Showing papers in "International Journal of Wireless Information Networks in 2011"
TL;DR: A modified SI model is proposed by leveraging the sleep mode of WSNs to perform system maintenance and can improve the network anti-virus capability and flexibly adapt to different types of virus, without causing any additional hardware effort and signaling overhead.
Abstract: We study the dynamics of virus spread in wireless sensor networks (WSNs). We first analyze the susceptible-infective (SI) epidemic model for WSNs. In the SI model, once a sensor node is attacked by a virus, the infective node then, using normal communications, spreads the virus to its neighboring nodes, which further spread the virus to their neighbors, the process continues until the whole network fails. To combat this drawback, we propose a modified SI model by leveraging the sleep mode of WSNs to perform system maintenance. The modified SI model can improve the network anti-virus capability and flexibly adapt to different types of virus, without causing any additional hardware effort and signaling overhead. We derive the explicit analytical solutions for the modified SI model, which can capture both the spatial and temporal dynamics of the virus spread process. Extensive numerical results are presented to validate our analysis. The proposed model and analysis method are expected to be used for analysis and design of information (including virus) propagation mechanisms in distributed wireless or computer networks.
38 citations
TL;DR: This paper presents an approach to reduce the manual calibration efforts needed to deploy an RSS-based localization system, both when using only one RF technology or when using a combination of RF technologies.
Abstract: Location estimation based on Received Signal Strength (RSS) is the prevalent method in indoor positioning. For such positioning systems, a massive collection of training samples is needed for their calibration. The accuracy of these methods is directly related to the placement of the reference points and the radio map used to compute the device location. Traditionally, deploying the reference points and building the radio map require human intervention and are extremely time-consuming. In this paper we present an approach to reduce the manual calibration efforts needed to deploy an RSS-based localization system, both when using only one RF technology or when using a combination of RF technologies. It is an automatic approach both to build a radio map in a given workspace by means of a signal propagation model, and to assess the system calibration that best fits the required accuracy by using a multi-objective genetic algorithm.
20 citations
TL;DR: It is shown that a dual-antenna structure with elements vertically oriented along the edges of a small 100 mm × 40 mm mobile terminal chassis achieves better performance in port-to-port isolation, gain imbalance and diversity gain compared to other studied dual-Antenna configurations when the user’s hand is present.
Abstract: This paper presents a comprehensive simulation study on the performance of coupling element-based dual-antenna structures on a mobile terminal at the 2,000 MHz Universal Mobile Telecommunications System (UMTS) frequency band with varying two significant hand effects; vertical position of hand along terminal chassis, and distance between hand palm and terminal chassis. The results reveal that in uniformly distributed isotropic environment, there exists a gain imbalance between antenna elements due to hand effects and it is shown that a gain imbalance of 3.7 dB lead to a reduction of 1.9 dB in diversity gain at 99% reliability level using maximal ratio combining (MRC) technique. For a dual-antenna configuration, the impact of gain imbalance on diversity gain is more significant when only one antenna element is in close proximity to the hand, compared to when both antenna elements are in the presence of the hand. It is also shown that a dual-antenna structure with elements vertically oriented along the edges of a small 100 mm × 40 mm mobile terminal chassis achieves better performance in port-to-port isolation, gain imbalance and diversity gain compared to other studied dual-antenna configurations when the user’s hand is present.
17 citations
TL;DR: This paper proposes a novel adaptive mobility prediction algorithm, which deals with location context representation and trajectory prediction of moving users, and relies on Adaptive Resonance Theory (ART) for trajectory prediction.
Abstract: Context-awareness is viewed as one of the most important aspects in the emerging pervasive computing paradigm. Mobile context-aware applications are required to sense and react to changing environment conditions. Such applications, usually, need to recognize, classify and predict context in order to act efficiently, beforehand, for the benefit of the user. In this paper, we propose a novel adaptive mobility prediction algorithm, which deals with location context representation and trajectory prediction of moving users. Machine Learning (ML) is used for trajectory classification. Our algorithm adopts spatial and temporal on-line clustering, and relies on Adaptive Resonance Theory (ART) for trajectory prediction. The proposed algorithm applies a Hausdorff-like distance over the extracted trajectories handling location prediction. Since our approach is time-sensitive, the Hausdorff distance is considered more advantageous than a simple Euclidean norm. Two learning methods (non-reinforcement and reinforcement learning) are presented and evaluated. Finally, we compare our algorithm with Offline kMeans and Online kMeans algorithms. Our findings are very promising for the use of the proposed algorithm in mobile context aware applications.
