Hybrid Power Line/Wireless System with Optimal Subcarrier Permutation under Uniform or Optimal Power Allocation

This paper studies optimal subcarrier permutation in hybrid power line/wireless systems to either maximize the achievable data rate or minimize the average bit error probability (BEP). In order to better exploit the frequency selectivity of power line and wireless media, subcarrier permutation is optimized under uniform or optimal power allocation over an orthogonal frequency-division multiplexing scheme using maximal-ratio combining. Different from previous works, we demonstrate that the normalized signal-to-noise (nSNR) must be considered instead of the SNR and prove that it can be extended to cases where the minimization of the average BEP and optimal power allocation are considered. Moreover, we show that subcarrier permutation and power allocation problems can be assumed to be decoupled. Numerical results show that performance gains associated with subcarrier permutation become more relevant as the frequency selectivity of the nSNRs increases. In addition, the optimal subcarrier permutation is more effective for minimizing the average BEP than maximizing the achievable data rate and yields similar improvement under the usage of uniform and optimal power allocations.