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Leyva-Mayorga I.,Polytechnic University of Valencia | Pla V.,Polytechnic University of Valencia | Martinez-Bauset J.,Polytechnic University of Valencia | Rivero-Angeles M.E.,Communication Networks Laboratory
Journal of Network and Computer Applications | Year: 2017

Evolution in electronics has led to the development of complex applications in wireless sensor networks (WSNs), where efficient and swift event reporting is needed. In time-critical applications, achieving an adequate report latency is particularly relevant as it allows a proper reaction from the network to the occurring phenomena. It is evident that mean report latency is insufficient as a QoS indicator for time-critical applications. Instead, high percentiles or the whole distribution are much better suited. In certain applications such as target tracking and positioning, the transmission of a certain number of event packets is required to accurately characterize the occurring phenomena. Building on this, we present a hybrid method for obtaining the probability distribution of report latency in random access (RA) WSN protocols. In this method, the distribution of the number of detecting nodes is obtained by simulation, which then allows us to obtain the desired QoS parameters analytically. In this study, we use our method to obtain and optimize the event report latency and energy consumption in RA WSNs. Results show that modifying the transmission parameters during backoff increases the robustness of RA event reporting and also enhances the performance of the WSN in environments where multiple types of events can be detected. © 2017 Elsevier Ltd


Wang Y.,Harbin Institute of Technology | Wang Y.,Shenyang Artillery Academy | Wang Y.,Communication Networks Laboratory | Zhang Z.,Harbin Institute of Technology | And 2 more authors.
KSII Transactions on Internet and Information Systems | Year: 2013

The spectrum allocation is an attractive issue for mobile cognitive radio (CR) network. However, the time-varying characteristic of the spectrum allocation is not fully investigated. Thus, this paper originally deduces the probabilities of spectrum availability and interference constrain in theory under the mobile environment. Then, we propose a prediction mechanism of the time-varying available spectrum lists and the dynamic interference topologies. By considering the node mobility and primary users' (PUs') activity, the mechanism is capable of overcoming the static shortcomings of traditional model. Based on the mechanism, two prediction-based spectrum allocation algorithms, prediction greedy algorithm (PGA) and prediction fairness algorithm (PFA), are presented to enhance the spectrum utilization and improve the fairness. Moreover, new utility functions are redefined to measure the effectiveness of different schemes in the mobile CR network. Simulation results show that PGA gets more average effective spectrums than the traditional schemes, when the mean idle time of PUs is high. And PFA could achieve good system fairness performance, especially when the speeds of cognitive nodes are high. © 2013 KSII.


Guzman-Medina C.A.,UPIITA IPN | Rivero-Angeles M.E.,Communication Networks Laboratory | Orea-Flores I.Y.,UPIITA IPN
2015 International Conference on Computing Systems and Telematics, ICCSAT 2015 | Year: 2015

WSNs are complex systems that are mainly limited by the battery life of the nodes in order to have an adequate performance. In most cases, it is possible to have a re-deployment of new nodes in order to prolong the system's lifetime. This leads to a situation where some nodes have a low energy level while other nodes have high energy levels. This scenario can also be found due to the use of a preferred route, where intermediate nodes consume more energy than the rest of the nodes. In these environments, and others, low energy nodes, i.e., nodes with very low residual energy must reduce the energy consumption since their operational lifetime is almost over. In this paper, we consider cluster-based WSNs for the event detection where there is a high concentration of high energy nodes and a low concentration of low energy nodes. Building on this, we propose to extend the battery life of low energy nodes in the steady stat phase. Specifically, we consider the case where nodes have random times in the sleep and active modes. To this end, we consider the case where dwelling times in each mode are related to the residual energy level. The system and the impact of the proposed residual energy-based mechanisms are evaluated and studied. © 2015 IEEE.


Zhang S.,National University of Defense Technology | Zhao H.,National University of Defense Technology | Wang S.,Communication Networks Laboratory | Wei J.,National University of Defense Technology
IEEE Communications Letters | Year: 2014

This letter investigates the sensing-throughput tradeoff problem in cognitive radio networks from a cross-layer perspective, jointly considering the impact of imperfect spectrum sensing and access contention. Furthermore, the optimized solution to this tradeoff is formulated via taking the interference probability, rather than the detection probability, as the optimization constraint. Compared with the results obtained only from the physical layer, the proposed solutions can improve the secondary throughput significantly. © 2014 IEEE.


