Irina Gudkova

A new stage in mathematical teletraffic theory

History of the development of theory of queues and mathematical teletraffic theory achieved at the MSU and PFUR are outlined. Basic theorems and algorithms for calculation of probability measures for multiservice loss networks with unicast connections, multicast connections, as well as with both types of connections are presented. A Triple Play network analysis is determined to be the key task for the future.

Modelling and Analysing a Dynamic Resource Allocation Scheme for M2M Traffic in LTE Networks

One of the main problems in LTE networks is the distribution of a limited number of radio resources among Human-to-Human (H2H) users as well as the increasing number of machine-type-communication (MTC) devices in machine-to-machine (M2M) communications. Different traffic types from user’s equipment and MTC devices transmitted over the network suggests a dynamic resource allocation in order to provide a better quality of service (QoS). In this paper, we propose a dynamic resource allocation scheme for M2M traffic in LTE networks. The suggested method is based on fixed bandwidth intervals at which traffic from MTC devices is serviced according to the Processor Sharing (PS) discipline. By means of a Markov model, an estimation of the behaviour of LTE for H2H and M2M traffics characteristics is shown. We propose an analytical solution to calculate the model performance measures, such as blocking probabilities for H2H users.

Analyzing Impacts of Coexistence between M2M and H2H Communication on 3GPP LTE System

In this paper, we consider 3GPP LTE cellular system where machine-to-machine (M2M) devices and human-to-human (H2H) users transmit their data into the network. By contrast to previous studies which primarily focused on M2M overload protection and respective control mechanisms, this work concentrates on system operation when M2M and H2H data flows coexist in the network. In particular, we propose an integrated simulation-analytical framework to evaluate relevant performance characteristics (data transmission delays, blocking probabilities, etc.) with both Markov process based analysis and system-level simulations. Our results indicate that the proposed methodology demonstrates acceptable levels of convergence between analytical and simulations components, as well as becomes useful to characterize impacts of M2M/H2H coexistence on radio resource allocation in 3GPP LTE across a number of important M2M-centric scenarios.

Development of Intelligent Core Network for Tactile Internet and Future Smart Systems

One of the main design aspects of the Tactile Internet system is the 1 ms end-to-end latency, which is considered as being the main challenge with the system realization. Forced by recent development and capabilities of the fifth generation (5G) cellular system, the Tactile Internet will become a real. One way to overcome the 1 ms latency is to employ a centralized controller in the core of the network with a global knowledge of the system, together with the concept of network function virtualization (NFV). This is the idea behind the software defined networking (SDN). This paper introduces a Tactile Internet system structure, which employs SDN in the core of the cellular network and mobile edge computing (MEC) in multi-levels. The work is mainly concerned with the structure of the core network. The system is simulated over a reliable environment and introduces a round trip latency of orders of 1 ms. This can be interpreted by the reduction of intermediate nodes that are involved in the communication process.

Modelling a Radio Admission Control Scheme for Video Telephony Service in Wireless Networks

Modern 4G wireless networks are multi-service networks, and an important issue is the development of an optimal radio admission control scheme (RAC) specific to various service types. The 3GPP recommendations for LTE and LTE-Advanced networks specify nine service classes that differ in terms of the priority level, bit-rate, and packet error loss. In this paper, we propose an RAC scheme for video telephony service that is provided in two modes: voice and video. Voice telephony users have a higher priority level than video telephony users; this is realised by the possibility of accepting voice calls owing to the degradation in video call quality. We analyse a model of a single cell with video telephony service, and we prove that the system state space is of an explicit form. This enables us to compute the performance measures, such as blocking probabilities, mean number of calls, and utilization factor.

