Leonid Ponomarenko

Approximate method for analysis of queuing models with jump priorities

An approximate method for analysis of the queuing models with jump priorities was developed. It is assumed that upon arrival of a low-priority call one call of such kind might be immediately transferred to the end of the queue of the high-priority calls. The transfer probabilities depend on the state of the queue of heterogeneous calls. Consideration was given both to the models with separate and common queues. Algorithms to calculate the quality of service metrics of such queuing models were described, and the results of the numerical experiments were presented.

Short Communication: Comment on Probabilistic framework and performance evaluation for prioritized call admission control in next generation networks

Major errors in the indicated work are point out. 2012 Elsevier B.V. All rights reserved. This note is aimed to point out a problem in [1]. In this paper, the following queuing system for analytical model of probabilistic CAC for two service classes (SCs) is proposed. Both SCs are assumed to be Poisson processes with rate k1 and k2, respectively. The channel holding time is assumed to be exponentially distributed for both classes, 1/l1 for SC1 and 1/ l2 for SC2 where l1 – l2. This queuing model is described by a 2D Markov chain (MC) with state n = (n1,n2), where n1 and n2 is the number of SC1 and SC2 calls, respectively. SC1 refers to low priority while SC2 refers to high priority calls. Calls belonging to SC1 are admitted to a network cell with a certain probability fn,1 (n 1⁄4 0;1; . . . ;M 1) associated with the number of ongoing calls in the cell n = n1 + n2, where M is the total number of channels in the cell. In the proposed probabilistic scheme, the specific CAC with threshold L has been considered, i.e. fn;1 1⁄4 f d; n 1, contains many micro-states n = (n1,n2) with condition n = n1 + n2. So, if at given value of n various pair’s n1 and n2, where n = n1 + n2, are used then from (2) we obtain various equations. What equation should be selected for a given n? Second, if n1 + n2 = n then ðn1 1Þ þ ðn2 1Þ– n 1 and ðn1 þ 1Þþ ðn2 þ 1Þ – nþ 1, i.e. coefficients in the right side of (2) are not adequate either. And thereafter based on these false equations (2) multiplicative solution for probabilities of merged states is developed. Similar false conclusions were also made to probabilistic CAC for multiple SCs (see page 1049). Note that the authors’ mistake in forming system of equations (2) is as follows. Equations for probabilities of merged states n, n 1⁄4 0;1; . . . ;M must be formed considering probabilities of micro-states n 2 S (S is defined in p. 1047 of paper [1]) of initial 2D MC, i.e. without definition of stationary distribution of initial 0140-3664/

Analysis of models of the integral cellular communication network with different schemes of channel partitioning

see front matter 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.comcom.2012.11.011 ⇑ Corresponding author. Tel.: +994 12 447 06 40. E-mail addresses: agassi.melikov@rambler.ru (A. Melikov), laponomarenko@ ukr.net (L. Ponomarenko). Computer Communications 36 (2013) 360–361

A unified approach to analyzing models of cellular communication networks with data call buffering

Two schemes of partitioning the shared channel pool between the calls of speech and data in the integral cellular communication networks were proposed. One uses the isolated partitioning procedure, the other, the virtual partitioning. The isolated partitioning forbids channel reassignment from one zone to another, whereas the virtual partitioning relies exactly on this procedure. In both schemes, the voice calls first occupy the free channels in their zone, and only if the channels of this zone are occupied, then a free channel is sought in another zone only for the handover voice call. In this case, the maximal number of handover speech calls in the zone of channels for data calls is limited. A scheme constraining the access of such calls depending on the total number of data calls in the cell is used to establish a rule for access of new data calls to the channels. Methods were developed to calculate the indices of service performance with the proposed access strategies. The results of numerical experiments were presented, and for different access strategies the indices were compared.

QoS Optimization Problems in Cellular Wireless Networks

A unified approach to the analysis of models of cellular communication networks with queues of data calls was developed. Consideration was given to the models with two types of strategies for admission to the cell channels and the buffer. In one strategy, admission to the voice call channels is based on reservation of channels for handover of calls of the given type, and in the other strategy, on the scheme of truncating the calls of the given type. In both models, the strategy of buffer admission by the data calls relies on the scheme of place reservation for handover of the calls of the given type. The models with finite and infinite data call queues were studied. For different admission strategies, algorithms to calculate the servicing performance indices were given, and the results of their comparative analysis were presented.

Parametric Optimization Problems in Multi-Rate Systems

The algorithms suggested in previous chapters for calculation of QoS (Quality of Service) metrics of integrated voice/data Cellular Wireless Networks (CWN) allow one to optimize their values in terms of defined QoS requirements. QoS requirements can be defined say by indicating upper bounds for the loss probabilities of original (o-calls) and handover calls (h-calls) of heterogeneous traffic as well as lower bounds for the number of busy channels. In this chapter some optimization problems for both cells without queues and with queues are considered. For the sake of simplicity we consider optimization problems for mono-service networks and we have attempted as much as possible to retain the notation from previous chapters.

Models of Mixed Multi-Rate Systems

Some access strategies investigated in the previous Chaps. 4 and 5 contain controllable parameters. In other words, by the choice of suitable values for these parameters, it is possible to optimize the QoS metrics of the investigated systems. Such problems we shall name problems of parametric optimization. In the present chapter similar problems for multi-rate queues (MRQ) are considered and algorithms are proposed for their solution. Realization of the results of the considered problems in real multimedia systems does not present any difficulties.

Performance Analysis of Call-Handling Processes in Buffered Cellular Wireless Networks

In this chapter models of multi-rate systems in which inelastic and elastic calls are jointly serviced are investigated. Elasticity of a call means that its width (i.e. the number of channels needed to service it) may vary as a function of the number of free channels. In such systems channel utilization may essentially be improved. Note that such models are not only of theoretical interest, but also of great interest for practical applications. In fact, in view of the development of the technology of coding and compression, some types of multimedia information in networks may be adapted to the available number of free bands. There are quite a number of such examples in telecommunication networks (cf. [3–5]).

Markov Decision Processes (MDP) Approach to Optimization Problems for Multi-Rate Systems

In this chapter effective numerical computational procedures to calculate QoS (Quality of Service) metrics of call-handling processes in mono-service Cellular Wireless Networks (CWN) with queues of either original (o-calls) or handover (h-calls) calls are proposed. Generalization of the results found here for integrated voice/data CWN is straightforward. Unlike classical models of mono-service CWN, here original and handover calls are assumed not to be identical in terms of time of radio channel occupancy. First we consider models of CWN with queues of h-calls in which for their prioritization a guard channels scheme is also used.

Performance Analysis of Multi-Parametric Call Admission Control (CAC) Strategies in Unbuffered Cellular Wireless Networks

In the previous chapter of the book various problems of improvement of characteristics of traditional and multimedia wireless communication networks were considered. At the same time improvement of desirable characteristics was reached, basically, due to a choice of corresponding values of parameters of the used access strategy, i.e. parametric optimization problems were examined. In other words, the admissible access strategy class is defined in advance, and the problem consists in definition of optimal (in a given sense) values of access strategy parameters.