Performance analysis of a discrete-time queueing system with priority jumps

Supporting multiple types of traffic with different Quality of Service (QoS) requirements is not an easy task in modern communication networks. An efficient priority scheduling scheme is thus of great importance. The static, Head-Of-Line (HOL) priority scheme achieves differentiation between different types of traffic, but may have a too severe impact on the performance level of lower-priority traffic. We therefore propose a priority scheme with priority jumps in this paper: the Head-Of-Line Jump-If-Arrival (HOL-JIA) scheme. We show that the use of probability generating functions (pgfs) is suitable for analytically studying the system, and for illustrating the impact of priority jumps on the performance of the system.     

Two-class priority queueing system with restricted number of priority customers

In this paper, we analyze a two-class single-server preemptive priority queueing system with arrivals to each class are assumed to follow a Poisson process with exponentially distributed service times. Customers are served on a first-come, first-served basis within their own queue. Explicit expressions for the mean queue length and the steady-state joint distribution of the number of high and low priority customers in the system are derived. The analysis is based on the generating function technique. The obtained expressions are free from Bessel functions or any integral functions. Moreover, numerical values testing the quality of our analytical results are also presented.     

A Markov modulated fluid queueing system with strict priority

We investigate a Markov modulated fluid queueing system with strict priority. The input process is composed of two fluid flows which are stored in buffer1 and buffer2, respectively. The rates of these fluid flows depend on the current state of a finite state Markov chain. Buffer1 has full assignment of priority (=strict priority) for service and so buffer2 is served at a residual service rate when buffer1 is empty. We explicitly derive the stationary joint distribution of the two buffer contents in the system by a spectral decomposition method. In the case of a twostate Markov chain, the joint distribution is explicitly expressed in terms of the system parameters. Also the joint moments and tail distributions of the two buffer contents are obtained and some numerical examples are presented.     

Handoff priority scheme with preemptive, finite queueing and reneging in mobile multiservice networks

A scheme supporting voice and data calls with some grade of service (GoS)¹ guarantee in mobile multiservice networks is proposed. In this system, voice calls have preemptive priority over data calls. Preempted data calls can wait in a queue for a random patience time after which they leave the queue. A data call can be preempted only if there is space left in the finite size queue. To assess the performance of this system, an analytical model is given and performance metrics such as call blocking, call dropping and call non‐completion probabilities are investigated. Although this scheme is a generic model, it can be easily adapted to take into account the specific definitions of practical and commercial data service standards in wireless mobile networks such as GPRS or DECT. This revised version was published online in June 2006 with corrections to the Cover Date.     

Switching plan for a cellular mobile telephone system

Federal Communication Commission Docket 18 262 allocated a 75-MHz band to the common carriers to implement high capacity mobile telephone systems. The Bell System has proposed a cellular arrangement of low-power transmitters/receivers that permits frequency reuse in a coverage area. This method of achieving spectrum efficiency will require extensive centralized coordination and control to properly administer channel assignments and to interconnect the mobiles with each other and with the direct distance dialing (DDD) network. This can be accomplished by means of an electronic switching system (ESS) with special data terminals and trunking arrangements, and a unique program. In the proposed plan the radio sites (base stations) act effectively as remote concentrators in the frequency domain under the control of ESS, which in turn acts primarily as a trunk-to-trunk switcher. In addition to the usual switching, signaling, and supervising functions, the switching office must also perform numerous special functions including paging of mobiles, location of mobiles (signal strength and ranging data analysis), channel reassignment of mobiles, and reswitching of mobiles to various base stations-these last three occurring while customers ate talking.     

Performance analysis of hierarchical cellular networks with queueing and user retrials

How to efficiently utilize the scarce radio channel resource while maintaining the desired user‐perceived quality level and improved network performance is a major challenge to a wireless network designer. As one solution to meet this challenge in cellular mobile networks, a network architecture with hierarchical layers of cells has been widely considered. In this paper, we study the performance of a hierarchical cellular network that allows the queueing of both overflow slow‐mobility calls (from the lower layer microcells) and macrocell handover fast‐mobility calls that are blocked due to lack of free resources at the macrocell. Further, to accurately represent the wireless user behaviour, the impact of call repeat phenomenon is considered in the analysis of new call blocking probability. Performance analysis of the hierarchical cellular structure with queueing and call repeat phenomenon is performed using both analytical and simulation techniques. Numerical results show that queueing of calls reduces forced call termination probability and increases resource utilization with minimal call queueing delay. It is also shown that ignoring repeat calls leads to optimistic estimates of new call blocking probability especially at high offered traffic. Copyright © 2005 John Wiley & Sons, Ltd.     