15 citations
TL;DR: This paper presents a discriminatively regularized least square classifier (DRLSC)-based localization algorithm that is aimed at making use of the class label information to better distinguish the RSS samples taken from different locations after proper transformation.
Abstract: In this paper, we address the received signal strength (RSS)-based indoor localization problem in a wireless local area network (WLAN) environment and formulate it as a multi-class classification problem using survey locations as classes. We present a discriminatively regularized least square classifier (DRLSC)-based localization algorithm that is aimed at making use of the class label information to better distinguish the RSS samples taken from different locations after proper transformation. Besides DRLSC, two other regularized least square classifiers (RLSCs) are also presented for comparison. We show that these RLSCs can be expressed in a unified problem formulation with a closed-form solution and convenient assessment of the convexity of the problem. We then extend the linear RLSCs to their nonlinear counterparts via the kernel trick. Moreover, we address the missing value problem, utilize clustering to reduce the training and online complexity, and introduce kernel alignment for fast kernel parameter tuning. Experimental results show that, compared with other methods, the kernel DRLSC-based algorithm achieves superior performance for indoor localization when only a small fraction of the data samples are used.
13 citations
TL;DR: Results show that the proposed adaptive CAC scheme has excellent BU under stressed network condition and the long term average revenue is calculated for different service flows and for the overall system to see the efficiency of the adaptive Cac scheme.
Abstract: In wireless environment the bandwidth resource is limited and therefore judicious use of the available resources is needed. A bandwidth efficient Call Admission Control (CAC) is proposed in this paper for quality of service (QoS) provisioning for the services defined in IEEE 802.16e mobile WiMAX standards to satisfy both bandwidth and delay guarantees to the admitted connections. The concept of adaptive bandwidth degradation is introduced to improve the bandwidth utilization (BU) of the system. The proposed CAC scheme is analyzed by Markov Chain model and performance evaluation is made in comparison with fixed step size degradation. Results show that the proposed adaptive CAC scheme has excellent BU under stressed network condition. Also the long term average revenue is calculated for different service flows and for the overall system to see the efficiency of the adaptive CAC scheme.
6 citations
TL;DR: The implementation results show that the proposed mining system performs well by extracting the significant RFID tags and its combinations and the nature of movement of the tags.
Abstract: Data warehousing and Data mining find enormous applications; RFID technology is one among them A RFID data warehousing system with novel data cleaning, transformation and loading technique has been proposed in the previous work The system has been dedicatedly implemented in one of the significant RFID applications tracking of goods in warehouses The warehoused RFID data is in specific format and so an effective mining system is required to mine the needed information from the database The existing mining algorithms are inefficient in extracting the information from the warehoused RFID data In this paper, a novel data mining system is proposed, which effectively extracts the information regarding the nature of movement of the RFID tags The proposed mining system generates an intermediate dataset (I-dataset) from the warehoused dataset From the I-dataset, sequential patterns are mined with different pattern length combinations From the mined sequential patterns, fuzzy rules are generated, which depicts the nature of movement of the RFID tags The implementation results show that the proposed mining system performs well by extracting the significant RFID tags and its combinations and the nature of movement of the tags
6 citations
TL;DR: An Adaptive Pull–Push (APP) based Event Tracking approach that allows sensor-to-actor communication as well as actors coordination in response to the events occurred and reveals significant performance improvement in terms of response time and energy conservation.
