| The medium access control (MAC) protocol is the most important component of any wireless network. Recently, two emerging wireless technologies: Smart antennas equipped ad hoc wireless networks and low power and low cost mission oriented wireless sensor networks have evolved. The first emerging wireless technology would enable high data rate applications such as video streaming, mobile computing, etc. The second emerging wireless technology would facilitate long term sensing applications such as seismic monitoring, habitant sensing, etc. Thus, we need a high throughput MAC protocol in the former case. An energy-efficient MAC protocol, which increases the network lifetime, is suitable in the latter case.;Smart antennas have certain advantages over omidirectional and directional antennas. Smart antennas can focus transmission energy towards a specific angular direction. Smart antennas can also track the user via direction of arrival algorithms. Furthermore, Smart antennas can boost SINR by means of nulling. Using Smart antennas in an ad hoc wireless network, we investigate how the throughput and delay can be improved? We use cross layer feedback between the link layer and the physical layer to develop high performance Smart MAC protocols. We evaluate Smart MAC protocols using both analysis and simulations, where we demonstrate the enormous benefits of using Smart MAC protocols. We also studied the impact of number of antenna elements on the performance of Smart MAC protocols.;Heterogeneous sensor networks, where some sensor nodes have enhanced energy or communication capabilities, will be a reality in the near future. We propose cross layer feedback mechanisms to develop a resource-aware heterogeneous sensor MAC (H-MAC) protocol. Using analysis and simulations, we evaluate the performance of H-MAC in networks of different sizes and densities. Our results are encouraging, and show that H-MAC significantly prolongs the network lifetime and improves the QoS (Quality of Service) of a sensing application.;Our contribution to the wireless research community is in terms of analysis, simulations, and cross layer feedback mechanisms, that resulted in new MAC protocols for emerging wireless technologies. |
