Adaptive downlink and uplink channel split ratio determination for TCP-based best effort traffic in TDD-based WiMAX networks

In this paper, we study the determination of downlink (DL) and uplink (UL) channel split ratio for Time Division Duplex (TDD)-based IEEE 802.16 (WiMAX) wireless networks. In a TDD system, uplink and downlink transmissions share the same frequency at different time intervals. The TDD framing in WiMAX is adaptive in the sense that the downlink to uplink bandwidth ratio may vary with time. In this work, we focus on TCP based traffic and explore the impact of improper bandwidth allocation to DL and UL channels on the performance of TCP. We then propose an adaptive split ratio (ASR) scheme which adjusts the bandwidth ratio of DL to UL adaptively according to the current traffic profile, wireless interference, and transport layer parameters, so as to maximize the aggregate throughput of TCP based traffic. Our scheme can also cooperate with the base station (BS) scheduler to throttle the TCP source when acknowledgements (ACKs) are transmitted infrequently. The performance of the proposed ASR scheme is validated via ns-2 simulations. The results show that our scheme outperforms static allocation (such as the default value specified in the WiMAX standard and other possible settings in existing access networks) in terms of higher aggregate throughput and better adaptivity to network dynamics.

[1]  Liu Yu,et al.  The improvement of TCP performance in bandwidth asymmetric network , 2003, 14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003..

[2]  Ieee Microwave Theory,et al.  IEEE Standard for Local and Metropolitan Area Networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems Draft Amendment: Management Information Base Extensions , 2007 .

[3]  Hsiao-Hwa Chen,et al.  Adaptive power allocation and call admission control in multiservice WiMAX access networks [Radio Resource Management and Protocol Engineering for IEEE 802.16] , 2007, IEEE Wireless Communications.

[4]  Wanjiun Liao,et al.  Improving TCP performance for asymmetric networks , 2001, ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240).

[5]  Wanjiun Liao.  The behavior of TCP over DOCSIS-based CATV networks , 2006, IEEE Transactions on Communications.

[6]  Randy H. Katz,et al.  The effects of asymmetry on TCP performance , 1997, MobiCom '97.

[7]  Wanjiun Liao,et al.  Adaptive Downlink/Uplink Bandwidth Allocation in IEEE 802.16 (WiMAX) Wireless Networks: A Cross-Layer Approach , 2007, IEEE GLOBECOM 2007 - IEEE Global Telecommunications Conference.

[8]  Wanjiun Liao,et al.  Adaptive slot allocation in DOCSIS-based CATV networks , 2004, IEEE Transactions on Multimedia.

[9]  Shamik Sengupta,et al.  Feedback-based real-time streaming over WiMax , 2007, IEEE Wireless Communications.

[10]  S. Wang,et al.  IEEE standard 802.16: a technical overview of the WirelessMAN/sup TM/ air interface for broadband wireless access , 2002, IEEE Communications Magazine.

[11]  Greg Goth.  Is WiMax's Future Up in the Air? , 2007, IEEE Internet Computing.

[12]  B. Bennett,et al.  Operational Considerations of Deploying Wimax Technology as a Last-Mile Tactical Communication System , 2006, MILCOM 2006 - 2006 IEEE Military Communications conference.

[13]  Jeffrey G. Andrews,et al.  Broadband wireless access with WiMax/802.16: current performance benchmarks and future potential , 2005, IEEE Communications Magazine.