Abstract: Wireless sensor networks have attracted significant interest for various scientific, military, and e-health applications. Recently a new class of sensor networks “sensor/actor networks” has been introducing new research challenges due to the unique coordination requirements among sensors and actors. In sensor/actor networks, actors are the nodes that have the capability to move in the field, equipped with powerful devices and can respond to the events of interest. With this capability, autonomous operation of the network is possible without a centralized controlling mechanism. This, however, requires the network to apply cooperative mechanism to decide when and how monitoring is done to track the event and how the event will be responded. In this regard, little work has been done in terms of co-existing Push and Pull data flows in the network. In this paper, we propose an Adaptive Pull–Push (APP) based Event Tracking approach that allows sensor-to-actor communication as well as actors coordination in response to the events occurred. APP proposes two models of sensors organization: region-based organization (RAPP) and neighbor-based organization (NAPP) to alert nodes in the vicinity of reported event. APP exploits the mobility of actor nodes to form dynamic responsibility clusters, thus ensuring an event specific response to emergencies. Routing in APP is based on Routing by Adaptive Targeting (RAT), which is a delay-constrained geographical routing protocol. Simulation results reveal significant performance improvement in terms of response time and energy conservation.
6 citations
TL;DR: The simulation results show that the investigated AMC-OFDMA system based on the proposed SRA strategy outperforms the conventional approaches.
Abstract: A cross-layer scheduling and resource allocation (SRA) strategy for an adaptive modulation and coding (AMC) based orthogonal frequency multiple access (OFDMA) system is proposed. The objective of this paper is to maximize the system throughput as a function of the bit error rate (BER) and the spectral efficiency based on the selected modulation and coding schemes (MCSs). The proposed strategy contains two main algorithms. Firstly, the scheduling algorithm that aims to maximize the average system throughput by arranging the users in distinct queues according to their priorities and selecting the best user of each queue individually in order to guarantee a fair user service amongst different priority levels. Secondly, the resource allocation algorithm that allocates the user, bit and power based on the channel conditions of the scheduling users and the transmission power constraints. The transmitter of the investigated AMC-OFDMA system at the assigned base station (BS) divides the transmitted OFDMA frame into sub-channels and assigns each sub-channel to a scheduled user. In this paper, we compare the performance of the proposed SRA with the conventional first in first out (FIFO) queuing based scheduling and resource allocation strategies used for an AMC-OFDMA system. The simulation results show that the investigated AMC-OFDMA system based on the proposed SRA strategy outperforms the conventional approaches.
6 citations
TL;DR: This paper provides a theoretical exercise to help understand the accuracy required for typical human motion sensing and gives an overview of various synchronisation strategies used and implemented in prototype systems.
Abstract: In this paper, we highlight considerations for synchronization issues in body area networks. Requirements for the synchronization accuracy in body area networks depend on the application at hand. Synchronization may be needed for power management, sample ordering, calculation of stimulus responses and for sensor fusion. This paper provides a theoretical exercise to help understand the accuracy required for typical human motion sensing. It gives an overview of various synchronisation strategies used and implemented in prototype systems. Lessons learnt from practical implementations using Bluetooth, an IEEE 802.15.4 proprietary network and Nanonet are presented to illustrate the principles involved. The discussion provides some considerations and the requirements for typical WBAN applications.
6 citations
TL;DR: This paper proposes a joint multi-target identification and classification (JMIC) algorithm for radar surveillance using the cognitive radar network and presents simulation results to evaluate the feasibility and effectiveness of the proposed JMIC algorithm in a query surveillance region.
Abstract: We investigate the problem of jointly classifying and identifying multiple targets in radar sensor networks where the maximum number of categories and the maximum number of targets in each category are obtained a priori based on statistical data. However, the actual number of targets in each category and the actual number of target categories being present at any given time are assumed unknown. It is assumed that a given target only belongs to one category and one identification number. The target signals are moreover modeled as zero-mean complex Gaussian processes. In this paper, we propose a joint multi-target identification and classification (JMIC) algorithm for radar surveillance using the cognitive radar network. The existing target categories are first classified and then the targets in each category are accordingly identified. Simulation results are presented to evaluate the feasibility and effectiveness of the proposed JMIC algorithm in a query surveillance region.
TL;DR: This paper recalls a complete architecture of an economic wireless transmission system with the implementation of an effective algorithm, adapted to the mobile terminal, allowing to the doctor to have the results of the ECG analysis and suggests to introduce and implement this complete treatment for revealing critical situations and pathologies on a simple mobile phone.
