Anjum Pervez

VQM-based QoS/QoE mapping for streaming video

Numerous new broadband and multimedia applications have emerged in recent years, in which streaming video services are particularly of interest. Unlike data communication, streaming video requires a subjective measure of quality referred to as the Quality of Experience (QoE), but the subjective evaluation is very time consuming and complex. We are proposing an objective approach to provide mapping between QoE and Quality of Service (QoS), in which Video Quality Metric (VQM) is utilized to indicate QoE. We have analyzed the emulation results and derived a simple formula to estimate QoE from QoS parameters for streaming video under certain conditions. This method is non-intrusive and quick to use.

Multi-level rule-based handover framework for heterogeneous wireless networks

An appropriate vertical handover process is the essential requirement for seamless mobility in heterogeneous wireless networks. The role of the handover process is to select the best target network. Several factors such as number of decision parameters and their relationships affect the handover decision. Little attention has been given to the understandability and modifiability of the decision model used, which leads to the difficulty to modify the model if need be. In this paper we have proposed a new multi-level rule-based approach for vertical handover. The proposed work is simulated and results analysed. The performance, in terms of network selection ability, is compared with two well-known techniques.

Improved UHF RFID localization accuracy using circularly polarized antennas

We present the design of two new antennas for an indoor angle-of-arrival based passive UHF RFID tag localization method. First, a circularly polarized patch antenna that can be used as the readers transmit antenna or as the tag antenna. Second, a circularly polarized three-element patch antenna array for the reader. We use measurements in a 3 m × 3 m test grid with 25 equally spaced measurement points, placed into a standard office room, to show that the new antennas improve localization accuracy by 53% compared to a system equipped with linearly polarized antennas. The new circularly polarized system is able to localize a tag in our setup with a measured mean error of 9 cm and a measured mean standard deviation of 7 cm.

Localization of Passive UHF RFID Tags Using the AoAct Transmitter Beamforming Technique

The localization of passive ultra-high frequ- ency (UHF) radio frequency identification (RFID) tags is an emerging technology that has reached a high level of interest in industry and research. Most solutions use classical techniques, such as the angle-of-arrival or the received-signal-strength methods. As an alternative, we present a new approach for estimating the position of a passive UHF RFID tag by using a transmitter beamforming technique that we call angle-of-activation (AoAct). It is based on manipulating the shape of the radiation pattern of the interrogators transmitter antenna array. By pivoting the main lobe of the pattern in the azimuth plane of the array and by utilizing the very sensitive response threshold of passive UHF RFID tags, we are able to estimate the tag direction. We use three-channel digital beamforming, where the phases and amplitudes of the antenna arrays feeding radio frequency signals are controlled by the baseband I and Q components of the interrogators transmitter signal. Our self-developed hardware pivots the main lobe of a three-element antenna array in a range of ±52° with a resolution of 0.02°. It senses the AoAct with a mean measured accuracy of 1.2° in the anechoic chamber, 1.9° in a basic multipath environment, and 2.5° in a real-world multipath environment. After estimating the AoAct of a tag from different locations, the tag position is triangulated. Experiments show that our AoAct system delivers a localization accuracy of 7 cm in a typical multipath environment.

An improved channel model for passive UHF RFID systems

For preliminary performance evaluation of an UHF RFID system, it is important to have a simple and fast simulation environment available. The calculation of the receive signal power at arbitrary positions of a predefined environment should be fast and accurate to find dead zones where tags cannot be read although they are well within the readers communication range. Changes in the system configuration or the simulated environment must be easy to implement. In this paper we use the simple and fast calculable UHF RFID channel model from [1] and improve it in different aspects to better fit the real indoor multipath signal propagation. A comparison between measurements and simulations shows that our model delivers 1.8 dB better performance in average than the original model, while adding only little complexity and computing time. Using our simulation environment, it is easy and fast to find dead zones for arbitrary system setups.

Using a circularly polarized patch antenna to optimize the passive UHF RFID indoor channel

In this paper we describe the design and performance of a new circularly polarized broadband patch antenna for RFID applications. It works both in the current European UHF range (865 MHz - 868 MHz) and the new European UHF range according to ETSI TS 102 902 (915 MHz - 921 MHz). Simulations show that circular patch antennas improve the multipath behavior of the channel significantly. In [2] we show that switching the system frequency strongly improves the channels fading characteristic. Because an RFID system can be equipped with the new antenna for readers and tags we can make use of both beneficial effects to increase tag read probabilities and read ranges in typical indoor environments. RSS measurements are used to verify the simulation results and to quantify the performance of the new antenna.

Automatic trust calculation for service-oriented systems

Among various service providers providing identical or similar services with varying quality of service, trust is essential for service consumers to find the right one. Manually assigning feedback costs much time and suffers from several drawbacks. Only automatic trust calculation is feasible for large-scale service-oriented applications. Therefore an automatic method of trust calculation is proposed. To make the calculation accurate, the Kalman filter is adopted to filter out malicious non-trust quality criterion (NTQC) values instead of malicious trust values. To offer higher detection accuracy, it is further improved by considering the relationship between NTQC values and variances. Since dishonest or inaccurate values can still influence trust values, the similarity between consumers is used to weight data from other consumers. As existing models only used the Euclidean function and ignored others, a collection of distance functions is modified to calculate the similarity. Finally, experiments are carried out to access the robustness of the proposed model. The results show that the improved algorithm can offer higher detection accuracy, and it was discovered that another equation outperformed the Euclidean function.

Rule-based dynamic TV white space spectrum sharing services composition framework

Abstract When developing a TV White Space (TVWS) system with the available TV spectrum after digital switchover, the smooth introduction of new technologies and components has to be supported because the requirements of users change frequently in a new system. We need to provide a modular, extensible and easy to implement framework rather than building highly integrated systems. According to environment, rules, polices and users’ requirements, advanced intelligent management functionalities that can guarantee the proper configuration of devices in TVWS networks and proper load balance, have to be developed. According to different requests from users, different algorithms and components have to be used to meet the needs of the users. How, when and which algorithms and components should be combined in order to meet the requests from the users become essential problems. Based on Service Oriented Architecture, all things in the proposed system including algorithms and components can be defined as services. This paper presents a framework of rule-based dynamic TVWS services composition that can meet the above needs and combine different TVWS services to fulfil users’ requirements dynamically.

An Automatic Trust Calculation Based on the Improved Kalman Filter Detection Algorithm

In service-oriented systems, how much a service can be trusted is increasingly crucial for service consumers to make the best decision. Because the methods for deriving trust based on manually assigned feedback cost much time and suffer several drawbacks, automatic trust calculation is the only feasible method for large-scale service-oriented applications. Therefore an automatic trust calculation using other non-trust quality criterion values is proposed. To make the calculation accurate, the Kalman Filter is employed to filter out malicious non-trust values instead of directly filtering out malicious trust values. Furthermore, an improved algorithm is proposed by taking the relationship between the non-trust criterion value and its variance into account to offer higher detection accuracy. Although malicious data can be filtered out, dishonest or inaccurate values can still influence trust values. Hence similarity between consumers is used to weight the values from others. Finally, experiments are carried out to access the validation and robustness of our model. The results show that our algorithm can offer higher detection accuracy under more strategic malicious situations.

Error-probability analysis of MIL-STD-1773 optical fiber data buses

In the late 1980s, a military avionics standard, called the MIL-STD-1773, was developed by the US Department of Defense to promote applications of sophisticated optical fiber technology to advanced military aircraft.1