Packet scheduling according to shorter packet and emergency packet first for WiMAX network

• Main Authors: Shi-Hong Li, 李世鴻
• Other Authors: Hann-Tzong Chern
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/35c2th

碩士 === 國立臺灣科技大學 === 電子工程系 === 106 === IEEE 802.16 is a standard of wireless communication network. This standard is for networks of high-speed transmission, long-distance communication, and low cost. It provides different types of QOS for different service flows. However, IEEE 802.16 does not define the scheduling method for service flows. Because of limited bandwidth, both the throughput of the real-time traffic and starvation of non-real-time traffic must be solved. So, the main issue is to design a scheduling algorithm which can satisfy demands of all classes. In this thesis, a scheduling algorithm according to deadline and length of packet(DAL) is proposed. By reordering the order of packets in the queues, the packet loss rate can be reduced without affecting the throughput. Each real time packet has its deadline. If a packet is not scheduled before its deadline, it will be discarded to avoid the wasting of bandwidth. If a packet is not scheduled in this frame and over its deadline before the following frame, it will be called emergency packet. First, for the packets of Extended Real-Time Polling Service (ertps) and Real-Time Polling Service (RTPS), all packets are sorted according to their deadlines. Then, all emergency packets are sorted according to packet length. Shorter packet is in front of longer packets. The remaining packets then are sorted according to the packets. In other word, the emergency packet will have higher priority in scheduling. Then, shorter packets have higher priority regardless of emergency or non-emergency. After sorting, BAQL algorithm is applied with weights which the scheduled bandwidth is proportion to queue length and weight. Since the emergency packet is considered, the packet loss rate of the real-time service flow is improved relative to the scheduling algorithm considering only the packet length.