Joint Semi-Blind Self-Interference Cancellation and Equalisation Processes in 5G QC-LDPC-Encoded Short-Packet Full-Duplex Transmissions

Abstract

The paper proposes a joint semi-blind algorithm for simultaneously cancelling the self-interference component and estimating the propagation channel in 5G Quasi-Cyclic Low-Density Parity-Check (QC-LDPC)-encoded short-packet Full-Duplex (FD) transmissions. To avoid the effect of channel estimation processes when using short-packet transmissions, this semi-blind algorithm was developed by taking into account only a small number (four at least) pilot symbols, which was integrated with the intended information sequence and used for the feedback loop of the estimation of the channels. The results showed that this semi-blind algorithm not only achieved nearly optimal performance, but also significantly reduced the processing time and computational complexity. This semi-blind algorithm can also improve the performances of the Mean-Squared Error (MSE) and Bit Error Rate (BER). The results of this study highlight the potential efficiency of this joint semi-blind iterative algorithm for 5G and Beyond and/or practical IoT transmission scenarios.

Secrecy Coding Analysis of Short-Packet Full-Duplex Transmissions with Joint Iterative Channel Estimation and Decoding Processes

“…Moreover, the SNR of the legitimate receiver is reduced when applying the proposed schemes to decode the intended message, which means that the system not only ensures the security factor well, but it also significantly improves the power consumption by reducing the transmitting power. It is also noted that the proposed blind and semi-blind algorithms have better performances in terms of processing time and computational complexity, which are shown in [ 27 , 28 ]. Therefore, the presence of joint iterative estimation and decoding with blind and semi-blind algorithms at the legitimate receiver is highly recommenced to enhance the security of FD wiretap transmission, especially in short-packet transmission-specific to IoT applications and green communications.…”

“…The conventional blind scheme without feedback and the semi-blind scheme without feedback have been studied in [ 27 , 28 ], respectively, and are presented in Figure 2 . At the receiver side, the received signal will pass through a Digital Self-Interference Cancellation (DSIC) process based on an adaptive filter with the Recursive Least Square (RLS) algorithm [ 36 ] to firstly estimate the SI channel and then reconstruct and cancel the SI component.…”

“…It can be seen that the signal-to-noise ratio at user A is reduced due to the impact of the jamming signal from user E, which leads to an increase in noise at the receiver of user A. Therefore, in addition to the proposed blind feedback scheme, the joint iterative SI channel estimation and equalization processes with the semi-blind algorithm, which have been studied in [ 28 ], should be used at user A in order to eliminate the SI component and estimate the intended signal because the proposed semi-blind algorithm shows its robustness in the low region of the SNR, compared to the blind algorithm. Indeed, the principle of this algorithm is to use at least four pilot symbols between the transceivers (which is a sufficient number of pilot symbols, as shown in [ 28 ]) to perform the channel estimation processes as well as the feedback loop.…”

“…Therefore, in addition to the proposed blind feedback scheme, the joint iterative SI channel estimation and equalization processes with the semi-blind algorithm, which have been studied in [ 28 ], should be used at user A in order to eliminate the SI component and estimate the intended signal because the proposed semi-blind algorithm shows its robustness in the low region of the SNR, compared to the blind algorithm. Indeed, the principle of this algorithm is to use at least four pilot symbols between the transceivers (which is a sufficient number of pilot symbols, as shown in [ 28 ]) to perform the channel estimation processes as well as the feedback loop. At the receiver side of user E, in order to distinguish the decoding behavior of the legitimate receiver (user A) and the eavesdropper (user E) and to also show the robustness of two proposed feedback schemes over the conventional schemes without feedback, user E will only use the blind scheme without feedback and the semi-blind scheme without feedback.…”

“…The results obtained show that their proposed scheme outperforms the punctured scheme in terms of the equivocation rate and the security gap. Last but not least, the authors in [ 27 , 28 ] proposed joint iterative blind and semi-blind algorithms for channel estimations and decoding processes in short-packet FD transmission. The results show that these algorithms outperform the conventional algorithms without feedback in terms of not only Mean Square Error (MSE) and BER performances but also processing time and computational complexity, which are suitable for IoT transmissions and green communications.…”