Kewei Sha

Multipath Routing Techniques in Wireless Sensor Networks: A Survey

Multipath routing is an efficient technique to route data in wireless sensor networks (WSNs) because it can provide reliability, security and load balance, which are especially critical in the resource constrained system such as WSNs. In this paper we provide a survey of the state-of-the-art of proposed multipath routing protocols for WSNs, which are classified into three categories, infrastructure based, non-infrastructure based and coding based, based on the special techniques used in building multiple paths and delivering sensing data. For each category, we study the design of protocols, analyze the tradeoff of each design, and overview several representing protocols. In addition, we give a summery of design goals, challenges, and evaluation metrics for multipath routing protocols in resource constrained systems in general.

Using Wireless Sensor Networks for Fire Rescue Applications: Requirements and Challenges

Research in wireless sensor networks has attracted a lot of attention in recent years. Real applications, such as habitat monitoring, environmental and structural monitoring, start to work in practical. In this paper, we argue that wireless sensor network is a very promising technology for fire rescue applications. First, we abstract four specific requirements of this application, including accountability of firefighters, real-time monitoring, intelligent scheduling and resource allocation, and Web-enabled service and integration. To meet these requirements, we propose FireNet, a wireless sensor network architecture for this specific type of application. Based on these requirements and the characteristics of wireless sensor networks, several research challenges in terms of new protocols as well as hardware and software support are examined. Finally, we conclude that wireless sensor network is a very powerful and suitable tool to be applied in this application

Enforcing Privacy Using Symmetric Random Key-Set in Vehicular Networks

Vehicular networks have attracted extensive attentions in recent years for their promises in improving safety and enabling other value-added services. Security and privacy are two integrated issues in the deployment of vehicular networks. Privacy-preserving authentication is a key technique in addressing these two issues. We propose a random keyset based authentication protocol that preserves user privacy under the zero-trust policy, in which no central authority is trusted with the user privacy. We show that the protocol can efficiently authenticate users without compromising their privacy with theoretical analysis. Malicious user identification and key revocation are also described

Adaptive Privacy-Preserving Authentication in Vehicular Networks

Vehicular networks have attracted extensive attentions in recent years for their promises in improving safety and enabling other value-added services. Most previous work focuses on designing the media access and physical layer protocols. Privacy issues in vehicular systems have not been well addressed. We argue that privacy is a user-specific concept, and a good privacy protection mechanism should allow users to select the degrees of privacy they wish to have. To address this requirement, we propose an adaptive privacy-preserving authentication mechanism that can trade off the privacy degree with computational and communication overheads (resource usage). This mechanism, to our knowledge, is the first effort on adaptive privacy-preserving authentication. We present analytical and preliminary simulation results to show that the proposed protocol is not only adaptive but also scalable.

On Sweep Coverage with Minimum Mobile Sensors

For some sensor network applications, the problem of sweep coverage, which periodically covers POIs (Points of Interest) to sense events, is of importance. How to schedule minimum number of mobile sensors to achieve the sweep coverage within specified sweep period is a challenging problem, especially when the POIs to be scanned exceeds certain scale and the speed of mobile sensor is limited. Therefore, multiple mobile sensors are required to collaboratively complete the scanning task. When the mobile sensor is restricted to follow the same trajectory in different sweep periods, we design a centralized algorithm, MinExpand, to schedule the scan path. When the scan path of the existing mobile sensors has been exceeds the length constraint, MinExpand gradually deploys more mobile sensors and eventually achieves sweep coverage to all POIs. When the mobile sensors are not restricted to follow the same trajectory in different sweep periods, we design OSweep algorithm, where all the mobile sensors are scheduled to move along a TSP (Traveling Salesman Problem) ring consists of POIs. We conduct comprehensive simulations to study the performance of the proposed algorithms. The simulation results show that MinExpand and OSweep outperform CSWEEP in both effectiveness and efficiency.

