Yoichi Matsumoto

Enhancement of mesh network oriented IEEE 802.11 MAC protocol

Wireless communications have become very diverse. Mesh network technologies represent a promising architecture for future communications to achieve a ubiquitous wireless access environment. However, when the IEEE 802.11 protocol is used in a mesh network, there are two issues. One is the total throughput degradation, and the other is fairness degradation. We present two methods to address these issues by defining new control packets: the invite to send (ITS) and copied CTS (CCTS) to address the total throughput degradation, and wait to send (WTS) to address fairness degradation. Based on computer simulations, we show that the proposed methods are very effective in improving the total throughput performance and degree of fairness.

Centralized Channel Allocation Technique to Alleviate Exposed Terminal Problem in CSMA/CA-Based Mesh Networks -Solution Employing Chromatic Graph Approach-

This paper proposes a channel allocation principle that prevents TCP throughput degradation in multihop transmissions in a mesh network based on the carrier sense multiple access with collision avoidance (CSMA/CA) MAC protocol. We first address the relationship between the network topology of wireless nodes and the TCP throughput degradation based on computer simulations. The channel allocation principle is discussed in terms of resolution into a coloring problem based on throughput degradation. The number of required channels for the proposed channel allocation principle is evaluated and it is shown that two channels are sufficient for more than 96% simulated multihop patterns. The proposed channel allocation principle is extendable to generic mesh networks. We also clarify the number of required channels for mesh networks. The simulation results show that three channels are sufficient for more than 98% patterns in the generic mesh networks when the number of nodes is less than 10.