Guzman-Medina C.A.,UPIITA IPN | Rivero-Angeles M.E.,Communication Networks Laboratory | Rubino G.,French Institute for Research in Computer Science and Automation
2014 11th International Symposium on Wireless Communications Systems, ISWCS 2014 - Proceedings | Year: 2014

WSNs are complex systems that are mainly limited by the battery life of the nodes in order to have an adequate performance. In most cases, it is possible to have a re-deployment of new nodes in order to prolong the systems lifetime. This leads to a situation where some nodes have a low energy level while other nodes (the majority of nodes instants after the re-deployment procedure) have high energy levels. In this environments, it is clear that ancient nodes, those with low energy level, have to contend for the shared medium against the majority of high energy nodes. As such, the remaining battery life of low energy nodes would be rapidly consumed. In this paper, we propose to extend the battery life of low energy nodes by means of assigning prioritized access to the shared channel to those nodes in order to content among a low population of such nodes, while delaying the contention access of high energy nodes which can support higher number of collisions before energy depletion. This is done by studying two different transmission strategies referred to as 'hard' and 'soft' transmission probabilities. Results show that, a soft transmission strategy achieves better results in terms of reduced energy consumption than both the conventional protocol or a hard transmission assignment. © 2014 IEEE.


Ramirez-Reyna M.A.,CINVESTAV | Cruz-Perez F.A.,CINVESTAV | Rivero-Angeles M.E.,Communication Networks Laboratory | Hernandez-Valdez G.,Metropolitan Autonomous University
IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC | Year: 2015

In this paper, dynamic spectrum leasing strategies (with and without anticIPated resource leasing) for coordinated cognitive radio networks with delay-tolerant (best effort) traffic are proposed and analyzed to mitigate the effects of unpredictable resource availability. To exploit the tolerance to delay a buffer for preempted secondary calls is considered. From the mathematical point of view, our contribution is to develop a teletraffic model for the performance evaluation of the proposed strategies. The tradeoff between the spectrum leasing cost and system Erlang capacity is also investigated. For a given maximum allowed number of simultaneously rented channels and Quality of Service (QoS) requirement in terms of new call blocking probability, maximum Erlang capacity is obtained for different traffic scenarios. Numerical results reveal that system performance strongly depends on the value of the mean secondary channel holding time relative to the mean primary channel holding time. Finally, the cost per capacity and mean transmission delay as a function of both the utilization factor of the primary resources and the maximum allowed number of simultaneously rented channels is evaluated. It is shown that anticIPated resource leasing is an effective mechanism to increase the possibility to have available resources when needed for the secondary network. © 2014 IEEE.


Leyva-Mayorga I.,SEPI | Rivero-Angeles M.E.,Communication Networks Laboratory | Arellano C.C.,SEPI
Proceedings - 2014 IEEE 28th International Conference on Advanced Information Networking and Applications Workshops, IEEE WAINA 2014 | Year: 2014

Evolution in Wireless Sensor Networks (WSNs) has allowed new applications that led to an increase in the complexity of communication protocols. Specifically, mobile surveillance applications (where the network is set to monitor mobile objects) require the system to respond in a certain manner so adequate and reliable object tracking and status reporting takes place. Mobile objects can be either independent or controlled by the system, in the former, some sort of transmitter is attached to the mobile entity in order to perform status reporting duties, which, in the case of human beings or specimens may comprise the reporting of vital signs. In view of this, information obtained from mobile objects must be sent with minimal delay and with certain degree of reliability in order to achieve adequate emergency handling when required. Furthermore, mobile environments usually incorporate additional phenomena that creates a multi-event environment, increasing the rate of detection and transmission in the nodes, hence, delaying the report. Hybrid algorithms that allow sensor networks to perform continuous monitoring and event driven applications have proven their ability to enhance performance in different environments where emergency alarms are required while performing a permanent surveillance of the phenomena. Also, these protocols may consider priority assignment in order to reduce report delay and increase reliability in important packets, thus enhancing QoS parameters. In this work, the performance of a non-preemptive hybrid protocol for WSN is studied considering multi-event environments containing mobile targets. Results show that, by using different transmission probabilities, assigned to high and low priority data packets, mobile event reporting delay can be reduced despite the occurrence of other events within the network. As such, a better performance is obtained for critical-time applications where emergency handling is a must. © 2014 IEEE.


