Power Control in Random Access Ad Hoc Networks

It has been shown that throughput in wireless networks is enhanced by using scheduled transmissions, low transmitter power, and multiple short hops to relay a packet from its source to its destination. There remain several difficulties with this approach. For example, relaying over many hops can cause large packet delays. The routing and slot assignment protocols can also incur a large overhead penalty. Thus, in many cases, it may be necessary to forego this approach and have nodes transmit directly to their intended receivers using random access techniques. If random channel access is used, a receiver may experience interference from packets intended for other radios. Interference can be limited by having nodes reduce their power to their intended destinations. However, without multi-hop routing, the possibility of a receiver experiencing very strong interference remains because it is likely that some transmitters may not be able to reduce their power levels substantially. Any gains achieved by lowering power levels to reduce interference may be countered by the loss of extra link margin that can protect against interference. Also, because frequency hopping (FH) is relatively immune to the near/far problem, it is not clear that a power control strategy which works well for FH systems would also work well for non-hopping networks. In this paper, the throughput attainable from several deterministic and random power control strategies will be considered for non-hopping and frequency-hop random access networks using a power-based capture model for reception.