| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 106 === IEEE 802.16 is a standard for wireless communication network. It has the advantages of high transmission rate, long transmission distance and supports various kinds of multimedia services such as voice and video. For these services, IEEE 802.16 defines five classes for quality of service (QoS) which will meet a variety of data service demands. Nevertheless, IEEE 802.16 does not define the scheduling algorithm for these classes. This is left for researchers and communication suppliers to explore. Therefore, it is important to design a good scheduling algorithm to satisfy the requirement of real time and non-real time service.
In real-time packet, a time stamp is included to indicate its deadline. Real-time packets have to be transmitted before their deadlines. Otherwise, they will be discarded. In this paper, an algorithm is proposed that can consider the packet loss rate (PLR) and modulation and coding scheme (MCS) in scheduling. First, the real-time service queues (including ertPS and rtPS) are sorted according to the deadlines of their packets. Then, a packet will be discarded if its deadline is over and the loss rate of the real-time service queues on each subscriber station (SS) will be recorded. The total available bandwidth for each class will be restricted ensure the available bandwidth of non-real time classes. Firstly, the emergency packets of each queue will be scheduled by the priorities according to MCS. Then, the remaining packets in each queue will be scheduled by the priorities according to PLR and MCS. The simulation result shows that the packet loss rate of the real-time service (ertPS and rtPS) can be improved with our scheduling algorithm.
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