The Research Of Multimedia Packet Scheduling Algorithms In Wireless Networks

With the rapid development of wireless networks and multimedia technology, notonly transmit data services in wireless networks, but multimedia services packetstransmit and scheduling has become an important research point in wireless networks.In the wireless environment, due to the time-varying bandwidth of wireless channel,transmission delay instability, BER is high and so on, that guarantee quality ofservice(QoS) requirements of multimedia data services has become a big challenge inwireless networks.In this paper, From the beginning of the QoS requirements of multimedia dataservices, summarized the main packet scheduling algorithms in wired network, thenanalyzed the characteristics of wireless networks, including error-prone links, limitedresources. Under the conditions proposed packet scheduling model for wirelessnetworks, many time-slot-allocation-based packet scheduling algorithms described inthe wireless packet scheduling model. However, MAC layer used DCF transmissionmechanism to contend channel access in WLAN, to guarantee the QoS requirementsof multimedia services, EDCA mechanism appeared in802.11e protocol. EDCAmechanism can guarantee QoS of high-priority audio, video streams, but unfair to alltraffic flows. If the high-priority traffic for long periods transmission and needs morebandwidth, the low-priority traffic will be difficult to access the channel, or even notget the channel access opportunities, which would result in starvation of low-prioritytraffic.Against the unfairness problem of packet scheduling in EDCA mechanism,proposed QoS-sensitive packet scheduling algorithm for urgent services. First,depending on the delay range of multimedia flows, packet transmission delay,transmission latency time, presentation of data packet scheduling indicators-packeturgent degree. Then, according to the urgent degree of flows, adjust the AC queueparameters of urgent flows, change the channel access priority of AC, so that urgentflows have more chance to access channel. Finally, we conducted a lot of simulationexperiments,the results show that the proposed packet scheduling algorithm for urgentflows is effectively. In addition, joint time-varying channel state and urgent packetscheduling algorithm, according to channel state to decide whether to use the urgentpacket scheduling algorithm. It can guarantee the total links throughput and links utilization.