Zhang Heli

Optimal access scheme for mobile vehicular small cells in layered heterogenous networks

Vehicular networks have been considered as an important compliment in providing ubiquitous communication services to the future wireless networks. Existing vehicular ad hoc networks (VANETs) allow the vehicles to access to Internet by dedicated roadside units (RSUs). In order to resolve the problem resulting from limited RSUs, insufficient resources and unsatisfied user experience, we propose to take the vehicles as special vehicular small cells (VSCs) and integrate them with the layered heterogeneous networks. Furthermore, an accordingly optimal access scheme has been designed for VSC to choose the proper access point in a candidate set. Several important factors have been considered, such as quality of service (QoS) requirements, handover frequency, moving speed, security and cost. Simulation results have proved the effectiveness of our proposed scheme in network throughput, packet loss rate and successful access rate.

Energy aware hierarchical cluster-based routing protocol for WSNs

Abstract Wireless sensor networks (WSNs) are emerging as essential and popular ways of providing pervasive computing environments for various applications. Unbalanced energy consumption is an inherent problem in WSNs, characterized by multi-hop routing and a many-to-one traffic pattern. This uneven energy dissipation can significantly reduce network lifetime. In multi-hop sensor networks, information obtained by the monitoring nodes need to be routed to the sinks, the energy consumption rate per unit information transmission depends on the choice of the next hop node. In an energy-aware routing approach, most proposed algorithms aim at minimizing the total energy consumption or maximizing network lifetime. In this paper, we propose a novel energy aware hierarchical cluster-based (NEAHC) routing protocol with two goals: minimizing the total energy consumption and ensuring fairness of energy consumption between nodes. We model the relay node choosing problem as a nonlinear programming problem and use the property of convex function to find the optimal solution. We also evaluate the proposed algorithm via simulations at the end of this paper.

Resource allocation scheme based on game theory in heterogeneous networks

Abstract As an effective solution for indoor coverage and service offloading from the conventional cellular networks, femtocells have attracted a lot of attention in recent years. This study investigates the resource block (RB) and power allocation in heterogeneous networks (HetNets). Specifically, the concern here is to maximize the signal to interference-plus-noise ratio (SINR) of macrocell and energy efficiency of femtocell while providing the finite interference. In this paper, the system model is divided to two layers, in which the macro base station and clusters constitute the first layer network; femtocells in cluster make up the second layer network. Because of the different model structures, different game theories are used in different layers. Stackelberg game is used in the first layer, and non-cooperation game is used in the second layer. Meanwhile RB and power levels stand for the actions that are associated with each player in the game. The problem of resource allocation is formulated as a mixed integer programming problem. In order to minimize the complexity of the proposed algorithm, the resource allocation task is decomposed into two sub problems: a RB allocation and a power allocation. The result is compared with the traditional methods, the analysis illustrates the proposed algorithm has a better performance regarding SINR and energy efficiency of the heterogeneous networks.