UC Irvine

Traditional solutions based on Modulation and Coding Schemes (MCSs) have been exhaustively used to improve the performance of wireless systems, striving to reach close to the maximum theoretical limits for channel capacity. In-Band Full-Duplex (IBFD) is an emerging technique that enables a wireless node to transmit and receive at the same time and on the same assigned frequency. Consequently, IBFD wireless communications can potentially double the channel capacity compared to contemporary Half-Duplex (HD) wireless systems. Therefore, IBFD techniques provide new insights into how available resources can be exploited.

In this dissertation, a novel IBFD Medium Access Control (MAC) protocol is presented for Wireless Local Area Networks (WLANs) using IEEE 802.11 Distributed Coordination Function (DCF). The concept of IBFD communications is examined from an unconventional perspective to propose a mechanism that increases the symmetry between uplink (UL) and downlink (DL) traffic loads in order to maximize the utilization of the channel. This dissertation also provides matching analytical and simulation results to show how frame collisions are reduced and how throughput increases when IBFD schemes are implemented for WLANs. Additionally, a collision-free mode enabled by IBFD communications is presented.

In order to study the feasibility and benefits of IBFD networks, this dissertation presents an accurate analytical model based on Discrete-Time Markov Chain (DTMC) analysis for IEEE 802.11 DCF with IBFD capabilities. The model captures all parameters necessary to calculate important performance metrics including latency and link utilization, which quantify enhancements introduced as a result of IBFD solutions. Moreover, two frame aggregation schemes for WLANs with IBFD features are proposed to increase the efficiency of data transmission. The dissertation also presents an analytical model for power consumption in IBFD-WLANs. Energy-efficiency is compared for both HD and IBFD networks. The results via the presented analytical model closely match the results generated by simulation.

Generated results show an increase in the aggregate throughput of the system. While a simple IBFD MAC protocol alone improves the aggregate throughput by an average increase of ~85% compared to standard IEEE 802.11 DCF, introducing the proposed IBFD-MAC scheme to increase traffic symmetry in the system improves the aggregate throughput by an additional average factor of up to ~20%. When using both the analyses presented in this dissertation and the simulator constructed to study the performance in IBFD systems, matching analytical and simulation results with less than 1% average errors confirm that the proposed frame aggregation schemes further improve the overall throughput by up to 24% and reduce latency by up to 47% in practical IBFD-WLANs. The results assert that IBFD transmission can only reduce latency to a suboptimal point in WLANs, but frame aggregation is necessary to minimize it. Power and energy analyses show that IBFD-WLANs consume more power but also have higher energy-efficiency in terms of transmitted data compared to contemporary HD WLANs.