot or buildings with high-traffic, such as business building, hotels and gymnasiums with large users.

Summary  Expansion solution  Add channel bandwidth

Advantages (1) Capacity increases in linear way with channel bandwidth.

Disadvantages

Typical scenario

Require additional spectrum resources.

Only fits for entire network expansion. Operators have idle frequency resources (consecutive).

(2) Have little impact on original network. Network replanning is not required.  Add carriers (multi-carrier configuration)

Same as above

Same as above

Adapt to cases that operators have remaining spectrum recourses (not consecutive) or cannot support higher channel bandwidth.

Use MIMO technology

1. Do not need additional carrier resources.

The product needs to support the MIMO function, and needs to replace partial devices (such as baseband board and RF devices). The cost is high.

Only adapt to conditions that existing network equipment does not support MIMO, and the operator is willing to pay for upgrading.

2. Have little impact on original network. Network replanning is not required.  Adopt more tight frequency reuse mode

New spectrum resources are not needed.

More tight frequency reuse mode has higher  Adapt to various scenarios (select requirement on system design, especially flexibly according to product the load control and sub-carrier scheduling technology maturity). algorithm.

Sector splitting

New spectrum resources are not needed.

Sector splitting solution has strict requirements on interference control. The expansion mode of sector splitting is used together with new antenna technology such as AAS.

 Adapt to the scenario that AAS is used in the intelligent antenna system. It is not a choice of Huawei expansion.

 Add micro-cell

Final method of expansion

Select new sites, and need to re-optimize the original network in a large scale. The cost is high.

 Adapt to areas needing larg escale expansion.

Reference