WiMAX 16e Principle and Key Technology

7/28/2019 WiMAX 16e Principle and Key Technology

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HUAWEI TECHNOLOGIES CO., LTD.

www.huawei.com

Huawei Confidential

2013/6/11

WiMAX Principle and

Key Technology


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HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential Page 2

WIMAX Key Technology2

1 WIMAX Overview

Content

Content


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Cellular Network (GSM, CDMA, UMTS, )

Fixed Network (xDSL, )

BWA (WiMAX 802.16e, )

1 10 1000,01 0,1Bandwidth

(Mb/s)

Fixed

W

alk/Vehicle

High Speed

SubUrban-incar

Personal

Urban fixed

Mobility

On foot

Urban-incar

Nomadic

What WiMAX can do?

Mobile WiMAX can meet both Mobility and Broadband Access!


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Canada2.3/2.5GHz

3.5/5GHz

USA1.5/2.3GHz

2.5/5GHz

C & SA2.5/3.5GHz

5GHz

ME & A

3.5GHz5GHz

Europe3.5GHz

5GHz

Russia2.3/2.5/3.5GHz

5GHz

Asia Pacific2.3/3.3/3.5GHz

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 2.3G, 2.5GHz, 3.5GHz, and

5.8GHz frequency bands, of which 5.8GHz is a license-exempt band.

Spectrum by Region


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SS: Subscriber Station

ASN: Access Service Network

CSN: Connectivity Service Network

NSP:Network Service Provider

NAP:Network Access Provider

ASP: Application service provider

WiMAX Network Structure


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WIMAX Key Technology2

1 WIMAX Overview

ContentContent


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WiMAX key technology

QOS & Mobility

OFDM/OFDMA MIMO Scalable Channel Bandwidth

NBTS

Multi-element

Transmitter

M

MS

Multi-element

Receiver

AMC & HARQ

64QAM

16QAM

From 1MHz to 20MHz

D D D U UD D D

D Downlink U Uplink

Spectrally-Efficient TDD

QPSK

Various WiMAX Key Technology configuration affect network planning increase network complexity


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OFDM/OFDMA introduction(1) OFDM

OFDM = Orthogonal Frequency Division

Multiplexing

Belongs to a family of transmission schemes

called multi-carrier modulation

OFDM dividing a high-bit-rate data stream into

several parallel lower bit-rate streams and

modulating each stream on separate carriers -

often called sub carriers

Low rate signals have large symbol periods,

which make OFDM signal resistant to multi-

path delay spread

OFDM use Fast Fourier Transform (FFT)

to allow overlap in frequency of

individual narrowband signals

More efficient than conventional multi-

carrier Guard


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OFDM/OFDMA introduction(2)

OFDMA is the foundation for 4G

1. OFDMA is a multi-carrier system

2. Available bandwidth is divided into many narrow bands ( sub - carrier )

3. OFDMA divide these sub-carriers into N Groups ( sub -Channel )4. Data is transmitted in parallel on these sub-Channels

OFDM Vs OFDMA


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OFDMA Permutations

Different ways of dividing the sub carriers to sub

channels in protocol are called Permutations

Main permutations:

FUSC - Full Usage of Sub-channels (downlink only )

Achieves best frequency diversity by

spreading tones over entire band

Distributed permutations

PUSC - Partial Usage of Sub channels (uplink & downlink) / Distributed permutations

Groups tones into tiles/clusters to enable fractional frequency re-use

Still has distribution of tones across band for each sub-channel

AMC - (or Band AMC) Adaptive Modulation and Coding (UL & DL) /

Adjacent Sub-carrier Permutation

Uses adjacent tones for each sub-channel for use with beam forming


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Sub-carrier Allocation

Pilot sub-carrier Data sub-carrier

Guard sub-carrier

DC sub-carrier

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

DL-PUSC

Parameters Values

System Bandwidth(MHz) 5 10

FFT Size(Nfft) 512 1024

Number of Guard Subcarriers 91 183

Number of Cluster/Subchannels 15 30

Number of Used Subcarriers 420 841

Number of Data Subcarriers 360 720

Number of Pilot Subcarriers 60 120

UL-PUSC

Parameters Values

System Bandwidth(MHz) 5 10

FFT Size(Nfft) 512 1024

Number of Guard Subcarriers 91 183

Number of Cluster/Subchannels 17 35

Number of Used Subcarriers 420 841

Number of Data Subcarriers 272 560

Number of Pilot Subcarriers 136 280


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OFDMA Frame Structure

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

frequency

TTG and RTG are the time intervals between the downlink sub-frame and uplink sub-frame

