Number Of Wireless Transmissions Research Articles

Obstacle mapping in wireless sensor networks via minimum number of measurements

In this study, a group of wireless sensors are tasked to trace indoor obstacles without the need to sense them, directly. The authors introduce a novel framework based on compressed sensing theory that allows sensors to map two-dimensional spatial details, non-invasively. By exploiting an alternative projection method which reduces the randomness nature of previous works, the resulting measurement matrix can provide linear samples from an unknown environment more efficiently. It is shown that how sparse representation of the spatial parameters in some domains can be utilised in order to realise obstacle mapping with minimum number of wireless transmissions and receptions. In addition, theoretical analyses along with simulation results illustrate premier performance of their framework. Furthermore, they test their method in different circumstances and show how drawbacks such as walls, bulkheads, and environmental constraints can affect the reconstruction performance. Therefore, they proposed two algorithms (i.e. reducing wall effect and reducing bulkhead effect) in order to decrease the impression of walls and bulkheads which is supported theoretically. Finally, a well-applicable scenario based on their framework is defined and proposing the next best transmitter algorithm remarkable results are achieved.

Auction-based Bandwidth Management with Network Coding and Cooperative Communication in Wireless Networks

In this paper, we propose a generalized Vickrey-Clarke-Groves auction mechanism for bandwidth management with network coding techniques. In our bandwidth auction, we utilize network coding and cooperative network coding in single-rate wireless networks and multi-rate wireless networks, respectively. Network coding techniques are used to reduce the number of wireless transmissions. Social surplus is maximized by deriving the optimization problem so as to efficiently allocate the bandwidth. We evaluate the performance of our proposed auctions with simulation. In numerical examples, we show the effectiveness of bandwidth auction mechanism. Then, we investigate the effectiveness of network coding in single-rate wireless networks and the effectiveness of cooperative network coding in multi-rate wireless networks.

Average consensus in sensor networks via broadcast multi-gossip algorithms

Motivated by applications to wireless sensor, peer-to-peer, and ad hoc networks, we propose a distributed algorithm called broadcast based multi-gossiping algorithm (BMGA), which is designed for exchanging information and computing in an arbitrarily connected network of nodes. Unlike traditional randomized gossip algorithms, push-sum mechanism based BMGA preserves the sums and weights, and admits stochastic diffusion matrices which need not be doubly stochastic. Based on the theory of weak ergodicity and message spreading, we derive a lower bound on the weight, and give an approximate value for this bound. By introducing a potential function, we show that BMGA converges almost surely to the average of initial node measurements with probability one. Specifically, we further provide the upper bounds on the diffusion speed, ϵ-convergence time and the number of radio transmissions. Finally, we present a numerical example to assess and compare the communication cost with several gossip-based algorithms to achieve a given performance.

Efficient incremental code update for sensor networks

Wireless reprogramming of sensor nodes is an essential requirement for long-lived networks since software functionality needs to be changed over time. During reprogramming, the number of radio transmissions should be minimized, since reprogramming time and energy depend chiefly on the number of radio transmissions. In this article, we present a multihop incremental reprogramming protocol called Zephyr that transfers the delta between old and new software versions, and lets the sensor nodes rebuild the new software using the received delta and the old software. Zephyr reduces the delta size by using application-level modifications to mitigate the effects of function shifts. Then it compares the two binary images at the byte level to generate a small delta, that is then sent over the wireless network to all the nodes. For the wide range of software change cases that we used as benchmarks, Zephyr transfers 1.83 to 1987 times less traffic through the network than Deluge (the standard nonincremental reprogramming protocol for TinyOS) and 1.14 to 49 times less traffic than an existing incremental reprogramming protocol by Jeong and Culler [2004].

TOA/TDOA Hybrid Relative Positioning System Based on UWB-IR Technology

In this work, a time-of-arrival/time-difference-of-arrival (TOA/TDOA) hybrid relative positioning system based on UWB-IR technology is developed. The system reduces both the complexity of system configuration and the number of wireless transmissions in a positioning sequence. The system performance over various distances between access points is verified by computer simulations and experiments under the assumption that the distance between the access points is less than that between the access point and the target node. For the experiments, the proposed system is implemented with in-house developed UWB transceivers. The experiments confirm that the developed TOA/TDOA hybrid system can detect the relative positions of target nodes (under the condition of two access points 4 m apart) with a measured-angle accuracy of 8.6 degrees.

The international comparison of atomic standards of time and frequency

Atomic frequency standards are now in use in a number of countries. The measurement, in terms of these standards, of the frequencies of a number of radio transmissions which are closely controlled, and the interchange of the results obtained, enables the standards themselves to be compared. Some details are given of the various atomic standards and of the methods of measurement employed at the National Physical Laboratory. The results obtained between January, 1958, and December, 1960, for seven standards are tabulated. It is shown that the use of the v.l.f. transmissions GBR, Rugby (16kc/s), and NBA, Summit (18kc/s), enables day-to-day comparisons to be made with a precision of ±2 parts in 1010. There is some evidence that there are at present differences between the different standards of ±2 parts in 1010.