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The internet of vehicles needs mobile communication systems for efficient communications. On the physical downlink control channel (PDCCH) of 5G, blind detection is performed to identify the downlink control information (DCI). Due to the uncertainty of DCI formats and PDCCH formats, the existing two-stage blind detection schemes separately decode every PDCCH code block under different DCI formats, leading to a high decoding complexity in the first stage. To reduce the detection complexity, this paper proposes an efficient DCI detection method, where a significance-test strategy is designed to detect the DCI formats. The significance-test strategy can forecast the DCI lengths without separately decoding the whole codeword, thus reducing the decoding complexity by several times. Moreover, the accuracy of the DCI detection is analyzed, with which the test scope of the test statistic is optimized for minimizing the decoding complexity on condition of meeting the detection accuracy requirements. Simulation results show that the proposed method significantly reduces the decoding complexity relatively to the existing two-stage detection schemes. [ABSTRACT FROM AUTHOR]

Mobile crowd sensing has emerged as a novel data collection paradigm by leveraging pervasive mobile sensing devices to enable various applications. To obtain good quality of service, incentive mechanisms are indispensable for attracting enough users. Most of the existing mechanisms focus on the offline scenario in which all users submit profiles in advance. However, the online scenario often appears in the real world wherein users arrive one by one in random order. In this paper, we investigate the frugal online incentive problem based on an online auction model, where users report their strategic profiles to the crowdsourcer in an online mode, and the crowdsourcer selects users before a deadline to complete a specific number of tasks while minimizing the total payment. We design two online mechanisms, namely, Frugal-OMZ and Frugal-OMG, satisfying computational efficiency, individual rationality, truthfulness, consumer sovereignty, and constant frugality under the zero arrival–departure interval model and the general interval model, respectively. Extensive simulations verify the desirable properties of our mechanisms. [ABSTRACT FROM AUTHOR]

This paper presents a cooperative, combinatorial search model for a multi-mobile sensor, multi-mobile target scenario in a two dimensional grid space. In the proposed model, sensors and targets act as searchers and hiders of a search game. A search game is a game between searcher and hider, modeled on a graph. In this paper, the identified problem states that multiple targets enter into a grid from the same or different sides and try to exit on the opposite directions of their respective entry sides. Alternatively, multiple mobile sensors are randomly deployed in the grid and try to maximize the number of target searched and to minimize search time before the targets leave the grid. This problem fits into several real life scenarios such as international border security, terrorist searching in a specified area, finding spies etc. The novelty of the proposed model is interpreting the problem as a search game and formulating strategies for the mobile sensors to optimize their moves to maximize the number of target searched and minimize search time. In this paper, shortest path and random walk strategies for the targets are analyzed by applying suitable mathematical models and on the other hand, advantages of cooperative over non-cooperative strategies for the mobile sensors are also shown with the help of analytical methods and simulation results. The significant mathematical concepts applied in the proposed model are as follows-computing shortest path, random walk, Markov chain, probability graph, overlapping of multiple probability graphs, cooperative and non-cooperative strategies etc. [ABSTRACT FROM AUTHOR]

In semiautonomous mobile sensor networks (MSNs), since human operators may be involved in the control loop, particular improper actions may cause accidents and result in catastrophes. For such systems, this paper proposes a command filtering framework to accept or reject the human-issued commands so that undesirable executions are never performed. In the present approach, Petri nets are used to model the operated behaviors and to synthesize the command filters for supervision. An application to a mobile wireless surveillance system is provided to show the feasibility of the developed approach. It is believed that the technique presented in this paper could be further applied to large-scale wireless MSNs. [ABSTRACT FROM AUTHOR]

