Self-Regulating Spectrum Management: A Case of Fractional Frequency Reuse Patterns in LTE Networks

In recent years, Self-management (Self-X) technologies that fully automate the tasks of managing (i.e. configuring, monitoring, and optimizing) a cellular network are emerging as an important tool in reducing service provider OPEX and CAPEX and will be a distinguishing feature of LTE (Long Term Evolution) networks. In this work, we focus on one such Self-X technology, namely, self-configuration of fractional frequency reuse (FFR) patterns for LTE/WiMAX. We contend that any solution to this problem must meet the following often-conflicting objectives: (1) Computational efficiency: The self-assignment procedure should be efficient and use only local neighborhood information for computation. (2) Controlled cascading and stability: in the event of cell addition or deletion, the impact of recomputing the FFR should be restricted to a well-defined local neighborhood of the base station and should not cascade over the entire network. (3) Optimality of solution: The spectrum utilization resulting from FFR computed should be closest to optimal as possible. We report design, analysis and simulation of distributed algorithms that provide the network designer a flexible tool to tune the above objectives. For each possible choice made by the system designer, our tool delivers a near-optimal spectrum utilization with specific guarantees on the rest of the properties. We report example results using realistic network topologies and our efforts to integrate the algorithms in the ALU LTE Simulator.