Abstract: The development and the design of telemedicine services have taken a great consideration and care in the domain of wireless communication nowadays. The set of these researches is concerned with old people and lack of infrastructures of reception for those who are at risk or tend to have deterioration in their health condition. Thus, several works of research contributed to develop telemedicine services. They notably focus on the conception and the development of communication architectures between the actors of these systems, monitoring and the development of human’s quality is based on the storage of the collected data at home and analytical tools, and processing of these large quantities of data. Therefore, it is useful to detect and prevent the occurrence of critical situations of a remote person, the transmission of the messages and alarms to concerned actors to be ready to intervene in a case of emergency. Many works and systems undertaken in this field carry out the complete analysis and synthesis of signals on large servers (great capacities, better resolutions…). Moreover, these systems would have required large means and a large infrastructure in their deployment (installation, configuration…), which generates the disadvantage of the excessive expenditure. In this paper, we suggest to introduce and implement this complete treatment for revealing critical situations and pathologies on a simple mobile phone by respecting theirs constraints. The principal objective is to permit a taking off for medical and social dependant people as aged ones, handicapped, in order to the adaptation with their environment domestically and make up their incapacities. In this case, it is indispensable to make a diagnostic in a real time and well manage the patient’s computerized data between the various medical actors with the permanent security insurance of highly risky patients. Furthermore, the need to make a speed diagnostic of patients and to detect their health state, their parameters (medical information) of analyses with efficacy, allows us to gain time while monitoring the cardiac patient. It concerns the implementation of services on mobile terminals for transferring medical information and results of ECG analysis (calculated parameters) in a real time with ensuring the mobility, the permanent security and the reliability insurance in covered zone by the mobile network, PLMN (GSM/GPRS…). Our attention has been focused on the choice of a relevant work. It concerns an application on a mobile terminal (MIDlet) for detecting some cardiac pathologies and monitoring patient in a non-hospital setting. This paper recalls a complete architecture of an economic wireless transmission system with the implementation of an effective algorithm, adapted to the mobile terminal, allowing to the doctor to have the results of the ECG analysis. Thus, the stakes of setting up such systems are numerous, so much for patients, medical staff and the society in general.
TL;DR: This paper categorize and position the communication players and model the interaction between players at different levels and introduces the learning aspects in the interaction and investigates the equilibrium strategies of involved stake-holders i.e., users and operators.
Abstract: In future wireless networks, we envision more dynamic telecommunication paradigm, where the dynamics may be translated into dynamic service offerings and user profiles etc. We further expect that the wireless communication market will be influenced when the user-centric network selection vision is realized. By the user-centric network selection vision, we mean that users will be free to select any available network operator or service provider on short term contractual basis. This dictates that operators will compete for their share of a common user pool on much smaller time quanta when compared with the current long term user contacts with the operators. One intuitive strategy of operators will be to incentivize users by offering different QoS and service price offers. As the operators’ offers are influenced by their incurring costs. This necessitates to study the market behavior at different levels and investigate the operator and user behavior at these level. In this paper, we categorize and position the communication players and model the interaction between players at different levels. We introduce the learning aspects in the interaction and investigate the equilibrium strategies of involved stake-holders i.e., users and operators. We also model the utility functions of all the involved stake-holders. We also examine the risk-sensitive utility functions in order to cover both risk-seeking and risk-averse in the user QoEs. We implement the user-centric approach and compare it against our proposed network-centric resource utilization and call blocking.
TL;DR: Numerical results show that simple adaptive systems that switch between diversity/ multiplexing or beamforming/multiplexing schemes obtain relatively good performance in realistic 2 × 2 MIMO channels, but it is shown that the imperfect channel estimation and feedback errors can have significant impact on the link performance.
Abstract: Performance evaluation of enhanced link adaptation method for MIMO-OFDM systems with limited feedback using measurement based channels and a stochastic channel model is presented in this paper. In particular, impact of practical channel estimation and feedback errors on link performance is analyzed. An adaptive spatial and modulation scheme selection process is based on the effective signal-to-interference-plus-noise ratio (ESINR). Mutual information effective SINR mapping method is applied for calculating ESINR values due to its capability of accurate estimation of the error rate performance of large variety of MIMO channels. Numerical results show that simple adaptive systems that switch between diversity/multiplexing or beamforming/multiplexing schemes obtain relatively good performance in realistic 2 × 2 MIMO channels. It is also shown that the imperfect channel estimation and feedback errors can have significant impact on the link performance. Furthermore, it is noticed that using the stochastic channel model in performance simulations can give rather pessimistic results compared to true measurement data.
