Research On Robust Resource Allocation Algorithm For Heterogeneous Wireless Networks

In heterogeneous networks(HetNets),the issue of interference management and resource al ocation(RA)is particularly important.Traditional RA is designed based on considering perfect channel state information(CSI).It is difficult to obtain the accurate CSI due to the influence such as channel randomness,estimation error and link delay.Therefore,how to achieve robust RA under the consideration of imperfect CSI(i.e.,parameter uncertainty)is of major theoretical and practical value.This thesis studies the energy efficiency(EE)based RA algorithms in different scenarios to improve the throughput of the HetNets and reduce the total transmis s io n power consumption.The main contributions of this dissertation are summarized as follows.Firstly,the robust RA algorithm for HetNets with a single femtocell scenario is studied.Under this assumption,the uncertainty of the interference link from the femtocell-transmitter to the macro-receiver is considered.A robust RA model is created by considering the weighted interference outage probability constraint and the maximum transmit power constraint.Assume that the probability distribution model of uncertain parameter is known,the original nonlinear and non-convex optimization problem are transformed into a solvable convex optimization form based on stochastic optimiza t io n theory and Dinkelbach method.The problem is resolved by using the classical convex optimization algorithm.Secondly,the robust RA algorithm for HetNets in a multiple femtocell scenario is studied.This thesis studies the RA problem of multiple femtocells considering the interference outage probability constraint,the maximum transmit power constraint of femtocell BS and the QoS of macrocell users and the FUs.The original problem with uncertainties is transformed into deterministic and convex one by using the Bernstein approximation theory.Then,the optimal solution is obtained by using the Lagrangia n dual principle and the gradient update method.Finally,the robust EE optimization algorithm is studied for HetNets with simultaneous wireless information and power transfer(SWIPT)technology.In order to further improve the operating life of the network and realize green communicat io n,combined with the SWIPT technology,the problem of power al ocation and power splitting coefficient optimization for maximizing the robust EE of HetNets is studied.This thesis studies how to achieve the joint optimization of power al ocation and power splitting control under considering the interference constraint and the QoS of users,and solve the EE optimization problem for energy-limited networks.The proposed robust RA algorithm can further improve the system performance in the HetNets.