Ji Hong

Routing Protocol with Optimal Location of Aggregation Point in Wireless Sensor Networks

Abstract A wireless sensor network is typically composed of hundreds, even thousands of tiny sensors used to monitor physical phenomena. As data collected by the sensors are often redundant, data aggregation is important for conserving energy. In this paper, we present a new routing protocol with optimal data aggregation. This routing protocol has good performance due-to its optimal selection of aggregation point locations. This paper details the optimal selection of aggregation point locations.

Status adaptive routing with delayed rebroadcast scheme in AODV-based MANETs

An efficient solution is proposed in this article to determine the best reliable route and to prolong the lifetime of the mobile Ad-hoc networks (MANETs). In the proposed solution, the route discovery process of the Ad-hoc on-demand distance vector routing protocol (AODV) has been modified using a novel delayed rebroadcast scheme. It combines the shortest route selection criterion of AODV with the real network status including the wireless link quality, the remaining power capacity, as well as the traffic load at each node. Simulation results show that the proposed scheme can significantly extend the network lifetime and provide fewer packet losses than the conventional AODV protocol.

Cross-layer optimized Chord protocol for separated ring convergence in MANET

Abstract An optimized Chord protocol is proposed to solve the convergence problem for separated Chord rings over mobile Ad-hoc networks (MANETs). This protocol exploits the information of topological neighbors in routing layer by utilizing a cross-layer design, and periodically detects whether there is any neighbor node that belongs to an alien Chord ring by sending detecting packets. The detection will be confirmed and then the corresponding predecessor node will be found out to initialize convergence of the Chord rings. Theoretical analysis and experiment results show that the proposed algorithm can detect separated Chord rings and implement the convergence process efficiently, and that a significant improvement in the successful lookup ratio is also achieved at an acceptable overhead for the system maintenance. Moreover, the proposed protocol can ensure the stability and scalability of the system.

Novel incremental relaying protocol based on spatial modulation

Abstract This paper presents a novel incremental relaying protocol based on spatial modulation for cooperative transmission over quasi-static rayleigh fading channel, namely spatial modulation incremental relaying (SMIR), which applies the concept of spatial modulation into incremental relaying. In the proposed protocol, information bits are mapped into two information carrying units: 1) a constellation point in the constellation diagram and 2) the spatial domain, i.e. into the location of a particular cooperative user number. The analytical expression of the frame error rate (FER) for SMIR protocol is derived. Simulation results confirm the presented mathematical analysis and show that SMIR protocol gains 2 and 3 dB in signal to noise ratio (SNR) over the conventional protocol for 3- and 5-bit/symbol transmissions respectively. Moreover, under this protocol the system can achieve a much higher throughput, which means that our proposed protocol brings significant gain in performance.

Joint power and spectrum allocation in multi-hop cognitive radio networks

Abstract Various cognitive network technologies are developed rapidly. In the article, the power and spectrum allocation in multi-hop cognitive radio network (CRN) with linear topology is investigated. The overall goal is to minimize outage probability and promote spectrum utility, including total reward and fairness, while meeting the limits of total transmit power and interference threshold to primary user simultaneously. The problem is solved with convex optimization and artificial bee colony (ABC) algorithm jointly. Simulation shows that the proposed scheme not only minimizes outage probability, but also realizes a better use of spectrum.

Systematic energy-balanced cooperative transmission scheme in wireless sensor networks

