Instead of achievable rate in the conventional association, we utilize theeffective rate to design two association schemes for load balancing inheterogeneous cellular networks (HCNs), which are both formulated as suchproblems with maximizing the sum of effective rates. In these two schemes, theone just considers user association, but the other introduces power control tomitigate interference and reduce energy consumption while performing userassociation. Since the effective rate is closely related to the load of some BSand the achievable rate of some user, it can be used as a key factor ofassociation schemes for load balancing in HCNs. To solve the associationproblem without power control, we design a one-layer iterative algorithm, whichconverts the sum-of-ratio form of original optimization problem into aparameterized polynomial form. By combining this algorithm with power controlalgorithm, we propose a two-layer iterative algorithm for the associationproblem with power control. Specially, the outer layer performs userassociation using the algorithm of problem without power control, and the innerlayer updates the transmit power of each BS using a power update function(PUF). At last, we give some convergence and complexity analyses for theproposed algorithms. As shown in simulation results, the proposed schemes havesuperior performance than the conventional association, and the scheme withjoint user association and power control achieves a higher load balancing gainand energy efficiency than conventional scheme and other offloading scheme.
展开▼