Ad hoc localization of wireless sensor nodes is a fundamental problem in wireless sensor networks. Despite the recent proposals for the development of ad hoc localization algorithms, the fundamental behavior in systems using measurements has not been characterized. In this paper, we take a first step toward such a characterization by examining the behavior of error inducing parameters in multihop localization systems in an algorithm independent manner. We first derive the Cramé Rao Bound for Gaussian measurement error for multihop localization systems using distance and angular measurements. Later on, we use these bounds on a carefully controlled set of scenarios to study the trends in the error induced by the measurement technology accuracy, network density, beacon node concentration, and beacon uncertainty. By exposing these trends, the goal of this paper is to develop a fundamental understanding of the error behavior that can provide a set of guidelines to be considered during the design and deployment of multihop localization systems. [ABSTRACT FROM AUTHOR]

This paper proposes the differential detection type direct sequence/code-division multiple-access (DS/CDMA) adaptive interference canceller (AIC) that can track the fast fading. The proposed AIC is composed of the fractionally chip-spaced code-orthogonalizing filter (COF) with tap length corresponding to several bit periods and the differential detector. The COF makes adaptively the tap weight orthogonal to all spreading codes of other users as a despreading code of the desired user so that the interferences from other users are cancelled and the signal component of the desired user is extracted. The differential detector compensation the carrier phase variation due to finding in the desired user's signal at the COF output. By such a structure, the tracking performance of AIC to the channel variation can be improved to the limit of the tracking performance of the differential detector. This paper evaluates the basic ability of the proposed AIC in the fast-fading channel. The AIC is especially expected to be utilized in the DS/CDMA mobile communications since the receiver is of the signle-user type, where no information concerning other users is needed. [ABSTRACT FROM AUTHOR]

In this paper, we study the delay-constrained information coverage problem in mobile sensor networks. Motivated by real application needs, our formulation takes advantage of the sensor mobility for sensing information collection, which takes place when a sensor moves into the proximity (single hop) of stationary sink nodes. To the best of our knowledge, we present the first formulation for the delay-constrained information coverage problem, which targets at optimal sink nodes placement with the objective of maximizing sensing information collection within a constrained time. We prove that this problem is NP-hard even under finite search space approximation and we develop theoretical analysis to derive its upper and lower performance bounds. We then develop approximation techniques and use simulations to verify their effectiveness. [ABSTRACT FROM AUTHOR]

This paper investigates the opportunities and challenges in the use of dynamic radio transmit power control for prolonging the lifetime of body-wearable sensor devices used in continuous health monitoring. We first present extensive empirical evidence that the wireless link quality can change rapidly in body area networks, and a fixed transmit power results in either waster energy (when the link is good) or low reliability (when the link is bad). We quantify the potential gains of dynamic power control in body-worn devices by benchmarking off-line the energy savings achievable for a given level of reliability. We then propose a class of schemes feasible for practical implementation that adapt transmit power in real-time based on feedback information from the receiver. We profile their performance against the off-line benchmark, and provide guidelines on how the parameters can be tuned to achieve the desired trade-off between energy savings and reliability within the chosen operating environment. Finally, we implement and profile our scheme on a MicaZ mote based platform, and also report preliminary results the ultra-low-power integrated healthcare monitoring platform we are developing at Toumaz Technonology [ABSTRACT FROM AUTHOR]

In wireless sensor networks (WSN), it is very important for sensor nodes to locate with low energy consumption and high accuracy, especially in a dangerous environment. This paper describes a range-free layered localization scheme using one mobile anchor node which can transmit gradient signals, and whose moving track is a straight-line along the x-axis. And this paper proposes a sleep/wake mechanism called sensor sleep-time forecasting to save energy consumption during localization. The relationship, between the key factors in localization algorithm and the average location error, is analyzed in detail. Simulation results show that the scheme performs better than other range-free mechanisms—the average location error is less than 0.7 m, and it is independent on sensor nodes density or sensor nodes radio range, the accuracy of the algorithm can be adjusted in different occasions, and the algorithm beacon overhand is small and average localization time is short. [ABSTRACT FROM AUTHOR]

