Mesud Hadzialic

Outage Performance of L-Branch Maximal-Ratio Combiner for Generalized k-μ Fading

Maximal-Ratio combiner (MRC) performances in fading channels have been of interest for a long time, which can be seen by a number of papers concerning this topic. Most of these papers treat Rayleigh, Nakagami-m, Hoyt, Rice or Weibull fading. This paper treats outage performances of MRC in presence of generalized kappa- mu fading. In this paper, we will present kappa- mu fading model, probability density function (PDF), cumulative distribution function (CDF), expression for n-th order moment and outage probability. We will also present PDF, CDF and outage probability of the L-branch MRC output. Outage performances of the MRC will be presented for different number of branches via Monte Carlo simulations and theoretical expressions.

Real time assuring QoE in the lowest OSI/ISO layers during delivering of IPTV services

This paper compares the values of data link layer QoS (Quality of Service) indicators of several access lines, which can serve as a measure of the physical link quality or QoPh (Quality of Physical Layer), in real environment without reference video signal (No Reference), during the delivering of IPTV (Internet Protocol Television) multicast services to multiple users. It also focuses on the fact that an increase in channel capacity reduces the number of signal degradation indicators in the data link layer, because it increases the resistance of useful information on the interference. The paper proves the fact that at the same time, improving the physical layer conditions, the values of network QoS indicators, such as packet loss or delay, is reduced which affects the final grade at the end-user QoE (Quality of Experience) of IPTV (Internet Protocol Television) services.

Simulation-based optimization of signaling procedures in IP multimedia subsystem

This paper presents a simulation-based optimization of signaling procedures in Internet protocol Multimedia Subsystem (IMS). The aim is to improve the performance of signaling procedures by applying an algorithm for Session Initiation Protocol (SIP) message classification and prioritization that is proposed in our previous work. This three-priority level classification of SIP messages is implemented in Network Simulator version 2 (ns-2). Its effectiveness is verified through the simulation-based study of SIP signaling procedures under different conditions. The simulation results are analyzed in terms of Registration Request Delay (RRD), Session Request Delay (SRD), and Session Disconnect Delay (SDD). These SIP performance metrics are improved if IMS is configured to process SIP messages using the proposed algorithm. Differentiated handling of SIP messages reduces the overload in IMS and thereby improves the overall Quality of Service (QoS). This encourages our next step in research activity, i.e., implementation and incorporation of SIP message classification and prioritization algorithm into experimental environment.

Performance Modelling and Optimization of IP Multimedia Subsystem

This paper proposes a Session Initiation Protocol (SIP) message classification and prioritization scheme. This three-priority classification of SIP messages is implemented in Internet protocol Multimedia Subsystem (IMS). Its effectiveness is verified through the analytical and simulation modelling of IMS using a queuing theory. The proposed IMS model is analysed in the normal load and overload conditions. The analytical and simulation results are compared in terms of utilization, mean waiting time, and mean queue length. The agreement between them verifies the applicability of the proposed model for IMS performance prediction and optimization. Moreover, the simulation results show better performance of IMS in the overload situation when SIP message classification and prioritization scheme is used. Being linked to various research areas, this scheme is going to become a starting point for our future research activities.

Symbol Error Probability Analysis of L-Branch Maximal-Ratio Combiner for Generalized eta-mu Fading

Maximal-Ratio Combiner (MRC) performances in fading channels have been of interest for a long time, which can be seen by a number of papers concerning this topic. Most of these papers treat Rayleigh, Nakagami-m, Hoyt, Rice or Weibull fading. This paper treats symbol error probability (SEP) performances of MRC in presence of generalized eta-mu fading. In this paper, we will present eta-mu fading model, and expressions for SEP of the L-branch MRC output. SEP will be treated for a broad class of modulation types and for non-coherent type of detection. SEP performances of the MRC will be presented via Monte Carlo simulations and theoretical expressions.

