VeSense: High-performance and energy-efficient vehicular sensing platform

Although vehicular sensing where mobile users in vehicles continuously gather, process, and share location-sensitive and context-sensitive sensor data (e.g., street images, road condition, traffic flow) is emerging, little effort has been investigated in a model-based energy-efficient network paradigm of sensor information sharing in vehicular environments. Upon these optimization frameworks, a suite of optimization subproblems: a program partitioning and network resource allocation problem, we propose a distributed vehicular sensing platform, called VeSense where mobile users in vehicles publish/access sensor data via a cloud computing-based distributed P2P overlay network. The key objective is to satisfy the vehicular sensing application’s quality of service requirements by modeling each subsystem: mobile clients, wireless network medium, and distributed cloud services. By simulations based on experimental data, we present the proposed system can achieve up to 37 times more energy-efficient and 73 times faster compared to a standalone mobile application, in various vehicular sensing scenarios applying a realistic mobility model.     

异构群智感知PPO多目标任务指派方法

现有移动群智感知系统的任务指派主要面向单一类型移动用户展开,对于存在多种类型移动用户的异构群智感知任务指派研究相对缺乏.为此,针对异质移动用户,定义其区域可达性,并给出感知子区域类型划分.进而,兼顾感知任务数量和移动用户规模的时变性,构建了动态异构群智感知系统任务指派的多目标约束优化模型.模型以最大化感知质量和最小化感知成本为目标,综合考虑用户的最大任务执行数量、无人机的受限工作时间等约束.为解决该优化问题,提出一种基于近端策略优化的多目标进化优化算法.采用近端策略优化,根据种群的当前进化状态,选取具有最高奖励值的进化算子,生成子代种群.面向不同异构群智感知实例,与多种算法的对比实验结果表明,所提算法获得的Pareto最优解集具有最佳的收敛性和分布性,进化算子选择策略可以有效提升对时变因素的适应能力,改善算法性能.     

Participant selection algorithms for large-scale mobile crowd sensing environment

Microsystem Technologies - Mobile crowd sensing (MCS) is an emerging sensing platform that concedes mobile users to efficiently collect data and share information with the MCS service providers....     

A survey of urban vehicular sensing platforms

Vehicular sensing where vehicles on the road continuously gather, process, and share location-relevant sensor data (e.g., road condition, traffic flow) is emerging as a new network paradigm for sensor information sharing in urban environments. Recently, smartphones have also received a lot of attention for their potential as portable vehicular urban sensing platforms, as they are equipped with a variety of environment and motion sensors (e.g., audio/video, accelerometer, and GPS) and multiple wireless interfaces (e.g., WiFi, Bluetooth and 2/3G). The ability to take a smartphone on board a vehicle and to complement the sensors of the latter with advanced smartphone capabilities is of immense interest to the industry. In this paper we survey recent vehicular sensor network developments and identify new trends. In particular we review the way sensor information is collected, stored and harvested using inter-vehicular communications (e.g., mobility-assist mobility-assisted dissemination and geographic storage), as well using the infrastructure (e.g., centralized and distributed storage in the wired Internet). The comparative performance of the various sensing schemes is important to us. Thus, we review key results by carefully examining and explaining the evaluation methodology, in the process gaining insight into vehicular sensor network design. Our comparative study confirms that system performance is impacted by a variety of factors such as wireless access methods, mobility, user location, and popularity of the information.     

Secure and efficient fine-grained multiple file sharing in cloud-assisted crowd sensing networks

Mobile crowd sensing significantly facilitates a broad range of emerging applications by treating mobile devices of ordinary users as basic sensing units to distribute sensing tasks and collect sensing data. Owing to the continuity of data sensing and richness of content, resource-constrained mobile devices always outsource their collected data into the cloud for file sharing. The existing work enables only batch decryption limited to RSA algorithm and merely allows one specific file to be shared among multiple authorized receivers by exploiting the technique of attribute-based encryption (ABE). In this paper, a generalized efficient batch cryptosystem GBC and its extension GBCS are firstly proposed to achieve both batch encryption and batch decryption from any public key encryption algorithm. Then, our proposed GBC is further extended to FMFS, TMFS and MMFS to address secure multiple file sharing in the cloud-assisted mobile crowd sensing network, respectively for fine-grained multi-receiver multi-file sharing, file authority transfer and multiple file owners’s settings. Finally, formal security proof is given to show our proposed generalized efficient batch cryptosystems GBC, GBCS and secure multiple file sharing schemes are respectively secure against adaptive chosen ciphertext attack (CCA2) in the random oracle model and under the assumption on the computational hardness of the subset decision problem in the standard model. Extensive evaluations illustrate our secure multiple file sharing in cloud-assisted crowd sensing network based on the newly-devised GBC dramatically outperforms the state-of-the-art in storage, computational and communication overhead.     

