In recent years, in-band full duplex (IBFD) has garnered significant attention in wireless communications due to its potential to enhance spectral efficiency. To fully exploit the benefits of IBFD, we design a novel medium access control (MAC) protocol for wireless local area networks (WLANs), which takes into account the realities of asymmetric traffic. However, key challenges involve inter-station interference within asymmetric topologies and wastage of idle time slots under asymmetric traffic conditions. We propose a successive full-duplex communication (SFD) protocol, integrating a CSMA/CA-based uplink selection mechanism and a weight-based downlink selection algorithm to minimize interference probabilities. Furthermore, SFD incorporates a control frame structure, power control algorithm, and successive interference cancellation (SuIC) technique to address the challenge of control frame interference in continuous IBFD communication. Both theoretical analysis and experimental evaluations demonstrate that SFD achieves a 52% increase in throughput compared to the 802.11 Distributed Coordination Function (DCF) with Request to Send/Clear to Send (RTS/CTS) and a 25% improvement over A-Duplex.

Full-Duplex (FD) has been widely recognized as one of the core technologies to enhance the spectral efficiency (SE) in the fifth generation (5G) cellular networks. FD technology (compared to traditional Half-Duplex (HD) technology in theory) can achieve twice the SE of cellular networks, but it introduces severe self-interference (SI) and co-channel-interference (CCI). Multi-domain (antenna-, radio frequency- and digital-domain) SI cancellation (SIC) techniques are proposed to reduce SI to a level close to the noise floor. However, due to the severe impact of Doppler shift and the absence of prior information, eliminating CCI is more challenging than eliminating SI, which has become a prominent obstacle to improving the performance of FD cellular networks. To achieve high-performance CCI cancellation (CCIC), perfect channel state information (CSI) is required. In this paper, we propose a superimposed pilot (SP) scheme for CCIC in FD cellular networks. Moreover, to address the Doppler shifts in FD cellular networks, two new SP-based channel estimation algorithms are developed for CCI channel and uplink/downlink channel, respectively. Furthermore, the Cram´er-Rao Lower Bounds (CRLBs) are also theoretically derived. In addition, we derive maximum achievable sum rate with imperfect CCIC in FD cellular networks. Finally, numerical results show that our proposed SP scheme outperforms the conventional time-multiplexed pilot (TP) scheme in terms of CCIC performance, BER performance and maximum achievable sum rate.

The machine-type communication (MTC) enables a broad range of applications from mission-critical services to massive deployment of autonomous devices in the Internet of Things (IoT) networks. To release more spectrum resources for facilitating the explosive traffic of MTC in ultradense Cellular-IoT (CIoT) networks, full-duplex (FD) technology has been considered as a candidate mechanic due to its respective advantages in terms of the spectral efficiency (SE). Compared with the traditional half-duplex (HD) technology, the FD technology can (in theory) attain twice the SE gain. Nevertheless, the performance of FD technology is severely limited by both the self-interference (SI) and the mutual interference (MI) in the presence of multiple users. What is more serious is that when FD technology is used in a multiuser communication system, the system performance is very sensitive to the service load of the entire network, and it may even appear fragile in an ultrahigh load environment. In this article, we will delve into investigating the performance of the FD technique in the CIoT networks by considering the impacts of a variety of aspects, including the SI cancelation capability (SICC) of the FD-mode devices, the network’s workload, as well as the devices’ distribution density (DDD), the purpose of which is to maximize both the SE and the sum throughput (ST) of the network by optimizing those critical parameters. It is shown that the FD mode is capable of improving the ST of the CIoT networks in either the low-traffic-volume or low-device-density regime, provided that the devices’ SICC could be up to 100dB. At the same time, research results show that further increasing both the devices’ density and the traffic load, even without compromising the FD devices’ SICC, will still help improve the performance superiority of FD technology. Numerical results show that by implementing an appropriate workload-driven mode-selection scheme, we can sufficiently exploit the FD/HD gain according to the instantaneous radio frequency environment.