Co-channel full-duplex system based on MPPSK modulation

Abstract

The invention discloses a co-channel full-duplex system based on MPPSK modulation. After the system isolates receiving and sending signals at the radio-frequency head normally, cancellation conducted on leakage self-interference signals is finished on a digital baseband; the cancellation method is conducted after conducting shock filter on MPPSK receiving and sending aliasing signals, extracting and multiplying by coherent carrier, band-pass filtering and digitizing, the result of initial channels of all self-interference channels between the output end of a modulator and a receiver ADC is estimated before formal communication, self-interference offset signals are rebuilt by the adoption of the estimated result, further residual errors are filtered out with the combination of methods of coding rate filtering and double matched filtering of a method of shock filtering-multiplying by the coherent carrier-band-pass filtering-coherent demodulation, and MPPSK receiving signals are demodulated reliably. The co-channel full-duplex system based on MPPSK modulation is free of radio-frequency self-interference cancellation, has low requirements for the dynamic range and sampling rate of the ADC, has high isolation degree for the self-interference signals, and is simple in structure, low in complexity, high in spectrum efficiency and good in demodulation performance.

Description

[0001] technical field [0002] The invention belongs to the field of anti-interference and demodulation in digital communication, and designs a digital communication system, specifically, relates to a co-channel full-duplex system based on MPPSK modulation. Background technique [0003] Duplex technology is the key to two-way communication between communication nodes. The traditional duplex mode is mainly frequency division duplex (FDD) or time division duplex (TDD). The frequency division duplex system uses the same time slot but different frequency bands to transmit data bidirectionally, thereby using the passband and forbidden band of the filter to isolate the interference between the uplink and the downlink; time division duplex uses the same frequency but different time slots to complete bidirectional transmission, thereby Isolate interference between uplink and downlink. In the process of isolating the uplink or downlink, these two duplex methods sacrifice freque...

AI Technical Summary

Problems solved by technology

Taking the 802.11WiFi system as an example, using the most common 12-bit ADC, the analysis must ensure that the transmission power of the self-interference signal is reduced by at least 40dB to ensure that the receiver is not completely occupied by the self-interference signal; If the suppression degree is not high enough, or the instantaneous strength of the leaked self-interference signal is still too large, the number of quantization bits of the ADC must be increased, which will inevitably increase the system cost and the system overhead and computational complexity of the digital baseband cancellation

[0030] 3) Deficiencies and improvements

[0061] We know that symmetrical voice services occupied the dominant business before 2G communication, but with the large-scale commercial use of 2.5G, 3G and now 4G and the large-scale growth of mobile communication data network service demand, the total amount of uplink and downlink bearer services As the asymmetry becomes more obvious, the difference between the total amount of uplink transmission and the downlink increases gradually, that is, there may be a large difference in the information transmission rate between the two, which naturally fits the above-mentioned "code rate Domain filtering" idea, so it is possible to expand the application to the same frequency full-duplex system

Images