Recently, wireless sensor networks featuring direct sink access have been studied as an efficient architecture to gather and process data for numerous applications. In this paper, we focus on the joint effect of clustering and data correlation on the performance of such networks. More specifically, we propose a novel cluster-based data collection scheme for sensor networks with direct sink access (CDC-DSA) and provide an analytical framework to evaluate its performance in terms of energy consumption, latency, and robustness. In our scheme, cluster heads use a low-overhead and simple medium access control (MAC) conceptually similar to ALOHA to contend for the reachback channel to the data sink. Since, in our model, data is collected periodically, packet arrival is not modeled by a continuous random process, and therefore, we base our framework on a transient analysis rather than a steady-state analysis. Using random geometry tools, we study how the optimal average cluster size and energy savings, under the proposed MAC, vary according to the level of data correlation in the network. Extensive simulations for various protocol parameters show that our analysis is fairly accurate for a wide range of parameters. Our results suggest that, despite the trade-off between energy consumption and latency, both can be substantially reduced by a proper clustering design. [ABSTRACT FROM AUTHOR]

Sensing coverage is an important issue for sensor networks and is viewed as one of the critical measures of the performance offered by a sensor network. In previous studies, the sensing range of a node is generally assumed to be a deterministic value in all directions. For most types of sensing signals emitted from a far field, the obstructions in the propagation path will induce an extra loss in the received signal power and cause a large variation in the received signal strength. This variation is classified as the shadowing effects similar to the phenomenon in radio wave propagation. The objective of this paper is to examine the impact of the shadowing effects on the sensing coverage. The analytical results of the sensing coverage for a large-scale randomly distributed sensor network in shadowed environments are provided. It was found that the increase in standard deviation of the shadowing effects severely degrades the sensing coverage. For an increase of 2 dB in the standard deviation, the sensing coverage degrades by about 10%. [ABSTRACT FROM AUTHOR]

Iterative equalization using optimal multiuser detector and optimal channel decoder in coded CDMA systems improves the bit error rate (BER) performance tremendously. However, given large number of users employed in the system over multipath channels causing significant multiple-access interference (MAI) and intersymbol interference (ISI), the optimal multiuser detector is thus prohibitively complex. Therefore, the sub-optimal detectors such as low- complexity linear and non-linear equalizers have to be considered. In this paper, a novel low- complexity block decision feedback equalizer (DFE) is proposed for the synchronous CDMA system. Based on the conventional block DFE, the new method is developed by computing the reliable extrinsic log-likelihood ratio (LLR) using two consecutive received samples rather than one received sample in the literature. At each iteration, the estimated symbols by the equalizer is then saved as a priori information for next iteration. Simulation results demonstrate that the proposed low-complexity block DFE algorithm offers good performance gain over the conventional block DFE. [ABSTRACT FROM AUTHOR]

Massive multiple-input multiple-output (M-MIMO) is a substantial pillar in fifth generation (5G) mobile communication systems. Although the maximum likelihood (ML) detector attains the optimum performance, it has an exponential complexity. Linear detectors are one of the substitutions and they are comparatively simple to implement. Unfortunately, they sustain a considerable performance loss in high loaded systems. They also include a matrix inversion which is not hardware-friendly. In addition, if the channel matrix is singular or nearly singular, the system will be classified as an ill-conditioned and hence, the signal cannot be equalized. To defeat the inherent noise enhancement, iterative matrix inversion methods are used in the detectors' design where approximate matrix inversion is replacing the exact computation. In this paper, we study a linear detector based on iterative matrix inversion methods in realistic radio channels called QUAsi Deterministic RadIo channel GenerAtor (QuaDRiGa) package. Numerical results illustrate that the conjugate-gradient (CG) method is numerically robust and obtains the best performance with lowest number of multiplications. In the QuaDRiGA environment, iterative methods crave large n to obtain a pleasurable performance. This paper also shows that when the ratio between the user antennas and base station (BS) antennas (β) is close to 1, iterative matrix inversion methods are not attaining a good detector's performance. [ABSTRACT FROM AUTHOR]

