Zhang Yinghai

A call admission control algorithm based on inter-link load balance in heterogeneous networks

“Pseudo Congestion” phenomenon may happen in heterogeneous networks due to the asymmetry of service resource requirements. A new Call Admission Control (CAC) algorithm based on Inter-link Load Balance (ILLB) is proposed to avoid the Pseudo Congestion as well as to improve the network performance. This algorithm aims to balance the Uplink (UL) load and Downlink (DL) load of the heterogeneous networks. Simulation results show that the presented new CAC can decrease the blocking rate effectively compared with the traditional load balance (LB) algorithms.

A k-coverage scheduling scheme in wireless sensor network based on hard-core process in rayleigh fading channel

Sensing coverage is a fundamental design issue in wireless sensor networks (WSNs), while sensor scheduling ensures coverage degree to the monitored event and extends the network lifetime.In this paper, we address k-coverage scheduling problem in dense WSNs, we maintain a connected k-coverage energy efficiently through a novel Hard-Core based Coordinated Scheduling (HCCS), in which hardcore is a thinning process in stochastic geometry that inhibits more than one active sensor covering any area redundantly in a minimum distance. As compared with existing coordinated scheduling, HCCS allows coordination between sensors with little communication overhead. Moreover, due to the traditional sensing models in k-coverage analysis is unsuitable to describe the characteristic of transmit channel in dense WSNs, we propose a novel sensing model integrating Rayleigh Fading and Distribution of Active sensors (RFDA), and derive the coverage measure and k-coverage probability for the monitored event under RFDA. In addition, we analyze the influence factors, i.e. the transmit condition and monitoring degree to the k-coverage probability. Finally, through Monte Carlo simulations, it is shown that the k-coverage probability of HCCS outperforms that of its random scheduling counterpart.

Minimal coverage set detecting algorithm for barrier coverage in wireless sensor networks

Barrier coverage has attracted much attention in the past few years for its various applications, such as border surveillance and intrusion detection. In these applications, it is critical to achieve a strong barrier to ensure detecting any penetration of intruders in an energy-efficient manner so that the barrier can be covered with as few active sensors as possible. In this paper, we study the target detection problem through collaborative detecting under probabilistic sensing model, and propose a MCSD (minimal coverage set detecting) based on Graph theory, which seeks to achieve a strong barrier with minimal active sensors, prolonging the network lifetime. Finally, comprehensive simulations demonstrate that the proposed strategy improves network lifetime effectively.

Decentralized antenna selection with no CSI sharing for multi-cell MU-MIMO systems

Joint User and Antenna Selection (JUAS) with global optimal solution for multi-cell Multi-User Multiple Input Multiple Output (MU-MIMO) systems needs the centralized processing and full Channel State Information (CSI) sharing that both require high capacity backhaul links. In this paper, decentralized JUAS algorithm is considered for multi-cell MU-MIMO systems with Block Diagonalization (BD) precoding. First, by introducing the eigenvalue-based lower bound on the capacity, the global optimal problem of JUAS is reformulated to a new problem that can achieve local optimum. Second, a decentralized fairness-based algorithm is proposed to select the antenna subset with no CSI sharing. Simulation results demonstrate that the proposed algorithm outperforms existing algorithms, such as capacity-based antenna selection and interference-aware user selection, with the same computation complexity. Moreover, the performance losses compared to centralized JUAS with full CSI sharing are marginal.

Sub-carriers bidirectional arrayed handover algorithm

Orthogonal Frequency Division Multiple Access (OFDMA) has already been the main multiple access technology for 3G long term evolution(LTE) and 4G. This paper analyzes characteristics of OFDMA multiple access technology and puts forward a new OFDMA handover algorithm (sub-carriers bidirectional arrayed handover algorithm, SBA). The simulation results show that, during handover process, SBA algorithm proposed in this paper guarantees users in OFDMA system keeping the best channel SIR and QoS. Moreover, SBA algorithm decreases the extra consumption of the handover, and improves OFDMA system performance.

QoS-guaranteed energy saving routing strategy using SDN central control for backbone networks

Abstract This paper targets on energy saving and considers network responding time for backbone networks. The objective is to find idle links as many as possible which can be put into sleep mode under the situation of quality of service (QoS)-guaranteed. This paper proposes a software defined network (SDN) based routing strategy which is especially aimed at QoS-guaranteed energy saving for backbone networks. Under SDN structure, the topology change of network can be detected directly by network controller. And network can be managed more easily and effectively. Based on the open shortest path first (OSPF) protocol, network topology can be changed as little as possible in our strategy. So, the network reconfiguring time caused by the energy saving strategy will be decreased dramatically. This makes the strategy more feasible. Then the backbone network energy optimizing problem is transformed to the maximum clique problem (MCP). And, this paper designed a routing strategy called backbone networks energy saving strategy (BNESS) for energy saving in backbone networks. Simulation result shows that our proposed strategy can save energy and QoS can be guaranteed.

A centralized iterative water filling algorithm in coordinated multipoint OFDMA network

In the wireless mobile communication system, the performance of system throughput is seriously affected by the interference, which can be divided into intra-cell and inter-cell interference. Intra-cell interference could be refrained by orthogonal frequency-division multiple-access (OFDMA). Coordinated multipoint (CoMP) transmission is an effect way to decrease inter-cell interference. A CIWF algorithm is proposed to maximize the system throughput subjected to per-BS power constraint (PBPC) in the downlink OFDMA cellular network supporting CoMP transmission. In this algorithm, co-channel users are selected and the power allocated by per resource block is computed with the confirmation of an analytical derivation. Simulation results demonstrate that the proposed algorithm outperforms traditional ones from the aspect of throughput.

Micro-level urban sensing through mobile data gathering with bus and SDMA technique

With the rapid development of urbanization, traditional urban sensing approaches cannot be sufficient to meet the growing demand of people. To achieve a highly reliable and stable urban sensing network, we propose a micro-level urban sensing schema. Participatory sensing and vehicle sensing are not suitable for this kind of network due to the active participation, the opportunistic or the deployment cost. In our schema, information is collected in a quite small scale by making full use of the existing sensing equipment and deploying a number of wireless distributed nodes. Buses equipped with data processor collect and process the sensing information. Since the reliability and stability of network depends on the energy consumption, the spatial-division multiple access (SDMA) technique is introduced to shorten transmission time in order to reduce sensor energy consumption. We apply linear decorrelator strategy of SDMA technique to reduce sensor energy consumption by equipping each bus station node and bus with dual antenna. Simulation results demonstrate that our approach outperforms the traditional approaches in reducing the energy consumption and then improving the reliability and stability to some extent.