Multiple access-based collision avoidance MAC protocols have typically used fixed transmission power, and have not considered power control mechanisms based on the distance of the transmitter and receiver in order to improve spatial channel reuse. This work proposes PCMA, a power controlled multiple access wireless MAC protocol within the collision avoidance framework. PCMA generalizes the transmit-or-defer "on/off" collision avoidance model of current protocols to a more flexible "variable bounded power" collision suppression model. The algorithm is provisioned for ad hoc networks and does not require the presence of base stations to manage transmission power (i.e. it is decentralized). The advantage of implementing a power controlled protocol in an ad-hoc network is that source-destination pairs can be more tightly packed into the network allowing a greater number of simultaneous transmissions (spectral reuse). Our initial simulation results show that the PCMA can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2 with potential for additional scalability as source-destination pairs become more localized, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.

This study investigates the potential of using transmission power control in wireless packet networks with differing number of hops between source and destination. Here we exploit the benefits of power control in the context of multi-hop wireless ad hoc type networks with a distributed media access control. For our investigations we choose several general ad hoc network topologies and studied the effect of power control with respect to energy consumption and network capacity. We show that power control largely improves the network capacity and energy savings in all investigated scenarios, and that utilizing a greater number of intermediate hops between base source and destination improves the energy savings, but often causes a tradeoff in capacity, depending on the network topology scenarios.

Multiple access-based collision avoidance MAC protocols have typically used fixed transmission power and have not considered power control mechanisms based on the distance of the transmitter and receiver in order to improve spatial channel reuse. We motivate transmission power control and investigate the challenges involved in implementing power control in multiple access wireless packet networks. For this work, we focus on wireless ad-hoc networks, where the links connecting source destination pairs are all wireless. Power control has been implemented in cellular networks such as CDMA (code division multiple access) for guide some time now. However these protocols depend on centralized control (i.e. base stations) and duplex communications that are not inherently, present in wireless multiple access packet networks. Our simulation results show that implementing power control in a multiple access environment can improve the throughput performance of the non-power controlled IEEE 802.11 by a factor of 2, thus providing a compelling reason for migrating to a new power controlled multiple access wireless MAC protocol standard.