Fifth-generation (5G) communications system is commercially introduced by several mobile operators where sub-6 GHz bands are the backbone of the 5G networks. A large-scale multiple-input multiple-output (MIMO), or massive MIMO (mMIMO), technology has a major impact to secure high data rate, high spectral efficiency, and quality of service (QoS). It could also have a major role in the beyond-5G systems. A massive number of antennas seek advanced signal processing to detect and equalize the signal. However, optimal detectors, such as the maximum likelihood (ML) and maximum posterior (MAP), are not desirable in implementation due to extremely high complexity. Therefore, sub-optimum solutions have been introduced to obtain and guarantee enough balance between the performance and the computational complexity. In this paper, a robust and joint low complexity detection algorithm is proposed based on the Jacobi (JA) and Gauss–Seidel (GS) methods. In such iterative methods, the performance, complexity, and convergence rate are highly dependent on the initial vector. In this paper, initial solution is proposed by exploiting the benefits of a stair matrix to obtain a fast convergence rate, high performance, and low complexity. Numerical results show that proposed algorithm achieves high accuracy and relieve the computational complexity even when the BS-to-user-antenna ratio (BUAR) is small. [ABSTRACT FROM AUTHOR]

Consider mobile targets in a plane and their movements being monitored by a network such as a field of sensors. We develop distributed algorithms for in-network tracking and range queries for aggregated data (for example, returning the number of targets within any user given region). Our scheme stores the target detection information locally in the network and answers a query by examining the perimeter of the given range. The cost of updating data about mobile targets is proportional to the target displacement. The key insight is to maintain in the sensor network a function with respect to the target detection data on the graph edges that is a differential form such that the integral of this form along any closed curve C gives the integral within the region bounded by C. The differential form has great flexibility, making it appropriate for tracking mobile targets. The basic range query can be used to find a nearby target or any given identifiable target with cost O(d), where d is the distance to the target in question. Dynamic insertion, deletion, coverage holes, and mobility of sensor nodes can be handled with only local operations, making the scheme suitable for a highly dynamic network. It is extremely robust and capable of tolerating errors in sensing and target localization. Targets do not need to be identified for the tracking, thus user privacy can be preserved. In this paper, we only elaborate the advantages of differential forms in tracking of mobile targets. Similar routines can be applied for organizing many other types of information—for example, streaming scalar sensor data (such as temperature data field)—to support efficient range queries. We demonstrate through analysis and simulations that this scheme compares favorably to existing schemes that use location services for answering aggregate range queries of target detection data. [ABSTRACT FROM AUTHOR]

A precise localization is required in order to maximize the usage of Mobile Sensor Network. As well, mobile robots also need a precise localization mechanism for the same reason. In this paper, we showed a combination of various localization mechanisms for precise localization in three different levels. Localization can be classified in three big categories: wide area and long distance localization with low accuracy, medium area and distance localization with medium accuracy, and small area short distance localization with high accuracy. In order to present localization methods, traditional map building technologies such as grid maps or topological maps can be used. We implemented mobile sensor vehicles and composed mobile sensor network with three levels of localization techniques. Each mobile sensor vehicles act as a mobile sensor node with the facilities such as autonomous driving, obstacle detection and avoidance, map building, communication via wireless network, image processing, extensibility of multiple heterogeneous sensors, and so on. For localization, each mobile sensor vehicle has abilities of the location awareness by mobility trajectory based localization, RSSI based localization and computer vision based localization. With this set of mobile sensor network, we have the possibility to demonstrate various localization mechanisms and their effectiveness. In this paper, the result of computer vision based localization, sensor mobility trail based localization and RSSI based localization will be presented. [ABSTRACT FROM AUTHOR]

