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A Scheme for Scheduling Real-Time Traffic in IEEE 802.16 Networks

Dabiran, Fatemeh | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41336 (19)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Rabiei, Hamid Reza
  7. Abstract:
  8. The IEEE 802.16 is an emerging standard that provides broadband wireless access in metropolitan area networks. The standard facilitates desirable capabilities including mesh topologies and multimedia communications for users.In IEEE 802.16 based mesh networks, there is no explicit uplink and downlink subframes in the physical frame structure and the uplink and downlink traffic scheduling is done within a single time frame. A frame is divided into two subframes: the control subframe and the data subframe. The control subframe is used to carry control messages and the data subframe is used for forwarding data packets to the users.In the mesh mode, two scheduling mechanisms, called centralized and distributed, are defined for each subframe. In the centralized scheduling of data subframes, the base station scheduling algorithm allocates the required bandwidth to each subscriber and set the priority for data packets transmission. However, this scheduling algorithm is undefined in the standard and its implementation is left open to the service providers for proper design based on the desired requirements. One may argue that; because of different characteristics of uplink and downlink traffic, different scheduling methods can be used for each of the traffic types.In this thesis, we focus on the centralized scheduling of data subframes in the mesh mode. We first provide an analysis on the downlink traffic characteristics, and then propose a new algorithm called the Downlink Flow Specifications-aware Scheduling (DFSS). In this algorithm, the flow propagation is tuned for the maximum concurrent transmission rate. This goal is achieved by sending out packets from the Base Station (BS) quickly and distributing the data packets in a chain-like manner into the network. In addition, the algorithm starts sending those packets that have lowest interference with other nodes on their path.The proposed algorithm was evaluated by simulations and the results show that it provides suitable performance in terms of scheduling length, delay, frequency reuse and throughput, while retaining the packet jitter within an acceptable limit
  9. Keywords:
  10. Multimedia Traffic ; Institute Electrical and Electronic Engineers (IEEE)802.16 Standard ; Mesh Mode ; Down Link Traffic ; Centralized Scheduling ; Frequency Reuse

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