Multiple Connectivity and Spectrum Access Utilisation in Heterogeneous Small Cell Networks

摘要

In the context of heterogeneous and small cell networks, users will have the possibility to connect to multiple radio access (RA) carriers that will be available by a dense deployment of RA infrastructure consisting of high-power and low-power access nodes. Determining which RAs a user should be associated with and select from, for its downlink transmissions, depends on the long-term and short-term data rates that these RAs may offer to the user. In this study the multi-RA association and utilisation is decomposed into a multi-RA to user association problem that assigns multiple RAs to users, and a multi-RA selection problem that determines which of the assigned RAs should be used at any time for the user transmissions. As a solution to the first problem, we propose a distributed dual-based spectrum access scheme (DSA) that considers multi-connectivity, whilst, the second problem is solved by means of a heuristic multi-RA selection scheme that utilise different multi-radio transmit diversity (MRTD) schemes while taking into account different inter-cell interference coordination (ICIC) schemes. Our two-step approach is evaluated by means of simulations which demonstrate cell- edge user throughput performance improvements that exceed 100 % when the multi-connectivity DSA is employed. Further significant user rate and energy efficiency improvements up to 69 and 38 % respectively can be achieved when MRTD is combined with ICIC.