The K-Nearest Neighbors (KNN) query has been of significant interest in many studies and has become one of the most important spatial queries in mobile sensor networks. Applications of KNN queries may include vehicle navigation, wildlife social discovery, and squad/platoon searching on the battlefields. Current approaches to KNN search in mobile sensor networks require a certain kind of indexing support. This index could be either a centralized spatial index or an in-network data structure that is distributed over the sensor nodes. Creation and maintenance of these index structures, to reflect the network dynamics due to sensor node mobility, may result in long query response time and low battery efficiency, thus limiting their practical use. In this paper, we propose a maintenance-free itinerary-based approach called Density-aware Itinerary KNN query processing (DIKNN). The DIKNN divides the search area into multiple cone-shape areas centered at the query point. It then performs a query dissemination and response collection itinerary in each of the cone-shape areas in parallel. The design of the DIKNN scheme takes into account several challenging issues such as the trade-off between degree of parallelism and network interference on query response time, and the dynamic adjustment of the search radius (in terms of number of hops) according to spatial irregularity or mobility of sensor nodes. To optimize the performance of DIKNN, a detailed analytical model is derived that automatically determines the most suitable degree of parallelism under various network conditions. This model is validated by extensive simulations. The simulation results show that DIKNN yields substantially better performance and scalability over previous work, both as k increases and as the sensor node mobility increases. It outperforms the second runner with up to a 50 percent saving in energy consumption and up to a 40 percent reduction in query response time, while rendering the same level of query result accuracy. [ABSTRACT FROM AUTHOR]

This paper considers the coverage problem for hybrid networks which comprise both static and mobile sensors. The mobile sensors in our network only have limited mobility, i.e., they can move only once over a short distance. In random static sensor networks, sensor density should increase as O(log L + k log log L) to provide k-coverage in a network with a size of L. As an alternative, an all-mobile network can provide k-coverage with a constant density of O(k), independent of network size L. We show that the maximum distance for mobile sensors is O(1/√k log3/4(kL)). We then propose a hybrid network structure, comprising static sensors and a small fraction of O(1/√k) of mobile sensors. For this network structure, we prove that k-coverage is also achievable with a constant sensor density of O(k). Furthermore, for this hybrid structure, we prove that the maximum distance which any mobile sensor has to move is bounded as O(log3/4 L). We then propose a distributed relocation algorithm, where each mobile sensor only requires local information in order to optimally relocate itself. We verify our, analysis via extensive numerical evaluations and show an implementation of the mobility algorithm on real mobile sensor platforms. [ABSTRACT FROM AUTHOR]

One of the fundamental and important operations in sensor networks is sink–source matching, i.e. target detection. Target detection is about how a sink finds the location of source nodes observing the event of interest (i.e. target activity). This operation is very important in many sensor network applications such as military battlefield and environment habitats. The mobility of both targets and sinks brings significant challenge to target detection in sensor networks. Most existing approaches are either energy inefficient or lack of fault tolerance in the environment of mobile targets and mobile sinks. Motivated by these, we propose an energy-efficient line proxy target detection (LPTD) approach in this paper. The basic idea of LPTD is to use designated line proxies as rendezvous points (or agents) to coordinate mobile sinks and mobile targets. Instead of having rendezvous nodes for each target type as used by most existing approaches, we adopt the temporal-based hash function to determine the line in the given time. Then the lines are alternated over time in the entire sensor network. This simple temporal-based line rotation idea allows all sensor nodes in the network to serve as rendezvous points and achieves overall load balancing. Furthermore, instead of network-wide flooding, interests from sinks will be flooded only to designated line proxies within limited area. The interest flooding can further decrease if the interest has geographical constraints. We have conducted extensive analysis and simulations to evaluate the performance of our proposed approach. Our results show that the proposed approach can significantly reduce overall energy consumption and target detection delay. Copyright © 2007 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, a complete Smart Space architecture and related system prototype are presented. The system is able to analyze situations of interest in a given environment and to produce related contextual information. Experimental results show that video information plays a major role for what concerns both situation perception and personalized contex-aware communications. For this reason, the poropsed multisensor system automatically extracts information from multiple cameras as well as diverse sensors describing environment status. This information is then used to trigger personalized and context-aware video messages adaptively sent to users. A rule-based module is encharged to customize video messages in relation to the user profile, contextual situation and users's terminal. The systems outputs graphically generated video messages consisting of an animated avatar (i.e. Virtual Character) closing the loop on users. Proposed results validate the conceptual schema behind the architecture and the successful adaption to the analysis of different situations. [ABSTRACT FROM AUTHOR]

