FPGA (Field Programmable Gate Array)-based biting differential OFDM (Orthogonal Frequency Division Multiplexing) communication system and method

Abstract

The invention belongs to the technical field of wireless mobile communication, and discloses an FPGA (Field Programmable Gate Array)-based biting differential OFDM (Orthogonal Frequency Division Multiplexing) communication system and method, the communication system is designed by adopting a time-frequency symbol hybrid differential OFDM technology and is built by using an FPGA; the system comprises: a sending end sends a data stream; carrying out channel coding; performing serial-parallel conversion; carrying out time-frequency symbol mixed double-bit differential modulation; mapping constellations; oFDM modulation is carried out; and the RF sending module sends. The receiving end RF receiving module receives the information; oFDM demodulation is carried out; time-frequency symbol mixed incoherent double-bit differential decoding is carried out; performing parallel-serial conversion; performing channel decoding; and recovering the data. According to the method, time-frequency symbol mixed double-bit differential coding and decoding are adopted, only one reference symbol is needed, and the system has the maximum information transmission efficiency; a receiving end does not need to perform channel estimation, so that decoding failure caused by phase inversion of a receiver is avoided; due to the parallelism of the FPGA and the high spectrum utilization rate of the OFDM, existing spectrum resources are fully utilized in high-hybrid communication and high-dynamic scenes, fading resistance is achieved, the bit error rate is low, and stability is good.

Description

technical field [0001] The invention belongs to the technical field of wireless mobile communication, and in particular relates to an FPGA-based head-biting differential OFDM communication system and method. Background technique [0002] At present, in the field of wireless mobile communication technology, wireless spectrum resources are increasingly scarce, and high-speed data networks are required. OFDM (Orthogonal Frequency Division Multiplexing) system, as a multi-carrier communication technology system, divides the channel into several orthogonal sub-channels, converts high-speed serial data signals into parallel low-speed sub-data flow signals, and modulates them into each orthogonal sub-channel. Transmission is carried out on the channel, and the orthogonal signal data is separated at the receiving end by demodulation correlation technology to reduce mutual interference between channels, so the fading effect on each sub-channel can be regarded as flat fading. [0003...

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Problems solved by technology

[0004] Chinese patent CN 112398771 A discloses the signal transmission method, system and equipment of the frequency modulation modulation constant envelope OFDM communication system. In this invention, the quadrature phase shift keying QPSK (Quadrature Phase Shift Keying) modulation method is adopted, but its disadvantage is that there is no method to overcome channel fading, still need to do complex channel estimation

[0005] Through the above analysis, the existing problems and defects of the existing technology are: the communication environment becomes increasingly complex, and the meteorological conditions, terrain, circuit length, buildings, etc. in the process of signal transmission will cause the change of the electric value of the received signal and lead to the change of the received signal. The high-speed relative movement between the receiving and receiving ends will lead to random fluctuations in the amplitude and phase of the received signal. At the same time, the processing efficiency and overhead of the system implementation need to be considered

[0006] The difficulty in solving the above problems and defects is: the design scheme of the existing wireless communication system is complex, and the signal transmission process is easily disturbed by noise

The frequency spectrum of subcarriers in OFDM system overlaps with each other, the communication environment is complex, the wireless channel is time-varying, and the Doppler frequency shift occurs during the transmission process, which will destroy the orthogonality between OFDM subcarriers and reduce the correctness of OFDM communication system transmission symbols.

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