Opportunistic Third-Party Backhaul for Cellular Wireless Networks

TL;DR

This paper proposes an opportunistic backhaul model using third-party open access femtocells to reduce cellular network costs, with a scalable architecture and an optimization algorithm for dynamic user association, showing significant capacity gains.

Contribution

It introduces a novel opportunistic backhaul architecture with a user association algorithm for third-party femtocells, enabling cost-effective capacity expansion in cellular networks.

Findings

Large capacity gains are achievable with even modest adoption of third-party femtocells.

The proposed algorithm efficiently approximates solutions for user association optimization.

Simulations based on real base station data demonstrate the potential benefits.

Abstract

With high capacity air interfaces and large numbers of small cells, backhaul -- the wired connectivity to base stations -- is increasingly becoming the cost driver in cellular wireless networks. One reason for the high cost of backhaul is that capacity is often purchased on leased lines with guaranteed rates provisioned to peak loads. In this paper, we present an alternate \emph{opportunistic backhaul} model where third parties provide base stations and backhaul connections and lease out excess capacity in their networks to the cellular provider when available, presumably at significantly lower costs than guaranteed connections. We describe a scalable architecture for such deployments using open access femtocells, which are small plug-and-play base stations that operate in the carrier's spectrum but can connect directly into the third party provider's wired network. Within the proposed architecture, we present a general user association optimization algorithm that enables the cellular provider to dynamically determine which mobiles should be assigned to the third-party femtocells based on the traffic demands, interference and channel conditions and third-party access pricing. Although the optimization is non-convex, the algorithm uses a computationally efficient method for finding approximate solutions via dual decomposition. Simulations of the deployment model based on actual base station locations are presented that show that large capacity gains are achievable if adoption of third-party, open access femtocells can reach even a small fraction of the current market penetration of WiFi access points.