An increase in the size of on-board antenna reflectors is a key technology in providing economical services by miniaturized portable equipment in future mobile satellite communication systems. In practice, a mesh antenna can be used as the on-board antenna. However, since the reflector surface of this antenna is supported by the cable and the mesh, and its size is larger, the surface is subject to larger thermal deformation in orbit than is the solid antenna reflector. Conventional compensation methods such as passive thermal control or rotation of the antenna reflector cannot maintain the required antenna performances. Various methods have been reported to compensate for the deterioration of antenna performance by thermal deformation. This paper describes a static shape control system for a 10-m diameter antenna which actively compensates for the deformation by using a shape-measuring sensor and shape-compensation actuator. The configuration of the sensor and the experimental results by a functional model are described to confirm the design validity. The shape-compensation method by the actuator was cone firmed to be useful in achieving a required surface accuracy. [ABSTRACT FROM AUTHOR]

In the last period (last 3 years) the maritime domain, especially the sea transportation and fossil resources exploitation became the most important aspects of the international politics and our lives. Because of the COVID19 situation and now the conflict between Russia and Ukraine, the maritime domain was pushed to its limits. What a few years ago was a safety area of navigation, now this one can be transformed very quickly in a dangerous one. It is important to develop fast, systems for monitoring sea areas and platforms of intervention in case of distress situations. To have a real-time system of monitoring and intervention on sea it is mandatory to have redundant maritime communications. The article presents the most relevant publications related to maritime offshore applications and communications that support them. [ABSTRACT FROM AUTHOR]

Currently, it is rapidly increasing convergence services based on various mobile devices with sensors like Smart Home. Specifically the mobility of the sensors in Smart Home merged with wireless sensor networks (WSN) brings security issues such as re-authentication and tracing the node movement. We extend our novel and efficient node authentication and key exchange protocol that support Irregular distribution. Compared with previous protocols, our protocol has only a third of communication and computational overhead. We expect our protocol to be the efficient solution that increases the lifetime of sensor network. [ABSTRACT FROM AUTHOR]

The communication capacity of Cooperative SEnsor Networks with Mobile Access (C-SENMA) is considered when some sensors may be misinformed with erroneous messages. It is assumed that a global message is first distributed to all the nodes, each node receiving the message correctly with probability 1 - β. The nodes cooperate in delivering the global message to the mobile access point. Three system configurations are discussed based on whether a polling channel and/or an energy constraint are present. The first type is C-SENMA with Polling with No Energy constraints (PNE), where the mobile access point has the ability to poll individual sensors. Without energy constraints, each sensor can transmit for an unlimited number of times. The second type is C-SENMA with No Polling with No Energy constraints (NPNE), where adaptive polling is not allowed and sensors have to transmit according to a predetermined schedule. The third type is C-SENMA with No Polling with an Energy constraint (NPE), where each node has a limit on the number of transmissions. The capacities of the three system configurations are analyzed. It is shown that, the capacity for C-SENMA PNE is the same as that when there are no misinformed sensors. For C-SENMA NPNE, with the absence of the polling channel, there is a loss on the achievable rate, proportional to β, the probability that a sensor is misinformed. Results are extended to multiple simultaneous transmissions with the presence of channel fading. The optimal number of simultaneous transmissions is investigated under three different fading situations. [ABSTRACT FROM AUTHOR]

