weiwei wang a , zihua guo b , jun cai c , xuemin(sherman) shen d , changjia chen a

Multiple Frequency Reuse Schemes in the Two-hop IEEE 802.16j Wireless Relay Networks with Asymmetrical Topology

Weiwei Wang a, Zihua Guo b, Jun Cai c, Xuemin(Sherman) Shen d, Changjia Chen a

a School of Electronics and Information Engineering, Beijing Jiaotong University, Beijing, China

b Lenovo Cooperate Research, Beijing, China

c Department of Electrical and Computer Engineering, University of Manitoba, Winnipeg, Manitoba, Canada

d Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, Canada

to appear in < Computer Communications 2009 >

Outline

• Introduction

• Motivation

• Frequency Reuse Schemes– IBFRS

– DFPP

– SR

• Simulation

• Conclusion

Introduction

• Relay-related function is being standardized as the extension to the basic standards, such as IEEE 802.16j.

• There are generally two advantages brought by Relay Stations in WiMAX :– to overcome the coverage hole of BS and provide ubiquitous wirele

ss services cost-efficiently

– to improve network throughput due to possible reuse of radio resources

• In this paper, throughput performance of the access links (i.e., BS to MS and RS to MS) is analyzed for the two-hop IEEE 802.16j wireless relay networks with asymmetrical topology.

Introduction

• RS in IEEE 802.16j– Transparent RS

– Non-transparent RS

RS

MS

BS

Transparent RS

DL Access Zone

(BS to MS or RS)

Optional transparent Zone

(Silent or BS transmitting)

UL Access Zone(MS to BS)

UL Relay Zone(BS receiving)

DL Access Zone

(RS receiving)

Optional transparent Zone

(RS to MS or RS)

UL Access Zone(MS to RS)

UL Relay Zone(RS to BS or RS to

RS)

RS

BS

Introduction



DL Access Zone

(BS to MS)

DL Relay Zone(BS to RS)



DL Access Zone

(RS to MS)

DL Relay Zone(RS to RS or RS

receiving)



RS)

RS

BS

Non-transparent RS

BS

MS

RS

Coverage Hole

Shadowing Area

Introduction – Non-transparent RS- Frequency reuse -

MS in BS’s Range

MS in RS’s Range

Motivation



DL Access Zone

(BS to MS)

DL Relay Zone(BS to RS)



DL Access Zone

(RS to MS)

DL Relay Zone(RS to RS or RS

receiving)



RS)

RS

BS

System Bandwidth==

f

BS

Isolation Band

RS Cluster

Reuse-Area

Frequency Reuse Scheme – IBFRS - Isolation Band based Frequency Reuse Scheme -

• S : the total acreage of the cell

• ABS : the area served by the BS with the acreage of SBS

• ARSc : the area served by the RS cluster with the acreage of SRSc

• AnrBS : the isolation band with the acre

age of SnrBS

• ArBS : the area served by the BS but ou

t of the isolation band, which has an acreage of Sr

BS

BS

Isolation Band

RS Cluster






age of SnrBS



BS

BS

Isolation Band

RS Cluster

not Reuse-Area






age of SnrBS



BS

BS

Isolation Band

RS Cluster

Reuse-Area




age of SnrBS



BS

BSnrBS

rBS SSS

not Reuse-Area

Reuse-Area


• B : system bandwidth

• CBS : the spectrum efficiency of ABS when no frequency reuse between the BS and the RS cluster (bit/s/Hz)

• CRSc : the spectrum efficiency of RS cluster (bit/s/Hz)

• Assume the users are uniformly distributed in ABS.


• Ө : [0,1] be the decrease of the spectrum efficiency of ArBS after

the RSs reuse the frequency from the reuse area.

• The throughput of ABS, denoted as TBS, is

• The throughput of ARSc, denoted as TRSc, is

)1()()(

BSBS

rBS

BSBS

nrBS

BS CBS

SCB

S

ST

RScBS

rBS

RSc CBS

ST

)( not Reuse-Area

Reuse-Area

System Bandwidth==

fBS


)1()()()(

BSBS

rBS

BSBS

nrBS

RScBS

rBS

BSRSc CBS

SCB

S

SCB

S

STTT

BS

BS

rBS

BSBS

rBS

BSBS

nrBS

RScBS

rBS CB

S

SCB

S

SCB

S

SCB

S

S )()()()(

)()(

BSRScBS

rBS

BS CCBS

SBC

BSnrBS

rBS SSS

)}()(

{maxarg]1,0[

BSRScBS

rBS

BSopt CCBS

SBC

BS

Isolation Band

RS Cluster


• Assume a location , in ABS of the cell 0

• The SINR at is given as :

• IBS is the set of the interference sources to

• is the transmitting power of BS in cell d

• is the path loss from BS in cell d

• is the shadowing from BS in cell d

• is the value of the noise in cell 0

)0()()()(

)0()0()0(

)0(

BSm

BSm

BSm

BSIm

BSBSBSx XLP

XLP

BS

BS

)0(BSx

)0(BSx

)0(BSx

)(dBSP

)(dBSL

)(dBSX

)0(BS


• can be approximated by a lognormal variable with– mean

– standard variance

))(

)()(log10(1)()(

)0(

)0(10

)0()0(

BS

BSxx x

xQPF

BSBS

)0(BSx

)( )0(BSx

)( )0(BSx

dZxQ Z

x)exp()( 22

1 2

C.D.F.

Frequency Reuse Scheme – DFPP - Dynamic Frequency Power Partition scheme -

• The frequency of each RS serving area is divided into two parts– Primary frequency : orthogonal among adjacent RSs and is transmi

tted by the high power level

– Secondary frequency : is transmitted by the low power level

PF1

PF3

PF2

PF2

PF1

PF2

PF1

SF…

System Bandwidth

==

f

PFk

…PF2

PF1

RS Cluster

Frequency Reuse Scheme – SF - Selective Reuse scheme -

• Due to the long distance, the sub-channel used by user A may be reused by the RS in the reuse group 2.

Simulation

• Matlab– Carrier frequency : 2.5GHz– System bandwidth : 10MHz– Number of sub-channels : 30– Number of sub-carriers in a sub-channel : 24– BS cell radius : 1Km– BS TX Power : 38dBm(high) ; 33dBm(low)– BS pathloss : 138.6+34.79log10(d)– RS cell radius : 0.1Km– RS TX Power : 5dBm(high) ; 1dBm(low)– RS pathloss : 143.69+37.2log10(d)– Shadowing : mean (0dB) and standard variance (8dB)– Modulation and coding scheme : as the definition in IEEE 802.16e

Simulationnot Reuse-Area

Reuse-Area

BS

Simulation

Tradition : no frequency reuse each user is allocated one sub-channel

Conclusion

• In this paper, three frequency reuse schemes for the two-hop relay network based on IEEE 802.16j has been proposed.

• The simulation results indicate that the proposed IBFRS+DFPP+SR scheme can significantly improve the throughput of the access links with little negative influence to other users served by the BS.

• Our future work will focus on more complex scenarios, such as networks with directional antennas.

The End

THANK YOUTHANK YOU

weiwei wang a , zihua guo b , jun cai c , xuemin(sherman) shen d , changjia chen a

Documents

total acreage

acreage of sbsarsc

acreage of srscanrbs

acreage of snrbsarbs

rs cluster w

coverage hole of bs

computer engineering

j wireless relay networks