Generalized Access for MIMO Cognitive Radios

Main goal of this work is to give insight on the possible performance improvement arising in the wireless local and/or ad-hoc access from the synergic cooperation of two emerging paradigms, e.g., multi-antenna and cognitive radios. As application scenario, we consider both the faded uplink of a WLAN working in infrastructure-mode, where noncooperative Multi-Antenna cognitive radios attempt to join to a (possibly multi-antenna) access point (AP) and an ad-hoc scenario where each node can communicate with each free node. The target can be twofold and two different approaches are considered. The first is the competitive maximization of own access throughput in the presence of multiple-access Interference (MAI) induced by the other accessing terminals, the second one is the BER minimization. Being the radios cognitive, they are capable to autonomously learn the ambient-context and, then, self-configure their access strategy via suitable power-allocation that is time-frequency-code-space signal-shaping. Furthermore, a generalized approach is developed that allows the node to access with a (possibly hybrid) scheme to the medium by combining different x-DMA strategies under QoS-guaranteed access policy.