Abstract Energy efficiency is a critical issue in wireless sensor networks (WSNs). In order to minimize energy consumption and balance energy dissipation throughout the whole network, a systematic energy-balanced cooperative transmission scheme in WSNs is proposed in this paper. This scheme studies energy efficiency in systematic view. For three main steps, namely nodes clustering, data aggregation and cooperative transmission, corresponding measures are put forward to save energy. These measures are well designed and tightly coupled to achieve optimal performance. A half-controlled dynamic clustering method is proposed to avoid concentrated distribution of cluster heads caused by selecting cluster heads randomly and to get high spatial correlation between cluster nodes. Based on clusters built, data aggregation, with the adoption of dynamic data compression, is performed by cluster heads to get better use of data correlation. Cooperative multiple input multiple output (CMIMO) with an energy-balanced cooperative cluster heads selection method is proposed to transmit data to sink node. System model of this scheme is also given in this paper. And simulation results show that, compared with other traditional schemes, the proposed scheme can efficiently distribute the energy dissipation evenly throughout the network and achieve higher energy efficiency, which leads to longer network lifetime span. By adopting orthogonal space time block code (STBC), the optimal number of the cooperative transmission nodes varying with the percentage of cluster heads is also concluded, which can help to improve energy efficiency by choosing the optimal number of cooperative nodes and making the most use of CMIMO.

Dynamic control approaches of spectrum sensing in multi-band cognitive radio networks

Abstract In this paper, the dynamic control approaches for spectrum sensing are proposed, based on the theory that prediction is synonymous with data compression in computational learning. Firstly, a spectrum sensing sequence prediction scheme is proposed to reduce the spectrum sensing time and improve the throughput of secondary users. We use Ziv-Lempel data compression algorithm to design the prediction scheme, where spectrum band usage history is utilized. In addition, an iterative algorithm to find out the optimal number of spectrum bands allowed to sense is proposed, with the aim of maximizing the expected net reward of each secondary user in each time slot. Finally, extensive simulation results are shown to demonstrate the effectiveness of the proposed dynamic control approaches of spectrum sensing.

Scalable peer-to-peer resource discovering scheme for wireless self-organized networks

Abstract Peer-to-peer technologies have attracted increasing research attention with fruitful protocols and applications proposed for wired networks. As to mobile environments, there are currently no mature deployments. A novel resource managing and discovering protocol, Cheer, is proposed to realize scalable and effective peer-to-peer lookup in wireless self-organized networks. Cheer resolves the topologies mismatch problem between peer-to-peer overlay networks and actual nodes distribution, allowing for frequent nodes membership changes. With specially designed resource storage table, Cheer also supports multikey and fuzzy lookup. Its hybrid architecture and improved routing scheme based on small-world theory may realize effective lookup routing. Theoretical analysis and simulation results both prove that Cheer makes using peer-to-peer applications in large-scale self-organized mobile networks feasible and promising.

An Energy-Aware Geographical Forwarding Protocol Utilizing Adaptive Sleeping in Wireless Sensor Networks

This paper proposes a novel energy-aware geographical forwarding protocol utilizing adaptive sleeping, in which each node selects its relay based on a new criterion that is based on its residual energy reserves and its geographical location to guarantee energy efficiency. In addition, this paper presents an adaptive sleep mechanism fully integrated into the new relay criterion, in which each node sleeps for a variable duration based on its residual energy reserves. Simulation results show that the proposed protocol significantly reduces the energy consumption of the network and improves its balance, especially when on heavy traffic load in dense networks. Our protocol is 20 times better in balancing the energy consumption compared with geographical random forwarding protocol.

Resource allocation algorithm in LTE uplink SC-FDMA system for time-varying channel with imperfect channel state information

Abstract In long term evolution (LTE) uplink single carrier frequency division multiple access (SC-FDMA) system, the restriction that multiple resource blocks (RBs) allocated to a user should be adjacent, makes the resource allocation problem hard to solve. Moreover, with the practical constraint that perfect channel state information (CSI) cannot be obtained in time-varying channel, the resource allocation problem will become more difficult. In this paper, an efficient resource allocation algorithm is proposed in LTE uplink SC-FDMA system with imperfect CSI assumption. Firstly, the resource allocation problem is formulated as a mixed integer programming problem. Then an efficient algorithm based on discrete stochastic optimization is proposed to solve the problem. Finally, simulation results show that the proposed algorithm has desirable system performance.