Performance evaluation of prioritized handoff schemes in mobilecellular networks

This paper deals with the performance analysis of two prioritized handoff schemes for mobile cellular networks in which handoff attempts finding all channels busy are queued for a maximum time. Fixed channel assignment is assumed. In the first prioritized handoff scheme considered, handoff attempts are queued according to the first-in-first-out (FIFO) policy. Conversely, the second scheme resorts to an ideal nonpreemptive priority queueing policy to enhance system performance. Differently from previous works, in this paper the performance analysis is carried out on the basis of a model which takes into account the event that a call may terminate when the mobile user is waiting for a handoff. Comparisons with simulation results and analytical predictions derived by means of alternative approaches highlight a better estimation accuracy for the proposed method. Moreover, it is also demonstrated here that the FIFO policy allows performance very close to that of the ideal prioritized handoff scheme and, hence, that it is a solution suitable for applications in mobile cellular networks where a high service quality is required     

Comments on “Teletraffic model and performance analysis forcellular mobile radio telephone systems with prioritized andnonprioritized handoff procedures”

Hong and Rappaport (see Proc. Inst. Electr. Eng., vol.136, pt.I, no.5, p.339-46, 1989) considered a handoff scheme for cellular systems, where priority is given to handoff calls in channel assignment and a queue of handoff calls is allowed. This paper points out and corrects their critical error in getting some performance measures for the scheme. We also discuss the effects of our correction on the related results in their paper and in the paper of Pavlidou (see IEEE Trans. Commun., vol.42, no.2/3/4, p.848-53, 1994)     

Traffic model and performance analysis for cellular mobile radio telephone systems with prioritized and nonprioritized handoff procedures

A traffic model and analysis for cellular mobile radio telephone systems with handoff are described. Three schemes for call traffic handling are considered. One is nonprioritized and two are priority oriented. Fixed channel assignment is considered. In the nonprioritized scheme the base stations make no distinction between new call attempts and handoff attempts. Attempts which find all channels occupied are cleared. In the first priority scheme considered, a fixed number of channels in each cell are reserved exclusively for handoff calls. The second priority scheme employs a similar channel assignment strategy, but, additionally, the queueing of handoff attempts is allowed. Appropriate analytical models and criteria are developed and used to derive performance characteristics. These show, for example, blocking probability, forced termination probability, and fraction of new calls not completed, as functions of pertinent system parameters. General formulas are given and specific numerical results for nominal system parameters are presented.     

Teletraffic performance of mobile radio networks with hierarchicalcells and overflow

Wireless mobile networks, comprising a hierarchical layer of cells, use the cell layering to provide alternate routing for calls. This paper proposes a model for multilayered wireless mobile communications networks that provides a unified treatment of overflow to account for intra- and interlayer overflow. This takes account of the inherent overlap between cells in the same layer and between layers, and hence the prospect of controlling the overflow to achieve a tradeoff between new call and handover performance. The mobility of users within the layers is included in the model, and this allows handover performance to be estimated. Network performance is evaluated in terms of caller-perceived performance by calculating the probability of call failure using a Markov chain model of call progress. An example is presented that provides a comparison of the network performance for a range of overflow policies. The main contribution of this paper is the development of an analytic method that treats overflow in a unified manner. This allows the approximate performance of overflow strategies that balance the need to maintain calls in progress with the desire to accept more new calls to be evaluated for large networks     

A learning approach for prioritized handoff channel allocation in mobile multimedia networks

An efficient channel allocation policy that prioritizes handoffs is an indispensable ingredient in future cellular networks in order to support multimedia traffic while ensuring quality of service requirements (QoS). In this paper we study the application of a reinforcement-learning algorithm to develop an alternative channel allocation scheme in mobile cellular networks that supports multiple heterogeneous traffic classes. The proposed scheme prioritizes handoff call requests over new calls and provides differentiated services for different traffic classes with diverse characteristics and quality of service requirements. Furthermore, it is asymptotically optimal, computationally inexpensive, model-free, and can adapt to changing traffic conditions. Simulations are provided to compare the effectiveness of the proposed algorithm with other known resource-sharing policies such as complete sharing and reservation policies     