Modeling unreliable LSA operation in 3GPP LTE cellular networks

Presently, we observe an unprecedented growth of traffic volumes in modern cellular networks. Consequently, to effectively meet the impeding capacity crunch, current spectrum bands can be extended by using LSA (Licensed Shared Access) - the promising technology that allows an operator to lease additional frequency bands in order to satisfy the increasing data rate requirements. This technology is naturally suitable for the state-of-the-art 3GPP LTE cellular networks, since it allows to flexibly control resource allocation across the network users. Owing to that, the operator can employ the LSA band whenever desired to improve area capacity and increase data rate. However, due to the fact that the LSA band may be unexpectedly revoked by its original owner, there exists a certain chance of degradation in system performance and user service quality. This paper focuses on studying a one-cell 3GPP LTE system over the LSA technology, with both analysis and simulations, by proposing a baseline methodology to model the unreliable operation of an LSA frequency band.

Service failure and interruption probability analysis for Licensed Shared Access regulatory framework

As it is predicted that mobile traffic demand will reach an astonishing 190 exabytes by 2018, current methods of spectrum allocation and management need to be rethought towards more advanced sharing of frequency bands. To this end, a novel regulatory framework has recently emerged, named Licensed Shared Access (LSA), which enables guaranteed spectrum access for a limited number of sharers. However, realistic LSA band operation may result in its abrupt unavailability, causing traffic delays and even network access failures in case of unsuccessful “evacuation” of a user back to conventional cellular bands. In this paper, we formulate an adequate queuing-theoretical model for evaluating such service failure and interruption probability for users that attempt to operate within a cell of a network with the LSA capability.

Modelling and performance analysis of pre-emption based radio admission control scheme for video conferencing over LTE

We perceive emerging developments in information and communication technologies (ICTs) in various areas of our dynamic live. The concept of getting services and applications “any time” and “any place” imposes the corresponding development in cellular networks. The rapid worldwide deployment of 4G LTE networks and increasing demand for new services are the key ICT trends that highlight the need for future improvements in technologies underling LTE. Although 3GPP concentrates all standardization activities in LTE, ITU-T recommendations reflect the main quality of service (QoS) requirements in ICTs. Nevertheless, not all QoS related ITU-T recommendations (i.e. E.800-E.899, G.1000-G.1999, Y.1500-Y.1599, Y.2100-Y.2199 series) correspond to todays variety of products and services provided by cellular networks. This fact raises the need for updates in these recommendations. In this paper, we explore QoS measures specific to LTE services adaptively occupying radio resources. This so-called pre-emption process assumes the service degradation as well as service interruption. We propose a pre-emption based radio admission control (RAC) model for two resource demanding video services - video conferencing and video on demand. We apply teletraffic and queuing theories to get a recursive algorithm for calculating its performance measures, namely, blocking probability, pre-emption probability, and mean bit rate.

Analysis of an admission model in a fourth generation mobile network with triple play traffic

A problem of calculating the quality of the Triple Play service in an LTE mobile network under conditions of unicast and multicast transfer modes is considered. A mathematical model of the resource admission in the LTE network is constructed in the form of a system with explicit losses and three disciplines of servicing the unicast, multicast, and elastic traffics. Approximate methods of calculating the stationary probability distribution of the states of the models with unicast and elastic traffics are discussed. An approximate method based on the calculation of the marginal distribution of the number of users with unicast and multicast traffics is proposed for calculating the average transfer time of the elastic traffic. An exact algorithm for determining the stationary probability distribution of the system’s states that provides a considerable decrease in the dimension of the problem is presented.

Sojourn Time Analysis for Processor Sharing Loss System with Unreliable Server

Processor sharing (PS) queuing systems and particularly their well-known class of egalitarian processor (EPS) sharing are widely investigated by research community and applied for the analysis of wire and wireless communication systems and networks. The same can be said for queuing systems in random environment, with unreliable servers, interruptions, pre-emption mechanisms. Nevertheless, only few works focus on queues with both PS discipline and unreliable servers. In the paper, compared with the previous results we analyse a finite capacity PS queuing system with unreliable server and an upper limit of the number of customers it serves simultaneously. For calculating the mean sojourn time, unlike a popular but computational complex technique of inverse Laplace transform we use an effective method based on embedded Markov chains. The paper also includes a practical numerical example of web browsing in a wireless network when the corresponding low priority traffic can be interrupted by more priority applications.