Battery-Aware TDMA Scheduling Schemes for Wireless Sensor Networks

Pattern transformation-invariant schemes for wireless sensor networks based on an edge detection gradient-based mechanism

To prevent scalability problem caused by increasing traffic of real-time applications, cluster architecture with Time Division Multiple Access (TDMA) scheduling scheme is mostly deployed in wireless sensor networks. However, even though it have proven good scalability and suitability for real-time communications, but static scheduling lacks of adaptability in several situations by not admitting some real-time flows where slots remain available. To solve mentioned problem, in this paper, we propose an adaptive cluster-based scheduling scheme for real-time flows by utilizing the time slots for flows according to type of flows such as inside or outside cluster. So, the proposed scheme can achieve better utilization of channel by minimizing the number of unused channels for real-time flows than static scheme through new adaptive TDMA scheduling scheme . Simulation results show that more flows are admitted and delivered within the deadline in the proposed scheme by utilizing unused time slots accordingly.

Cognitive radio technology is widely accepted as an efficient approach to solve the problem that the wireless spectrum has been getting scarcer and scarcer due to the rapid growth in the ubiquitous wireless applications. Several cognitive medium access control (MAC) protocols have been proposed for the secondary users (non-licensed users) to take advantage of the vacant channels whenever they are not occupied by the primary users (licensed users) in the wireless time division multiple access (TDMA)-based networks. In this paper, by exploiting the unique property of the wireless fading channel and cross-layer design technique, we develop a packets scheduling scheme for the primary users in the context of wireless TDMA networks, which is set up to operate friendly towards the secondary users in terms of vacant-channel probability. Our proposed scheme can be implemented with just slight modification on the traditional TDMA scheduling algorithm. We develop a rigorous queuing model and then quantitatively analyze the tradeoff among multiple performance metrics to identify when and where the cost for favoring the secondary users is worthy. The analytical results show that our proposed scheme can generate more vacant-channel opportunities for secondary users, at the expense of little increasing packet delay, as compared with the traditional wireless TDMA scheduling algorithm. In addition, since the implementation of our proposed scheme only needs little modification on the existing TDMA scheduling algorithm, our proposed scheme is a practical and cost-effective approach to increase the wireless spectrum utilization.

Resource allocation using time division multiple access over wireless relay networks

The main purpose of this paper is to propose a novel bandwidth allocation scheme for facilitating quality of service (QoS) routing in mobile ad hoc networks (MANETs). In a MANET using time division multiple access (TDMA), each node communicates with its neighbors in the same time slot. In general, finding a route with the maximum end-to-end bandwidth subject to the constraint of collision-free transmission is an NP-complete problem. This paper proposed a sub-optimal solution to this problem. The solution is based on a centrally controlled bandwidth allocation scheme to properly assign the available time slots to each intermediate link. The advantage of our proposed scheme is that the resource utilization of MANET is maximized and the end-to-end QoS is guaranteed during the route establishment period. Performance analyses show that when using the proposed scheme with AODV to perform QoS routing, it achieves about 25% throughput higher than its best-effort counterpart if the node is moving at 5mps speed.

The Randomly deployed wireless sensor nodes form an unpredictable structure. Normally wireless sensor networks are distinguished from conventional networks by their energy constraints and limited computational power. Huge volumes of data are sensed and generated by the sensor nodes when they are deployed in the dynamic environment. Mostly the source and sink nodes are not within each other's transmission range. Congestion occurs when the intermediate nodes forward the data from source to sink. Many of the existing approaches focus on controlling the link level congestions in the network. Our proposed Queue reloading scheme controls the node level congestion. In order to avoid the retransmission of packets, the proposed scheme uses an alternative queue for caching the overflowed packets. The dropped packets are reloaded from the alternative queue when the current queue becomes available. The lifetime of the nodes depend on allocation rate. Our scheme saves the network resources; consuming less energy and aids achievement of improved efficiency and throughput. The node level congestion control is basically needed for WSNs, because the node can be deployed anywhere in the environment.

