無線多跳網路中考慮網路負載平衡之跨階層路由演算法設計

Abstract

無線多跳網路，例如IEEE802.11b WLAN，為目前廣為應用的無線傳輸技術。然而，由於無線傳輸具有媒體共用、訊號干擾、通道競爭及傳輸錯誤的特性，使無線多跳網路的效能及產出量受到限制。在近來的相關研究中，傳輸速率控制、傳輸功率控制及空間重用為網路實體層及媒體存取層有效提升無線網路產出效能的網路機制。在本篇碩士論文中，我們觀察到:大部分現有的無線網路路由協定缺少同時針對以上傳輸速率、功率、空間重用機制及無線傳輸特性的通盤考量。 本篇碩士論文中提出一跨階層無線網路路由演算法，其中包含1) 傳輸速率及功率控制演算法TXPR，其依照傳輸連線之SINR值調整相對應的傳輸速率及功率；2) 分散式空間重用演算法DSRC，其依據傳輸連線的品質調整實體載波感測的門檻值以提升網路空間利用度並同時維護傳輸連線的品質。另外我們並提出3) 新的無線路由度量演算法 SRIR，經由SRIR路由度量選出具有較高無線媒體存取頻率及較低訊號干擾的路由路徑，將有效的提升其路徑的網路產出效能。在網路模擬的結果中亦顯示本論文中提出之跨階層無線網路路由演算法不僅有效提升網路的產出量；相較於既有的路由度量演算法，SRIR亦具有較佳的產出效能。

Multi-hop wireless network, such as IEEE 802.11b WLAN, is one of the popular communication technologies. However, the wireless features such as media sharing, interference, channel contention and link-loss, bound the network performance and cause low aggregate throughput in network. In resent researches, there are three basic PHY/MAC mechanisms improving the network throughput, transmit rate control, transmit power control and spatial reused control. In this thesis, we addressed the problem that there are rare routing protocols take all of the interference, spatial reuse and transmit rate and power control into account in multi-hop wireless network. We propose an iterative cross-layer routing algorithm which is combined with 1) the transmit power and rate control algorithm: TXPR, which adjusts the transmit rate and power based on the estimated SINR value for each link, 2) the distributed spatial reuse algorithm: DSRC, which adjust the physical carrier sensing threshold based on the link quality for each transmission, and 3) the new routing metric: SRIR which selects high performance routing paths with high channel access frequency and low interference level. And the simulation experiments also show that our cross-layer routing algorithm with SRIR metric has better network performance in aggregate throughput than existing wireless routing metrics.