Degrees of Freedom of Signal Alignment for Generalized MIMO Y Channel with General Signal Demands
Jiaju She, Shanzhi Chen, Bo Hu, Yingmin Wang, Weiguo Ma, Xin Su · 2012
In this paper, the original Multiple Input Multiple Output (MIMO) Y channel is extended into a more generalized circumstance, called a generalized MIMO Y channel with general signal demands. The model consists of K(K≥2) nodes each equipped with Mkantennas and an intermediate relay equipped with N antennas. There is no direct link between the nodes. Therefore, supposing that node i and node j (i ≠ j∈{1,2,···, K}) exchange nijsignals, each node has to transmit mk(mk=Σi ≠ kknki, mk≤Mk) signals for other nodes in the MAC phase, and then receive mksignals in the BC phase, via the relay. Then, it's proved that Σk=1Kmkdegrees of freedom (DoF) can be achieved by making use of signal space alignment (SSA) and interference nulling beamforming in this model, when N ≥ 1/2(Σk=1Kmk) and (Mi+Mj) ≥ (N+nij).