In recent years, the MIMO-based underwater acoustic (UWA) wireless sensor networks have attracted significant research attention because of its wide and critical applications in marine research, oceanography, marine commercial operations, offshore oil industry, and defense systems. The cooperative-communications-based wireless relay networks have been widely cited as a very efficient technique to enhance the transmission and lifespan performances of the wireless networks. However, how to make the energy-efficient relay selection in the MIMO-based UWA wireless sensor networks, particularly under the harsh underwater wireless environments with the stringent power supply constraint, have been not well understood, neither thoroughly studied. To overcome the above problems, in this paper we propose the optimal relay selection scheme to minimize the energy consumption while guaranteeing the quality of service (QoS) of each link over the MIMO-based UWA cooperative wireless sensor networks. We use the Finite-state Markov chain to model the UAW channel. Moreover, we also incorporate MIMO multiplexing-gain and diversity-gain techniques, as well as residual relay energy in the relay selection process. We implement our proposed optimal relay selection scheme by the linear programming (LP) technique. We conduct the simulations to validate and evaluate our proposed scheme, showing its superlatives over the other existing schemes.

The design of an efficient medium access control (MAC) for wireless ad hoc networks or wireless sensor networks is challenging. These kinds of network can benefit from communication protocols that avoid frame collision: time division multiple access (TDMA). However, ad hoc networking and sensor networks enable novel communication paradigms which require the definition of new quality-of-service (QoS) parameters and frameworks for QoS support. The relevant QoS requirements are frequently antagonist and, consequently, an appropriate tradeoff has to be determined to fit all of them. In the distributed TDMA paradigm the speed of schedule exchange is important to have updated information about collision-free slots when the topology network changes. The high speed of the schedule update is paid in terms of power consumption. In this work, an analytical framework allowing an evaluation of the tradeoff between energy efficiency and responsiveness in the update process in a generic, distributed TDMA system is derived. The main objective of this work is to maximize the probability that the schedule updating process is realized in an interval time [0, t], given a constraint in terms of power consumption.

A time division multiple access (TDMA) scheduling protocol is proposed for solving the inter-cluster interference of medium access control (MAC) in cluster-based wireless sensor networks (WSN). Through each cluster-head snooping into the neighbor nodes' networking packets and creating the TDMA schedule based on these packets, the protocol can avoid inter-cluster interference. The protocol is implemented in an assumed single-physical-channel network, thus its implementation does not depend on specific hardware, and has the advantage of generality. The implementation of the protocol is based on TinyOS software platform and MICA2 hardware platform. The generation of the cluster-heads, the networking cost, the networking packet loss rate and the accuracy of sensing data transmission are tested, and the results show that the protocol can avoid the inter-cluster interference and has moderate reliability.

Multicast in wireless sensor networks (WSNs) is an efficient way to spread the same data to multiple sensor nodes. It becomes more effective due to the broadcast nature of wireless link, where a message transmitted from one source is inherently received by all one-hop receivers, and therefore, there is no need to transmit the message one by one. Reliable multicast in WSNs is desirable for critical tasks like code updation and query based data collection. The erroneous nature of wireless medium coupled with limited resource of sensor nodes, makes the design of reliable multicast protocol a challenging task. In this work, we propose a time division multiple access (TDMA) based energy aware media access and control (TEA-MAC) protocol for reliable multicast in WSNs. The TDMA eliminates collisions, overhearing and idle listening, which are the main sources of reliability degradation and energy consumption. Furthermore, the proposed protocol is parametric in the sense that it can be used to trade-off reliability with energy and delay as per the requirement of the underlying applications. The performance of TEA-MAC has been evaluated by simulating it using Castalia network simulator. Simulation results show that TEA-MAC is able to considerably improve the performance of multicast communication in WSNs.

Time division multiple access (TDMA) is often used in wireless sensor networks (WSNs), especially for critical applications, as it provides high energy efficiency, guaranteed bandwidth, bounded and predictable latency, and absence of collisions. However, TDMA is vulnerable to selective jamming attacks. In TDMA transmission, slots are typically pre-allocated to sensor nodes, and each slot is used by the same node for a number of consecutive superframes. Hence, an adversary could thwart a victim node’s communication by simply jamming its slot(s). Such attack turns out to be effective, energy efficient, and extremely difficult to detect. In this paper, we present JAMMY, a distributed and dynamic solution to selective jamming in TDMA-based WSNs. Unlike traditional approaches, JAMMY changes the slot utilization pattern at every superframe, thus making it unpredictable to the adversary. JAMMY is decentralized, as sensor nodes determine the next slot utilization pattern in a distributed and autonomous way. Results from performance analysis of the proposed solution show that JAMMY introduces negligible overhead yet allows multiple nodes to join the network, in a limited number of superframes.

