Beamforming for heterogeneously equipped nodes in wireless ad hoc networks

It has long been known that adaptive beamforming has the potential to enhance the performance of wireless ad hoc networks significantly. However, due to the decentralized nature of such infrastructure-less networks, it is not straight forward to fully realize the potential performance gains of beamforming in a realistic manner. To this end we devise a fully distributed cross-layer concept, comprising physical and MAC layer functionalities. Our proposed Channel Information Exchange (CIE)-MAC protocol enables to benefit from beam-forming capabilities, such as interference management by means of nulling, thus increasing the spatial reuse. Moreover, it can handle heterogeneous scenarios with nodes which are equipped with different numbers of antennas, including the extreme case of single antenna nodes. The novel CIE-MAC protocol succeeds to avoid common drawbacks of existing protocols, like deafness and hidden terminal problems, and it is designed to operate in realistic fading environments. Simulation results, including a spatio-temporal correlated channel fading model as well as channel estimation errors, illustrate the CIE-MAC capabilities.