Garik Markarian

Fast Chase algorithm with an application in turbo decoding

Turbo product codes (TPCs) provide an attractive alternative to recursive systematic convolutional (RSC)-based turbo systems. Rather than employ trellis-based decoders, an algebraic decoder may be repeatedly employed in a low-complexity, soft-input/soft-output errors-and-erasures decoder such as the Chase algorithm. Taking motivation from efficient forced erasure decoders, this implementation re-orders the Chase algorithms repeated decodings such that the inherent computational redundancy is greatly reduced without degrading performance. The result is a highly efficient fast Chase implementation. The algorithm presented here is principally applicable to single error-correcting codes although consideration is also given to the more general case. The new decoders value in practical turbo schemes is demonstrated via application to decoding of the (64,57,4) extended Hamming TPC.

Trellis decoding for block codes

Disclosed is a novel bigraft copolymer comprising a polyhydrocarbon backbone selected from the class consisting of aromatic homopolymers, saturated and unsaturated hydrocarbon homopolymers, such homopolymers having halogen functionality and copolymers and terpolymers formed therefrom, and two different branches which are selected from the group consisting of monovinyl aromatic compounds and isoolefins. The bigraft copolymer is formed by the selective sequential cationic initiation of a first charge of one monomer onto the backbone at specific functional positions thereon and in the presence of a suitable solvent and an alkylaluminum compound. The resultant monograft copolymer is subsequently subjected to a second charge of another monomer, in the presence of a suitable solvent and an alkylaluminum compound, which becomes polymerized at the remaining, different functional positions available on the backbone. Also described are steps for substituting desired functional groups on the backbone and for the separation and purification of the mono and bigraft copolymer products.

Trellis decoding of block codes: practical approach

We present a number of techniques which promise to make the soft-decision trellis decoding of block codes as powerful and cost effective as that of convolutional codes. The techniques are based on the concept of generalised array codes (GACs) and enable sufficient simplification in the decoding complexity.

Minimal trellis design for linear codes based on the Shannon product

A novel trellis design technique for both block and convolutional codes based on the Shannon (1956) product of component block codes is introduced. Using the proposed technique, structured trellises for block and convolutional codes have been designed. It is shown that the designed trellises are minimal and allow reduced complexity Viterbi decoding.

Cross-Layer Optimization Architecture for WiMAX Systems

The traditional layered-protocol architecture seems to be inefficient in wireless network environment as the wireless channel is time-varying in nature. The IEEE 802.16 standard which the WiMAX system is based upon is also designed according to such layered-protocol stacks. To obtain overall performance gain however, cross-layer optimization is essential. In this paper, we propose a cross-layer optimization architecture for WiMAX system. It consists of a cross-layer optimizer which acts as an interface between MAC and PHY layers. It gathers and optimized the parameters from both layers to achieve optimum performance gain. Preliminary simulations were conducted to justify the need for cross-layer optimization.

Video Distribution Techniques Over WiMAX Networks for m-Health Applications

In this paper, we propose a novel approach for video distribution over IEEE 802.16 networks for mobile Healthcare (m-Health) applications. The technique incorporates resource distribution, scheduling, and content-aware video streaming taking advantage of a flexible quality of service functionality offered by IEEE 802.16/WiMAX technology. The proposed technique is thoroughly investigated using network simulator software under various real-life m-Health scenarios, which include streaming video over medium access control layer service connections. It is shown that the technique is fully compatible with the WiMAX standard specification and allows a 9-16% increase in the overall network throughput, which is dependent upon the initial system configuration and the selection of WiMAX user parameters.

A modified Blahut algorithm for decoding Reed-Solomon codes beyond half the minimum distance

A modification of the Blahut algorithm is proposed for decoding of Reed-Solomon codes beyond half the minimum distance. An effective method is offered for the searching of unknown discrepancies needed for analytical continuation of the Berlekamp-Massey algorithm through two additional iterations. This reduces the search time by 2(q-1)n/((n+t+1)(n-t)) times, compared with the Blahut algorithm. An architecture of a searcher for unknown discrepancies is given. The coding gain of the proposed algorithm is shown for some practical codes.

Smartphone-based Approach for Monitoring Vital Physiological Parameters in Humans

Long-term monitoring of physiological parameters is crucially important for patients with chronic diseases, having high risk of severe consequences like myocardial infarction or stroke. Monitoring is equally important for healthy humans for early detection of the changes in physiological conditions and following diagnosis of the developing diseases and for controlling the intensity of physical exercise. The goal of our project is development the systems for monitoring a number of parameters using smartphones with Symbian Series 60 OS and Windows Mobile OS. Our approach is based on the use of the self-developed (in case of ECG monitor) or commercially available monitors with BlueTooth (BT) radiolink and smartphone with the program for processing and analysis the signals by the processor of the smartphone and further transmission to the server or/and to the smartphone of the general practitioner. For intermittent monitoring the Blood Pressure monitor was used (AND, Model UP 767PC modified by the addition of BT radio module). ECG was monitored by two types of the devices. One-was developed in our group and consists of the chest belt with two electrodes, ECG amplifier and BT radiomodule. Second — is ECG monitoring device with frequency modulation (CardioSaunder), that uses 1 lead ECG recording electrodes on the chest belt, ECG amplifier and frequency modulator with the small speaker. Smartphone receives audio signal, modulated by the ECG signal by the internal microphone, demodulates it by the original program, determines the main characteristics of the ECG signal, shows ECG curve on the display and sends the data in digital form to the server. For measuring heart rate (HR) and oxygenation of the blood the Nonin Pulse Oxymeter 4100 with BlueTooth is used.

Distribution of digital TV signals over home power line networks

Nowadays the interest in transmitting video over home networks increases rapidly and services like video on demand are getting more attention. This article starts by providing an overview of the power line communication technology. Then the article presents the results of series practical measurements of the throughput, the response time, the transaction rate and the quality of different kinds of video streams, including real time video and kinds of video files, over the power line network at different locations in rooms of the research lab at the University of Leeds. Following that, a comparison between power line network and other networks serving as the backbone of home network to transmit video signals is given. Finally, a discussion of the feasibility of distributing digital TV signals over home power line networks and a brief description of market perspectives and promising applications are included.

Simulation of virtual MIMO base stations for mobile location in IMT-Advanced networks

The conventional Location and Positioning (L&P) methods rely on availability of base station (BS) locations as well as mitigation of propagation effects. It is known that the location estimation accuracy suffers from poor geometric dilution of precision (GDOP) caused by BS location as the conventional location algorithms which result in large GDOP values correspond to poor geometrical topology. In addition, NLOS effects cause a large error in time of arrival (TOA) reading; thus affecting mobile station (MS) estimation accuracy. In this paper a novel concept of virtual BS (VirBS) utilizing multiple input multiple output (MIMO) technology has been introduced and applied for improving L&P accuracy. The performance of the proposed algorithm has been evaluated via computer simulations. The simulation results demonstrate that the proposed algorithm allows up to 30 percent improvement in L&P accuracy without additional expenditure on network architecture.