QoS-guaranteed Transmission Scheme Selection for OFDMA

Multi-hop Cellular Networks

Jemin Lee, Sungsoo Park,

Hano Wang, and Daesik Hong,

ICC 2007

OutlineOutline

Introduction OFDMA Multi-hop cellular model Transmission Scheme Selection Algorithm

(TSSA) Performance Conclusion

Introduction

Multi-hop cellular networks (MHCN) have been proposed to enhance throughput and extend coverage

The advantage of multi-hop networks comes from the reduction in the overall path loss

Base Station -> Relay Station -> Mobile Station

Introduction

The penalty of transmission with multi-hop is in need for additional resources

Eg. power and bandwidth

[2] IEEE Trans. on Wireless Comm. 2003 resource reuse

• transmission enhances the system capacity in multi-hop networks

Introduction

QoS guarantee of MS Supported various QoS requirements of MSs Increasing the number of QoS-guaranteed MSs BS controls the number of subcarriers allocated to the

MS

Proposed a transmission scheme selection SH MH MHSR

Introduction

Goal Select the best performance scheme for the efficient

utilization of subcarriers

OFDMA Multi-hop cellular model

Cellular Architecture Two-hop relaying system BS-FRS link

• LOS BS-MS and FRS-MS link

• NLOS

OFDMA Multi-hop cellular model

SINR

Channel gain of the link between x and yBS’s transmission power

Noise powerTotal interferences

Transmission scheme

OFDMA Multi-hop cellular model

Channel gain Channel gain

constantDistance between x and y

Path loss exponent

Shadowing random variable

OFDMA Multi-hop cellular model

Total interferences Total interferences The interference from BSs of other cells

The interference from FRSs of other cells

The interference from spatial reuse of subcarrier

OFDMA Multi-hop cellular model

Example of interferenceExample of interference

OFDMA Multi-hop cellular model

data rate per subcarrier of the kth MS at the nth hop

Satisfying the target rate of the kth MSrequired number of subcarriers

OFDMA Multi-hop cellular model

Example Example Calculating the number of subcarriers Calculating the number of subcarriers

subcarrier 13 )5

50

20

50(

1

13,2

bps

bps

bps

bpsC

BS

RS

MS3

R2,3,1 =20 bps

R2,3,2 =5 bps

Rk=50 bps

r4subcarrie )12

60

20

60(

2

12,3

bps

bps

bps

bpsC

MS2

R3,2,2 =12 bps

Rk=60 bps

BS

RS

R3,2,1 =20 bps

OFDMA Multi-hop cellular model

ak=1 If the kth MS is supported

Total number of subcarriers

TSSA

Performance

Performance

Performance

Conclusion

This paper has verified that the best transmission scheme which requires the fewest subcarriers to guarantee QoS

The simulation results have demonstrated that subcarriers are used efficiently by the proposed algorithm.

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