Users of wireless 3GPP LTE networks are provided with a wide range of multimedia services with varying QoS requirements; due to this fact a problem of an effective network resources’ distribution arises and, consequently, a task of the optimal RAC schemes development. According to the international standards, two types of services are defined within LTE networks – GBR services and non-GBR services. The GBR services generate streaming traffic and non-GBR services – elastic traffic the bit rate of which can dynamically change depending on the cell load. Also, the service priorities differ and are organized with the help of different mechanisms, e.g. service interruption mechanism and mechanism of bit rate degradation. The paper proposes a formal unique description of RAC schemes that is used to develop an example set of models realizing three possible pre-emption based scenarios in multiservice wireless networks.

The concept of getting services and applications at “any time” and at “any place” requires the corresponding development of cellular networks, namely in LTE networks. At present, there is a lack of quality of service related recommendations describing various popular services, e.g., video conferencing. The problem is to find the optimal bit rate values for this service while not affecting the background lower priority services. In this paper we propose an instrument for solving this problem. First, we obtain mathematical model in the form of a queueing system with multicast highpriority traffic and unicast background traffic. The admission control assumes the adaptive bit rate change of multicast traffic and unicast traffic interruption. Second, we obtain the recursive algorithm for calculating mean bit rate and other performance measures. Third, we study the problem of optimizing mean bit rate.

Machine type communications (MTC) or machine-to-machine (M2M) services become one of the drivers towards 5th generation (5G) wireless network. Various MTC devices such as smart meters and sensors form the basis of smart cites and homes. The question is how to efficiently transmit the information from MTC devices via a wireless network, which is primarily used for human-to-human (H2H) communications. Nevertheless, one of the important qualities of service (QoS) measure is still blocking probability. In the simplest case, the Erlang B formula is used to calculate the blocking probability. A more precise value can be obtained considering the MTC devices positons within a cell and applied radio resource management (RRM) mechanisms. First of all, it is expressed in the distances from the devices to eNodeB. In the paper, following the approach of including the stochastic distance in the queuing system, we propose formulas for calculating stationary probability distribution in product form considering a channel quality indicator (CQI) reported by MTC devices. Two RRM schedulers working according to the round robin policy (RRP) and full power policy (FPP) are considered. The former assumes full occupation of a time frame by all MTC devices and a variable devices’ power such that to achieve a needed uplink bit rate. The latter assumes a constant power and variable time frame occupation.

Shared access to spectrum by several parties seems to become one of the most promising approaches to solve the problem of radio spectrum shortage. The framework proposed by ETSI, licensed shared access (LSA), gives the owner absolute priority in spectrum access, to the detriment of the secondary user, LSA licensee. The latter can access the spectrum only if the owner’s QoS is not violated. If the users of both parties need continuous service without interruptions, the rules of shared access should guarantee the possibility of simultaneous access. Balancing the radio resource occupation between parties could take quite a long time compared to the dynamics of the system due to the coordination process by the national regulation authority (NRA). We examine a scheme of the simultaneous access to spectrum by the owner and the LSA licensee that minimizes the coordination activities via NRA. According to this scheme, when the owner needs the spectrum, the power of the LSA licensee’s eNB/UEs is limited. From the LSA licensee’s perspective, the scheme is described in the form of a queuing system with reliable (single-tenant band) and unreliable (multi-tenant band) servers. We show that the infinitesimal generator of the system has a block tridiagonal form. The results are illustrated numerically by estimating the average bit rate of viral videos, which varies due to aeronautical telemetry corresponding to the owner’s traffic.

In the paper an approach to the analysis of business process efficiency is proposed. A method for the estimation of a business process execution time as an important performance measure of business processes efficiency is developed. It represents a combination of queuing networks modelling and simplex algorithm of linear programming. The method allows the calculating of the minimum business processes execution time. A method of optimizing activity of the telecommunication company at a predetermined threshold for the business processes execution time is given. The developed technique was illustrated with an end-to-end business process flow “Request-to-Answer” with initial data close to reality.

Licensed shared access (LSA) framework is becoming one of the promising trends for future 5G wireless networks. Two main parties are involved in the process of sharing the frequency band – the primarily user (owner) and the secondary user (licensee). From the LSA licensee’s perspective, who has access to the band when the owner does not need it, the band is unreliable and its customers (e.g. users of wireless network) suffer from possible service interruptions. This can only occur when there is at least one customer in service (i.e. in busy period). The aim of this paper is to estimate the impact of the LSA band unreliability to the LSA licensee within the period when some interruptions are possible. The metric is the relation between the number of service interruptions and the number of customers served during a busy period. We model the occupancy of the LSA band as a multi-server homogeneous queueing system with finite and infinite buffer size and deal with the busy period analysis. The system is analyzed in steady state by deriving expressions in terms of the Laplace-Stiltjes transforms for the continuous time distributions and in terms of the probability generating functions for the number of customers served during a busy period and number of failures which occur in a busy period. The non-monotonic nature of some probabilistic measures is identified. Some illustrative examples are added to the paper.

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.

Machine-type communication (MTC) is a new service defined by the 3rd Generation Partnership Project (3GPP) to provide machines to interact to each other over future wireless networks. One of the main problems in LTE-advanced networks is the distribution of a limited number of radio resources among enormously increasing number of MTC devices with different traffic characteristics. The radio resources allocation scheme for MTC traffic transmission in LTE networks is also standardized by 3GPP and implements the Random Access Channel (RACH) mechanism for transmitting data units from a plurality of MTC devices. Until now, there is a number of problems with the congestion in radio access network, as evidenced by a series of articles calling attention to the fact that more research is required, and even modification of the RACH mechanism in order to address drawbacks, exhibiting for example when a large number of devices are trying to access simultaneously. However, not many results have been obtained for the analysis, which allows to explore a variety of performance metrics of RACH mechanism on a qualitative level. In this paper the mathematical model in a form of the discrete Markov chain is built taking into account the features of the access procedure under congestion conditions and collisions. This baseline model allows to obtain the solution for key performance measures of RACH mechanism, such as the access success probability and the average access delay, in an analytical closed-form. Based on the proposed baseline model it is possible to obtain new results for the analysis of some modifications of RACH mechanism such as ACB (Access Class Baring).

The need for efficient resource utilization at the air interfaces in heterogeneous wireless systems has recently led to the concept of downlink and uplink decoupling (DUDe). Several studies have already reported the gains of using DUDe in static traffic conditions. In this paper we investigate performance of DUDe with stochastic session arrivals patterns in LTE environment with macro and micro base stations. Particularly, we use a queuing systems with random resource requirements and to calculate the session blocking probability and throughput of the system. Our results demonstrate that DUDe association approach allows to significantly improve the metrics of interest compared to conventional downlink-based association mechanism.