Estimation of nakagami distribution parameters based on signal samples corrupted with multiplicative and additive disturbances

The problem of estimating the Nakagami-m distribution parameters in noisy slowly fading channels is studied. Previous published works have mainly examined estimation based on faded samples, not including phase fluctuations, shadow fading and additive noise. In this paper, a system model which uses samples corrupted by multipath and shadow fading, phase fluctuations and noise is examined. Expressions for the probability density function and n-th order moment of noisy channel samples are presented. Moment-based estimator for operation in noisy environments is developed based on presented probability density function. The sample mean and variance of the estimator are determined. Numerical results show that this estimator has better performances then previously published estimators treating noisy samples, and superior performances over estimators designed for noiseless samples in applications where noise is present.

Moment-based and Maximum Likelihood-based Quotiential estimation of the Nakagami-m fading parameter

In order to estimate m-parameter of Nakagami-m multipath fading, different estimation models have been proposed and simulated, and their performances have already been compared. In this paper, we propose new method for estimation of m-parameter, which is not based on estimation from signal envelope samples, but on quotient of successive samples. For that purpose, analytical model which describes statistics of successive samples quotients has been developed. Two models have been treated, these are moment based method (MM) and maximum likelihood method (MLM). Numerical simulations will demonstrate performances of proposed methods and will compare them with some known methods in cases of presence and absence of shadow fading with arbitrary distribution.

An Analytical Approach to Probability of Outage Evaluation in Gamma Shadowed Nakagami-m and Rice Fading Channel

In this paper a unified analytical approach to performance analyses in gamma shadowed Nakagami- m and Rice fading channel is presented. Instead of lognormal probability density function (PDF), gamma PDF is used for shadowing while multipath fading is represented with Nakagami-m and Rice distributions. A mathematical framework is developed for deriving key statistical parameters such as PDFs of signal to noise ratio(SNR) and signal to interference ratio (SIR) of several special scenarios in mobile channel as well as performance metrics including outage probability. In this way, one can conclude that presented results are reliable for lognormal shadowing spread <9 dB (note that, the shadowing spread actually observed in macro-cells has a typical value that lies between 4 and 9 dB). The final results are remarkably simple and can serve as a quick way of assessing performance. In addition, presented analytical expressions are suitable for the asymptotic analyses, which is significant feature for both theoretical and practical aspect of theirs applications.

An example of mapping the degradation of network parameters with video QoE parameters in case of IPTV service

This paper aims to consider how changes in QoS (Quality of Service) indicators affect the quality of IPTV (Internet Protocol Television) video. Degradation of QoS indicators can occur at any point in time, when the value of transfer channel function changes or if there is an appearance of additional noise. Therefore, for this purpose it is necessary to conduct a temporal analysis of the impact of the QoS indicator degradation on the delivery of MM (Multimedia) service in real time. Also, the phenomenon of degradation of QoS can be associated with queues, flow control or with analog-to-digital conversions that occur on the network elements. The combination of all these phenomena in the higher layers of the OSI (Open System Interconnection) reference model can be identified as packet loss, delay or jitter, and this paper examines their impact on the level of video perception by the end consumer. That perception can be identified as QoE (Quality of Experience).

An example of real time QoE IPTV service estimator

This paper will consider an estimator which includes mathematical modelling of physical channel parameters as information carrier and the weakest links in the telecommunication chain of information transfer. It will also identify necessary physical layer parameters which influence the quality of multimedia service delivery or QoE (Quality of Experience). With the modelling of the above mentioned parameters, the relation between degradations will be defined which appear in the channel between the user and the central telecommunication equipment with domination of one media used for information transfer with certain error probability. Degradations in a physical channel can be noticed by observing the change in values of channel transfer function or the appearance of increased noise. Estimation of QoE IPTV (Internet Protocol Television) service is especially necessary during delivery of real time service. In that case the mentioned degradations may appear in any moment and cause a packet loss.