移动群智感知中基于联邦学习的参与者选择机制

移动群智感知的发展使得一些任务收集的数据量过大,需要在不接收参与者原始数据的情况下评估数据质量并进行参与者选择。针对这一问题,提出一种基于联邦学习的移动群智感知参与者选择机制。考虑参与者智能终端资源水平、所处交互状态构建参与者智能终端资源评价机制,提出基于线性回归和长短期记忆网络的智能终端资源预测模型。通过预训练测试模型,评估参与者提供的数据质量,结合历史任务完成情况建立参与者信誉评价模型,实现对参与者的动态评价选择。仿真实验结果表明,所提的参与者选择机制在任务完成质量、能量消耗、通信轮数及任务完成时间等多方面体现出较好的性能。     

基于公交网络的车载群智感知方法及其优化

公交车具有固定的行驶路线和发车周期、统一的车载设备标准、低隐私泄露风险等特性。根据公交车的特性,设计了一个基于公交网络的车载群智感知系统,系统中的数据中心通过公交网络中的公交车来采集城市数据,以满足数据用户的需求;随后研究系统中的任务分配问题和数据交易问题。基于贪婪算法设计优化任务分配策略以最小化系统的数据采集能耗成本,和根据博弈论设计最优数据交易策略以最大化系统的经济效益。最后通过仿真,验证了提出的策略的有效性和优越性。     

基于GACO的群智感知参与者选择方法研究

参与者选择方法作为群智感知研究的重要内容之一,现有研究还存在不足,只单一考虑任务发布时间或任务区域覆盖等属性,导致选择的参与者执行任务效率较差。因此针对这一问题综合考虑任务时间和任务区域覆盖等约束条件下,为实现任务执行效率最高和群智感知平台激励成本最少的优化目标,提出一种基于贪婪蚁群算法的群智感知参与者选择方法（PS-GACO）。该方法主要通过候选参与者聚集蚂蚁信息素浓度的多少准确选出适合执行发布任务的参与者,大大提高了任务执行效率。最后通过仿真实验将提出的PS-GACO方法与普通参与者选择方法进行比较,实验结果表明PS-GACO在算法运行时间、任务执行效率以及激励成本等方面都优于其他两种方法,对于群智感知参与者选择有很好的应用前景。     

一种多向链路感知的车载Ad Hoc网络传播协议

为了提高车辆自组织网络（Vehicular Ad Hoc Network,VANET）的数据传输效率,并使车辆间的数据通信能够持续进行,提出一种多向链路感知的车载Ad Hoc网络传播协议。为了保证车辆节点在执行通信任务的过程中实现数据的持续传输,防止通信链路频繁断连影响传输质量,提出了车辆网络的时间关联模型来讨论车辆间的速度差与通信持续时间的关系。为了缩短VANET中用于数据传输任务的总时间,协议基于改进蚁群的方法进行了多向链路感知,从而寻找在保证通信需求时间下的最短传输路径。实验结果分析表明,相比基于改进地理信息路由和基于优化链路状态路由的VANET数据传输算法,该算法的数据传输任务完工时间分别缩短了38.4%和27.3%,平均传输延迟分别降低了25.5%和12.1%。     

Participant selection for <Emphasis Type="Italic">t</Emphasis>-sweep <Emphasis Type="Italic">k</Emphasis>-coverage crowd sensing tasks

With the popularization of wireless networks and mobile intelligent terminals, mobile crowd sensing is becoming a promising sensing paradigm. Tasks are assigned to users with mobile devices, which then collect and submit ambient information to the server. The composition of participants greatly determines the quality and cost of the collected information. This paper aims to select fewest participants to achieve the quality required by a sensing task. The requirement namely “t-sweep k-coverage” means for a target location, every t time interval should at least k participants sense. The participant selection problem for “t-sweep k-coverage” crowd sensing tasks is NP-hard. Through delicate matrix stacking, linear programming can be adopted to solve the problem when it is in small size. We further propose a participant selection method based on greedy strategy. The two methods are evaluated through simulated experiments using users’ call detail records. The results show that for small problems, both the two methods can find a participant set meeting the requirement. The number of participants picked by the greedy based method is roughly twice of the linear programming based method. However, when problems become larger, the linear programming based method performs unstably, while the greedy based method can still output a reasonable solution.     

