Recently, the content-based publish/subscribe (pub/sub) paradigm has been gaining popularity in opportunistic mobile networks (OppNets) for its flexibility and adaptability. Since nodes in OppNets are controlled by humans, they often behave selfishly. Therefore, stimulating nodes in selfish OppNets to collect, store, and share contents efficiently is one of the key challenges. Meanwhile, guaranteeing the freshness of contents is also a big problem for content dissemination in OppNets. In this paper, in order to solve these problems, we propose an incentive-driven and freshness-aware pub/sub Content Dissemination scheme, called ConDis, for selfish OppNets. In ConDis, the Tit-For-Tat (TFT) scheme is employed to deal with selfish behaviors of nodes in OppNets. Moreover, a novel content exchange protocol is proposed when nodes are in contact. Specifically, during each contact, the exchange order is determined by the content utility, which represents the usefulness of a content for a certain node, and the objective of nodes is to maximize the utility of the content inventory stored in their buffer. Extensive realistic trace-driven simulation results show that ConDis is superior to other existing schemes in terms of total freshness value, total delivered contents, and total transmission cost.

A standard-throughput-approaching LDPC decoder has been implemented on a mid-range GPU in this paper. Turbo-Decoding Message-Passing algorithm is applied to achieve high throughput. Different from traditional host managed multi-streams to hide host-device transfer delay, we use kernel maintained data transfer scheme to achieve implicit data transfer between host memory and device shared memory, which eliminates an intermediate stage of global memory. Data type optimization, memory accessing optimization, and low complexity Soft-In Soft-Out algorithm are also used to improve efficiency. Through these optimization methods, the 802.11n LDPC decoder on NVIDIA GTX480 GPU, which is released in 2010 with Fermi architecture, has achieved a high throughput of 295Mb/s when decoding 512 codewords simultaneously, which is close to highest bit rate 300Mb/s with 20MHz bandwidth in 802.11n standard. Decoding 1024 and 4096 codewords achieve 330 and 365Mb/s. A 802.16e LDPC decoder is also implemented, 374Mb/s (512 codewords), 435Mb/s (1024 codewords) and 507Mb/s (4096 codewords) throughputs have been achieved.

A novel near field communication system for s-martphones based on visible light (NECAS) is presented in this paper. NECAS encodes information using combinations of different colors (red, green and blue) and their intensity levels of a smartphone screen, while the receiver captures the light signal via color sensors. In our scheme, a smartphone screen is segmented into four sub-blocks, and each of them can be used to encode information independently. NECAS can be used in a range of Near Field Communication applications such as contactless payments, electronic ticket checking and device paring. We design the color encoding scheme by experimentally profiling the interference of three color channels and the refresh rate of smartphones. We implement a joint decoding algorithm to deal with the significant interference among color channels. With a feedback channel, the retransmission scheme is adopted to improve communication reliability, and the system can dynamically adjust the number of combinations of different colors and intensity levels to fit the communication environment. Our design is validated via extensive experiments using a hardware implementation on Android smartphones and an Arduino platform.

In this paper, we develop a smart phone-based driving behavior evaluation system, named Join Driving, which helps drivers notice how aggressive their driving behaviors are and be aware of the riding comfort level of passengers. The proposed evaluation system is made of two parts: driving events detection and evaluation part and riding comfort level evaluation part. In driving events detection and evaluation part, the proposed system, Join Driving, first presents a model to detect drivers' driving events, based on the data collected from the acceleration, orientation and GPS sensors in smart phones. Then, based on the detected drivers' driving events, Join Driving implements a novel scoring mechanism to quantitatively evaluate how aggressive these driving events are. In riding comfort level evaluation part, the proposed system gives the specific scores to rate passengers' riding comfort level based on ISO 2631. Finally, several practical experiments are conducted to evaluate the effectiveness of the proposed scoring system.

Parallel implementations of Turbo decoding has been studied extensively. Traditionally, the number of parallel sub-decoders is limited to maintain acceptable code block error rate performance loss caused by the edge effect of code block division. In addition, the sub-decoders require synchronization to exchange information in the iterative process. In this paper, we propose loosening the synchronization between the sub-decoders to achieve higher utilization of parallel processor resources. Our method allows high degree of parallel processor utilization in decoding of a single code block providing a scalable software-based implementation. The proposed implementation is demonstrated using a graphics processing unit. We achieve 122.8Mbps decoding throughput using a medium range GPU, the Nvidia GTX480. This is, to the best of our knowledge, the fastest Turbo decoding throughput achieved with a GPU-based implementation.

