Spatial diversity impact on the local delay of homogeneous and clustered wireless networks

The law of the time to transmit a packet from a node to its intended receiver, in a wireless network with randomly deployed, multiple-antennas equipped nodes, whose communication is impaired by fading and interference, is investigated. SINR-based coverage at the physical layer is assumed, and the useful signal strength is shaped through either cooperative or non-cooperative beamforming. In particular, two rate-optimizing strategies are exploited, i.e. dominant eigenmode transmission (DET) and interference alignment (IA). The MAC is governed by spatial ALOHA with prescribed medium access probability. The rationale of the work stems from the fact that even in the case of observed individual (per-node) finite-mean random geometric delay (which implies a non-vanishing next-hop throughput) the large population average of such delay may be unbounded in several cases of practical interest. Both the case of homogeneous Poisson point process as well as of clustered Poisson are analyzed, providing monotonicity results on the average local delay achievable under a set of common assumptions on the communication scenario, and varying the number of spatial degrees of freedom available for transmit beamforming and/or interference suppression.