Dynamic spectrum access for small cells

More flexible spectrum access policies that take advantage of the cognitive radio capabilities of small cells are required to improve the suboptimal spectrum utilization at small cells. However, care must be taken to ensure that interference from autonomously deployed small cells is tightly controlled when developing such policies. This paper presents a dynamic spectrum access framework that enables small cells employing a specific Radio Access Technology (RAT) to access the spectrum allocated to other RATs as secondary users without degrading the performance of primary RATs. Secondary small cells opportunistically access unutilized spectrum in their coverage area and the protection of primary RATs is achieved by preventing secondary small cells from accessing spectrum when a potential interference scenario is detected. A system where HSPA and LTE-Advanced are co-deployed is considered. Simulation results show that substantial performance gains for both RATs are achieved by increasing spectrum utilization through secondary access for small cells. Furthermore, gains are achieved without degrading the performance of primary RATs.