Current Issue : October - December Volume : 2013 Issue Number : 4 Articles : 6 Articles
In this work, we focus on framed slotted Aloha (FSA) and passive ultra high-frequency radio frequency identification\r\nmulti-antenna systems with physical layer collision recovery. We modify the tags slightly by adding a so-called\r\nââ?¬Ë?postpreambleââ?¬â?¢ that facilitates channel estimation. Furthermore, we investigate the throughput performance of\r\nadvanced receiver structures in collision scenarios. More specifically, we analyse the throughput of FSA systems with\r\nup to four receive antennas that can recover from a collision of up to eight tags on the physical layer and\r\nacknowledge all tags involved in that collision. Due to the higher collision recovery capabilities, the frame sizes can be\r\nsignificantly reduced, and thus, the throughput can be increased. We also derive analytically optimal frame sizes,\r\ngiven that a certain number of collisions can be resolved. We further study the constraints to the throughput due to\r\nthe structure of our receiver and channel estimation for different collision scenarios. Furthermore, we propose a novel\r\ncollision recovery method with two phases: first, a successive interference cancellation and, second, a projection of\r\nthe constellation into the orthogonal subspace of the interference. Additionally, the inventory time, i.e. the number of\r\nslots necessary to successfully decode all tags in the reader range, is calculated and compared for different receiver\r\ntypes. A validation of our theoretical predictions is achieved by means of simulations. We show that by our proposed\r\nmethods, we can realistically achieve more than ten times higher throughput or, equivalently, a reduction of the\r\ninventory time by more than 90%....
In this contribution, four automatic adjustment algorithms for leakage carrier cancellation in radio frequency\r\nidentification (RFID) readers are compared: full search, gradient search, fast and direct I/Q algorithms. Further, we\r\npropose two enhanced adjustment procedures.\r\nFirst, we analytically calculate the performance of the fast adjustment algorithm in the presence of noise and derive its\r\ntheoretical bias. We compare the theoretical results with the numerical results from accompanying simulations.\r\nFurther, we evaluate the performance of these algorithms based on real-world measurements acquired with our RFID\r\ntestbed.\r\nFinally, we propose and discuss the merits of two enhanced adjustment procedures based on the fast adjustment\r\nalgorithm. The fast adjustment procedure with bipolar probing signals achieves the isolation gain of the (much\r\nslower) gradient search algorithm at the expense of a mean penalty of 0.48 dB. We observe that the fast adjustment\r\naided gradient algorithm requires 72% less steps than the gradient search algorithm in our measurements....
This paper discusses the design approach to control the intra vehicular applications comprising of anti-theft and anti-alcoholic system. For anti theft system, the major sensor used is the MQ-3 sensor. There is programming being done for anti-alcoholic system is that if the person is drunk then the system will sense the alcohol level and will not grant the permission to start his vehicle. There is secondary situation, if the person is having the alcohol while driving his vehicle then it will be reported to nearest police server with the help of GSM modem .For anti ââ?¬â??theft system we are designing the system comprising of GPS antenna and Receiver, GSM modem will be interfaced by programming with the microcontroller AVR-32 bit for storing and interfacing purposes. The system is so programmed that when the owner of the vehicle message to the system about his vehicle position, the programmed system gets the location from GPS receiver and send its position with help of GSM modem back to the owner. The design is robust and simple....
Schedulers in radio frequency identification dense environments aim at distributing optimally a set of t slots between\r\na group of m readers. In single-channel environments, the readers within mutual interference range must transmit at\r\ndifferent times; otherwise, interferences prevent identification of the tags. The goal is to maximize the expected\r\nnumber of tags successfully identified within the t slots. This problem may be formulated as a mixed integer\r\nnon-linear mathematical program, which may effectively exploit available knowledge about the number of\r\ncompeting tags in the reading zone of each reader. In this paper, we present this optimization problem and analyze\r\nthe impact of tag estimation in the performance achieved by the scheduler. The results demonstrate that optimal\r\nsolutions outperform a reference scheduler based on dividing the available slots proportionally to the number of tags\r\nin each reader. In addition, depending on the scenario load, the results reveal that there exist an optimum number of\r\nreaders for the topology considered, since the total average number of identifications depend non-linearly on the\r\nload. Finally, we study the effect of imperfect tag population knowledge on the performance achieved by the readers....
As the adoption of the radio-frequency identification (RFID) technology is increasing, many applications require a\r\ndense reader deployment. In such environments, reader-to-reader interference becomes a critical problem, so the\r\nproposal of effective anti-collision algorithms and their analysis are particularly important. Existing reader-to-reader\r\nanti-collision algorithms are typically analyzed using single interference models that consider only direct collisions.\r\nThe additive interference models, which consider the sum of interferences, are more accurate but require more\r\ncomputational effort. The goal of this paper is to find the difference in accuracy between single and additive\r\ninterference models and how many interference components should be considered in additive models. An in-depth\r\nanalysis evaluates to which extent the number of the additive components in a possible collision affects the accuracy\r\nof collision detection. The results of the investigation shows that an analysis limited to direct collisions cannot reach a\r\nsatisfactory accuracy, but the collisions generated by the addition of the interferences from a large number of readers\r\ndo not affect significantly the detection of RFID reader-to-reader collisions....
Network on Chip (NoC) is a new archetype to formulate the interconnections in a System on Chip (SoC) system. With encroachment in NoC technology the bus structure which often results in traffic congestion, is replaced with an integrated network. Today a NoC consists of devices that use the network routers directing traffic among devices and wires analogous to the Internet. Thus efficient network topology and routing algorithm are imperative to the NoC design. There are different routing algorithms available today; the choice of one is often system dependant. This report presents a modified XY routing algorithm combined with a scheduler to be used on NoCs. The proposed method is a fast way to transferring data via a specific path between two nodes in the network and the scheduler further helps to avoid collision....
Loading....