Handling mobility in wireless sensor networks presents several new challenges. Techniques developed for other mobile networks, such as mobile phone or mobile adhoc networks can not be applicable, as in these networks energy is not a very critical resource. This paper presents a new adaptive Mobility-aware Sensor MAC protocol (MS-MAC) for mobile sensor applications. In MS-MAC protocol, a node detects its neighbor’s mobility based on a change in its received signal level from the neighbor, or a loss of connection with this neighbor after a timeout period. By propagating mobility presence information, and distance from the nearest border node, each node learns its relative distance from the nearest mobile node and from the nearest border node. Depending on the mobile node movement direction, the distances from mobile and border nodes, a node may trigger its neighbor search mechanism to quicken the connection setup time. The simulation results show that, the new mobility-aware MAC protocol can work very energy-efficiently when the network is stationary, whereas it performs much better in terms of throughput than the existing sensor MAC (SMAC) protocol in scenarios involving mobile sensors. [ABSTRACT FROM AUTHOR]

It is pointed out that the mean power distribution recently introduced by McGuffin has been known since 1990. Several references are given for the detailed properties of the distribution. [ABSTRACT FROM AUTHOR]

Location-based routing has been considered as an efficient routing paradigm for wireless sensor networks (WSNs). The performance of location-based routing highly depends on the way the position information of mobile sinks are updated and managed, which is the typical function of location service. Frequent location updating can improve the location accuracy at the expense of additional communication overhead. In this study, the authors propose a scalable location service for supporting efficient location-based routing in WSNs with mobile sinks. The proposed location service enables each sensor node to locate its closest (mobile) sink with low overhead. Analytical and simulation results show that it can significantly reduce the communication overhead for providing location service while maintaining high routing performance. [ABSTRACT FROM AUTHOR]

The Intelligent Space is an area (room, public space, etc.) that has networked distributed sensors, which can be used for observing and gathering information from the space. The main objective for the introduction of Intelligent Space is to provide services to humans inside the space. These services can be either informational, such as the ones provided by displays, or physical. In order to be able to provide physical services mobile robots are introduced in the Intelligent Space as actuators. The network of distributed sensors in the space can therefore be utilized to provide data from the space needed for the control of the robot. Here we present our implementation of an Intelligent Space system that uses spatially distributed laser range finders for tracking the mobile robot and humans inside the space and building the map of the space. Based on these measurements, the control of mobile robot acting as physical agent of the Intelligent Space is developed. [ABSTRACT FROM AUTHOR]

Recent research shows that significant energy saving can be achieved in wireless sensor networks by using mobile elements (MEs) capable of carrying data mechanically. However, the low movement speed of MEs hinders their use in data-intensive sensing applications with temporal constraints. To address this issue, we propose a rendezvous-based approach in which a subset of nodes serves as the rendezvous points (RPs) that buffer data originated from sources and transfer to MEs when they arrive. RPs enable MEs to collect a large volume of data at a time without traveling long distances, which can achieve a desirable balance between network energy saving and data collection delay. We develop two rendezvous planning algorithms: RP-CP and RP-UG. RP-CP finds the optimal RPs when MEs move along the data routing tree, while RP-UG greedily chooses the RPs with maximum energy saving to travel distance ratios. We design the Rendezvous-based Data Collection protocol that facilitates reliable data transfers from RPs to MEs in presence of significant unexpected delays in ME movement and network communication. Our approach is validated through extensive simulations. [ABSTRACT FROM AUTHOR]

We provide a better sufficient condition for the connectivity of cluster heads asymptotically almost surely (a.a.s.) and a tighter bound on the number of cluster heads in HEED [1]. [ABSTRACT FROM AUTHOR]