GSM数字蜂窝移动交换系统测试

介绍了GSM数字蜂窝移动交换子系统,以及利用宝隆大北通信公司（EAC-GN Communication Equipmet CO.Ltd）信令测试仪表MPA7300测试交换子系统的硬件环境,并对测试内容和方法进行了论述。     

Analysis of a cutoff priority cellular radio system with finitequeueing and reneging/dropping

Queueing of new or handoff calls can minimize blocking probabilities or increase total carried traffic. This paper investigates a new cutoff priority cellular radio system that allows finite queueing of both new and handoff calls. We consider the reneging from the system of queued new calls due to caller impatience and the dropping of queued handoff calls by the system as they move out of a handoff area before being accomplished successfully. We use signal-flow graphs and Mason's formula to obtain the blocking probabilities of new and handoff calls and the average waiting times. Moreover, an optimal cutoff parameter and appropriate queue sizes for new and handoff calls are numerically determined so that a proposed overall blocking probability is minimized     

Delay analysis for multidimensional queueing processes in CSMA/CD local area networks

A CSMA/CD local area network consists of a single server (the channel) and multiple interacting queues of message packets. The message queueing process in a buffered,p-persistent CSMA/CD system is modeled as a multidimensional semi-Markov chain. An effective approximation method to compute the mean packet delay in equilibrium is developed, based on an exact joint probability generating function of the queue length vector at embedded Markov epochs. We also develop a simulation model to validate approximation results. To the best of our knowledge, this work is the first in the literature that enables optimization of the control parameterp for the CSMA/CD system with more than two users.     

Improving mobile network performance with two queueing buffer allocations of priority-based queueing scheme

As current mobile core network systems are expected to evolve into all-IP networks, packet switching will be a prerequisite for all mobile applications. Next-generation mobile networks, as envisioned by ITU-T, are packet-based networks capable of providing consistent and ubiquitous service to end users, independent of the network, access technology, and device used. This study discusses the differentiated packet forwarding performance of four major types of mobile network traffic under the proposed mobile network priority-based queueing (MPQ) scheme with two queueing buffer allocations, namely dynamic queueing buffer (DQB) allocation and overflow queueing buffer (OQB) allocation. As different queueing buffer allocations are adopted to store arriving packets in DQB and OQB, the MPQ scheme shows different packet forwarding performance under these two methods. In this study, we use ns2 (Network Simulator version 2) as the simulation platform to simulate several scenarios. The simulation results show that the MPQ scheme is able to support differentiated packet forwarding behavior for mobile traffic with both DQB and OQB allocations in a mobile core network. Some issues were identified in the MPQ scheme with both DQB and OQB allocation, which will need to be addressed.     

Design and analysis of cellular mobile communications system basedon DQRAP/CDMA MAC protocol

Future third-generation mobile communication systems will need multi-access control (MAC) protocols suitable for multimedia code division multiple access (CDMA) radio communications. Distributed queueing random access protocol (DQRAP)/CDMA is a general purpose MAC protocol oriented to the CDMA environment. Analytical model expressions and computer simulations have shown its capacity to achieve near-optimum performance under heterogeneous traffic scenarios in a unicellular environment. A cellular environment has been designed to verify that DQPAP/CDMA maintains its near-optimum performance in a packet switched mobile communication system. A new handover technique based on the protocol is proposed to further improve the system performance     

Performance analysis of a preemptive and priority reservation handoff scheme for integrated service-based wireless mobile networks

We propose an analytical model for integrated real-time and non-real-time services in a wireless mobile network with priority reservation and preemptive priority handoff schemes. We categorize the service calls into four different types, namely, real-time and non-real-time service originating calls, and real-time and non real-time handoff service request calls. Accordingly, the channels in each cell are divided into three parts: one is for real-time service calls only, the second is for non-real-time service calls only, and the last one is for overflow of handoff requests that cannot be served in the first two parts. In the third group, several channels are reserved exclusively for real-time service handoffs so that higher priority can be given to them. In addition, a realtime service handoff request has the right to preempt non-real-time service in the preemptive priority handoff scheme if no free channels are available, while the interrupted non-real-time service call returns to its handoff request queue. The system is modeled using a multidimensional Markov chain and a numerical analysis is presented to estimate blocking probabilities of originating calls, forced termination probability, and average transmission delay. This scheme is also simulated under different call holding time and cell dwell time distributions. It is observed that the simulation results closely match the analytical model. Our scheme significantly reduces the forced termination probability of real-time service calls. The probability of packet loss of non-real-time transmission is shown to be negligibly small, as a non-real-time service handoff request in waiting can be transferred from the queue of the current base station to another one.     

