Degrees of freedom of two-user MIMO networks with random medium access control mechanism

This paper studies a multiple access network with two users and one Access Point (AP). It is assumed that the users and the AP are equipped with M and N antennas, respectively. To access the network, each user independently decides whether to transmit in a time slot or not (no coordination between users). Focusing on the high SNR behavior of the system, this paper presents the optimal value of the network average Degrees of Freedom (DoF) in different network settings. To this end, after finding an upper-bound for the network average DoF, we propose a transmission scheme (based on interference alignment) which achieves this upper-bound. Some illustrative examples are also presented in the paper.