Zhengqiang Wang

Performance Modeling and Analysis of Control Plane for SDN Based on Queuing Theory

Software defined networking is an emerging network paradigm which is considered to be the future evolution trend of network, the network efficiency is determined by the controller. A modeling approach is proposed to evaluate the throughput and time delay of the control plane based on queuing theory. The influence of the number of switches and threads on throughput and latency is analyzed. The accuracy of the model is verified by simulation and the results show that the throughput and time delay increase as the number of switches and threads increase. The throughput and latency can be calculated and evaluated effectively by the proposed model.

Robust power allocation in two-tier spectrum-sharing femtocell networks

This paper investigates the robust power allocation problem in spectrum-sharing femtocell networks, where there is one central macrocell and multiple femtocells. The problem aims to maximize the sum-rate of femtocell user equipments (FUEs) while guaranteeing the quality of service (QoS) of the macrocell user equipment (MUE) in the sparsely deployed scenario and densely deployed scenario of two-tier femtocell networks. Based on ellipsoid sets to describe channel uncertainties, we transform the formulated problem into a deterministic convex optimization problem adopting the worst-case optimization. We give the closed-form optimal robust power allocation of each FUE in the sparsely deployed scenario. In the densely deployed scenario, we obtain the lower bound on the sum-rate of FUEs. Simulation results demonstrate the effectiveness of the proposed robust power allocation algorithm.

Optimal power control in cognitive radio networks under interference power constraint and quality of service constraints

Optimal Power Control in cognitive radio networks (CRNs) under interference power constraint (IPC) and quality of service (QoS) constraints is investigated in this paper. Since the sum rate maximization of cognitive users (SUs) are non-concave maximization problem, it is challenging to design an optimal power control algorithm for the SUs such that the sum rate of the SUs is maximized under the IPC and QoS constraints. In this paper, we transform the sum rate problem into an equivalent maximization problem by variable substitution. Based on the equivalent maximization problem, we prove that only at most one SU with the best effective channel gain will obtain the signal to interference plus noise ratio (SINR) larger than the QoS constraint. Based on this result, we give the optimal power control algorithm for SU in a closed-form expression. Simulation results show that the effectiveness of the proposed power control algorithm.

Power Allocation Algorithm for Heterogeneous Cellular Networks Based on Energy Harvesting

Cellular network can use renewable energy through energy harvesting technology in green communication. In this paper, power allocation for heterogeneous cellular networks (HetNets) with energy harvesting is proposed to maximize the system energy efficiency. Considering the minimal transmit rate of the users and the battery capacity of the system, a low complexity power allocation algorithm based on fractional programming is proposed to maximize the energy efficiency of the system. Simulation results demonstrate the effectiveness of the proposed algorithm.