In Part II of this two-part paper, a sum-rate-maximizing power allocationwith minimum power consumption is found for multiple-input multiple-output(MIMO) decode-and-forward (DF) two-way relaying (TWR) in a network optimizationscenario. In this scenario, the relay and the source nodes jointly optimizetheir power allocation strategies to achieve network optimality. Unlike therelay optimization scenario considered in part I which features low complexitybut does not achieve network optimality, the network-level optimal powerallocation can be achieved in the network optimization scenario at the cost ofhigher complexity. The network optimization problem is considered in two caseseach with several subcases. It is shown that the considered problem, which isoriginally nonconvex, can be transferred into different convex problems for allbut two subcases. For the remaining two subcases, one for each case, it isproved that the optimal strategies for the source nodes and the relay mustsatisfy certain properties. Based on these properties, an algorithm is proposedfor finding the optimal solution. The effect of asymmetry in the number ofantennas, power limits, and channel statistics is also considered. Suchasymmetry is shown to have a negative effect on both the achievable sum-rateand the power allocation efficiency in MIMO DF TWR. Simulation resultsdemonstrate the performance of the proposed algorithm and the effect ofasymmetry in the system.
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