Modeling and Evaluation of the Effects of Outages on the Quality of Service of GPRS Network Systems (original) (raw)

Modeling and analysis of the behavior of GPRS systems

Proceedings Sixth International Workshop on Object-Oriented Real-Time Dependable Systems, 2001

The General Packet Radio Service (GPRS) has recently become a standard to extend the services provided by the Global System for Mobile Communications (GSM). GPRS addresses packetoriented traffic, by allowing a more efficient usage of the radio resources with a consequent improvement in the QoS of subscribers. This paper focuses on a preliminary evaluation of dependability and performance figures of the GPRS, by analyzing its behavior during the contention phase where users compete for the channel reservation using a random access procedure. The presented work constitutes the first step towards the analysis of the GPRS under critical conditions, as determined by periods of outages, which significantly impact on the dependability of the GPRS itself. In fact, outages imply service unavailability, with a consequent accumulation of users actively waiting for making a service request, leading to a higher probability of collisions on requests (and therefore a degradation of the QoS perceived by the users) when the system comes back up again. Here, some analysis have been performed, using a simulation approach, to gain insights on appropriate settings for the GPRS, at varying values of internal and external system conditions (mainly, users requests, available radio channels devoted to packet traffic, outages duration).

Service-Level Availability Estimation of GPRS

IEEE Transactions on Mobile Computing, 2003

The General Packet Radio Service (GPRS) extends the Global System Mobile Communication (GSM) by introducing a packet-switched transmission service. This paper analyzes the GPRS behavior under critical conditions. In particular, we focus on outages, which significantly impact the GPRS dependability. In fact, during outage periods, the cumulative number of users trying to access the service grows proportionally over time. When the system resumes its operations, the overload caused by accumulated users determines a higher probability of collisions on resources assignment and, therefore, a degradation of the overall QoS. This paper adopts a Stochastic Activity Network modeling approach for evaluating the dependability of a GPRS network under outage conditions. The major contribution of this study lies in the novel perspective the dependability study is framed in. Starting from a quite classical availability analysis, the network dependability figures are incorporated into a very detailed service model that is used to analyze the overload effect GPRS has to face after outages, gaining deep insights on its impact on user's perceived QoS. The result of this modeling is an enhanced availability analysis, which takes into account not only the bare estimation of unavailability periods, but also the important congestion phenomenon following outages that contribute to service degradation for a certain period of time after operations resume.

Evaluation of the Impact of Congestion on Service Availability in GPRS Infrastructures

Lecture Notes in Computer Science, 2005

This paper deals with the congestion analysis of a GPRS infrastructure composed by a number of adjacent cells partially overlapped. We consider one cell as affected by an outage and through a transient analysis we evaluate the effectiveness of a specific class of resource management techniques for congestion treatment in terms of service availability related indicators. The classical availability analysis is thus enhanced, by taking into account the congestion following outages and its impact on user's perceived QoS, both in each cell and in the overall GPRS network. In order to efficiently solve the large and complex model capturing the network's behavior, we introduce a solution technique in which the solution of the entire model is constructed on the basis of the solutions of the individual sub-models.

Model-based congestion analysis during outage and system reconfiguration in GPRS networks

2003

a class of congestion treatment techniques that ultimately results in a switching of users from the congested cell to the other one. For this purpose, we introduce a modelling technique to support a proper calibration of the parameters involved in a reconfiguration action, in order to successfully treat the congestion phenomenon. The effectiveness of a reconfiguration action is evaluated in terms of indicators that represent the Quality of Service (QoS) perceived by the users in the congested and adjacent cells.

QoS Reliability in GPRS Systems

Modern Applied Science, 2011

Wireless link quality is closely related to the received signal strength. Hence, transmit power control can be used to adjust the communication link quality to avoid asymmetric or weak links. This paper proposes a spatial radio resource model for quality of service (QoS) reliability in General Packet Radio Service (GPRS) networks. To model the propagation parameters, we adopt the empirical modeling approach by measuring signal outages at various base stations from a well established network, operating in Nigeria. We collect these data over a period of three months and apply the resultant data as parameters to the proposed model. We simulate the model under ideal conditions and evaluate the system's performance as well as the power control tradeoff. A qualitative analysis using processed GIS maps, calls for effective power control in the system. Simulation results indicate that the existing system still requires further improvements to enhance its QoS reliability.

Analyzing quality of service of GPRS network systems from a user's perspective

Proceedings ISCC 2002 Seventh International Symposium on Computers and Communications, 2002

With reference to the General Packet Radio Service (GPRS), an extension of the Global System Mobile Communication (GSM) addressing packetoriented traffic, this paper contributes to the analysis on the service accomplishment level perceived by GPRS users. The proposed modeling approach builds separately the GPRS and user models; the focus is on the GPRS access random procedure on one side, and different classes of users behavior on the other side. The overall model is obtained composing the basic submodels. Quantitative analysis, performed using a simulation approach, is carried out, showing the impact of users characteristics and network load on identified indicators expressing the QoS as perceived by users.

Modeling and performance evaluation of GPRS

IEEE VTS 53rd Vehicular Technology Conference, Spring 2001. Proceedings (Cat. No.01CH37202), 2001

This paper provides an accurate model of the General Packet Radio Service (GPRS). GPRS is modeled as a single server queue in a Markovian environment. The queueing performance of data packets is evaluated by matrix geometric methods. The arrival process is assumed to follow a two state Markov modulated Poisson process (MMPP), and the service rate fluctuates based on voice loading. The analytical results are confirmed by simulation.

A bandwidth-on-demand strategy for GPRS

IEEE Transactions on Wireless Communications, 2005

General packet radio service (GPRS) is a global system for mobile communications (GSM) packet data service. In order to efficiently accommodate GPRS traffic while maintaining the desired service quality of GSM calls, we propose a GPRS bandwidth-allocation strategy called the bandwidth-on-demand (BoD) strategy. The BoD strategy is adaptive to the change of traffic conditions, and thus can dynamically adjust the number of channels for GSM and GPRS traffic. Taking the effect of packet dropping due to movements of mobile stations into account, this paper develops an analytical model to study the BoD performance in terms of GSM-call-blocking probability and GPRSpacket-dropping probability. Index Terms-Bandwidth-on-demand (BoD), general packet radio service (GPRS), global system for mobile communications (GSM).

Analysis of a traffic model for GSM/GPRS

2001

A traffic model for GSM/GPRS, the hybrid radio resource allocation (HRRA) algorithm is evaluated. A dedicated number of GPRS channels plus idle periods between voice calls are used for GPRS data packet transfers. A simulator was developed in order to evaluate the HRRA algorithm, which provides a reasonable forecast on the voice blocking probability and on packet delay for a single cell system. Since the major issue is the correct resource allocation, results are shown for the influence of some choices and assumptions on the overall system performance.