CSIT Sharing over Finite Capacity Backhaul for Spatial Interference Alignment

CSI Feedback Reduction for MIMO Interference Alignment

“…• Special case I (Feedback Truncated CSI): In [13], [14], a truncated CSI feedback scheme is proposed in MIMO interference network. The feedback scheme corresponds to the feedback profile L :…”

“…, M e j and N e i are given in ( 7) and ( 12) respectively. Note the above solution structures (14) automatically satisfy the IA constraints (4) for links from Tx i to Rx j, where i ∈ Ω II j Ω III j , ∀j and they satisfy the partial CSI feedback constraints in Problem 1.…”

“…In this section, we study the feasibility conditions of Problem 1 under a feedback profile L and the precoder / decorrelator structure in (14). Based on the feasibility conditions, a low complexity greedy algorithm is further proposed to derive a feedback profile L for a given DoF requirements in the interference network.…”

“…Theorem 1 (Necessary Feasibility Conditions): Given a feedback profile L and the precoder / decorrelator structure in (14), if Problem 1 is feasible, then the following three conditions must be satisfied:…”

“…Schemes which reduce feedback overhead by adapting to the spatial/temporal correlation of CSI are proposed in [11], [12]. While the aforementioned works try to quantize and feedback entire CSI matrices, [13], [14] propose more efficient schemes by exploiting an interesting fact that IA algorithms do not need full knowledge of these matrices and hence CSI matrices can be truncated before quantization. Besides these approaches, a greedy algorithm is also proposed in [15] to reduce the size of the CSI submatrices feedback in MIMO interference networks with single stream transmission.…”