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A Joint Bandwidth Allocation and Routing Scheme for the IEEE 802.16j Multi-hop Relay Networks

A Joint Bandwidth Allocation and Routing Scheme for the IEEE 802.16j Multi-hop Relay Networks. Kyungjoo Lee, Hyukjoon Lee, Yong-Hoon Choi, Younguk Chung Kwangwoon University , Seoul , Korea Young-il Kim Electronics and Telecommunications Research Institute , Daejon , Korea. IEEE ICOIN 2009.

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A Joint Bandwidth Allocation and Routing Scheme for the IEEE 802.16j Multi-hop Relay Networks

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  1. A Joint Bandwidth Allocation and Routing Scheme for the IEEE 802.16j Multi-hop Relay Networks Kyungjoo Lee, Hyukjoon Lee, Yong-Hoon Choi, Younguk Chung Kwangwoon University , Seoul , Korea Young-il Kim Electronics and Telecommunications Research Institute , Daejon , Korea IEEE ICOIN 2009

  2. Outline • Introduction • Motivation and Goal • Joint Bandwidth Allocation and Routing Scheme • Simulation • Conclusion

  3. MS MS Introduction • IEEE 802.16j multi-hop relay system • Transparent Relay Mode – Enhance link throughput • Non-Transparent Relay Mode – Extend service coverage MR-BS MR-BS High rate RS Low rate RS Transparent Relay Mode Non-Transparent Relay Mode

  4. RS1 RS1 RS1 RS1 MR-BS MR-BS MR-BS MR-BS Introduction • IEEE 802.16j Transparent Relay Mode • Frame structure MS2 MS2 MS2 MS2 MS1 MS1 MS1 MS1

  5. MS MS MS MS MS MS MS RS RS RS RS Motivation • IEEE 802.16j Transparent Relay Mode • Limited radio resource • Routing path selection • Allocation of corresponding resource MR-BS Transparent Relay Mode

  6. Goal • Base on the IEEE 802.16j transparent relay mode. • In order to maximizing the total downlink system throughput in a single cell. • The proposed scheme is on the selection of routes and the allocation of corresponding resources.

  7. MS MS MS MS MS MS MS MS MS MS MS MS MS MS RS RS RS RS RS RS Joint Bandwidth Allocation and Routing Scheme • Problem description • The lengths of DL access zone and transparent zone should be determined according to the total amount of data transported to the MSs directly from the MR-BS and via the RSs. • Therefore, the two problems of routing and resource allocation must be solved jointly. DL-Subframe MR-BS DL-Access DL-Transparent DL-Subframe MR-BS DL-Access DL-Transparent

  8. (RjTw/B1j )B1j = RjTw Joint Bandwidth Allocation and Routing Scheme • Problem description • Assume • MS receive all of its downlink traffic from the MR-BS either directly or through one RS. • No two MSs communicate without going through the MR-BS. • At each OFDMA slot, only one station can transmit data to a receiver. • One BS, M-1 RSs , N MSs are placed randomly. Objective function: , Bij: The maximum amount of data that can be transported by transmitter i for receiver j in a single OFDMA slot. Rj : The required average data rate for receiver j. Tw : The frame duration N : Number of MSs M : Number of BS and RSs

  9. B1j (RjTw/B1j ) (RjTw/B2j )B2j / B12= RjTw / B12 RjTw MR-BS1 MR-BS1 RjTw RjTw B12 Bij RjTw RjTw/Bij MSj MSj MSj RS2 RSi Joint Bandwidth Allocation and Routing Scheme • Constraint(1) for the problem • DL-access zone and DL-transparent zone ωACCESS : Total length of DL-Access Zone ωRELAY: Total length of DL-Access Zone Bij: The maximum amount of data that can be transported by transmitter i for receiver j in a single OFDMA slot. Rj : The required average data rate for receiver j. Tw : The frame duration N : Number of MSs M : Number of BS and RSs

  10. RS2 R2Tw … RjTw RMTw MR-BS1 MR-BS1 RSM MSM+1 MSM+N MSM+1 MSM+N RM+1Tw RM+NTw … RjTw RM+1Tw … RM+NTw RS2 Joint Bandwidth Allocation and Routing Scheme • Constraint(2) for the problem • Maximal transmission data ki: The number of slots allocated for the transmitters in the DL access zone Bij: The maximum amount of data that can be transported by transmitter i for receiver j in a single OFDMA slot. N : The number of MSs M : The number of BS and RSs

  11. M items (M-dimensional) RS2 RSi RSM MSM+N MSj Joint Bandwidth Allocation and Routing Scheme • Multi-Dimensional Multi-choice Knapsack Problem (MMKP) • The goal of MMKP is to select exactly one item from each of N groups of items for the maximum total value of the selected items, subject to the M volume constraints. MR-BS1 … … … … MSM+1 N groups Each MS is mapped to a group with nj= M+1 items. The (M+1)th item means the amount of the data needed to be transmitted per frame by an MS should remain.

  12. MR-BS1 C2= RS2 MSM+1 a2M+3 a2M+8 a2M+1 MSM+8 MSM+3 Joint Bandwidth Allocation and Routing Scheme • Multi-Dimensional Multi-choice Knapsack Problem (MMKP) • Maximal transmission data Ci : The total allowable volume of ith dimension N : The number of MSs M : The number of BS and RSs

  13. The (M+1)th item means the amount of the data needed to be transmitted per frame by an MS should remain. Joint Bandwidth Allocation and Routing Scheme • Multi-Dimensional Multi-choice Knapsack Problem (MMKP) Rj : The amount of data which is receiving from j Ci : The total allowable volume of ith dimension N : The number of MSs M : The number of BS and RSs

  14. Joint Bandwidth Allocation and Routing Scheme [9] M. Moser, D. P. Jokanovic, and N. Shiratori, "An algorithm for the multidimensional multiple-choice knapsack problem,“IEICE Transaction Fundamentals,1997 • Multi-Dimensional Multi-choice Knapsack Problem (MMKP) • Since the MMKP is a NP-hard problem, polynomial time sub-optimal heuristic algorithms such as proposed in [9] are used in general. • Based on Lagrange multipliers Let λ1 ,λ2 ,… , λM be the M non-negative Lagrange multipliers. constraints(1) constraints(2)

  15. MR-BS1 Remain some MSs RS3 RS2 RS4 Update MS1 MS2 MS3 MS4 Check constraints(2),(1) • Heuristic algorithm based on Lagrange multipliers Find anther BS or RS Update

  16. MR-BS1 RS3 RS2 RS4 RS5 MS1 MS2 MS3 MS4 • Heuristic algorithm based on Lagrange multipliers Check anther BS or RS

  17. RS2 RS1 Simulations • Simulation parameter 300 m 145 m 145 m MR-BS

  18. Simulations • Simulation result The LQB scheme computes for each MSj, and selects the route with the highest value of Qj. The number of slots allocated for the MR-BS, RS1 and RS2 in the DL access zone

  19. Conclusion • The paper proposes a joint resource allocation and routing scheme for the downlink of IEEE 802.16j MR system. • And transform the optimization problem to a MMKP and then derived a sub-optimal polynomial-time heuristic algorithm based on Lagrange multipliers. • Through simulation we showed our scheme performed better than a link quality-based scheme but did not reach the optimal solution as expected. Future work • An adaptive scheme to adjust the boundary of DL access zone and transparent zone needs to be added in order to make scheme more complete. Our pursuit for this scheme along with more extensive simulation study is left for future works.

  20. Thank you very much

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