Fast Feedback and Buffer Congestion Control Improvement for Real-Time Streaming over WiMAX Networks
Wireless broadband technologies provide ubiquitous broadband access to wireless users, enabling services that were available only to wireline users. At the same time, with the steady growth of real-time streaming applications such as video on demand (VoD), voice over IP (VoIP), massive online gaming, and so forth, the IEEE 802.16 standard (commonly known as WiMAX) has emerged as one of the strongest contenders to provide such kind of broadband wireless access services. WiMAX has specified some advanced lard features at physical (PHY) layer techniques and media access control (MAC) layer protocols, which adopted many Quality of Service (QoS) scheduling algorithms, resource allocation, Hybrid ARQ and so on. Moreover, forward error correction (FEC) and automatic repeat request (ARQ) techniques have already specified in the standard and they are used to support real-time streaming services in all kind of channel conditions.
Inside this thesis, we propose an efficient fast feedback algorithm and buffer congestion control improvement scheme for data streaming over WiMAX networks. Two reserved bits in Generic MAC header (GMH) of each MPDU in WiMAX systems are utilized. The first reserved bit is used as a trigger in fast feedback strategy to add more robust coding and choose better feedback channel when the feedback message does not arrive properly within its cycle time trip (CTT) or after timeout. The second reserved bit is used to inform the base station about the serving subscriber stations¡¦ buffers states when their buffers are above the predefine-threshold value.
Increasing number of retrieval of the feedback message, which means we can increase restore-bit-error probabilities within each frame, and then the throughput performance shall increase as well. In addition, by having each subscriber stations or service station¡¦s buffer states knowledge, the BS will be able to provide extra bandwidth allocation to the SSs more efficiency and accuracy.
Keywords: WiMAX, PHY, MAC, Hybrid ARQ, QoS, Generic MAC header, CTT, Fast Feedback, Buffer Congestion Control Improvement, Real-Time streaming.
Advisor:Wen-Shyong Hsieh; Wei-Kuang Lai; Hsiao Kuang Wu; Rung-Hung Gau
School:National Sun Yat-Sen University
School Location:China - Taiwan
Source Type:Master's Thesis
Keywords:real time streaming mac buffer congestion control improvement phy generic header ctt fast feedback qos wimax hybrid arq
Date of Publication:07/29/2008