On the Performance of Hybrid Carrier System Based on WFRFT With Power Allocation

Abstract

A unified framework for bridging the power allocation (PA) strategies of single carrier (SC) and orthogonal frequency division multiplexing (OFDM) systems is proposed through the hybrid carrier (HC) scheme based on weighted-type fractional Fourier transform (WFRFT). The performance analyses of multiple indicators are easily achieved in the proposed framework, and the expected performances could be obtained according to the flexible WFRFT order. The closed BER expressions of arbitrary PA strategies in the HC scheme are derived and verified by the simulations, where the equal gain PA and minimum mean square error (mmse) PA are given as the examples. Compared with the OFDM and SC systems, the tradeoff between BER, achievable rate, and peak-to-average power ratio is achieved in the HC system. In addition, an approximate minimum bit error rate method through joining the PA and subcarrier allocation is investigated in the HC scheme as a generalization of the proposed framework. Considering the novel structure, the dynamic threshold could be established in the HC scheme, and thus the tradeoff between BER and complexity is obtained in comparison with the OFDM and SC systems. In order to illustrate the anti-interference characteristics of the proposed HC framework with PA, the BER performance with insufficient cyclic prefix is investigated. The better BER performance is captured in the HC system with the proposed mmse PA strategy.

Keywords

• Single carrier (SC)
• orthogonal frequency division multiplexing (OFDM)
• hybrid carrier (HC)
• weighted-type fractional Fourier transform (WFRFT)
• minimum mean square error (MMSE)
• power allocation (PA)