Cooperative Adaptive Partner Selection for Real-Time Services in IEEE j Multihop Relay Networks Cheng-Kuan Hsieh, Jyh-Cheng Chen, Jeng-Feng Weng Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan IEEE WCNC 2010
Outline Introduction Problem Goals & Assumptions CAPS Algorithm Simulations Conclusions 2
Introduction IEEE e is a promising standard for mobile Broadband Wireless Access (BWA) Base Station (BS) Mobile Stations (MSs) IEEE j is defined for Multihop Relay (MR) operations Base Station (BS) Mobile Stations (MSs) Relay Stations (RSs) 3
Introduction IEEE j MR network architecture 4 Relay link : between an MR-BS and an RS between two RSs Access link : between an RS and an MS between an MR-BS and an MS
Introduction IEEE j provides real-time services for multi-hop users Bandwidth resource is allocated to each intermediate hop along the path between the MS and the MR-BS Real-time services require the strict QoS requirement UGS/rtPS/ertPS 5 BSBS RS1RS1 RS2RS2 RS3RS3 MSMS
Introduction IEEE j provides real-time services for multi-hop users The MS doesn’t need to request bandwidth for each packet in each hop. Therefore overhead is eliminated and packet latency is reduced. 6 BSBS RS1RS1 RS2RS2 RS3RS3 MSMS
Problem An MS suffers from bad channel and cannot transmit packets to its access RS correctly all bandwidths allocated from the access RS to the MR-BS along the multihop path are wasted. Existing researches all focus on how to select a best path from MR-BS to an MS. How to maintain the multi-hop connection when an MS experiences bad channel ? 7 BSBS RS1RS1 RS2RS2 RS3RS3 MSMS
Goals An MS is currently experiencing bad channel condition The QoS of real-time services could still be maintained by a good cooperative partner with good channel condition How to design an algorithm to select a cooperative partner with best capability in IEEE j networks ? Cooperative Adaptive Partner Selection (CAPS) algorithm Select a partner with the most effective path 8 BSBS RS1RS1 RS2RS2 RS3RS3 MSMS
Assumptions MR-BS maintains the location information of MSs. On experiencing bad channel condition and cannot transmit packets to its access RS correctly, an MS can communication with its neighboring MSs. 9
CAPS Algorithm Cooperative Adaptive Partner Selection algorithm Candidate selection phase Partner selection phase 10
Error Detection Initialization MS’s Operation Scheduling in MR-BS Candidate Selection CAPS Algorithm_ Candidate selection phase 11 C : Cooperative candidates set C = { MS 2, MS 3, MS 4 } erroneous MS MR-BS RS 5 MS 4 RS 2 RS 4 RS 3 RS 1 MS 2 MS 3 MS 1 C : Cooperative candidates set C = { MS 2, MS 3, MS 4 } erroneous MS
CAPS Algorithm_ Partner selection phase D e : end-to-end delay D c : delay in the cooperative link 12 DeDe DcDc erroneous MS MR-BS RS 5 MS 4 RS 2 RS 4 RS 3 RS 1 MS 2 MS 3 MS 1
CAPS Algorithm_ Partner selection phase Weighted Moving Average (WMA) maintain a database (many D e ’s for different paths and many D c ’s for different links) flush old data keep n samples (old data may not reflect instantaneous delay) 13
CAPS Algorithm_ Partner selection phase Weighted Moving Average (WMA) MS 1 MR-BS RS 5 MS 4 RS 2 RS 4 RS 3 RS 1 MS 2 MS 3 WMA De1 =51 D c4 DelayWeight 1st161 2nd182 3rd153 4th174 5th195 D c2 DelayWeight 1st251 2nd212 3rd203 4th234 5th225 D c3 DelayWeight 1st181 2nd232 3rd203 4th194 5th215 WMA Dc2 = 21.9 WMA Dc4 = 20.3 WMA De4 =38 WMA De2 =43 D p4 = = 55.3 D p2 = = 64.9 D p3 = = 71.3
CAPS Algorithm_ Partner selection phase Weighted Moving Average (WMA) 15 MS 1 MR-BS RS 5 MS 4 RS 2 RS 4 RS 3 RS 1 MS 2 MS 3 WMA De1 =51 WMA De4 =38 WMA De2 =43 D p4 = = 55.3 D p2 = = 64.9 D p3 = = 71.3
Simulations Simulator : NS2 Map size : 5 km * 5 km Packet size : 150 bytes Bandwidth is allocated evenly to MSs because they generate the same traffic. 16
Simulations Simulation topology 1 MR-BS 15 RSs 35 MSs 17
Simulations Average packet delay versus different PERs 18
Simulations Average jitter versus different PERs 19
Simulations Average packet loss rate versus different PERs 20
Simulations Throughput versus different PERs 21
Conclusions The MR-BS will select an MS with minimum delay to help the erroneous MS. Therefore, the erroneous MS can still use other path to transmit packets to the MR-BS. The results show CAPS can improve the performance significantly in terms of the packet delay, jitter, packet loss rate, and throughput. 22