Recently, the content-based publish/subscribe (pub/sub) paradigm is gaining popularity in opportunistic mobile networks (OppNets) for its flexibility and adaptability. Since nodes in OppNets is controlled by humans, they often behave selfishly with an aim to maximize their own revenues without considering the performance of others. Therefore, stimulating nodes in OppNets to collect, store, and share content efficiently is one of the key challenges under this scheme. Meanwhile, guaranteeing the freshness of content is also a big problem for content dissemination in OppNets. In this paper, in order to solve these problems, we propose an incentive-driven and freshness-aware pub/sub content dissemination scheme, called ConDis (Content Dissemination), for selfish OppNets. In ConDis, the Tit-For-Tat (TFT) scheme is employed to deal with selfish behaviors of nodes in OppNets. ConDis also implements a novel content exchange protocol when nodes are in contact. Specifically, during each contact, the exchange order is determined by the content utility, which is calculated by the direct subscribed value and the indirect subscribed value, and the objective of nodes is to maximize the utility of the content inventory stored in their buffer. Extensive realistic trace-driven simulation results show that ConDis is superior to other existing schemes in terms of total freshness value, total delivered contents, and total transmission cost.

With the development of Internet of Things (IoT), bridging wireless sensor networks (WSNs) and other networks has become important. We divide bridging solutions into two categories: hardware solutions and middleware solutions. Hardware solutions have both low power short distance wireless interfaces and other types of transmission interfaces, e.g. GPRS, 3G/4G, via hardware implementations. This kind of solutions is more stable and more applicable for deployed sensor networks. In middleware solutions, the whole system processes appropriate protocol conversion. This kind of solutions is more independent of hardware, making it easier to be reused in different networks. This paper briefly presents key points of each solution and evaluates advantages and disadvantages of them in terms of different criteria. Eventually, we derive the most appropriate situation for each solution from our comparisons and discussions.

Bluetooth Low Energy (BLE) is a newly emerged technology targeting at low-power, low-cost wireless communications within medium or short range. Since BLE is well designed in favor of Wireless Body Area Networks (WBANs) or Wireless Personal Area Networks (WPANs), fast network access has been considered an important issue for users. This paper studies the performance about BLE device discovery particularly with multiple devices. An analytical model is developed, based on classical ALOHA analysis, in consideration of three advertising channels of BLE. In addition, an enhanced mechanism is proposed enabling BLE scanner/initiator to learn the network contention and adjust parameters accordingly, so as to achieve lower latency. Through extensive simulations, the model has been validated highly accurate, and the proposed mechanism has shown its effectiveness in reducing unexpected long latency in crowd BLE networks.

Bluetooth Low Energy (BLE) is drawing more and more attention due to its recent appearance in consumer electronic products. As a low-power wireless solution, BLE provides attractive energy performance that makes it particularly suitable for portable, battery-driven electronic devices. Although there are some prior arts focusing on BLE energy performance, it still lacks a thorough study on the important aspect of device discovery. Such energy cost, introduced by intermittent scanning or connection setup, could seriously affect the battery endurance ability of the devices. In this paper, we present quantitative analysis on the neighbor discovery energy for BLE. The modeling results that built upon measurement of CC2541 Mini-Development Kit have been validated quite accurate via extensive experiments. In addition, several interesting conclusions are found while investigating the achieved energy model, which may provide precious guidelines to the design of energy-efficient applications for BLE.

Wireless Sensor Networks (WSNs) are embracing an increasing number of real-time applications subject to strict delay constraints. Utilizing the methodology of potential field in physics, in this article we effectively address the challenges of real-time routing in WSNs. In particular, based on a virtual composite potential field, we propose the Potential-based Real-Time Routing (PRTR) protocol that supports real-time routing using multipath transmission. PRTR minimizes delay for real-time traffic and alleviates possible congestions simultaneously. Since the delay bounds of real-time flows are extremely important, the end-to-end delay bound for a single flow is derived based on the Network Calculus theory. The simulation results show that PRTR minimizes the end-to-end delay for real-time routing, and also guarantees a tight bound on the delay.

