Load-aware user association with quality of service support in heterogeneous cellular networks

In this study, the authors propose a user association scheme with quality of service support for load balancing in heterogeneous cellular networks (HCNs), which jointly considers user´s achievable rate and load level of each BS instead of only utilising the former. To reveal how HCNs should self-organise, the authors formulate it as a network-wide weighted utility maximisation problem. Note that the formulated problem is a non-linear mixed-integer one, and its optimal solutions may be very difficult to be found when it is large-scale. To solve the proposed problem, the authors design a low-complexity distributed algorithm via dual decomposition. Numerical results show that, compared with the range expansion association (REA) and best power association (BPA), the strategy has a higher load balancing level (LBL) and a lower call blocking probability (CBP). Meanwhile, the proposed algorithm occupies a very fast convergence rate when its parameters are set properly.