IEEE 802.16 Mesh Networks排程之設計

Abstract

Abstract IEEE 802.16 is the new wireless standard, and it has some advantages, including wider coverage, higher bandwidth, and QoS supporting. As the new wireless last mile technology, there are two established modes for IEEE 802.16. One is PMP (point to multipoint) another is Mesh, and in this paper we focus on Mesh mode. Traditionally, Mesh has two scheduling modes, centralized and distributed. Based on the previous research, we propose the combined scheduling mode. Time frames are managed by BS (Base Station) centrally, and select the shortest path from source to destination, and implement the Spatial Reuse [8] mechanism. On the other hand, we want to reduce end-to-end delay of the QoS type UGS (Unsolicited Grant Service). We propose the Expedited Queue to cut down the transmission time. As similar as bypass mechanism, data not transmitted hop by hop, but transmitted to destination in a frame time as possible. We can prove that Expedited Queue reduces a lot of end-to-end delay in our simulation. In this paper, we also compare two different time frame schedulers, PQ (Priority Queue) and WRR (Weighted Round Robin). When mesh network in the heavy load, we find that the low priority type has starvation problem. In our research, simulation results show that WRR is more suitable than PQ in the heavy load, and WRR solves the starvation of low priority type like BE (Best Effort).