The resources especially energy in wireless sensor networks (WSNs) are quite limited. Since sensor nodes are usually much dense, data sampled by sensor nodes have much redundancy, data aggregation becomes an effective method to eliminate redundancy, minimize the number of transmission, and then to save energy. Many applications can be deployed in WSNs and various sensors are embedded in nodes, the packets generated by heterogenous sensors or different applications have different attributes. The packets from different applications cannot be aggregated. Otherwise, most data aggregation schemes employ static routing protocols, which cannot dynamically or intentionally forward packets according to network state or packet types. The spatial isolation caused by static routing protocol is unfavorable to data aggregation. To make data aggregation more efficient, in this paper, we introduce the concept of packet attribute, defined as the identifier of the data sampled by different kinds of sensors or applications, and then propose an attribute-aware data aggregation (ADA) scheme consisting of a packet-driven timing algorithm and a special dynamic routing protocol. Inspired by the concept of potential in physics and pheromone in ant colony, a potential-based dynamic routing is elaborated to support an ADA strategy. The performance evaluation results in series of scenarios verify that the ADA scheme can make the packets with the same attribute spatially convergent as much as possible and therefore improve the efficiency of data aggregation. Furthermore, the ADA scheme also offers other properties, such as scalable with respect to network size and adaptable for tracking mobile events.

Bluetooth Low Energy (BT LE) is a low power air interface technology recently released by the Bluetooth Special Interest Group (BT SIG). As a promising radio, BT LE realizes many designing features to fulfill foreseeable requirements of short range communication, such as fast device discovery, power-saving transmitting, encryption and authentication, etc. In this paper, we focus on the modeling and performance analyzing of the device discovery process in BT LE networks. A general model for device discovery on multi-channel is proposed primarily, which is then tailored and simplified for the BT LE case, where three broadcasting channels are used. Via theoretical analysis, our study reveals that some potential pitfalls are residing in the current version of BT LE specification, i.e. improper parameter settings can significantly deteriorate the device discovery latency and increase meaningless energy consumption. We accordingly propose several strategies seeking ways to tackle the problem. The results of extensive simulation show that our strategies can largely reduce undesirable latency and effectively improve the efficiency of device discovery in BT LE networks.

In this paper1, we present the architecture, design, and simulation of an intelligent system for Temperature Monitoring used in metropolitan heating. The system consists of several TelosB-compatible motes, a Nokia uSDCard, and a smart phone. We use TelosB Motes to collect temperature data, and to transport the data to the smart phone. The uSDCard, as the middle layer, connects the smart phone with the ZigBee compatible devices. The smart phone, as the terminal, processes data and manages the TelosB Motes. We use the smart phone as the final terminal because it has a rich set of user interfaces and has access to various kinds of networks, allowing our system to be extended more easily and more user-friendly. In real scenes, our system can reduce the temperature reading fluctuation, and ultimately save the energy consumption for heating companies, providing a better living environment for indoor users.

This paper presents a cross-platform solution of smartphone-based mobile sink for wireless sensor networks, named uSink. With a cross-platform SD card, named uSD card, any smartphone with SD interface can be empowered with the capability to communicate with wireless sensor nodes. Furthermore, a middleware on mobile phone, named uSinkWare, is also designed to provide a typical mobile sink's functionalities, including sensor detection, topology monitoring, routing, sensor data collection and sensor control, etc. Thanks to Qt, uSinkWare can also work on many popular mobile platforms, such as Symbian, Maemo, Windows mobile and embedded Linux. uSink has been implemented, and its performance has been verified by experiments. The experiment results show that current high-end smartphones have enough capabilities to work as mobile sinks, and uSink can be regarded as an attempt on this aspect.

Wireless ad hoc networks can experience significant performance degradation under fading channels. In this work, we present a robust forwarding extension (RFE) for reactive routing protocols in wireless ad hoc networks. RFE is designed to enhance existing reactive routing protocols to provide reliable and energy-efficient packet delivery against the unreliable wireless links. Specifically, we introduce a biased backoff scheme during the route discovery phase to find a robust virtual path, which can provide more cooperative forwarding opportunities. Along this virtual path, data packets are greedily progressed toward the destination through nodes cooperation. We extend the widely used AODV routing protocol with RFE to study its performance. Through extensive simulations, we demonstrate that AODV-RFE effectively improves the reliability, end-to-end energy efficiency and latency.

