Description

In this proposed system, efficient spectrum sharing approach is proposed where narrowband channel is sensed frequently. The detected available channel is used for transmitting the aggregated data with effectively. Applied two approaches such as wideband sensing based spectrum sharing scheme and the wideband opportunistic spectrum access scheme where optimal sensing time and power allocation strategy are implemented. Finally analyze the ergodic throughput of the system.The minimum mean-squared error (MMSE) of the signal waveform estimation at the destination node is adopted as the design criterion. We develop two iterative methods Tri-step algorithm and Bi-step algorithm to solve the nonconvex joint source, relay, and receiver optimization problem. Simulation results demonstrate the improved robustness of the proposed algorithms against CSI errors. Weighted Sum-Rate (WSR) maximization in the multiple input multiple output broadcast channel (MIMO-BC). The problem of finding the optimal transmit filter is non-convex and intractable to solve using low complexity methods. Motivated by recent results highlighting the relationship between mutual information and minimum mean square error (MMSE), this paper establishes a relationship between weighted sum-rate and weighted MMSE in the MIMO-BC.