Distributed flexible spectrum use for uncoordinated scenarios

Data rates are growing, and limited availability of spectrum drives wireless systems to use higher center frequencies, leading to smaller cell sizes in wireless communication systems. This requires new solutions for dealing with deployments of much larger number of access points, in particular in places with restricted access. Such uncoordinated deployments are likely to consist of separate, overlapping local area networks, creating a demand for a solution enabling networks to co-exist in the same frequency band. Uncoordinated deployments would benefit significantly on self-organizing Flexible Spectrum Use (FSU), in practice providing some degree of automated network optimization for the system. In our paper, we propose a new distributed FSU mechanism for uncoordinated deployments. The concept is based on creating understanding of the local spectrum usage situation, i.e. introducing local awareness to the access point. The mechanism for creating the local awareness is based on new broadcast control messages, FSU beacons, transmitted by access points, and received by user terminals. In order to achieve fairness in the deployed system a model of a priority based fairness is proposed. The performance of the proposed FSU scheme is analyzed using a system simulator. The results indicate that the proposed FSU scheme is beneficial especially when traditional frequency reuse one approach leads to serious coverage problems.