Teletraffic modeling and analysis of flexible hierarchical cellularnetworks with speed-sensitive handoff strategy

Hierarchical cellular networks with subscribers of varying mobility are considered. Microcells are used to address the high-intensity traffic of mainly slow mobility areas, and macrocells are overlaid over the microcells to cater mainly to high-mobility lower density traffic. The two tiers of microcells and macrocells provide a secondary resource for new traffic as well as handoffs for mobile subscribers of different mobility classes. Furthermore, resources in alternate layers are monitored to assign the appropriate resource types when they become available. We develop an analytical model to evaluate the performance of such systems, and quantify the gain obtained by providing overflow to alternate resources as well as the advantages in resource reassignment according to the speed classification     

Teletraffic performance of highway microcells with overlaymacrocell

The teletraffic performance of a highway microcellular digital mobile radio system having an oversailing macrocell that spans many microcells is presented. The microcellular cluster is composed of concatenated segments of the highway where each segment is a microcell, typically 500-2000 m in length, with the base stations located at lamp-post elevations. A narrowband time-division-multiple-access arrangement supporting ten channels per carrier and one carrier per base station is used. The teletraffic analysis assumes there are n-up and n-down lanes, and that the vehicular speeds conform to a truncated Gaussian distribution whose mean speed is 100 or 50 km/h when the vehicular traffic is free-flowing or in traffic-congested conditions, respectively     

Performance evaluation of hierarchical cellular CDMA networks with soft handoff queueing

We consider hierarchical cellular code-division multiple-access networks supporting soft handoff, where users with different mobility are assigned to different layers, i.e., microcells in the lower layer are used to carry slow users, whereas macrocells in the upper layer are for fast users, and handoff queues are provided for handoff calls that cannot obtain the required channel immediately, so that forced termination probability can be reduced. According to whether handoff queues are provided in microcells and/or macrocells, four different call admission control schemes are proposed and studied. We derive the mathematical model of the considered system with multidimensional birth-death process and utilize Gauss-Seidel iterative method to find the steady-state probability distribution and thus the performance measures of interest: new call blocking probability, handoff failure probability, and forced termination probability. Analytical results show that providing handoff queues in both microcells and macrocells can achieve largest performance improvement. Furthermore, handoff queue size greater than a threshold is shown to have little effect on performance measures of interest. Last but not least, the studied two-tier system is compared with a one-tier counterpart. It is shown that the two-tier system performs better in terms of average number of handoffs per fast call.     

Analysis of secondary user performance in cognitive radio networks with reactive spectrum handoff

Cognitive radio networks use dynamic spectrum access of secondary users (SUs) to deal with the problem of radio spectrum scarcity . In this paper, we investigate the SU performance in cognitive radio networks with reactive-decision spectrum handoff. During transmission, a SU may get interrupted several times due to the arrival of primary (licensed) users. After each interruption in the reactive spectrum handoff, the SU performs spectrum sensing to determine an idle channel for retransmission. We develop two continuous-time Markov chain models with and without an absorbing state to study the impact of system parameters such as sensing time and sensing room size on several SU performance measures. These measures include the mean delay of a SU, the variance of the SU delay, the SU interruption probability, the average number of interruptions that a SU experiences, the probability of a SU getting discarded from the system after an interruption and the SU blocking probability upon arrival.     

