アドホックネットワークにおけるパケット到達率改善ためのODMRPの拡張

摘要

An Ad Hoc network is a set of wireless terminals and almost of them have the characteristics of mobility and portability. Therefore, even if the communication paths are constructed between wireless terminals, the communications happen to become impossible by terminal moving. In order to improve the data transmission quality in a Ad Hoc network, we propose some enhancements of On-Demand Multicast Routing Protocol (ODMRP) that is originally designed as a multicast protocol for Ad Hoc networks. The ODMRP creates Forwarding Group (FG) nodes for data transmission, which is executed by means of broadcasting only by the FG nodes. However, since the FG nodes are selected only on the shortest path between the source and destination nodes, the date transmission can be broken by FG node moving. In order to cope with this problem, we propose some enhancements of ODMRP, where the nodes, which are located within some range of FG nodes, are added to FG. Moreover, the effectiveness of our proposed method is evaluated comparing with the ODMRP-SG method.%アドホックネットワークは，大部分が移動性・携帯性をもつ無線中継端末の集合体である．それゆえに，無線中継端末間で通信経路を構築しても，端末の移動により通信が不可能となる場合がある．本稿では，アドホックネットワークのマルチキャストプロトコルであるOn-Demand Multicdast Routing Protocol（ODMRP）を拡張し，データ転送品質の向上を図る方式を提案する．ODMRPでは，ソースノードと目的ノードの間の最短ホップ上のノードのみをFG Nodeに選択するため，FG Nodeモの移動により通信が途切れる問題が発生する．そこで，本稿では，FGから一定距離範囲のノードをFGに追加することで，高いデータ到達率の確保を図る方式を提案する．また，ODMRP-SG方式と性能をシミュレーションにより比較し，提案方式の有効性を示す．