TL;DR: A new routing strategy for MANETs is proposed which is called Snack Routing Strategy (SRS), which uses no periodic routing advertisement messages but uses artificial snacks instead, thereby reducing the network bandwidth overhead and minimizing end-to-end transmission delay.
Abstract: Recently, Mobile Ad Hoc networks (MANETs) are growing in popularity and importance. They present a possible communication among a set of mobile nodes with no need for either a pre-established infrastructure or a central administration. However, in order to guarantee an efficient communication among network nodes, efficient routing algorithms should be established. Routing plays the central role in providing ubiquitous network communications services in such dynamic networks. The problem is further aggravated through the node mobility as any node may move at any time without notice. Several routing protocols had been proposed; however, most of them suffer from control packet flooding, which results in a scalability problem. In this paper, a new routing strategy for MANETs is proposed which is called Snack Routing Strategy (SRS). The basic idea of SRS is to continuously inform the network mobile nodes with any changes in the network topology without overloading the network by a huge amount of control messages. SRS is a hybrid routing strategy that relies on Learning by accumulation, hence, new routes can be discovered by learning the accumulative data stored in the nodes routing tables by several foraging artificial snacks. SRS uses no periodic routing advertisement messages but uses artificial snacks instead, thereby reducing the network bandwidth overhead and minimizing end-to-end transmission delay. SRS has been compared against two well known protocols AODV and DSR. Experimental results have shown that SRS outperforms both AODV and DSR as it introduces the minimal routing overheads.
TL;DR: The obtained results show that sharing of bandwidth resource is essential for the existence of CCWC systems.
Abstract: In this paper, we analyze the behavior of Cooperative Cognitive Wireless nodes for the bandwidth resource competition using the ecological models of mutualism. We transform our cooperative cognitive wireless communication (CCWC) system as mutually interacting species. The two types of species are primary and secondary users. The Primary users have under-utilized licensed bandwidth to be shared with the secondary users. On the other hand, secondary users are willing to behave as possible relays for cognitive primary users, in exchange of shared licensed bandwidth. So, instead of pricing model, the proposed system is analyzed with the traditional barter system (exchange of commodities). We analyzed our proposed system based on three ecological models. Our first model is based on the coalitional form of Lotka–Volterra equations, where predator-prey role of mobile nodes are replaced with cooperation as in symbiosis. The second model deals with the population dynamism of strategically interacting partner for conflicting bandwidth resource. The third model adds the dynamism for the varying amount of bandwidth to be shared among the individual mobile users. For each type, a mathematical model is derived and then simulated for the equilibrium position analysis. The obtained results show that sharing of bandwidth resource is essential for the existence of CCWC systems.
TL;DR: Data collection from the sensor nodes by the mobile node or element without data loss is termed as the scheduling of the Mobile Element (ME), and the speed of the ME is varied based on the simplex method such that the data Loss is minimized.
Abstract: In Wireless Sensor Networks, collection of data from the sensor nodes without data loss is a major challenge of great concern. Nodes are deployed statically and will relay the data to the base station which lead to the problem of energy-drain to the nodes near the base station since these nodes have to constantly relay data to the base station. Data collection from the sensor nodes by the mobile node or element without data loss is termed as the scheduling of the Mobile Element (ME). The proposed problem can be classified into three phases. In the initial phase, the nodes are clustered according to their geographical region in a hierarchical fashion. In the second phase, the nodes within each cluster which are in the active state are only visited by the mobile element. Quad-tree based partitioning is performed in order to schedule the visit by ME to the nodes in the active state within each cluster. In the third phase, the ME visits only the boundary-near nodes and the speed of the ME is varied based on the simplex method such that the data loss is minimized.
TL;DR: A case is made for why continued research in the area of joint compression and encryption is relevant to the field of wireless sensor networks and an approach based on the LZW algorithm combined with cryptographically strong pseudo-random number generators is presented.