NA

In this paper, a platform "uSensing" is proposed to support mobile smartphones accessing into wireless sensor networks(WSNs). Since phones have different platforms, e.g. operating systems and CPU processors, it is a challenge to provide a universal platform for smartphones. To solve it, we design novel hardware and software: 1) "uSD": a SD card with zigbee radio; 2) "uSinkWare": a software running on smartphones. The uSD card and uSinkWare consists of uSensing platform. With uSensing, any phones can communicate with WSNs and parse sensor messages. We demonstrate the proposed uSensing in Nokia 5800XM to connect with our WSNs testbed, and evaluate the performance of uSensing through measuring the phone CPU and RAM. The experiment results show that the uSensing can support the smartphones very well to access into the WSNs as the data sink.

Location Based Notification (LBN) aims to alert the users in a target area with the information of interest to them. With a wide range of applications, LBN has been gaining more and more attraction among wireless users and service providers. The mainstream centralized solution based on cellular networks may incur high service cost. In this paper, we present an innovative scheme called Phoenix, which does not rely on any infrastructure, to implement for location based notification service. In our design, devices (users) across the target area form a dynamic peer-to-peer network, where a user can be a message source, a message carrier, or a message subscriber. When a user meets the message carrier, the user can get a copy of the message. Phoenix keeps messages of interest being circulated in the target area, hence users are being notified. To achieve desired notification performance, Phoenix adaptively controls when a user should take the carrier role and help disseminating a message in order to keep the message ``alive", given the fact that message carriers may leave the target area and drop the message. Extensive simulations have been conducted to show the efficacy of Phoenix notification system.

In this poster, we present the architecture, design, and the preliminary simulation results of a system for Metropolitan Heating, via intelligent temperature monitoring. The system consists of several Crossbow TelosB-compatible motes, a Nokia uSDCard, and a smart phone. The motes are used to collect indoor temperature data, which is further relayed to the smart phone's uSD interface. The uSDCard connects the phone with IEEE 802.15.4/ZigBee compatible devices. We use the smart phone as the sink terminal because it has a rich set of user interfaces and can access to different kinds of networks, such as GPRS and 3G. In real scenes, our system can reduce the reading fluctuation, and ultimately save the energy consumed for heating company, achieving a better living condition in the houses.

Service unavailability frequently occurs in dynamic environments, like mobile ad hoc networks (MANET), due to service provider failure, network partitioning, or service scope outage by service provider or user mobility. Service handoff is needed to provide users with alternate matching services in case the original service becomes unavailable. However, existing service discovery solutions for MANET do not address this problem. In this paper, we propose a novel service discovery solution which employs service handoff to facilitate seamless service access for mobile users. The major concerns of service handoff are -- reducing handoff frequency, message cost, and delay as well as balancing loads on service providers. Addressing the above issues are challenging in the dynamic MANET environment. We design a reliable and seamless service discovery solution which employs two different service handoff protocols for different situations. Simulation results show that our protocols can support seamless service access for mobile users at low message cost and time delay while achieving high load balance among service providers.

It has been shown that sink mobility provides an energy-efficient approach to data delivery in wireless sensor networks (WSNs). Most of the approaches targeted to WSNs with mobile sinks (MSs) addressed the problem of data delivery where only a few messages are reported during a long time frame. However, transmitting streaming data is becoming relevant in WSNs, as more and more multimedia sensor nodes - equipped with image, audio, and video capabilities - are being used to characterize the sensing environment. In this scenario, a sequence of messages propagates into the network, hence the problem of finding an effective routing path for delivering data to MSs becomes even more challenging, since the communication overhead for reaching the MS might also be significant. In this paper, we present an energy-efficient streaming data delivery (SDD) protocol for cluster-based WSNs with MSs. Different from existing works, we focus on the mobility support for the delivery of streaming data in hierarchical WSNs. By introducing a cross-cluster handover mechanism and a path redirection scheme, SDD maintains the end-to-end connectivity between the source and the MS, while avoiding the constant transmission of the MS location as it moves across multiple clusters. We evaluate the performance of the proposed SDD protocol, and compare it with a hierarchical cluster-based data dissemination protocol. Simulation results demonstrate its effectiveness, in terms of both end-to-end delivery delay and energy-efficiency.