With the development of sensing devices and wireless communication technologies, wireless sensor networks are composed of a large number of sensor nodes that are equipped with limited computing performance and restricted communication capabilities. Besides, the sensor nodes are deployed in hostile or unattended environments. Therefore, the wireless sensor networks are vulnerable to security. In particular, the fatal damage may be occurred when data are exposed in real world applications. Therefore, it is important for design requirements to be made so that wireless sensor networks provide the strong security. However, because the conventional security schemes in wired networks did not consider the limited performance of the sensor node, they are so hard to be applied to wireless sensor networks. In this paper, we propose a secure multipath transmission scheme based on one-way hash functions in wireless sensor networks considering the limited performance of the wireless sensor nodes. The proposed scheme converts a sensor reading based on one of one-way hash functions MD5 in order to make it harder to be cracked and snooped. And then, our scheme splits the converted data and transfers the split data to the base station using multi-path routing. The experimental results show that our proposed scheme consumes the energy of just about 6% over the existing security scheme.

Aiming at the problems, such as difficulties in deployment and immovability during roller changing, which exist in traditional cold rolling backup roller bearing temperature monitoring technologies, a new temperature remote monitoring method based on wireless sensor network (WSN) is proposed. With a structure design of high water resistant and anti-vibration level, the monitoring sensor node can adapt to hot, humid and vibrating working environment. Autonomous power supply and wireless communication facilitate the installation of sensor nodes and bring good movability to sensor nodes. The topologic structure of the WSN is multi-layered and cluster-based. The cluster layer is mesh style, which can guarantee valid data communication while the sensor nodes moving into and out from the network during backup roller changing. Inside a cluster, star style network topology and the time division multiple access (TDMA) communication protocol are used to reduce node energy consumption and to prolong the network life. Remote communication between WSN and enterprise local area network is realized through a multi-hop relay tactic. Practical application in industrial fields shows that the proposed method is efficient to deal with the harsh and complicated operation environment, which is of great significance to monitoring bearing working condition accurately and in time.

Wireless sensor node is an autonomous and compact device that has capability to monitor a variety of real-world phenomena. It is designed composed of sensing device, embedded processor, communication module, and power equipment. Wireless sensor node is part of wireless sensor network where hundred or thousand sensor node can be deployed. Over the past decade Wireless Sensor Networks (WSNs) have emerged as one of the computing platforms of note within the electronics community. In prediction, there will be more than 127 million wireless sensor nodes deployed worldwide by 2014. We have surveyed 100 currently available wireless sensor network node platforms have been developed and produced not only by the research institutions, the universities but also some companies in last ten years. In this paper, we present a review of 27 different wireless sensor node platforms. We review these devices under a number of different parameters, and we highlight the key advantages of each node platform according to dimension and power consumption. We also discuss the characteristics and trend of development and deployment a wireless sensor node technology.

Wireless sensor networks (WSNs) have gained much attention in today’s research domain for supporting a wide variety of applications including the multimedia applications. Multimedia applications that are regarded as the quality-of-service (QoS)-aware, delay sensitive, and bandwidth hungry applications require enough energy and communication resources. WSNs being the energy-scarce network have now been designed in such a way that they can support these delay-sensitive and time-critical applications. In this paper, we propose an energy-efficient routing protocol for heterogeneous WSNs to support the delay sensitive, bandwidth hungry, time-critical, and QoS-aware applications. The proposed QoS-aware and heterogeneously clustered routing (QHCR) protocol not only conserves the energy in the network, but also provides the dedicated paths for the real-time and delay sensitive applications. The inclusion of different energy-levels for the heterogeneous WSNs also provides the stability in the networks while minimizing the delay for the delay-sensitive applications. Extensive simulations have been performed to validate the effectiveness of our proposed scheme. Our proposed routing scheme outperforms other state-of-the-art schemes in terms of the delay performances.