Abstract:  In a single-source single-destination multi-relay MIMO network, the problem to achieve the maximum transmit rate with the total relay power constraint is proved to be nonconvex. This paper proposed two advanced algorithms: TFSA (Target Function Simplified Algorithm) and CCSA (Constrain Conditions Simplified Algorithm), respectively. TFSA transforms the problem into a convex optimization one by approximating eigenvalues of the product of channel matrix and its transposed conjugate matrix, so that traditional convex optimization methods can achieve the optimal numerical solution of this problem. CCSA makes the problem become convex optimization by reducing the constraint set and transforming variables. It achieves a closedform solution with the Lagrange method, so as to implement the tradeoff between the algorithm complexity and system performance. The simulation results show that TFSA approaches performance of the optimal algorithm and CCSA can get performance gains over the existing schemes with a low implement complexity.

Key words: multi input multi output (MIMO), relay networks, transmission rate, amplify-and-forward, beamforming