Opportunistic Temporal Fair Mode Selection and User Scheduling for Full-duplex Systems

Abstract

In-band full-duplex (FD) communications -enabled by recent advances in antenna and RF circuit design -has emerged as one of the promising techniques to improve data rates in wireless systems.One of the major roadblocks in enabling high data rates in FD systems is the inter-user interference (IUI) due to activating pairs of uplink and downlink users at the same time-frequency resource block.Opportunistic user scheduling has been proposed as a means to manage IUI and fully exploit the multiplexing gains in FD systems. In this paper, scheduling under long-term and short-term temporal fairness for single-cell FD wireless networks is considered. Temporal fair scheduling is of interest in delay-sensitive applications, and leads to predictable latency and power consumption. The feasible region of user temporal demand vectors is derived, and a scheduling strategy maximizing the system utility while satisfying long-term temporal fairness is proposed. Furthermore, a short-term temporal fair scheduling strategy is devised which satisfies user temporal demands over a finite window-length. It is shown that the strategy achieves optimal average system utility as the window-length is increased asymptotically. Subsequently, practical construction algorithms for long-term and short-term temporal fair scheduling are introduced. Simulations are provided to verify the derivations and investigate the multiplexing gains. It is observed that using successive interference cancellation at downlink users improves FD gains significantly in the presence of strong IUI.

Three-Mode Opportunistic Full-Duplex Switching

“…The system models for TNFD and BiFD shown in Fig. 1 are the same as the typical ones in the literature on FD cellular networks [9], [20]- [23]. We consider a multicell scenario; however, for simplicity in illustration, only one exemplary cell is depicted in Fig.…”

“…FD simultaneously transmits both uplink and downlink signals in the same frequency band, while HD transmits uplink and downlink signals in separate time slots within the same band. This essentially results in a time resource division, requiring twice the time resource and leading to a reduction in capacity by a factor of 0.5 [3], [9], [10], [17], [23]. The variables g are determined not only by the channel fading characteristics, but also by the number of antennas in BS and UE and the employed beamforming or MIMO techniques.…”

“…provided in Table 1, the term β BS P (d) l in (3) represents the residual SI power after cancellation assuming that the instantaneous residual SI follows a complex Gaussian distribution with mean = 0 and variance = β BS P (d) l . This is a common model for residual SI of FD [3], [11], [14], [23]. The parameter β BS is a system constant that depends on the specific SI cancellation algorithm employed VOLUME 11, 2023 in the BS, including passive (such as antenna separation), analog and digital cancellations.…”

“…The parameter β BS is a system constant that depends on the specific SI cancellation algorithm employed VOLUME 11, 2023 in the BS, including passive (such as antenna separation), analog and digital cancellations. The term g k,l L k,l P (u) k in (4) represents the inter-UE interference (IUI) power from the kth UE's uplink to the lth UE's downlink assuming that the IUI follows a complex Gaussian distribution with mean = 0 and variance = g k,l L k,l P (u) k [3], [11], [23]. As for the downlink of the kth UE and the uplink of the lth UE, another RB will be allocated, and their SEs are formulated similarly to (3) and (4).…”

Power allocation and temporal fair user group scheduling for downlink NOMA

“…While UF scheduling provides a guarantee for the users' utilities (e.g., throughput) (see [21,28]), TF scheduling ensures a fair temporal share (a.k.a. airtime share) allocation among the users (see [20,31,32]). Additionally, in PF scheduling, the objective is to maximize the sum of the logarithm of users' throughputs.…”