Hybrid user association for maximising energy efficiency in heterogeneous networks with human-to-human/machine-to-machine coexistence

摘要

In this study, a hybrid user association scheme for maximising energy efficiency is proposed in a wireless uplink heterogeneous network with human-to-human and machine-to-machine communications coexistence. Different from conventional user association algorithms, the authors consider access control protocol for both the human-type-communications (HTCs) users equipments' (UEs) and machine-type-communications (MTCs) UEs according to their characteristics during user association phase, i.e. a contention-free access mechanism for HTC UEs and a random access based on access class barring mechanism for MTC UEs. They formulate the user association problem as a maximisation of the overall UEs' energy efficiency in consideration of both the HTC and MTC UEs' quality of service (QoS) guarantees and load balance among base stations simultaneously. To solve the problem, they propose a distributed iterative algorithm which adopts both the matching theory and the dual decomposition theory, and prove its convergence. Finally, simulation results show that their proposed user association scheme not only outperforms existing schemes in terms of the load balance and the overall energy efficiency but also achieves the same performance as exhaustive search in the case of less number of UEs, while satisfying both the HTC and MTC UEs' QoS requirements.