A mobile crowd sensing ecosystem enabled by CUPUS: Cloud-based publish/subscribe middleware for the Internet of Things

Mobile crowd sensing (MCS) is a novel class of mobile Internet of Things (IoT) applications for community sensing where sensors and mobile devices jointly collect and share data of interest to observe phenomena over a large geographic area. The inherent device mobility and high sensing frequency has the capacity to produce dense and rich spatiotemporal information about our environment, but also creates new challenges due to device dynamicity and energy constraints, as well as large volumes of generated raw sensor data which need to be processed and analyzed to extract useful information for end users. The paper presents an ecosystem for mobile crowd sensing which relies on the CloUd-based PUblish/Subscribe middleware (CUPUS) to acquire sensor data from mobile devices in a flexible and energy-efficient manner and to perform near real-time processing of Big Data streams. CUPUS has unique features compared to other MCS platforms: It enables management of mobile sensor resources within the cloud, supports filtering and aggregation of sensor data on mobile devices prior to its transmission into the cloud based on global data requirements, and can push information of interest from the cloud to user devices in near real-time. We present our experience with implementation and deployment of an MCS application for air quality monitoring built on top of the CUPUS middleware. Our experimental evaluation shows that CUPUS offers scalable processing performance, both on mobile devices and within the cloud, while its data propagation delay is mainly affected by transmission delay on wireless links.     

Duration of stay based weighted scheduling framework for mobile phone sensor data collection in opportunistic crowd sensing

Advancement of mobile phone based new sensing paradigm like opportunistic and participatory crowd sensing has lead to increase in both multimedia and scalar sensor data traffic over wireless networks. In opportunistic crowd sensing, there are more chances of missing required mobile phones sensor data due to unpredictable mobility nature of users. Analysis of scheduling schemes under realistic human mobility models has become an important issue for pervasive sensing applications specifically for mobile phone based crowd sensing. This paper refers to a weighted scheduling framework for collecting mobile phone sensor data under Levy Walk mobility model. The proposed method uses duration of stay of mobile phone users as one of the important parameter to improve the scheduling performance in terms of reducing the rate of missing of mobile nodes and thereby increasing the rate of collection of required sensor data. The simulation results show that for improving the scheduling performance in opportunistic crowd sensing, high weight value should be given for duration of stay parameter, when mobile nodes stay within the data collection region for more than schedule iteration time with high probability.     

移动群智感知中支持隐私保护的动态激励机制

针对移动群智感知中高质量感知数据与参与用户隐私之间的矛盾,提出一种支持隐私保护的动态激励机制。首先,采用轻量级隐私保护方法,利用安全加密哈希函数为竞标用户生成不少于256位的可变地址序列,并结合随机数对候选用户节点的效用报价进行隐匿和约束;其次,通过定义区域热度、时间热度、数据完整率和数据质量等多维参数,实现任务价值与用户效用报价的动态平衡;最后,依据用户提交的效用报价和任务预算,并利用逆向拍卖思想,完成对任务参与节点的最优选择和动态激励。在群智感知系统模拟平台上进行仿真实验,结果表明所提机制不仅增强了隐私保护度和数据精确度,同时提升了时间效率和激励效果。     

An energy-efficient data transmission protocol for mobile crowd sensing

Mobile crowd sensing, as a new paradigm, means that mobile users equipped with smart devices to solve large-scale mobile sensing tasks through wireless communication. Data transmission schemes with opportunistic network in mobile crowd sensing have attracted widespread attention recently, which attempt to reach high delivery and low consumption. However, most transmission schemes resort to users’ trajectory and connection history that are dynamic and difficult to calculate, causing it so hard to establish stable connection channel. For achieving energy-efficient transmission, an energy-efficient data transmission protocol is proposed in this paper, which deploys static nodes to assist in information transmission based on Archimedes curve. Meanwhile, the significant performance of the proposed protocol is demonstrated through extensive simulations based on the ONE platform.     

移动群智感知中任务分配的研究

随着内置高性能传感器的移动智能终端的广泛应用,新兴的移动群智感知技术逐渐成为实时感知与收集环境信息的有效方式。为协调与鼓励用户参与感知任务,并最大限度地保证感知数据的有效性与可靠性,针对移动群智感知相关研究中的关键问题—任务分配进行了研究。首先,介绍移动群智感知的相关背景;其次,根据感知任务的要求对任务分配的约束条件进行分类;然后,讨论与分析了任务分配的研究现状,包括平台为中心的优化算法设计以及用户为中心的激励机制设计;最后,指出现有研究工作中的不足,展望了未来的研究方向。     

Game theoretic approach for real-time data dissemination and offloading in vehicular ad hoc networks