Contention-based geographic forwarding (CGF) is a state-free communication paradigm for data delivery in multihop wireless sensor networks. CGF is robust to frequent topology changes, scalable to large-scale node deployment and applicable to data-centric applications and resource constrained networks. However, CGF may experience significant performance degradation under unreliable links. In this work, we present the intelligent CGF (ICGF) to combat the channel variation. IGCF combines the advantages of both cooperative and contention-based forwarding, involving multiple neighbours of the sender into the local forwarding to improve the transmission reliability. ICGF differs from existing work in that it extends the cooperation scope intelligently, by sending one additional control message on demand. For this reason, the probability of cooperation void in ICGF is decreased and the single-hop packet progress is increased. The authors conduct extensive simulations to study the performance of the proposed ICGF compared with existing protocols. Simulation results demonstrate that ICGF improves the end-to-end data delivery delay, energy efficiency and data delivery ratio.

How to organize and visualize big amount of text messages stored on one's mobile phone is a challenging problem, since they can hardly be organized by threads as we do for emails due to lack of necessary metadata such as "subject" and "reply-to". In this paper, we propose an innovative approach based on clustering algorithms and natural language processing methods. We first cluster the text messages into candidate conversations based on their temporal attributes, and then do further analysis using a semantic model based on Latent Dirichlet Allocation (LDA). Considering that the text messages are usually short and sparse, we trained the model using a large scale external data collected from twitter-like web sites, and applied the model to text messages. In the end, the text messages are organized as conversations based on their topics. We evaluated our approach based on 122,359 text messages collected from 50 university students during 6 months.

Usually, sensor data needs to be disseminated from the source sensors to data collectors (e.g., sink nodes), making those spatially distributed sensor data available for applications to access. The widespread and ubiquitous nature of mobile devices, e.g., PDAs and cell phones around the world, makes them attractive to be used as mobile data collectors (MDCs) to collect and deliver the sensor data. The goal of this work is to design a dissemination protocol that leads to efficient data delivery from the source sensors to ubiquitous MDCs. We propose the Wait-Focus-Spray (WFS) scheme for wireless sensor networks with ubiquitous MDCs. The main objective of WFS is to balance the data delivery latency and transmission overhead when considering the existence of ubiquitous MDCs. In WFS, we also propose a corresponding mechanism-probabilistic scattered binary spraying (PSBS), to reduce the spatial redundancy when spraying data copies, which can increase the probability of meeting a MDC. Through extensive simulations, we demonstrate that our WFS scheme reduces the transmission cost per message while provides comparable delivery delay compared with the existing work.

Energy efficient multicast routing is one of the fundamental problems in wireless sensor networks (WSNs). Previous work has shown that when the goal is to find multicast trees with minimum transmission cost, the problem becomes NP-complete. In this work, we present a heuristic distributed minimum transmission multicast routing protocol (MTMRP) for WSNs. By introducing the biased backoff scheme and taking advantage of the broadcast nature of wireless communication, MTMRP chooses the forwarding routes which can connect more multicast receivers. Moreover, MTMRP introduces a path handover scheme, which can prune redundant routes for multicast routing. As a result, the multicast transmission cost is reduced in a distributed manner. We conduct extensive evaluations to study the performance of the proposed MTMRP compared with existing protocols. Simulation results demonstrate that our scheme effectively improves the multicast routing energy efficiency.

Cooperative forwarding has been considered as an effective strategy for improving the geographic routing performance in wireless sensor networks (WSNs). However, we observe that existing works do not fully utilize the forwarding opportunities provided by available neighboring nodes. In this paper, we redesign the cooperative forwarding process and present a novel cooperative contention-based forwarding (CCBF) protocol for WSNs. CCBF extends the scope of cooperation and attains the full potential of cooperative forwarding at the expense of sending one additional control message on demand. We conduct extensive simulations to study the performance of the proposed CCBF compared with existing protocols. Simulation results demonstrate that CCBF decreases the end-to-end hop counts, hence, further improves the end-to-end energy efficiency and latency. Remarkably, it provides up to 50% improvement for the packet loss ratio when the retransmission mechanism is not adopted.