Wang J.,National University of Defense Technology | Xiong C.,National University of Defense Technology | Zhang K.,National University of Defense Technology | Wei J.,Communication Networks Laboratory
IEEE Transactions on Signal Processing | Year: 2015

The radix-2k algorithm plays a crucial role in the pipelined implementation of fast Fourier transform (FFT). This paper presents a fixed-point analysis and hardware evaluation of radix-2k FFT under the framework of the single-path delay feedback (SDF) and multi-path delay commutator (MDC) pipelined structure. The investigation is carried out with variable operating word-lengths to ensure the generality. Furthermore, the main streams to fulfill FFT coefficients weighting, namely, the approach using complex multipliers and the one adopting memoryless CORDIC units, are both considered in the analysis. Based on these derivations, a joint optimization of radix-2k algorithm and operating word-length is discussed to achieve a reasonable trade-off between computational accuracy and hardware expenditure. Simulations and experiments indicates that the derived SQNR is reliable to unfold the quantization effects of fixed-point radix-2k FFT. In addition, the proposed joint optimization strategy is capable of providing better solutions to implement the radix-2k FFT processor efficiently. © 2015 IEEE.


Leyva-Mayorga I.,SEPI | Rivero-Angeles M.E.,Communication Networks Laboratory | Arellano C.C.,SEPI
Proceedings - International Conference on Advanced Information Networking and Applications, AINA | Year: 2014

Evolution in Wireless Sensor Networks (WSNs) has allowed new applications that led to an increase in the complexity of communication protocols. This in turn has led to the study of additional Quality of Service (QoS) parameters in order to provide an acceptable system performance. As such, hybrid algorithms that allow sensor networks to perform continuous monitoring (CntM) and event driven detection (EDD) duties have proven their value in different environments where emergency alarms are required in addition to a permanent surveillance of the phenomena, specially when considering time-critical applications. Furthermore, priority assignment may help reduce report delay and enhance transmission probability in important packets, specifically when different types of events are considered or certain data from the same event has higher relevance to the end user than the rest of the packets. In this paper, event report delay and energy consumption in a priority-based hybrid WSN protocol is studied using a Markov chain, when considering a two-priority event detection scheme in a hybrid WSN. Results show that, by using different transmission probabilities, assigned to high and low priority data packets, event reporting delay can be reduced, representing better performance for critical-time applications. On the other hand, energy consumption and network lifetime are not affected by the selected priority assignment scheme. © 2014 IEEE.


Leyva-Mayorga I.,Polytechnic University of Valencia | Pla V.,Polytechnic University of Valencia | Rivero-Angeles M.E.,Communication Networks Laboratory
Proceedings - 2015 8th IFIP Wireless and Mobile Networking Conference, WMNC 2015 | Year: 2015

Efficient event reporting is of vital importance in wireless sensor networks (WSNs). This is especially true in critical-time applications, where ensuring an adequate report latency allows a proper reaction from the network to the occurring phenomena. Despite a QoS analysis based on mean report latency is clearly insufficient for critical-time applications, it is oftentimes presented as the main performance indicator. For instance, high percentiles or the whole distribution of the report latency are much better suited. Furthermore, several applications, such as target positioning, require the transmission of a certain number of event packets to accurately characterize occurring events. Building on this, we present a hybrid method for obtaining the report latency distribution of random access (RA) WSN protocols. Here, the distribution of detecting nodes is obtained by simulation and then we perform the mathematical analysis of QoS parameters. Since the proposed method comprises a general structure, it can be easily adapted for analyzing the QoS of a wide range of RA WSN protocols. We use this method for evaluating the report latency, along with the energy consumption of RA protocols in applications that require the transmission of, at least, k event messages. Results show that the combination of higher detection ranges with low congested wireless environments leads to a clear reduction in report latency and event overlooking probability. This leads to an overall performance increase. © 2015 IEEE.

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