| Summary: | 碩士 === 國立臺灣科技大學 === 電子工程系 === 97 === In IEEE 802.16 system, the bandwidth is allocated by the Downlink & Uplink scheduler. All Subscriber Stations know when they should send or receive by DL_MAP and UP_MAP. For most existing schedulers, the bandwidth is allocated using the minimum reserved rate maximum sustained rate. If the allocated bandwidth of one queue has reached the maximum sustained rate, there will be no more bandwidth given to it. However, for some light loaded system, there may be some free slots left after the scheduler assigns slots to all packets in queue. Those packets arriving after the scheduling will wait until next frame although there are free slots available. So, we can allocate those free slots to these arriving packets beforehand.
For this, we propose a new allocation method in this thesis.
In this thesis, we divide the allocation work into three rounds. In the first round, the slots are allocated orderly based on maximal sustained rate of each queue. In the second round, the left slots are allocated by Round Robin. If there are free slots left in this frame, the packets in all service queues have been assigned slots after this round. Then, the third round can be continued. For this round, a method for forecasting the packet arrival rate is proposed. Then, the left slots are assigned according to the forecasted arrival rate of each queue. Comparing to other protocols, there is one more round in our protocol. Those packets sent by this round can be delivered almost one frame earlier. This can decrease the average delay of the network and improves its performance clearly.
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