In a pervasive computing environment, the devices are embedded in the physical world, providing services and interconnected by a communication network. Composition of these services is important issue of pervasive applications which integrate the physical and cyber worlds. Most existing research on service composition in pervasive computing relies on the existence of one or more entities that maintain the global service information. However, such an approach is not always practical due to dynamicity of the environment. In this paper, we propose a fully decentralized approach to service composition. We first model the service composition problem as finding an overlay of the communication network that matches the composition graph. The problem is proved to be NP-complete. We propose an algorithm for the devices to cooperatively construct the requested services through localized interactions. For the purpose of reducing redundant broadcast we propose the service composition backbone built in a fully localized way. We have carried out extensive simulations. to evaluate the performance of our algorithm. Compared with existing pull-based centralized techniques our decentralized service composition algorithm on the service composition backbone is more efficient in terms of response delay and message overhead, while achieving similar quality of composed service.

In this paper, we exploit the geographic opportunistic routing (GOR) for QoS provisioning with both end-to-end reliability and delay constraints in wireless sensor networks (WSNs). Recent work exploits multipath routing to guarantee both reliability and delay QoS constraints in WSNs. However, the multipath routing approach suffers from a significant energy cost. We also find that existing GOR protocol may not be suitable for QoS provisioning in WSNs, due to the large computation delay at each hop. To improve the efficiency of QoS routing in WSNs, we study the problem of efficient GOR for multiconstrained QoS provisioning in WSNs, which can be formulated as a multiobjective multiconstraint optimization problem. We look in depth at the properties of the multiple objectives. Based on the analysis and observations, we then propose a heuristic efficient GOR (EGOR) algorithm for QoS provisioning in WSNs. We evaluate EGOR by comparing it with the multipath routing approach through ns-2 simulation and evaluate its time complexity through measurement on the MicaZ node. Evaluation results demonstrate that EGOR can significantly improve both the end-to-end energy efficiency and latency for multiconstrainted QoS provisioning in WSNs, and that EGOR is characterized by its low time complexity.

Considering sensor nodes deployed densely and uniformly a mobile sink moving through the sensing field queries a specific area of interest for monitoring information. The Query packet, injected by the mobile sink, is routed to the specific area and the corresponding Response packet is expected to return via multi-hop communication. In this paper, we analyze such a network model to address the problem of efficient data collection for mobile wireless monitoring applications. We first propose a meeting position-aware routing (MPAR) protocol for routing the Response packet efficiently and then propose an efficient query-based data collection scheme (QBDCS) for mobile wireless monitoring applications based on the MPAR. In order to minimize the energy consumption and packet delivery latency, the QBDCS chooses the optimal query time of injecting the Query packet and tailors the routing mechanism for sensor nodes forwarding packets. Simulation study has verified the analysis and demonstrated that the QBDCS can significantly reduce the energy consumption and end to end delivery latency.

Utilizing mobile devices such as PDAs, cell phones to collect and deliver sensor data is considered as a promising application in future ubiquitous computing environment. In such application scenarios, the human factor is becoming increasingly important. In this paper, we propose a group-level incentive scheme targeted for encouraging mobile users to collect sensor data. Such idea of widening the scope of incentive from device- level to group-level is inspired by the incentive scheme of blood donation in real life. Mobile users earn credits by collecting and delivering sensor data with their mobile devices and they may consume the credits to access the services provided by wireless sensor networks applications. The main idea of the group-level incentive scheme is to group mobile users into social groups and share credits so that credits earned by one user can be consumed by another user in the same group. Through theoretical analysis and simulation we illustrate the potential of the proposed solution.

Considering sensor nodes deployed densely and uniformly in the sensing field, we focus on a scenario that a mobile sink moving through the sensing field queries a specific area or a point of interest for data collection. A Query packet is injected by the mobile sink and routed to the specific area, then the corresponding Response packet is returned to the mobile sink via multi-hop communication. Due to the mobility of the sink, the Query and Response should have different routes. We analyze such a network model to address the problem of efficient data collection in wireless sensor networks and propose an efficient Query-Based Data Collection Scheme (QBDCS). In order to minimize the energy consumption and packet delivery latency, QBDCS chooses the optimal time to send the Query packet and tailors the routing mechanism for partial sensor nodes forwarding packets. Simulation results demonstrate that QBDCS completes a query-based data collection cycle with minimum energy consumption and delivery latency.

