Juan Luo

Opportunistic Routing Algorithm for Relay Node Selection in Wireless Sensor Networks

Energy savings optimization becomes one of the major concerns in the wireless sensor network (WSN) routing protocol design, due to the fact that most sensor nodes are equipped with the limited nonrechargeable battery power. In this paper, we focus on minimizing energy consumption and maximizing network lifetime for data relay in one-dimensional (1-D) queue network. Following the principle of opportunistic routing theory, multihop relay decision to optimize the network energy efficiency is made based on the differences among sensor nodes, in terms of both their distance to sink and the residual energy of each other. Specifically, an Energy Saving via Opportunistic Routing (ENS_OR) algorithm is designed to ensure minimum power cost during data relay and protect the nodes with relatively low residual energy. Extensive simulations and real testbed results show that the proposed solution ENS_OR can significantly improve the network performance on energy saving and wireless connectivity in comparison with other existing WSN routing schemes.

Geographic load balancing routing in hybrid Vehicular Ad Hoc Networks

To improve the quality of wireless communication and extend the range of networking applications in Vehicular Ad Hoc Networks (VANET), a hybrid VANET structure is proposed by the combination of the Wireless Mesh Network (WMN) and the Ad Hoc Network. Making use of location information, congestion monitoring and routing switch, we design a geographic load balancing routing in hybrid VANETs, namely GLRV. The mesh routers are deployed to provide backbone supports. Data packet are transmitted in the form of forwarding set to provide multiple forwarding candidates. Three routing switch strategies are designed to ensure the Quality of Service (QoS) under various network connectivity and load scenarios, which are mesh routing when the mesh router is available, geographic greedy routing when the network connectivity is good, and opportunistic routing when the network connectivity is poor. Simulation results show that GLRV can reduce the transmission latency and increase network delivery ratio in hybrid VANET architecture.

Optimal Energy Strategy for Node Selection and Data Relay in WSN-based IoT

Datacollection and dissemination in wireless sensor networks (WSN) for Internet of Things (IoT) require stable multi-hop networking path from source to sink. However, due to the limited energy capacity, relay nodes that run out of battery may cause disconnected path and result in failure of end-to-end data transmission in WSN-based IoT. Therefore, besides saving energy in itself, each sensor involved in the multi-hop transmission activity also needs a feasible strategy to select the relay nodes by leveraging their residual energy and multi-hop IoT network connectivity. In this paper, we first analyze energy consumption model and data relay model in WSN-based IoT, and then propose the concept of “equivalent node” to select relay node for optimal data transmission and energy conservation. A probabilistic dissemination algorithm, called ENS_PD, is designed to choose the optimal energy strategy and prolong the lifetime of whole network. Extensive simulation and real testbed results show that our models and algorithms can minimize energy consumption while guarantee the quality of communication in WSN-based IoT in comparison with other methods.

Efficient data dissemination by crowdsensing in vehicular networks

WiFi access points, mesh routers, wireless sensors and any other wireless routers along the road can serve as roadside unit (RSU), and these RSUs can provide infrastructural supports for wireless access and data dissemination in cyber-transportation systems. We present a hybrid routing scheme in vehicular networks for inter-vehicle, vehicle-to-roadside and inter-roadside data dissemination in urban hybrid networks. First, a location-based crowdsensing framework, including online sensing and offline crowdsourcing, is proposed to retrieve the number and location of available RSU resources. Then, we combine RSU resources and ad hoc solutions to design a routing switch mechanism, which can guarantee quality of data dissemination under various network connectivity and deployment configurations. The performance of our hybrid data dissemination scheme is evaluated using both simulation and real testbed experiments.

Power Control in Distributed Wireless Sensor Networks Based on Noncooperative Game Theory

A game theoretic method was proposed to adaptively maintain the energy efficiency in distributed wireless sensor networks. Based on a widely used transmission paradigm, the utility function was formulated under a proposed noncooperative framework and then the existence of Nash Equilibrium (NE) has been proved to guarantee system stability. To pursuit NE, an NPC algorithm was proposed to regulate heterogeneous nodes with various communication demands given the definition of urgency level. Results from both simulation and real testbed presented the robustness and rapid convergence of NPC algorithm. Furthermore, the network performance can remain in a promising state while the energy consumption is greatly decreased.