The minimum unit of the time is symbol. There are totally 48 symbols per frame

The minimum unit of the frequency is sub channel, there are totally 30 sub channels DL and 35 UL

DL Sub-frame TTG UL Sub-frame RTGLast Frame

frequency

Time

Next Frame


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R=1/2 X1 -X2*X2 X1*

X4

X3

X2

X1

Matrix A

Matrix B

QPSK

16QAM

64QAM

R=2/3

R=4/5

MIMO

MIMO in WiMAX system Exploit multiple antennas at both transmitter and receiver side to transmit and receive

multiple parallel data stream. Also adopt spacial multiplexing. Without increased broadband MIMO technology can improve system capacity, frequency

utilization and data transmit rate.

MIMOMultiple Input Multiple Output


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Supported to provide transmit

diversity and reduce fading

margin by 2-8dB depending on

the environment &terminal

antenna number

STTD: Space Time Transmit Diversity

Compare with SISO, MIMO 22 can improve the coverageradius about 40%~60%

Support fixed and mobile service

One dual-polarization antenna can support 2T2R MIMO

Can support single or dual antenna terminal

MIMO Matrix A-2T2R

800

MHZ

1T2R 2T2R1T1R

X1

X2 X1*

-X2*


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SM: Spatial Multiplexing

With 2x2 MIMO, the DL user and

sector peak data rate are

theoretically doubled. But 1.3~1.6

times than SISO is realizable.

SM: Each signal may convey different data to the same or different users, thus increase

the capacity.

Sector throughput, peak data rate and spectrum efficiency can be improved

Single antenna SS can support UL collaborative SM

UL collaborative SM (Virtual MIMO) can not increase the peak data rate of users, but

can improve the UL sector throughput (about 20~30%)

MIMO Matrix B-2T2R

X4

X3

X2

X1


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Adaptive MIMO Switch

STC mode at the cell

edge, to improve

coverage

SM mode at the cell

center, to improve

system throughput

Works on SM or STCmode based on CINR

level


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MS

Tx /Rx

Tx /Rx

Tx/Rx

Tx/Rx

MIMO 4T4R

Huawei DBS3900 can support MIMO 4x4 (4Tx

antenna,4 Rx antenna)

Near2.5 dBPB3 channel of coverage gain can be

obtained using MIMO 4Rx compared with MIMO 2Rx

Coverage radius increase 15~20 thank to2.5dB

additional diversity gain of MIMO 4T4R

MS

BS

Tx /Rx

Tx /Rx

UL_PUSC_PB3_QPSK12_Float

HARQReTransDelay=10

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

-4 -2 0 2 4 6 8 10

SNR

RCT_test_point 1X1 1X2_MRC_HARQ0

1X2_M RC_ HA RQ1 1X2_ MRC_ HA RQ2 1X2_ MRC_ HA RQ 3

1X4_MRC

PER

2.5dB


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Multipath effect will make different phases for one signal so that the compound signal

will be offset or reduced. The CINR will be lower since the multipath effect is there.

This situation occurs especially at the cell edge

BF is a technology which through adjusting different signals phasebefore transmitting

to get the same signal phases at the receiver, it adjusts the phase base on the

estimate of the UL channel status, So it can improve the signal quality for the special

user

BF brings 25% increment of border user throughput and 10% increment of sector

throughput

BF can obtain additional 3~4dB coverage gain at DL compared with MIMO Matrix A

4T4R MIMO A/B+BF (Beamforming)


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Huawei MIMO Evolution Roadmap

WiMAX industry development roadmap is from MIMO Matrix-A&B to MIMO-BF;