Abstract: More and more, wireless sensor networks (WSNs) are making their way out of the laboratory and into real-world deployments where they must be concerned with issues of security. These networks of motes are also being tasked with sensing and monitoring duties that often require high-fidelity data to be delivered from individual nodes, a situation which precludes the use of data aggregation and other techniques to reduce the volume of sensing data by condensing it within the network. This paper makes a case for why continued research in the area of joint compression and encryption is relevant to the field of wireless sensor networks and presents an approach based on the LZW algorithm combined with cryptographically strong pseudo-random number generators.
TL;DR: It was demonstrated that the Adaptive Pursuit Reward-Only scheme guarantees updating the probability of the channel selection for all the links—even the links whose current channel allocations do not provide a satisfactory performance—thereby reducing the frequent channel switching of the links that cannot achieve the desired performance.
Abstract: Single-channel based wireless networks have limited bandwidth and throughput and the bandwidth utilization decreases with increased number of users. To mitigate this problem, simultaneous transmission on multiple channels is considered as an option. In this paper, we propose a distributed dynamic channel allocation scheme using adaptive learning automata for wireless networks whose nodes are equipped with single-radio interfaces. The proposed scheme, Adaptive Pursuit learning automata runs periodically on the nodes, and adaptively finds the suitable channel allocation in order to attain a desired performance. A novel performance index, which takes into account the throughput and the energy consumption, is considered. The proposed learning scheme adapts the probabilities of selecting each channel as a function of the error in the performance index at each step. The extensive simulation results in static and mobile environments provide that the proposed channel allocation schemes in the multiple channel wireless networks significantly improves the throughput, drop rate, energy consumption per packet and fairness index—compared to the 802.11 single-channel, and 802.11 with randomly allocated multiple channels. Also, it was demonstrated that the Adaptive Pursuit Reward-Only (PRO) scheme guarantees updating the probability of the channel selection for all the links—even the links whose current channel allocations do not provide a satisfactory performance—thereby reducing the frequent channel switching of the links that cannot achieve the desired performance.
TL;DR: The demonstrator shows how the modular CRM together with its open interface, the universal link-layer API (ULLA), facilitates the implementation of efficient radio resource management techniques guaranteeing the quality of service in the LTE system.
Abstract: In this article we describe a demonstrator that shows how the cognitive resource manager (CRM) and the radio-environmental map (REM) can be efficiently implemented in full commercial grade cellular system (i.e., LTE system). The demonstrator shows how the modular CRM together with its open interface, the universal link-layer API (ULLA), facilitates the implementation of efficient radio resource management techniques guaranteeing the quality of service in the LTE system. The CRM, through ULLA, is able to obtain PHY/MAC status information of the link between the tested eNode B and the user equipment, and reconfigure link parameters. This measure-and-control by CRM/ULLA is independent of the underlying radio access technology, which shows the neutrality of CRM/ULLA towards PHY/MAC characteristics. The article also shows how the REM can be easily implemented in such system and how the REM provides the CRM with environmental information that enhances system management performance.
TL;DR: Frequency domain pre-equalization (Pre-FDE) is developed for broadband cyclic prefix-code division multiple access as a single carrier transmission scheme and for multi carrier-CDMA and orthogonal frequency division multiplexing as multi carrier transmission schemes.
Abstract: In this paper, frequency domain pre-equalization (Pre-FDE) is developed for broadband cyclic prefix-code division multiple access (CP-CDMA) as a single carrier transmission scheme, and for multi carrier-CDMA (MC-CDMA) and orthogonal frequency division multiplexing (OFDM) as multi carrier transmission schemes. A comparison study is held between these schemes and the traditional equalization schemes. Experimental results show that pre-equalization improves significantly the performance of the single and multi carrier communication systems with a very low complexity at the receiver. The comparative study between MIMO pre-equalization for single carrier systems and for multi carrier systems shows that MIMO pre-equalization for single carrier systems outperforms that for multi carrier systems in terms of bit error rate (BER) performance since single carrier transmission has more frequency diversity than multi carrier transmission in the uncoded case.
TL;DR: Research indicates that the throughputs of DS-CDMA with S-ALOHA steadily increase as the parameters of fading signals m and the length of code N progressively enhance and gradually step-up as the value of capture ratio Q and the number of users K progressively step-down.
