Decentralized traffic management for heterogeneous networks with opportunistic unlicensed spectrum sharing

Abstract

This paper studies how to maximize the per-user-based throughput in an M-tier heterogeneous wireless network (HetNet) by optimally managing traffic flows among the access points (APs) in the HetNet. The APs in the first M − 1 tiers can use the licensed spectrum at the same time whereas they share the unlicensed spectrum with the APs in the Mth tier by the proposed opportunistic CSMA/CA protocol. The APs that access the licensed and unlicensed spectra simultaneously are able to integrate their spectrum resources by the carrier aggregation technique. For an AP in each tier, the tight bounds on its mean spectrum efficiencies in the licensed and unlicensed spectra are derived in a low-complexity form for general random channel gain and AP association weight models, and they can provide some insights into how channel gains, AP association weights and void AP probabilities affect the mean spectrum efficiencies of APs. The per-user throughput based on the mean spectrum efficiencies in the licensed and unlicensed spectra is found and maximized by the proposed decentralized traffic management scheme. Numerical results show that the mean spectrum efficiencies and the per-user throughput can be significantly improved by the proposed decentralized traffic management scheme.