Performance Analysis And Research Of Frequency-hopping Multiple-access Communications System With OFDM Scheme

Orthogonal Frequency Division Multiplexing (OFDM) is one kind of communication technology which uses multiple orthogonal carriers to transmit data in parallel ways. Frequency-hopping (FH) communication uses Pseudo Noise (PN) code to control frequency synthesizer, which makes the carrier frequency of transmitted signal hop in certain way and spreads the spectrum of transmitted signal in order to improve the anti-interference capacity. Combining the FH technique and the OFDM technique, we can obtain the FH-OFDM technique which provides high anti-interference and spectral efficiency.This paper has three main points. First of all, it describes the component, feature and performance of the OFDM-FHMA. Based on characteristic function method, the bit error rate (BER) performance of the system is derived in additive white Gaussian noise and Rayleigh fading channels. Secondly, it discusses the BER performance in OFDM (OFDM-MASK-FHMA) system derived in phase modulation. And it makes a comparison with other similar OFDM-MASK-FHMA communication systems. By simulation results, the frequency resource of the proposed system is saved and the BER is decreased, in compared with other similar OFDM-FHMA communication systems. Finally, it discusses the performance effects of phase error on the OFDM-BPSK-FHMA. The diversity receiver is applied in the system to analyze the parameter relationship among the phase error, the number of user, the number of FH and phase error which resulted from the Gaussian noise. And the theoretical average BER is presented. By the simulation results and analysis, the BER performance is degraded by phase error, which results in the error floor. It also shows that the effect of phase error in multi-user system is negligible compared to the multi-access interference (MAI). In addition, the diversity reception has the ability to combat the phase errors.