WEAR: a balanced, fault-tolerant, energy-aware routing protocol in WSNs

As more and more real Wireless Sensor Networks (WSN)applications have been tested and deployed over the last five years, the research community of WSN realises that several issues need to be revisited from practical angles, such as reliability and security. In this paper, we address the reliability issue by designing a general energy-efficient, load balanced, fault-tolerant and scalable routing protocol. We first abstract four fundamental requirements of any practical routing protocol based on the intrinsic nature of WSN and argue that none of previous proposed routing protocols satisfies all of them at the same time. A novel general routing protocol called WEAR is then proposed to fill the gap by taking into consideration four factors that affect the routing policy, namely the distance to the destination, the energy level of the sensor, the global location information and the local hole information. Furthermore, to handle holes, which are a large space without active sensors caused by fault sensors, we propose a scalable, hole size-oblivious hole identification and maintenance protocol. Finally, our comprehensive simulation shows that WEAR performs much better in comparing with GEAR and GPSR in terms of eight proposed performance metrics; especially, it extends the Lifetime of the Sensor Network (LSN) about 15% longer than that of GPSR.

SPA: a smart phone assisted chronic illness self-management system with participatory sensing

The medical system has not been able to effectively adapt to the dramatic transformation in public health challenges; from acute to chronic and lifestyle-related illnesses. Although acute illnesses can be treated successfully in an office or hospital, chronic illnesses comprise the bulk of health care needs and require a very different approach. There is overwhelming consensus that the prevention and treatment of cardiovascular disease, diabetes, hypertension, chronic pain, obesity, asthma, HIV, and many other chronic illnesses require substantial patient self-management [2].

Revisiting the lifetime of wireless sensor networks

Prolonging the lifetime of wireless sensor networks (WSN) is one of the most important goals in the sensor network research. A lot of work has been done to achieve this goal; however, current definition of lifetime is either superficial or impractical. In this paper, we take the first step to modeling the lifetime of a wireless sensor network by considering the relationship between the whole sensor network and individual sensors, as well as the importance of different sensors based on their positions. We envision that the proposed lifetime model can be used to evaluate energy-efficient protocols and algorithms, which is validated by simulation results.

Asymmetry-Aware link quality services in wireless sensor networks

Recent studies in wireless sensor networks (WSN) have observed that the irregular link quality is a common phenomenon, rather than an anomaly. The irregular link quality, especially link asymmetry, has significant impacts on the design of WSN protocols. In this paper, we propose two asymmetry-aware link quality services: the neighborhood link quality service (NLQS) and the link relay service (LRS). The novelty of the NLQS service is taking the link asymmetry into consideration to provide timeliness link quality and distinguishing the inbound and outbound neighbors with the support of LRS, which builds a relay framework to alleviate the effects of link asymmetry. To demonstrate the proposed link quality services, we design and implement two example applications, the shortest hops routing tree (SHRT) and the best path reliability routing tree (BRRT), on the TinyOS platform. We found that the performance of two example applications is improved substantially. More than 40% of nodes identify more outbound neighbors and the percentage of increased outbound neighbors is between 14% and 100%. In SHRT, more than 15% of nodes reduce hops of the routing tree and the percentage of reduced hops is between 14% and 100%. In BRRT, more than 16% of nodes improve the path reliability of the routing tree and the percentage of the improved path reliability is between 2% to 50%.

A Secure and Efficient Framework to Read Isolated Smart Grid Devices

With increasing deployments of smart grid systems, a large quantity of energy usage and grid status data have been collected by smart grid devices like smart meters. To secure these critical and sensitive data, it is crucial to prevent unauthorized readings from these devices. Many authentication protocols have been proposed to control access to smart grid devices that are a part of the smart grid data communication network; however, authentication protocols to control readings from the isolated smart grid devices are mostly ignored. In this paper, we propose a secure and efficient framework to enable secure data readings from the isolated smart grid devices based on a two-phase authentication protocol. The framework not only makes use of the smart reader as a bridge to connect the isolated smart grid device and the smart grid cloud, but also considers the physical constraints of all the devices in the system. Security analysis shows that our framework is efficient and secure under most typical attacks, meanwhile it satisfies the hardware constraints of smart grid devices. Comprehensive performance evaluation also validates the efficiency of the proposed framework.