Improving reliable transport and handoff performance in cellular wireless networks

TCP is a reliable transport protocol tuned to perform well in traditional networks where congestion is the primary cause of packet loss. However, networks with wireless links and mobile hosts incur significant losses due to bit-errors and handoffs. This environment violates many of the assumptions made by TCP, causing degraded end-to-end performance. In this paper, we describe the additions and modifications to the standard Internet protocol stack (TCP/IP) to improve end-to-end reliable transport performance in mobile environments. The protocol changes are made to network-layer software at the base station and mobile host, and preserve the end-to-end semantics of TCP. One part of the modifications, called the snoop module, caches packets at the base station and performs local retransmissions across the wireless link to alleviate the problems caused by high bit-error rates. The second part is a routing protocol that enables low-latency handoff to occur with negligible data loss. We have implemented this new protocol stack on a wireless testbed. Our experiments show that this system is significantly more robust at dealing with unreliable wireless links than normal TCP; we have achieved throughput speedups of up to 20 times over regular TCP and handoff latencies over 10 times shorter than other mobile routing protocols.This work was supported by ARPA Contract J-FBI-93-153. This paper was in part presented at the ACM Mobile Computing and Networking Conference (Mobicom '95), Berkeley, California, 14–15 November 1995.     

基于预测的平滑切换机制及其性能评价

针对微观移动协议现有切换机制存在的问题,提出了基于预测的平滑切换机制,该机制利用移动预测技术,在切换发生前预测移动主机将要切换的下一蜂窝以及切换的时刻,为移动主机预先建立新路径;为了保证基于预测的平滑切换机制的实现,提出了一个易于实现的简单移动预测算法--SMPA算法;通过理论分析和系统仿真的方法对基于预测的平滑切换机制进行了性能评价,结果表明该切换机制以相对较小的代价获得了可观的性能改善.     

Teletraffic analysis and mobility modeling of PCS networks

Channel holding time is of primary importance in teletraffic analysis of PCS networks. This quantity depends on user's mobility which can be characterized by the cell residence time. We show that when the cell residence time is not exponentially distributed, the channel holding time is not exponentially distributed either, a fact also confirmed by available field data. In order to capture the essence of PCS network behaviour, including the characterization of channel holding time, a correct mobility model is therefore necessary. The new model must be good enough to fit field data, while at the same time resulting in a tractable queueing system. We propose a new mobility model, called the hyper-Erlang distribution model, which is consistent with these requirements. Under the new realistic operational assumption of this model, in which the cell residence time is generally distributed, we derive analytical results for the channel holding time distribution, which are readily applicable to the hyper-Erlang distribution models. Using the derived analytical results we demonstrate how the distribution of the cell residence time affects the channel holding time distribution. The results presented in this paper can provide guidelines for field data processing in PCS network design and performance evaluation     

Asymptotic performance evaluation of token-passing networks

Analytical formulae for evaluating the performance of token passing networks with a finite number of buffered users are presented. The effect of the buffer capacity of users on performance characteristics is investigated, and the maximum achievable throughput with respect to the buffer capacity of users is derived     

Sparse deployment scheme in mobile sensor networks with prioritized event area

Sensor deployment is a fundamental issue in Internet of things. In this paper, It addressed the problem of how to effective deployment for prioritized event area in mobile sensor networks with low density sensors, which coverage completely cannot be realized. When event areas have been detected, the problem how to make mobile nodes moved to a suitable place with effective deployment is studied. Firstly, a coverage weight by priority function of event area is defined. It deduced conclusion that coverage effectiveness have maximization as if all of nodes coverage weight are identical. A nodes deployed strategy have presented that combined coverage weight and virtual force. Finally, some simulations shown that the proposed deployment algorithm are accurate and effective. Copyright © 2015 John Wiley & Sons, Ltd.     

Virtual private networks: an overview with performance evaluation

Virtual private networks have gained immense popularity among commercial and defense organizations because of their capability to provide secure connectivity at lower costs. Several commercial and open source VPN products are now available that can be configured to provide VPN services with varying characteristics. This article studies some of the most popular open-source Linux-based VPN solutions (OSLVs) and compares them with respect to network performance (measured in terms of overhead, bandwidth utilization, and latency/jitter), features and functionalities (e.g., algorithm plugins and routing), and operational concerns (defined by security and scalability). Our experiments suggest that there is no single OSLV solution that excels in all considered aspects, and a combination of different VPN products and/or trade-off among desired characteristics may be required to deliver optimal performance. Our experiments also suggest that on an average, OSLVs using UDP-based tunnels have 50 percent lower overhead, 80 percent higher bandwidth utilization, and 40-60 percent lower latency/jitter than those using TCP.     

