Power adjustment and scheduling in OFDMA femtocell networks

Densely-deployed femtocell networks are used to enhance wireless coverage in public spaces like office buildings, subways, and academic buildings. These networks can increase throughput for users, but edge users can suffer from co-channel interference, leading to service outages. This paper introduces a distributed algorithm for network configuration, called Radius Reduction and Scheduling (RRS), to improve the performance and fairness of the network. RRS determines cell sizes using a Voronoi-Laguerre framework, then schedules users using a scheduling algorithm that includes vacancy requests to increase fairness in dense femtocell networks. We prove that our algorithm always terminate in a finite time, producing a configuration that guarantees user or area coverage. Simulation results show a decrease in outage probability of up to 50%, as well as an increase in Jain's fairness index of almost 200%

Coordinated fair resource sharing in dense indoor wireless networks

In dense indoor multi-cell wireless networks, such as WLANs and OFDMA-based femtocell networks (e.g., LTE, WiMAX), the wireless bandwidth waste has become more dramatic due to the large interference and contention occasioned by uncoordinated channel access methods such as CSMA. Coordinating resource allocation in the network can be a good compromise solution to this problem. However, in general, resource allocation in wireless networks is a complex multi-dimensional problem that involves four tasks: client association to select a base station to associate with, antenna beam selection when directional antennas are used, link scheduling to ensure conflict freedom, and power adaptation to reduce mutual interference. In this paper we study the joint optimization of the above four components, and propose a unified conflict-free scheduling algorithm that solves the joint problem with two alternative objectives: (1) power-utility-maximization and (2) fair-throughput-maximization. Our scheduling algorithm can be directly implemented in OFDMA-based femtocell networks. In addition, to enable realistic deployment in WLANs, we design the so-called TD-CSMA, a coordinated access protocol that is compatible with the legacy IEEE 802.11 MAC protocol. With extensive simulations in ns-2 we notably show that our model outperforms some benchmark algorithms on a wide range of metrics. © 2014 IFIP