Joint beamforming and power control for multiantenna relay broadcast channel with QoS constraints
IEEE Transactions on Signal Processing
Linear relaying for the Gaussian multiple-access and broadcast channels
IEEE Transactions on Wireless Communications
The effect of noise correlation in amplify-and-forward relay networks
IEEE Transactions on Information Theory
IEEE Transactions on Communications
Power allocation for a MIMO relay system with multiple-antenna users
IEEE Transactions on Signal Processing
Distributed power allocation in multi-user multi-channel cellular relay networks
IEEE Transactions on Wireless Communications
Duality of MIMO multiple access channel and broadcast channel with amplify-and-forward relays
IEEE Transactions on Communications
Optimal rate region of two-hop multiple access channel via amplify-and-forward scheme
Information Theory, Combinatorics, and Search Theory
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In this paper, we consider multihop multiple access (MAC) and broadcast channels (BC) where communication takes place with the assistance of relays that amplify and forward (AF) their received signals. For a two-hop parallel AF relay MAC, assuming a sum power constraint across all relays we characterize optimal relay amplification factors and the resulting optimal rate regions. We find the maximum sum rate and the maximum rate for each user in closed form and express the optimal rate pair (R1, R2) that maximizes mu1R1+mu2R2 as the solution of a pair of simultaneous equations. We find that the parallel AF relay MAC with total transmit power of the two users P1+P2=P and total relay power PR is the dual of the parallel AF relay BC where the MAC source nodes become the BC destination nodes, the MAC destination node becomes the BC source node, the dual BC source transmit power is PR and the total transmit power of the AF relays is P. The duality means that the rate region of the AF relay MAC with a sum power constraint P on the transmitters is the same as that of the dual BC. The duality relationship is found to be useful in characterizing the rate region of the AF relay BC as the union of MAC rate regions. The duality is established for distributed multiple antenna AF relay nodes and multiple (more than 2) hops as well.