Multiple spreading codes based MAC protocol for wireless networks

Abstract

This paper presents a medium access protocol for spread spectrum networks. We have focus on the use of the protocol in MANETs to increase the throughput of the network. We focus on the use of the protocol in mobile ad-hoc networks (MANETs) to increase the throughput of the network. The existing IEEE 802.11 MAC protocol uses spread spectrum technique at the physical layer. However, it uses the same PN code for spreading all the transmitted signals. This makes it impossible for concurrent transmissions to occur in the vicinity of a receiver. We use multiple spreading codes at the physical layer to allow for the simultaneous interference-limited transmissions to take place in the vicinity of the receiver. A node gains information about ongoing transmissions in its neighborhood from the overheard control packets (RTS and CTS). Using this channel-gain information obtained from these transmissions, a node can estimate the required power for its data packets. This power control mechanism has been utilized to further enhance the gains from the use of multiple spreading codes at the physical layer. Simulation results indicate that the modified protocol is able to yield about 80% gain in the throughput.