Optimization framework for simultaneous transmit and receive operations in wireless local area network

Abstract

Full duplex communication technology draws substantial interest among wireless network operators due to its ability to increase the network capacity through concurrent transmissions. Despite this advantage, interference issue caused by close distances between stations makes it challenging to integrate simultaneous transmit and receive mode into wireless networks. Motivated by the objective of minimal overhead in full duplex transmissions of access points, we provide an optimization framework to minimize the latest completion time of transmissions. In this problem, we aim to find an optimal schedule of transmissions that maximizes concurrent operations in order to reduce the makespan. We formulate the problem for both single and multiple concurrency assumptions separately. For single concurrency, we provide a mixed integer programming (MIP) model using scheduling based formulation along with a greedy heuristic. Modeling the problem as a matching problem between two disjoint sets of supplies and demands, we develop a linear programming (LP) model with a totally unimodular constraint matrix. We utilize Hopcroft-Karp algorithm for solving the resulting maximum cardinality bipartite matching problem. For multiple concurrency; we formulate a flow based integer programming model, demonstrate properties of the extreme points in its LP relaxation, develop valid inequalities and optimality cuts. As an extension, we add due dates for each station to complete their transmissions and formulate an MIP model and develop an algorithm for this variant. Additionally, we provide a proof for NP-completeness of minimum total tardiness problem with single concurrency. To evaluate the performance of the proposed formulations, we perform a range of computational experiments. Finally, we conduct sensitivity analyses to evaluate the effects of the parameters on the objective value and the solution times.