Autonomous Spectrum Sharing for Unstructured Cellular Networks With Femtocells

To fulfill the needs for high speed ubiquitous coverage, fourth generation networks give rise to dense deployments of short range cells, such as femtocells. Generally deployed in residential or business areas, they complement the macrocellular service, thanks to guaranteed indoor coverage and improved multimedia experience. However, the addition of user-installed femtocells along with macrocells in a shared spectrum band raises critical management issues for controlling interference. In this paper, we address the problem of spectrum resource selection by the femtocells. The aim is to devise autonomous mechanisms for femtocells to adjust their spectrum resources, without manual configuration, so that they achieve high data rates and generate no interference to traditional macrocells. In this work, we are mainly concerned with the performance of solutions that are compliant with standards like Long Term Evolution (LTE). Detailed performance analysis is provided thanks to a complete simulation platform combining a physical layer ray-tracing tool with an upper layer orthogonal frequency division multiple access (OFDMA) simulator. Our results suggest that user channel quality measurements can be used to set the level of sharing between femtocells and macrocells and that finding the correct level of sharing is important for optimal network performance. (C) 2010 Alcatel-Lucent.