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

1. 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 aSchool of Electronics and Information Engineering, Beijing Jiaotong University, Beijing, China bLenovo Cooperate Research, Beijing, China cDepartment of Electrical and Computer Engineering, University of Manitoba, Winnipeg, Manitoba, Canada dDepartment of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, Canada to appear in < Computer Communications 2009 >

2. Outline • Introduction • Motivation • Frequency Reuse Schemes • IBFRS • DFPP • SR • Simulation • Conclusion

3. 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 wireless 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.

4. BS RS 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) BS MS 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 Introduction • RS in IEEE 802.16j • Transparent RS • Non-transparent RS

5. Shadowing Area RS BS Coverage Hole MS Non-transparent RS DL Access Zone(BS to MS) DL Relay Zone(BS to RS) UL Access Zone(MS to BS) UL Relay Zone(BS receiving) BS DL Access Zone(RS to MS) DL Relay Zone(RS to RS or RS receiving) UL Access Zone(MS to RS) UL Relay Zone(RS to BS or RS to RS) RS Introduction • RS in IEEE 802.16j • Transparent RS • Non-transparent RS

6. Introduction – Non-transparent RS- Frequency reuse - MS in BS’s Range MS in RS’s Range

7. Isolation Band RS Cluster BS f System Bandwidth = = DL Access Zone(BS to MS) DL Relay Zone(BS to RS) UL Access Zone(MS to BS) UL Relay Zone(BS receiving) BS DL Access Zone(RS to MS) DL Relay Zone(RS to RS or RS receiving) UL Access Zone(MS to RS) UL Relay Zone(RS to BS or RS to RS) RS Motivation • RS in IEEE 802.16j • Transparent RS • Non-transparent RS Reuse-Area

8. Isolation Band RS Cluster BS 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 acreage of SnrBS • ArBS : the area served by the BS but out of the isolation band, which has an acreage of SrBS

9. Isolation Band RS Cluster BS 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 acreage of SnrBS • ArBS : the area served by the BS but out of the isolation band, which has an acreage of SrBS

10. Isolation Band RS Cluster BS 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 acreage of SnrBS • ArBS : the area served by the BS but out of the isolation band, which has an acreage of SrBS

11. Isolation Band RS Cluster BS 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 acreage of SnrBS • ArBS : the area served by the BS but out of the isolation band, which has an acreage of SrBS not Reuse-Area

12. Isolation Band RS Cluster BS 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 acreage of SnrBS • ArBS : the area served by the BS but out of the isolation band, which has an acreage of SrBS Reuse-Area

13. Frequency Reuse Scheme – IBFRS- Isolation Band based Frequency Reuse Scheme - • ABS : the area served by the BS with the acreage of SBS • AnrBS: the isolation band with the acreage of SnrBS • ArBS : the area served by the BS but out of the isolation band, which has an acreage of SrBS Reuse-Area not Reuse-Area

14. Frequency Reuse Scheme – IBFRS- Isolation Band based Frequency Reuse Scheme - • 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.

15. f System Bandwidth = = Frequency Reuse Scheme – IBFRS- Isolation Band based Frequency Reuse Scheme - • Ө: [0,1] be the decrease of the spectrum efficiency of ArBSafter 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 not Reuse-Area BS Reuse-Area

16. Isolation Band RS Cluster BS Frequency Reuse Scheme – IBFRS- Isolation Band based Frequency Reuse Scheme -

17. Frequency Reuse Scheme – IBFRS- Isolation Band based Frequency Reuse Scheme - • 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

18. Frequency Reuse Scheme – IBFRS- Isolation Band based Frequency Reuse Scheme - • can be approximated by a lognormal variable with • mean • standard variance C.D.F.

19. PF1 PF2 PF2 PF3 PF1 PF1 PF2 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 transmitted by the high power level • Secondary frequency : is transmitted by the low power level f System Bandwidth PF1 PF2 = = … PFk RS Cluster SF…

20. 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.

21. 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

22. Simulation not Reuse-Area BS Reuse-Area

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

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

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

26. 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.

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