Joint Iterative Blind Self-Interference Cancellation, Propagation Channel Estimation and Decoding Processes in Full-Duplex Transmissions

Abstract

The paper proposes a joint blind iterative Self-Interference (SI) cancellation, propagation channel estimation and decoding algorithm in Full-Duplex (FD) transmissions via feedback of channel estimates and decoded messages combined with the process of Digital Self-Interference Cancellation (DSIC). Different from the conventional algorithm, the proposed blind algorithm simultaneously estimates the self-interference and propagation channels and decodes messages in each decoding iteration of 5G Quasi-Cyclic Low Density Parity Check (QC-LDPC) codes. The temporary propagation channel estimate and decoded message are fed back to improve the self-interference cancellation and also the channel estimation as well as decoding in the next iteration. The results show that the proposed algorithm outperforms the conventional algorithm, especially at high signal to noise ratio (SNR) and small number of symbols, and requires much less processing time and computational complexity while achieving the convergence performance. The results also show that the proposed algorithm is less sensitive to SI level than the conventional algorithm. The paper further proposes a partial feedback scheme, which only use few feedback symbols for channel estimation, to significantly reduce the processing time and computational complexity while maintaining the performance. These good properties seem quite suitable for a use of this proposed blind iterative algorithm for short-length packet FD transmissions in Internet-of-Things (IoT) applications and green communications.

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.…”

“…Next, we will briefly describe the joint iterative blind channel estimation and decoding processes, which were studied in [ 27 ].…”

“…It is not suitable for short-packet FD transmission due to the high estimation error of the SI channel [ 10 ] and power consumption in IoT applications and green communications due to the high latency of the 5G QC-LDPC decoder [ 42 , 43 ]. To overcome these drawbacks, the authors in [ 27 ] proposed a joint iterative algorithm for blind channel estimation and decoding, named the blind feedback scheme. The fundamental process of the blind feedback scheme is that the SI cancellation, intended channel estimation, and decoding processes of the desired signal can benefit from each other through the temporary decoding and feedback loop.…”

“…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.…”