Feedback Mechanism Based Dynamic Fingerprint Indoor Localization Algorithm in Wireless Sensor Networks

In location fingerprint based indoor localization system, the received signal strength (RSS) from a set of Wi-Fi access points are used as a unique fingerprint to identify a specific location. However, indoor environment is much more complex and changeable compared to outdoor environment, which leads to larger localization error brought by outdated RSS fingerprints. And re-measuring RSS fingerprints for all locations to maintain a dynamically changing fingerprint database will cause high cost and complexity. To solve this problem, this paper proposes a feedback mechanism based dynamic fingerprint indoor localization algorithm called FMDFLA, it makes RSS fingerprint update timely to cope with changes in the indoor environment. FMDFLA adds distance between grids matrix in offline database which used for scope judgment in online phase. In online phase, we update fingerprint to obtain the “update-point” and “non-update-point”, feedback the RSS of “update-point” to “non-update-point” by using specific method. Furthermore, we update fingerprint for a number of times to obtain the best result of localization. Simulation results show that the localization accuracy and the stability of FMDFLA are higher than traditional CS based localization algorithm and fingerprint localization algorithm in dynamic indoor environment.

H-Mac: A Hybrid MAC Protocol for VANET

This paper proposes a Hybrid Mac protocol(H-MAC) that combines reservation and competition mechanisms to solve the sudden burst data flow at link layer of the VANET(Vehicle Ad hoc Network). Based on the entire network time synchronization, H-MAC protocol divides a frame cycle into two parts. The first part is reservation period in which each node has its own slot. Node could send stable data flow such as beacon packets in the slot. The second part is competition period in which burst data could be sent. Therefore, beacon frames and burst data are divided. H-MAC improves the utilization of channels and reduces delays that caused by collision of the burst data. Simulation results show that the proposed H-MAC protocol provides high reliability of broadcast data at MAC layer.

Wireless Sensor Network InterConnection Design Based on IPv6 Protocol

Application driven Wireless Sensor Network (WSN) has a great prospect, interconnecting WSN to current network infrastructure is the research hotspot. An interconnection method is proposed, which connected large-scale WSN to Internet based on IPv6. To satisfy application requirements, IPv6 address is mapped based on geography location in WSN, and a geography location routing protocol named as Clockwise Grid Routing Protocol (CGRP) is proposed. Simulation results show that CGRP was stable and has a high transmission success rate of routing packet. At last, we described a communication mechanism that used the access gateway to communicate between WSN and Internet. It can not only make WSN addressable by IPv6, but also reduce the high routing overhead, which satisfy the requirements of WSN.

Location-based data aggregation in 6LoWPAN

Location-based information has recently been exploited to assist the aggregated process of data, thereby reducing the spatial redundancy efficiently. The constraints nature in 6LoWPAN becomes one of the major concerns in data aggregation methods. However, traditional CSMA/CA in MAC layer may cause significant transmission and control overhead as well as delay on listening and competing for channels. It is a low efficient way to transfer IPv6 packet due to the big packet header. To overcome these shortages, in this paper, we propose LDAA, a location-based novel data aggregation model that aggregates data from the network layer according to the MAC layer queuing delay. When the queuing delay becomes larger, more packets will be dynamically aggregated into one packet to increase the proportion of application data. Otherwise, the amount of packets involved in aggregation will decrease to improve channels utilization. Simulation results show that our approach could provide better real-time guarantees and reduce data spatial redundancy and energy consumption efficiently.

Opportunistic Energy Cooperation Mechanism for Large Internet of Things

The limited capacity of battery power becomes one of the major constraints in the applications of Internet of things (IoT). Ambient energy harvesting technologies and wireless energy transfer technologies have appeared to resolve the energy supply problem, making it possible for the sensor nodes to operate perpetually. In this paper, we focus on energy efficiency maximization and network throughput optimization problems for energy cooperation in Energy Harvesting Cooperative Wireless Sensor Networks (EHC-WSNs). In order to maximize the efficiency of energy charging phase, a Region-based Proactive Energy Cooperation (RPEC) charging strategy is developed, which is used to charge the life-critical cooperators or receivers in time. By introducing a novel metric that converts optimal forwarder selection from the multi-dimensional problem to one-dimensional problem, an Energy-Neutral-based Opportunistic Cooperative Routing (ENOCR) algorithm is proposed to optimize the relay nodes selection and improve the network throughput. Extensive simulations show that the proposed Opportunistic Energy Cooperation Mechanism (OECM) can significantly improve energy efficiency and network lifetime.