Smooth handoff with enhanced packet buffering-and-forwarding in wireless/mobile networks

Packet buffering-and-forwarding is a simple mechanism and has been widely used to provide seamless handoffs in many wireless/mobile networks. However, some undesirable side effects of this mechanism, if not managed appropriately, can easily diminish its effectiveness in providing seamless inter-cell transitions during a handoff. We first examine these side effects and show how inappropriate buffer management by a mobility agent could affect the TCP performance. The throughput of TCP is then studied with special emphasis on the effects of a handoff. We then propose a Last-Come-First-Drop (LCFD) buffer management policy (to be employed by mobility agents) and post-handoff acknowledgement suppression (to be used by mobile nodes) to improvement the TCP performance. Our enhancements are backward compatible and suitable for the gradual/incremental deployment. By deriving an analytical model and conducting numerical analysis, we show that our scheme can improve the TCP throughput up to 30%. Finally, we conduct the ns-2-based simulation to confirm these numerical results, and demonstrate the applicability of the analytic model for predicting TCP throughput in other handoff schemes. Chun-Ting Chou is currently a senior member research staff in Philips Research North America, Briarcliff Manor, New York. He received both the B.S. and M.S. degrees in Electrical Engineering from National Taiwan University in 1995 and 1997, respectively. He received the Ph.D. degree in Electrical Engineering and Computer Science from the University of Michigan, Ann Arbor, in 2004. He is actively involved in standardization of WiMedia Ultra-Wide Band (UWB) Wireless PANs, IEEE 802.15.3c high-speed wireless PANs and IEEE 802.15.5 meshed Wireless PANs. His current research interests include quality of service (QoS), MAC protocols for UWB Wireless PANs, 60-GHz wireless PANs using directional antennas, meshed wireless LANs and PANs, and spectrum agile and cooperative communication. Kang G. Shin is the Kevin and Nancy O’Connor Professor of Computer Science and Founding Director of the Real-Time Computing Laboratory in the Department of Electrical Engineering and Computer Science, The University of Michigan, Ann Arbor, Michigan. His current research focuses on QoS-sensitive networking and computing as well as on embedded real-time OS, middleware and applications, all with emphasis on timeliness and dependability. He has supervised the completion of 54 PhD theses, and authored/coauthored around 630 technical papers and numerous book chapters in the areas of distributed real-time computing and control, computer networking, fault-tolerant computing, and intelligent manufacturing. He has co-authored (jointly with C. M. Krishna) a textbook “Real-Time Systems,” McGraw Hill, 1997. He has received a number of best paper awards, including the IEEE Communications Society William R. Bennett Prize Paper Award in 2003, the Best Paper Award from the IWQoS’03 in 2003, and an Outstanding IEEE Transactions of Automatic Control Paper Award in 1987. He has also coauthored papers with his students which received the Best Student Paper Awards from the 1996 IEEE Real-Time Technology and Application Symposium, and the 2000 UNSENIX Technical Conference. He has also received several institutional awards, including the Research Excellence Award in 1989, Outstanding Achievement Award in 1999, Service Excellence Award in 2000, Distinguished Faculty Achievement Award in 2001, and Stephen Attwood Award in 2004 from The University of Michigan; a Distinguished Alumni Award of the College of Engineering, Seoul National University in 2002; and 2003 IEEE RTC Technical Achievement Award. He received the B.S. degree in Electronics Engineering from Seoul National University, Seoul, Korea in 1970, and both the M.S. and Ph.D degrees in Electrical Engineering from Cornell University, Ithaca, New York in 1976 and 1978, respectively. From 1978 to 1982 he was on the faculty of Rensselaer Polytechnic Institute, Troy, New York. He has held visiting positions at the U.S. Airforce Flight Dynamics Laboratory, AT &T Bell Laboratories, Computer Science Division within the Department of Electrical Engineering and Computer Science at UC Berkeley, and International Computer Science Institute, Berkeley, CA, IBM T. J. Watson Research Center, Software Engineering Institute at Carnegie Mellon University, and HP Research Laboratories. He also chaired the Computer Science and Engineering Division, EECS Department, The University of Michigan for three years beginning January 1991. He is Fellow of IEEE and ACM, and member of the Korean Academy of Engineering, is serving as the General Chair for the 3rd ACM/USENIX International Conference on Mobile Systems, Applications, and Services (MobiSys’05), was the General Chair of the 2000 IEEE Real-Time Technology and Applications Symposium, the Program Chair of the 1986 IEEE Real-Time Systems Symposium (RTSS), the General Chair of the 1987 RTSS, the Guest Editor of the 1987 August special issue of IEEE Transactions on Computers on Real-Time Systems, a Program Co-Chair for the 1992 International Conference on Parallel Processing, and served numerous technical program committees. He also chaired the IEEE Technical Committee on Real-Time Systems during 1991--93, was a Distinguished Visitor of the Computer Society of the IEEE, an Editor of IEEE Trans. on Parallel and Distributed Computing, and an Area Editor ofInternational Journal of Time-Critical Computing Systems,Computer Networks, and ACM Transactions on Embedded Systems.     