Performance analysis of cellular mobile communication systems fordata transmission

Buffers are used to overcome the data losses due to the interruption of data transmission when a mobile station is handed over in a cellular network. Data traffic from a wireline network to its mobile data terminal, such as access to large commercial databases or data transmission from a main computer to its remote mobile terminal, is studied. Compound Poisson (CP) is used to approximate the arrival process of the data traffic, and a modulated D (MD) distribution is used to approximate the service and handover process. The performance of the queueing model CP/MD/1/N is analyzed. Probability generating functions and characteristic functions are used to evaluate the mean queue length and the mean burst delay for an infinite buffer system and the overflow probabilities versus the buffer size for a finite buffer system. A method is presented to find the probability transition matrix entries by recursively taking derivatives of the probability generating function of the number of the characters arriving during the service-time. The queue length distributions for a finite buffer, both at departure instants and at arbitrary time instants are derived. Comparison with simulation indicates that the model is accurate. The numerical results of the model confirm the effectiveness of the scheme     

Adjacent cell interference in FH-MFSK cellular mobile radio system

The effect of adjacent cell interference in cellular mobile system using FH-MFSK transmission is evaluated quantitatively. The performance of base to mobile communication in the system is analyzed, assuming perfect synchronization between users in all the cells. Analysis of the system employing no power control shows that the number of simultaneous users possible at average bit error probability Pbof less than 1 × 10^-3is reduced greatly from the corresponding figure for the isolated cell (which is about 170). It is then shown that a simple power control strategy could reduce the adjacent cell interference significantly. A reasonable knowledge of the distribution of users within a cell allows the optimization of the receiver threshold with respect to distance from the base. With this optimization, each cell could accomodate ≳ 115 users at Pb< 10^-3, the exact figure being dependent on the user distribution. The power control also helps to reduce the average power transmitted from a base.     

Impact of handoff protection strategies on cellular mobile system capacity

In the future cellular mobile systems, the steadily growing mobile subscriber community and their demand for diversity of service place great challenge on the bandwidth utilization, especially in the wireless network part, as radio spectrum is a limited resource. Carefully planned radio usage is critical for both system capacity and service quality. Current research work in literature cares about two aspects of the service provision capability of cellular networks. One is capacity related that emphasizes the user admission capability and the other is service quality related that targets the connection continuity. However, actually achievable user accommodation capability is a cooperative result of both aspects. This paper mathematically reveals the impact of handoff protection, which is introduced to enhance connection robustness, on the capacity of cellular mobile systems. We first extract the basic mobility characteristics from the real world cellular environment to establish an ideal traffic model. Then a Markov approach is proposed to analyze the correlation between the user admission capability and the channel reservation, which is one strategy for handoff protection, and furthermore to answer the question how the user accommodation capability is affected by channel reservation in this ideal model. Simulation outcomes are provided for the creditability verification on the theoretical results. We find that system capacity and service quality are two conflicting objectives and tradeoff is inevitable. Finally, a dynamic channel reservation scheme is described to provide a mechanism for the tradeoff coordination between system revenue and service quality.     

A low-cost cellular mobile communication system: a hierarchicaloptimization network resource planning approach

This paper deals with the optimization of the design and radio network resource planning for cellular mobile communication systems. The key element to be considered for mobile network planning is cost. A hierarchical optimization planning method (HOP) is utilized since there are so many factors like system performance, terrain features, base station parameters, and cost factors which are involved in the large-scale system design. We present a three-level optimization approach for designing a cellular mobile system. It determines the cell number, cell site allocation, and the specific base station parameters in order to minimize the total system cost and to comply with the required system performance. The problem is formulated as a large combinatorial optimization model which can determine the optimal number of cells and select the best base stations' locations. The simulated annealing approach is developed to solve the hard combinatorial problem. Simulation results demonstrate the feasibility and effectiveness of the HOP approach for radio network planning     

Iterative approximation analysis of guard-channel-based strategies in mobile cellular networks

A new mathematical method to analyse the performance of guard-channel-based strategies is proposed. The analysis is based on the iterative calculation of the average effective channel holding time. The method presented provides higher accuracy than alternative solutions previously reported in the literature     

Performance analysis of cellular mobile communication networks supporting multimedia services

This paper illustrates the development of an analytical model for a communication network providing integrated services to a population of mobile users, and presents performance results to both validate the analytical approach, and assess the quality of the services offered to the end users. The analytical model is based on continuoustime multidimensional birth–death processes, and is focused on just one of the cells in the network. The cellular system is assumed to provide three classes of service: the basic voice service, a data service with bit rate higher than the voice service, and a multimedia service with one voice and one data component. In order to improve the overall network performance, some channels can be reserved to handovers, and multimedia calls that cannot complete a handover are decoupled, by transferring to the target cell only the voice component and suspending the data connection until a sufficient number of channels become free. Numerical results demonstrate the accuracy of the approximate model, as well as the effectiveness of the newly proposed multimedia call decoupling approach.     

Performance analysis of cellular mobile communication systems withdynamic channel assignment

The traffic analysis of small-cell mobile networks with dynamic channel assignment is investigated to determine their blocking performance, using a hybrid method of analysis and simulation. The authors particularly focus on the performance problems presented by networks with heterogeneous cell traffic loads, the impact of traffic volatility among the cells, and the impact of multichannel traffic on the channel blocking probabilities. Significant improvement in network performance with dynamic channel assignment is established by numerical results