A methodology to help operators share the spectrum through an enhanced form of Carrier Aggregation

This paper analyses performance aspects and initial methodology for a form of spectrum sharing for cellular operators, based on an enhanced form of Carrier Aggregation. Our motivation is to provide the appropriate framework and encourage systematic spectrum sharing, taking into account Quality of Service (QoS) requirements that the cellular operators may have. The enhanced form of Carrier Aggregation combines statically assigned spectrum at 2 Ghz, with the spectrum resources from a shared spectrum pool. We also identify different forms of shared spectrum - the fee-paying, exclusively shared and free, commonly shared spectrum classes. In modelling the exclusively shared spectrum class, we broadly adopt approaches for the Licensed Shared Access and Priority Access, and focus on 2.3 GHz band. For the common band, we adopt the TV White Space model as a good fit and observe TV UHF channel 40 at 622-630 MHz. Our focus is a typical urban scenario, where macro cells at 2 GHz provide coverage and small cells are deployed to boost the capacity of the system while using the shared spectrum resources. Although the use of lower frequencies for low power nodes and higher frequencies for providing coverage and mobility may seem counter-intuitive, this may be a realistic case due to currently developed spectrum sharing models. To analyse system performance, we use 50%-ile and lowest 5%-ile user throughput as the metric, and define target capacities. The premise is that should free, commonly shared spectrum fail to meet the target capacities, the operator also resorts to the fee-paying, exclusively shared spectrum. Provided the availability of TV White Space channel, our results show that for a low number of users, the operator can meet target capacities by using maximum permitted power levels in that channel, without resorting to the fee-paying, exclusively shared band.