An application scenario embracing the area of Intelligent Transportation Systems (ITS) is studied in this paper. The infrastructure of the application scenario is wireless sensor networks with mobile sinks. The WSN is query-based and with multi-hop transmission for data sensing. The application-specific network architecture was introduced and exploited. The detailed routing algorithm as well as its initialization phase were developed. Analysis was given on the end-to-end delivery latency, aiming to optimize the routing in both real-time ability and energy efficiency. Compared with the existing routing mechanism for the same application scenario, the proposed algorithm demonstrates less delivery latency and consequently lower energy consumption. Extensive simulations were conducted to evaluate the performance of the routing mechanism as well as to compare it with existing method numerically.

In this paper, meeting position aware routing (MPAR) is proposed for query-based mobile enabled wireless sensor network (mWSN). We consider mWSNs with dense sensor nodes deployed in the sensing field. A mobile sink (MS) moving through the sensing field with random speed queries a specific area or a point of interest for information from physical world. Queried data over a area is aggregated to a source node and delivered to the mobile sink via multi-hop communication. The feature of MPAR is that the mWSNs can predict the position of the mobile sink at the time it meets the data packet. The queried data packet is delivered towards this predicted position from the source node during the propagation. We compared MPAR with the existing routing protocol for the similar scenarios. Analysis was conducted to discover the conditions under which MPAR demonstrates the optimal performance. Extensive simulations were also conducted to evaluate the performance of the routing mechanism as well as to compare it with existing method. Evaluation results show that MPAR outperforms the existing mechanism in that it provides less end-to-end delivery latency, and consequently reduces the energy consumption. The robustness to variation of MS velocity is also improved.

Deploying multiple mobile sinks is an attractive approach to enhance the performance of wireless sensor networks. In this paper, we address the scenario of two mobile sinks. The two sinks can travel in the same region or in the divided regions separately. The problems are formulated by a lattice-based network model. We deduce the network lifetime and delay of data delivery in different mobility patterns. The relation between network performance and number of mobile sinks is also discussed. Simulation results are provided to validate our theoretic analysis followed by performance comparison of different mobility patterns.

Aiming at the periodical data gathering application of wireless sensor network, the transmission delay and the network traffic loads are analyzed for the route-based data aggregation algorithm. It is then investigated how to minimize the network traffic within the data delay bound. An optimization problem is deduced based on the traffic aggregation model. Inspired by the hill-climbing algorithm, a centralized algorithm named as ldquoEffectiveness based Aggregation Time Allocation (EATA)rdquo is introduced and evaluated. In our simulation experiments, EATA can lead the network to a maximal traffic aggregation performance and good adaptability compared with other existing algorithms.

Prolonging the network lifetime and reducing the delay of event delivery are both important in event-driven multi- hop wireless sensor networks. In this paper, an optimum predefined mobility trajectory of the sink was explored to balance the two performance metrics. We focus on a lattice-based analytical model for understanding performance as system and mobility parameters are scaled. Based on the model, the theoretical analysis and the simulation results validate our statements. The case of multiple mobile sinks are also discussed and simulated.

Aiming at the periodical data gathering application of Wireless Sensor Network, this paper first analyzed the network traffic flow and transmission delay in typical aggregation model. Then it investigated how to properly allocate aggregation time to minimize total network traffic within certain delay bound. An optimization problem was deduced and numerical solutions for regular network are calculated. Inspired by the numerical results, this paper introduced the concept of the critical aggregation level and presented an algorithm called Triangle-shaped Hierarchy aggregation Time Allocation (THTA). In our simulation experiments, THTA can lead the network to the maximum aggregation performance and fine adaptability compared with other existing algorithms.

