Degrees of freedom and sum rate maximization for two mutually interfering broadcast channels
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
Degrees of Freedom for the MIMO Interference Channel
IEEE Transactions on Information Theory
Interference Alignment and Degrees of Freedom of the -User Interference Channel
IEEE Transactions on Information Theory
Gaussian Interference Channel Capacity to Within One Bit
IEEE Transactions on Information Theory
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In this paper, we provide a lower and upper bound for the number of degrees of freedom (DOF) of B multiple-input single-output (MISO) broadcast channels (BC) where each base station (BS) equipped with M antennas supports its corresponding K single antenna users suffering from inter-cell interference. We show that two bounds meet with each other when M = 1 or M ≥ K or B max(M,K)/min(M,K). From the derived result, we learn that the available DOF of the B-user multiple-input multiple-output (MIMO) interference channels is degraded by disabling receive cooperation if and only if M K and B ≤ max(M,K)/min(M,K). We observe that even for that case, the multiple BCs where interference mitigation should be fully performed at the transmitters due to the distributed receive antennas can achieve the DOF more than 2/3 of the DOF of the MIMO interference channels. In addition, the exact number of DOF is derived for two mutually interfering and deterministic broadcast channels in the presence of cognitive BSs. Our result shows that in two BCs interfering with each other, whether receive cooperation exists or not, it does not affect the DOF if one of two transmitters is a cognitive BS.