异构网中一种能效最优的垂直切换算法

针对传统垂直切换算法中未能考虑能效这一关键因素,提出了一种能效最优的垂直切换算法,算法核心是移动终端检测并计算来至不同候选网络中的接收信号强度以及各候选小区中的系统容量,以候选小区中每单位能量所能提供的容量作为判决准则切入到最佳网络,同时结合传统的网络因子对多属性判决算法进行能效扩展。仿真结果表明,基于单位能量容量的切换算法较传统的切换算法节省10%左右的能量,扩展的多属性判决算法较传统的切换算法节省7%左右的能量,同时减少了“乒乓效应”,提高了用户的通信体验质量。     

Teletraffic performance of GSM900/DCS1800 in street microcells

Studies the teletraffic issues of the Global System of Mobile Communications at 900 MHz (GSM900), and its sister, the Digital Communication System at 1800 MHz (DCS1800). The teletraffic simulations have the essential elements of GSM900 and DCS1800, but they are not be exact simulations of these two systems. The approach is to site microcellular base stations, using the microcellular prediction tool MIDAS, into a fictitious city and into parts of two real cities. The radio coverage plots are then imported into a teletraffic simulator TELSIM. The simulator is loaded with the basic GSM900 and DCS1800 parameters to give an indication of the teletraffic performance of these systems in the three environments     

Performance evaluation of sequential spectrum handoff in cognitive radio networks: a single‐user case

Powerful spectrum handover schemes enable cognitive radios to exploit transmission opportunities in primary users’ channels appropriately. In this paper, modeling and performance evaluation of sequential spectrum sensing strategy are addressed. To this end, the average number of handovers required for finding a transmission opportunity is evaluated assuming that a prior knowledge of the presence and absence probabilities of the primary users is available. Moreover, the average throughput maximization of a secondary user by optimizing its spectrum sensing time is formulated, and a set of illustrative numerical results is then presented to validate the analytical analysis.Copyright © 2013 John Wiley & Sons, Ltd.     

Performance analysis of soft handoff in CDMA cellular networks

A unique feature of code division multiple access (CDMA) systems is the use of soft handoff between cells. Soft handoff, in general, increases the system capacity because while the link between a mobile and one base station is poor, it might be better between the same mobile and some other base station. Hence, the user may transmit at a lower power in a soft handoff situation. Teletraffic analysis of soft handoff is complex because one cannot separate transmission issues from traffic issues. Many papers in the literature have independently analyzed the effect of soft capacity and soft handoff on network performance. Some papers have analyzed the effect of soft handoff on soft capacity but there has been no proper teletraffic analysis that includes both soft capacity and soft handoff. This paper proposes a traffic model for a DS-CDMA cellular network that includes both soft capacity and soft handoff. Network performance is then computed in terms of call blocking