Hailan Kuang

An Optimal Power-Controlled Topology Control for Wireless Sensor Networks

The efficacy of topology control has been shown to be a vital process to maximize the network lifetime of wireless sensor networks. In this paper, we present a distributed topology algorithm with transmission power adjustment based on optimal number of neighbors to raise the network energy-efficiency and the network throughput by reducing channel competition intensity and simplifying the complexity of initial network topology. In the algorithm, every node can adjust its transmission power level and calculate its optimal transmission power according to the optimal number of neighbors, and a virtual clustering scheme based on optimal transmission power is proposed for network topology control, where the network connectivity is also guaranteed. Analysis and simulation results demonstrate the correctness and effectiveness of our algorithm.

A Vehicle Steering Recognition System Based on Low-Cost Smartphone Sensors

Recognizing how a vehicle is steered and then alerting drivers in real time is of utmost importance to the vehicle and driver’s safety, since fatal accidents are often caused by dangerous vehicle maneuvers, such as rapid turns, fast lane-changes, etc. Existing solutions using video or in-vehicle sensors have been employed to identify dangerous vehicle maneuvers, but these methods are subject to the effects of the environmental elements or the hardware is very costly. In the mobile computing era, smartphones have become key tools to develop innovative mobile context-aware systems. In this paper, we present a recognition system for dangerous vehicle steering based on the low-cost sensors found in a smartphone: i.e., the gyroscope and the accelerometer. To identify vehicle steering maneuvers, we focus on the vehicle’s angular velocity, which is characterized by gyroscope data from a smartphone mounted in the vehicle. Three steering maneuvers including turns, lane-changes and U-turns are defined, and a vehicle angular velocity matching algorithm based on Fast Dynamic Time Warping (FastDTW) is adopted to recognize the vehicle steering. The results of extensive experiments show that the average accuracy rate of the presented recognition reaches 95%, which implies that the proposed smartphone-based method is suitable for recognizing dangerous vehicle steering maneuvers.

VNE-TS: A novel virtual network mapping algorithm in SDN

Network Virtualization allows multiple tenants share physical network resources flexibly. As a newly emerging architecture, Software-defined network (SDN) decouples the control plane and data plane, realizes the efficient control of network traffic. The emergence of SDN provides network virtualization a new solution for virtual network deployment. One of the most challenging issues, called Virtual Network Embedding, is assigning substrate network resources to virtual network topologies. Although there exist some algorithms to solve VN embedding problem, they are not appropriateto the SDN virtualization environment. In this paper, we come up with a VN mapping algorithm VNE-TS for SDN. Our algorithm considers the flow entry capacity of switch which is essential in SDN virtualization environment. Besides, in order to make our algorithm more efficient, we propose the node mapping strategy as well as link strategy to decide the mapping order and select the best substrate node or link. The simulation results show that our algorithm increases the acceptance ratio and revenue while reducing cost came from substrate network.

An efficient backoff algorithm for QoS guaranteeing in wireless networks

Wireless networks are required to guarantee the Quality of Service (QoS), including throughput, fairness, delay, etc. IEEE802.11 MAC protocol employs a typical backoff mechanism, Binary Exponential Backoff (BEB) algorithm, to avoid collisions when multiple users try to access the shared wireless channel. Many works on QoS guaranteeing point out that the BEB algorithm introduces the unfairness and serious delay problem into channel access. To solve the problem above, this paper proposes a novel backoff algorithm, which adopts a retransmission counter to measure the network congestion situation. The proposed algorithm also divides the contention window interval into small intervals, and in different intervals, it leverages different backoff strategies. Performance of this algorithm is compared with BEB and other improved backoff algorithms through simulation. The analysis and simulation results show that the proposed backoff algorithm can provide better QoS guaranteeing in terms of throughput, fairness, and delay.

A generic model of multi-interface and multi-channel for multi-hop wireless networks

The performance of multi-hop wireless networks can be improved through using multi-interface and multi-channel (MIMC). In this paper, a generic model of MIMC (abbreviated as GMM) for multi-hop wireless networks is proposed for NS2. The architecture of GMM consists of an MIMC control sublayer, separated interfaces, and dynamic channels. The MIMC control sublayer manages all interfaces and channels, and provides MIMC services to upper layers. Each separated interface has its own physical layer, MAC layer, link layer, and propagation model so that it can support heterogeneous interfaces. The dynamic channels are shared by all the interfaces, and each interface can be assigned to one or more channels by a preset channel assignment algorithm. Compared with other existing MIMC models, the proposed GMM is more generic and more flexible. The proposed GMM is validated through experiments, and network performances are discussed as well.