Ad hoc networks with power-controlled multi-antenna systems: MAC protocols and multihop relaying applications

Wireless Networking is quickly becoming an integral part of our lives. This seamless integration has led to a huge demand that will only increase, especially when wireless networks are integrated with the existing cellular communication systems infrastructure. With limited bandwidth, this expansion might not continue. A solution to this problem is to use multi-antenna systems instead of omni-directional ones to increase spatial reuse and consequently to increase capacity. In addition, antenna arrays significantly enhance power consumption and security as well.; In this thesis, we propose novel architectures and protocols aimed at substantially increasing the wireless networking capacity using different kinds of antenna arrays without adding much complexity to the current systems. First, a media access control protocol is proposed for ad hoc network nodes that use directional antennas arrays. The protocol is based on the IEEE 802.11 distributed coordination function (DCF) and uses omni-directional RTS/CTS exchanges to initiate beamformed-mode DATA packet transmissions. A number of protocol variants are proposed and studied. When stations communicate using their antenna arrays, the gain across the link can be very large, and thus transmit power can often be significantly reduced compared with the omni-directional case. We show that the ensuing reduction in interference is a key factor in improving the capacity of an ad hoc network with antenna arrays.; Then, a fully distributed power control protocol is proposed that achieves capacities comparable to the best centralized power control schemes. Performance results are presented that show the significant capacity improvements possible using the proposed protocols. Directional handshaking schemes for interference reduction are introduced and their performance is evaluated.