MIMO antenna technology is the basis for all 4G standards

MIMO 2T2R

Matrix-A

Adaptive

Matrix-A&B

MIMO 4T4RMIMO 4T4R

Beamforming


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Variable theoretical

TDD Ratio =35:12CCH Overhead: 7symbols(DL),

3symbols(UL)

Data symbol: DL:UL=28:9

1 2 3 4 5 6 7 8 33 34 35 36 37 38 39 40 47 48

DL-CCH DL-Data TTG UL-CCH UL-Data

TDD Ratio=29:18

CCH Overhead:7symbols(DL),

3symbols(UL)

Data symbol: DL:UL=22:15

DL-CCH DL-Data TTG UL-CCH UL-Data

1 2 3 4 5 6 7 8 27 28 29 30 31 32 33 34 47 48

Main TDD ratios supported by Industry products : (35: 12), (32 : 15), (29 : 18), (26 : 21)

More symbols, higher throughput

Select the TDD ratio for each network base on the throughput requirement of DL and UL

TDD: Time Division Duplex


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AMC: Adaptive Modulation and Coding

16QAM

64QAM

QPSK

25%~30%

65%~70%

DL modulation and coding type:

QPSK1/2, QPSK3/4

16QAM1/2, 16QAM3/464QAM1/2, 64QAM2/3, 64QAM3/4, 64QAM5/6

UL modulation and coding type:

QPSK1/2, QPSK3/4

16QAM1/2, 16QAM3/4

Peak throughput

Average throughput

Name Modulation And Efficiency Channel Coding Rate Bearer Efficiency (bits/symbol)

QPSK 1/2 QPSK 2 0.5 1

QPSK 3/4 QPSK 2 0.75 1.5

16QAM 1/2 16QAM 4 0.5 2

16QAM 3/4 16QAM 4 0.75 3

64QAM 1/2 64QAM 6 0.5 3

64QAM 2/3 64QAM 6 0.67 4

64QAM 3/4 64QAM 6 0.75 4.5

64QAM 5/6 64QAM 6 0.833 5


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Known number : bits data per symbol per carrier

frame length (5 millisecond)

Throughput = (modulation efficiency * coding efficiency * number of data symbols per frame

* number of data sub carriers per frame) / duration of each frame

Site Capacity Calculation - Concept

47 symbols for DL

sub-frame and UL

sub-frame. wetake 7 symbols for

common message

at DL and 3

symbols at UL.

Example: TDD

ratio 35:12,

symbols for data is

28 DL and 9 UL


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Mobile WIMAX PHY Data Rates with PUSC Sub-Channel

Parameter Downlink Uplink Downlink Uplink

System Bandwidth 5MHz 10MHz

FFT Size 512 1024

Null Sub-Carriers 92 104 184 184

Pilot Sub-Carriers 60 136 120 280

Data Sub-Carriers 360 272 720 560

Sub-Channels 15 17 30 35

For the PUSC permutation mode, each sub-channel includes 24 data sub-carriers DL and 16 data sub-

carriers UL. Different channel bandwidth can directly affect the single-site throughput. The number of sub-channels

assigned to single user directly affect the single-user throughput.

Site Capacity Calculation - Concept


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Site Capacity Calculation-PHY Layer

Fixed parameters:

DL-PUSC: The number of sub-channels is 30. Each sub-channel includes 24 data sub-carriers

UL-PUSC: The number of sub-channels is 35. Each sub-channel includes 16 data sub-carriers

Assumption condition:

The channel bandwidth is 10MHz.

The TDD scale time is DL:UL = 35:12.

The downlink modulation mode is 64QAM, and the coding mode is 5/6.

Uplink modulation mode is 16QAM, and the coding mode is 3/4.Calculation:

DL-PUSC throughput per sector

= number of sub-channels * data sub-carriers per sub-Channel * number of symbols

* Modulation Efficiency * coding Efficiency / duration of each frame

= 30*24*(35-7)*6*(5/6)/(5/1000)

= 20.16MbpsUL-PUSC throughput per sector = 35*16*4*(3/4)/(5/1000)

= 3.36Mbps

MAC efficiency is about 90% of the PHY throughput

The theoretical peak throughput can be doubled when Use MIMO B DL and CSM UL

Case:


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WiMAX 16e Principle and Key Technology

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