The combined and separated research advancement in the fields of sensing, communication, and computing have driven the research efforts in wireless sensor networks (WSN) in recent years. According to the traditional definition of WSNs, a dense, static, and prohibitively expensive sensor deployment is implicitly required, which has limited the feasibility of WSNs in non-military approaches. Aside from stationary sensor and sink deployment, the introduction of mobility of mobile terminals into WSNs can be leveraged to alleviate the burden of certain static sinks in order for efficient information repository, dissemination and sharing. In this paper, an architecture of multi-radio enabled mobile wireless sensor network (MEMOSEN) has been introduced, which has taken the heterogeneity and mobility of sensors and sinks into account. The capacity gain due to mobility in MEMOSEN has been addressed, and the design challenges and potential applications of MEMOSEN have been analyzed as well.

Introducing heterogeneous mobile devices, such as mobile phones into the large scale sparse wireless sensor networks is a promising research direction. These devices acting as mobile sinks offer many benefits to the network. For instance, they help to improve scalability, maintain load balance, conserve energy, prolong network lifetime and implement commercially. The paper investigates the impacts of different features and behavior of mobile sinks on the hybrid wireless sensor networks. Analysis and simulation results show that, instead of deploying mobile sinks as much as possible, choosing appropriate number, transmission range, velocity and gathering mode of the sink nodes can significantly decrease the average end-to-end data delivery delay and improve the energy conservation. The comparisons of performance metrics between fixed sinks and mobile sinks are also made in sparse networks along with the results that mobile sinks can bring higher data success rate and energy balance.

Multipath routing in mobile ad hoc networks has recently received more research efforts, where more than one route will be searched and maintained between every source-destination pair. Compared with traditional single-path routing, utilizing multiple paths in parallel would be of benefit to reduce end-to-end delivery delay as well as to split traffic for load balancing to achieve better utilization of bandwidth resource under moderate traffic load. Besides, multipath routing will enhance routing robustness in the sense of lengthening route lifetime. In this paper, we propose an analytical modeling framework to investigate multipath routing in ad hoc/multihop networks. The single-path model is considered as a multi-node M/M/1 tandem network with several congestion queues, and multiple paths can be viewed as several parallel rays originating from the focus of a convex lens. This proposed framework allows us to investigate issues such as optimal load distribution, end-to-end delivery delay and multipath routing reliability in ad hoc networks. Due to the flexibility, our modeling framework is applicable for heterogeneous network as well as homogeneous case

Multipath routing in mobile ad hoc networks has recently received more research efforts, where more than one route will be searched and maintained between every source destination pair. Compared with traditional single-path routing, utilizing multiple paths in parallel would be of benefit to reduce end-to-end delivery delay as well as to split traffic for load balancing to achieve better utilization of bandwidth resources. Besides, multipath routing will enhance the route robustness in the sense of lengthening route lifetime. In this paper, we propose an analytical modeling framework to investigate multipath routing in ad hoc/multihop networks. The single-path model is considered as a multi-node M/M/1 tandem network, and the multi-path model as a set of multiple parallel paths. This proposed framework allows us to investigate issues such as optimal load distribution, end-to-end delay and multipath routing reliability in ad hoc networks. Due to the flexibility, our modeling framework is applicable to a heterogenous network as well as the homogenous case.

A scheme for enhancing the TCP performance when a handoff occurs within a heterogeneous mobile network is proposed. Currently, the research on the interworking between 3G cellular networks and a WLAN is actively being conducted. To integrate these two technologies, there are many issues such as the network architecture, mobility management, and security which should he solved. Implementing a seamless handoff between WLAN and 3G networks is an essential issue. In this paper, we present some issues to develop a network that supports interworking between WLANs and 3G cellular networks, especially focusing on the TCP challenges. We examine a TCP performance during an intersystem handoff between a WLAN and a 3G cellular network and discuss some problems that the current TCP experiences during intersystem handoff and propose some schemes to improve TCP performance.

A scheme for enhancing the TCP performance when a handoff occurs within a heterogeneous mobile network is proposed. Currently, the research on the interworking between 3G cellular networks and a WLAN is actively being conducted. To integrate these two technologies, there are many issues such as the network architecture, mobility management, and security which should he solved. Implementing a seamless handoff between WLAN and 3G networks is an essential issue. In this paper, we present some issues to develop a network that supports interworking between WLANs and 3G cellular networks, especially focusing on the TCP challenges. We examine a TCP performance during an intersystem handoff between a WLAN and a 3G cellular network and discuss some problems that the current TCP experiences during intersystem handoff and propose some schemes to improve TCP performance.