Kosuke Sanada

End-to-end throughput and delay analysis for IEEE 802.11 string topology multi-hop network using Markov-chain model

This paper proposes the analytical expressions for the IEEE 802.11 string-topology multi-hop networks using Markov-chain model. For achieving that, the proposed analysis procedure includes two proposals, which are: (i) Bianchis Markov-chain model is modified for considering a relationship between the backoff timer and frame length, and (ii) the interferences, such as hidden node collision and carrier sensing, among network nodes are expressed by merging the proposed Markov-chain model and airtime expression. The analytical expressions are verified by comparisons with simulation results.

A directional MAC protocol with the DATA-frame fragmentation and short busy advertisement signal for mitigating the directional hidden node problem

This paper proposes a MAC protocol for ad hoc networks with directional antennas for mitigating the directional hidden-node problem. In the proposed protocol, it is possible to tell the communication situation to the directional hidden node by using DATA-frame fragmentations and short busy advertisement signals. As a result, the frame collisions induced by the directional hidden nodes can be reduced and the network throughput is enhanced compared with the conventional protocol. Simulation results show the validity and effectiveness of the proposed protocol.

Multi-channel MAC protocol with channel grouping in wireless ad-hoc network

This paper proposes a MAC protocol using multiple control channels for multi-channel ad-hoc network. In the proposed protocol, all channels are divided into some groups. Each group has a control channel. All nodes hops the control channels for searching a receiver. Because of using multiple control-channels, control frame collisions and the effect of searching overhead are mitigated in the proposed protocol. This paper also derives the optimum number of groups and the optimum contention window size, which maximizes the system throughput. Analysis results and simulation results show the effectiveness of the proposed protocol.

Generalized analytical expressions for end-to-end throughput of IEEE 802.11 string-topology multi-hop networks

Abstract It is an effective approach for comprehending network performance is to develop a mathematical model because complex relationship between system parameters and performance can be obtained explicitly. This paper presents generalized analytical expressions for end-to-end throughput of IEEE 802.11 string-topology multi-hop networks. For obtaining expressions, a relationship between the durations of the backoff-timer (BT) decrements and frame transmission is expressed by integrating modified Bianchi’s Markov-chain model and airtime expression. Additionally, the buffer queueing of each node is expressed by applying the queueing theory. The analytical expressions obtained in this paper provide end-to-end throughput for any hop number, any frame length, and any offered load, including most of analytical expressions presented in previous papers. The analytical results agree with simulation results quantitatively, which shows the verifications of the analytical expressions.

An asynchronous multi-channel MAC protocol with Pulse/Tone exchange for RTS collision avoidance

In multi-channel wireless ad-hoc network, the nodes need to negotiate the channel reservation. Preparing the control channel is one of the strategies for the channel reservation. When the control channel congests due to frame collisions, the control channel is bottleneck for obtaining high throughput. This paper proposes a MAC protocol for multi-channel wireless ad-hoc network for frame collision avoidance on the control channel. The proposed protocol requires only one transceiver in each node, no time-synchronization mechanism among nodes, and few overheads. In the protocol, the node negotiates the channel using the RTS/CTS handshake. The Pulse/Tone exchanges are applied prior to the RTS/CTS handshake for RTS-frame collision avoidance. Additionally, the exposed node problem due to Pulse/Tone exchange is also mitigated, because of the good compatibility between multi-channels and the Pulse/Tone exchanges. It is shown from simulation results that the proposed protocol achieves higher throughput than the previous protocols, especially for heavy offered load condition.