Abstract: This research aims to investigate the throughputs of DS-CDMA with S-ALOHA systems over Nakagami/Nakagami dual-path gain fading models with capture effects. The effects of fading on bit error rates (BERs) have been analysed by taking path gains into consideration. Due to the discrepancy between path gain for the desired signals and path gain for interferences, the BERs employed in our computations are the BERs of two different path gain models. Research indicates that the throughputs of DS-CDMA with S-ALOHA steadily increase as the parameters of fading signals m and the length of code N progressively enhance. Likewise, the throughputs of DS-CDMA with S-ALOHA gradually step-up as the value of capture ratio Q and the number of users K progressively step-down.
TL;DR: A distributed rate control algorithm for multicast session in ad hoc networks with dynamic scheduling policy is developed and the stability of the resulted system is established.
Abstract: Network coding is a powerful coding technique that has been proved to be very effective in achieving the maximum multicast capacity. It is especially suited for new emerging networks such as ad-hoc and sensor networks. In this paper, we develop a distributed rate control algorithm for multicast session in ad hoc networks. With random network coding, the algorithm can be implemented in a distributed manner, and work at transport layer to adjust source rates and at network layer to carry out network coding. The scheduling element of our algorithm is a dynamic scheduling policy. The stability of the resulted system is established, and simulation results are provided to support our conclusions.
TL;DR: A novel analytical model of handoff management in mobile IP networks based on general distribution of both successful transmission attempts and the residence time to be applicable in all cases of traffic characteristics and user mobility is introduced.
Abstract: Mobile IP has been developed to provide the continuous information network access to mobile users. The performance of Mobile IP mobility management scheme is dependent on traffic characteristics and user mobility. Consequently, it is important to assess this performance in-depth through these factors. This paper introduces a novel analytical model of handoff management in mobile IP networks. The proposed model focuses on the effect the traffic types and their frame error rates on the handoff latency. It is derived based on general distribution of both successful transmission attempts and the residence time to be applicable in all cases of traffic characteristics and user mobility. The impact of the behavior of wireless connection, cell residence time, probability distribution of transmission time and the handoff time is investigated. Numerical results are obtained and presented for both TCP and UDP traffics. As expected, the reliability of TCP leads to higher handoff latency than UDP traffic. It is shown that, higher values of FER increase the probability of erroneous packet transfer across the link layer. A short retransmission time leads to end the connection most likely in the existing FA; however a long retransmission time leads to a large delivery time. The proposed model is robust in the sense that it covers the impact of all the effective parameters and can be easily extended to any distribution.
TL;DR: This study analyzes all of the power parameters for the PMPS for sensor nodes and establishes the design model of PMPS, which is verified by experiments and simulations based on wireless sensor node (Ginze3).
Abstract: For the wireless sensor node integrated with photoelectric micro-power supply, the photoelectric micro-power supply (PMPS) determines their life time, stability and adaptability to the local environment The design of PMPS involves the study related to incident light power, photoelectric conversion efficiency of solar cells, characterization of storage devices, energy management and operation state control of sensor nodes, etc The design process of PMPS is complicated In this study, in order to simplify the design process of the PMPS and optimize it, we analyze all of the power parameters for the PMPS for sensor nodes According to the energy transmission modes of PMPS for sensor nodes, the design model of PMPS is established The rationality of PMPS is verified by experiments and simulations based on wireless sensor node (Ginze3)
TL;DR: Simulation results are presented and show that the errors in estimating the CSI are to a large extent absorbed by the quantization error and the performance with quantized imperfect CSI is close to full CSI even with a reduced number of quantization bits.
Abstract: Uplink scheduling in OFDMA systems with imperfect CSI is investigated. An efficient CSI quantization scheme is proposed and shown to achieve good perfor- mance with a limited number of quantization bits in the perfect CSI scenario. The probability of error in quantizing imperfect CSI is studied and analytical formulas are derived. Simulation results are presented and show that the errors in estimating the CSI are to a large extent absorbed by the quantization error and the performance with quan- tized imperfect CSI is close to full CSI even with a reduced number of quantization bits.