On the Fundamental Limits of Multi-user Scheduling under Short-term Fairness Constraints

Abstract

In the conventional information theoretic analysis of multiterminal communication scenarios, it is often assumed that all of the distributed terminals use the communication channel simultaneously. However, in practical wireless communication systems -due to restricted computation complexity at network terminals -a limited number of users can be activated either in uplink or downlink simultaneously. This necessitates the design of a scheduler which determines the set of active users at each time-slot. A well-designed scheduler maximizes the average system utility subject to a set of fairness criteria, which must be met in a limited window-length to avoid long starvation periods. In this work, scheduling under short-term temporal fairness constraints is considered. The objective is to maximize the average system utility such that the fraction of the time-slots that each user is activated is within desired upper and lower bounds in the fairness window-length. The set of feasible window-lengths is characterized as a function of system parameters. It is shown that the optimal system utility is non-monotonic and super-additive in window-length. Furthermore, a scheduling strategy

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

“…We note that the proof depends on the structure of virtual users. Hence, the arguments provided in [17] for NOMA systems are not directly applicable.…”

“…The parameter c is the step-size. Lines (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23) verify that the temporal demand constraints and dual feasibility conditions are satisfied. The computational complexity of the algorithm is proportional to the number of virtual users which is O(n 2 ).…”

“…For a given pair of threshold vectors (λ n UL , λ n DL ) the steps in the corresponding ATBS strategy is described in Algorithm 2. In this algorithm, at each time-slot Equations (18) and (19) The proof follows by similar arguments as in the proof of Theorem 4 in [17] and is omitted due to space limitations.…”

“…However, optimal long-term and short-term temporal fair scheduling in FD systems, which is the topic of this paper, have not been investigated before. In our recent works, we have investigated optimal user scheduling under long-term [16] and short-term [17] fairness in non-orthogonal multiple access (NOMA) systems. In this paper, we extend our results to FD systems.…”

“…In this paper, we extend our results to FD systems. Several of the results in [16] and [17] depend on the underlying NOMA system constraints which are essentially different in the FD system model considered in the paper as articulated in Sections III and IV. The main contributions of this paper are as follows:…”