Specifically, to optimize spectral efficiency (SE) for single-relay cooperative communication in UWB-based weANseeke seek the relay with the optimal location together with the corresponding optimal power allocation.
This is further highlighted in [18], where an analytical model determines the optimal energy-spectral efficiency tradeoff for the downlink in OFDMA networks.
Taking the abovementioned design criteria into consideration, the ultimate goal of pulse design is to have short pulses with maximal spectral efficiency, optimal time-frequency localization, minimized interference, and best SINR performance for arbitrary channels.
Finally, numerical results validate the effectiveness of the proposed algorithm and show that the optimal energy efficiency and spectral efficiency can be achieved simultaneously in the low SNR region; while in the middle-high SNR region, the maximization of spectral efficiency usually cannot bring optimal energy efficiency at the same time and vice versa.
The vector of transmitted symbols x k, ∀ k ∈ K is an S-dimensional complex circularly symmetric Gaussian random variable with zero mean and covariance matrix P k = 피 x k x k H = diag p k, 1, …, p k, S. Assuming the transmit symbols to be Gaussian and independent is optimal in terms of spectral efficiency, as shown in [26, 27].
We also present a closed form calculation of the optimal symbol period that maximizes spectral efficiency.
Therefore, use of the GI interval with the optimal does not significantly reduce spectral efficiency.
We know from [3] that the optimal precoder to maximize the spectral efficiency of the secondary link is semi-unitary.
If we compare the relay-assisted transmissions with cooperation of BSs for BS RS link ('relayed network-MIMO' in legend) when using the optimal and the suboptimal precoding structure, it can be observed that when using the optimal structure results in terms of spectral efficiency and outage rate are slightly enhanced.
