Two-stage decision making policy for opportunistic spectrum access and validation on USRP testbed

“Recently, various paradigms, for instance, device-to-device communications, LTE-unlicensed and cognitive radio based on an opportunistic spectrum access (OSA) are being envisioned to improve the average spectrum utilization. In OSA, secondary (unlicensed) users (SUs) need decision making policies (DMPs) to identify and transmit over optimum frequency bands without any interference to the primary (licensed) users as well as minimize the number of collisions among SUs. In this paper, we have proposed a two-stage DMP consisting of Bayesian Multi-armed Bandit algorithm to accurately characterize the frequency band statistics independently at each SU and frequency band selection scheme for orthogonalization of SUs. The analytical and simulation results show that the proposed DMP leads to 45% improvement in the average spectrum utilization compared to 36–39% in the existing DMPs. Furthermore, the number of collisions are 58.5% lower in the proposed DMP making SU terminals energy-efficient. The performance of the proposed DMP has been verified on the proposed USRP testbed in real radio environment and the experimental results closely match the simulated results .”     

A dynamic threshold based approach for mitigating black-hole attack in MANET

Mobile ad-hoc network is an infrastructure less type of network which does not require any kind of fixed infrastructure. It provides multi-hop communication between the source and destination nodes which are not within the direct range of each other through the intermediate nodes. These intermediate nodes cooperate with other nodes in finding an optimum and shortest route toward the destination. However, in holistic environments, some nodes do not cooperate with other nodes in finding the optimal route towards the destination and intentionally give the false route information of having the shortest path toward the destination with a high destination sequence number in order to attract the traffic toward itself and start dropping of the data packets instead of forwarding it. This type of routing misbehaviour is generally called as black hole attack or full packet dropping attack which is one of the most severe destructive attacks that lead to the network degradation. In this paper, we have proposed a protocol called as Mitigating Black Hole effects through Detection and Prevention (MBDP-AODV) based on a dynamic threshold value of the destination sequence number. In order to validate the efficiency of proposed protocol, the NS-2.35 simulator is used. The simulation results show that proposed protocol performs better as compared with existing one under black hole attack.     

Power consumption analysis of video streaming in 4G LTE networks

Video streaming, one of the most popular technologies for online video playback, has already been applied to 4G LTE networks. Previous work has been devoted to understanding the power consumption in general 4G LTE networks, while it is still unclear how the online video streaming makes impact on the power performance of mobile devices. Inspired by this, this paper investigates the relationship between the mobile device’s power performance characteristics and the behaviours of video streaming in 4G LTE networks. There are many natural issues/questions that are clearly interesting and important, while it is non-trivial to answer these issues/questions exactly (e.g., where is the energy saving room? how much is it?). To address a series of issues like the above, we formulate our energy models together with an algorithm that can assist our analysis. Particularly, we design a systematic platform, and conduct a comprehensive and also deep analysis on the power consumption of video streaming in 4G LTE networks. Our experiments reveal us a series of valuable findings—the saving room in the network part is large (from 41.86 to 69.62%), the number of RRC tails and the transmission pattern could be promising for optimizing the power consumption, for example.     

Enhanced EDCA with Deterministic Transmission Collision Resolution for Real-Time Communication in Vehicular Ad Hoc Networks

The collision prevention system is one of most important research issues on vehicle safety technology. Sending worming messages within the right time and reliable transmission will get prevention of a possible vehicle accident. The communication standards of vehicular networks (VANET) are unable to guarantee the delivery of critical messages within tight deadlines. Indeed, the transmission collisions are handled with probabilistic manner that can reduce the transmission latency; however, it is inept to predict an upper bound value of this delay to verify the deadline. In this paper, we propose a medium access protocol that ensures the delivery of critical messages within a deadline. It is a hard real-time system with delay constant guarantee. We are focusing on improving the EDCA medium access protocol to prioritize critical messages and to get access to the transmission channel within a predictable communication delay. We create a new enhanced access protocol that is compatible with the IEEE 802.11p VANET standards and adapted to real-time communication requirements related to the vehicle collision avoidance problem.     

Underlay Device to Device Communication with Imperfect Interference Channel Knowledge

The objective of any night vision system is to enable a person to see in the dark. A low-contrast image puts a contrast constraint on the human observer visibility at night. This is the basic reason for the large number of accidents at night. This research presents two proposed approaches to enhance the visibility of the infrared (IR) night vision images through an efficient histogram processing. The first approach is based on contrast limited adaptive histogram equalization. The second proposed approach depends on histogram matching. The histogram matching uses a reference visual image for converting night vision images into good quality images. The obtained results are evaluated with quality metrics such as entropy, average gradient, contrast improvement factor and sobel edge magnitude.     

Novel Fault-Tolerant Decompression Method of Corrupted LZSS Files

Data compression and decompression have been widely applied in modern communication and data transmission fields. But how to decompress corrupted lossless compressed files is still a challenge. This paper presents an effective method to decompress corrupted LZSS files. It is achieved by utilizing source prior information and heuristic method. In this paper, we propose to use compression coding rules and grammar rules as the source prior information. Based on the prior information, we establish a mathematical model to detect error bits and estimate the rough range of the error bits. As for error correction, a heuristic method is developed to determine the accurate positions of error bits and correct the errors. The experimental results demonstrate that the proposed FTD method can achieve a correction rate of 96.45% for corrupted LZSS files when successfully decompressed. More importantly, the proposed method is a general model that can be applied to decompress various types of lossless compressed files of which the original files are natural language texts.     

Efficient optimization of integrated spiral inductor with bounding of layout design parameters

In this paper we present an efficient method of determining the optimized layout of on chip spiral inductor. The method initially identifies the feasible region of optimization by developing layout design parameter bound curves for a large range of physical inductance values that satisfies the same area specification. For any desired inductance value the upper and lower bounds of the optimization variables are determined graphically. An enumeration algorithm implemented finds the global optimum layout that gives the highest quality factor in less than 1 s of CPU time with less function evaluations. The optimization method also gives the performance of all possible combinations that results the same inductance value. Subsequently important fundamental tradeoff of the design like quality factor and area, quality factor and inductance, quality factor and operating frequency, maximum quality factor and the peak frequency is explored in few seconds. The method also gives other valuable information such as sensitivity of the inductance and quality factor to the layout design parameters. The accuracy of the proposed method is verified using a 3D electromagnetic simulator.     

A large class of binary ZCZ sequence families constructed by period doubling

In an Approximately Synchronized Code Division Multiple Access （AS-CDMA） communication system, a family with large number of Zero Correlation Zone （ZCZ） sequences is desired, which can satisfy the rapid increase of users. This paper presents a method to generate a （2L,2M, ZCZ＇）-ZCZ sequence family from an original （L,M,ZCZ）-ZCZ sequence family, where ZCZ＇ = ZCZ if ZCZ is even and ZCZ＇ =ZCZ - 1 if ZCZ is odd. This method can also recursively act on a ZCZ sequence family to construct a series of ZCZ sequence families with large sequence number and zero correlation zone length identical to or one less than that of original ZCZ sequences.     

RF Testing on a Mixed Signal Tester

In this paper, testing of radio frequency (RF) devices with mixed-signal testers is discussed. General purpose automatic test equipment (ATE) will be used. In this paper, a more universal test structure utilizing RF building blocks is proposed. A global positioning system (GPS) device is used as an example to illustrate how to develop the RF test plan with this usage. The test plan developed includes fast, cost-effective and dedicated circuitry.