Due to high velocity of the vehicles, data dissemination and mobile data offloading are most difficult tasks to be performed in vehicular ad hoc networks (VANETs). In recent years, due to an exponential increase in the data generated from various sources such as smart devices, gadgets, and actuators, there arises a need of usage of an efficient communication infrastructure to handle the aforementioned issues. Most of the earlier solutions reported in the literature for data offloading problem have used the cellular communication, which may be congested in handing a large number of requests from community of users. This may result a performance bottleneck in terms of call drops and data dissemination to the other vehicles in the VANET environment. Also, these schemes lack a comprehensive approach of data dissemination to meet the quality of service (QoS) in real time. Hence, to overcome this problem, some of the mobile data can be disseminated using the existing vehicular infrastructure and Wi-Fi access points (APs). In this paper, we propose a new schedule based on game theoretic approach where the APs and vehicles act as players in a game and compete for offloading the cellular data. The proposed scheme is based on the selection of the best vehicle or AP based on the utility of the players (vehicles and APs) in the game. The utility of vehicle and AP is decided based on the parameters such as distance, velocity, connectivity to destination, bandwidth, and area of the network. A novel algorithm has been designed using the proposed game theoretic approach for handling mobile data offloading and data dissemination. The proposed solution not only successfully offloads the data but also maintains QoS with respect to the parameters such as end-to-end delay, message progress, and message dissemination speed. Results obtained confirm the superiority of the proposal in comparison with the other existing schemes. Specifically, the proposed scheme achieves improvement of 4.16 and 20.5 % in message progress, 18.91 and 4.75 % in extra messages generated, 11.26 and 54.94 % in message dissemination speed, and 78.71 and 87.94 % in end-to-end delay in sparse network as compared to GyTAR and GPCR, respectively.     

移动群智感知中时间窗口相关的参与者选择机制

目前许多移动群智感知应用要求参与者收集一段时间内连续的感知数据,而现有研究在这方面却考虑不足。针对上述应用场景提出了时间窗口相关的参与者选择机制,主要包括基于动态规划算法设计了一种时间窗口相关的参与者选择方法,目标为覆盖任务时间段的同时最大化数据效益;参与者信誉值更新机制,根据参与者参与任务的意愿程度和数据质量更新参与者的信誉值。最后通过仿真实验与两种普遍应用的参与者选择方法作比较,实验证明所提出的参与者选择机制在数据可靠性、数据效益和感知成本等方面具有更好的效果,因此所提出的参与者选择机制在时间窗口相关的任务中有更好的应用前景。     

基于数据冗余控制的移动群智感知任务分配方法

移动群智感知系统中任务之间存在时空覆盖重叠性,这可能导致重复数据收集从而引发数据冗余问题,为此,提出了一种可同时控制任务内以及任务间数据冗余的任务分配方法。该方法首先提出基于长短期记忆（LSTM）神经网络的轨迹序列预测模型,对任务参与者进行细分时空单元的轨迹序列预测,然后根据轨迹预测结果提出最小化数据冗余的优化模型。通过最小化时空单元的数据冗余度来控制单个任务内的数据冗余问题,并通过让单个任务参与者在时空单元中的感知数据被最大化重复利用来控制多个任务之间时空覆盖重叠性带来的数据冗余。实验结果表明,提出的任务分配方法可以有效地减少任务内及任务间的数据冗余。     

基于移动边缘计算的GI/GI/1排队建模与调度算法EI北大核心CSCD

针对车联网环境下路侧边缘计算节点部署不均衡、服务密度小、实时调度计算压力大等问题,提出一种基于智能车移动边缘计算(Mobile edge computing,MEC)的任务排队建模与调度算法,提供弹性计算服务,将具备感知、计算、控制功能的智能车作为移动边缘计算服务器,设计了车联网环境下的MEC体系架构.首先基于虚拟化技术对智能车进行虚拟化抽象,利用排队论对虚拟车任务构建了GI/GI/1排队模型.然后基于云平台Voronoi分配算法对虚拟车任务进行分配绑定,进而实现了智能车的优化调度与分布式弹性服务,解决了边缘计算任务分配不均衡等问题.最后通过城市交通路网中的车辆污染排放的实时计算实验,验证了该方法的有效性.     

TAPAS: Trustworthy privacy-aware participatory sensing

With the advent of mobile technology, a new class of applications, called participatory sensing (PS), is emerging, with which the ubiquity of mobile devices is exploited to collect data at scale. However, privacy and trust are the two significant barriers to the success of any PS system. First, the participants may not want to associate themselves with the collected data. Second, the validity of the contributed data is not verified, since the intention of the participants is not always clear. In this paper, we formally define the problem of privacy and trust in PS systems and examine its challenges. We propose a trustworthy privacy-aware framework for PS systems dubbed TAPAS, which enables the participation of the users without compromising their privacy while improving the trustworthiness of the collected data. Our experimental evaluations verify the applicability of our proposed approaches and demonstrate their efficiency.