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     

Plans and considerations for SONET deployment

A perspective is given from the local exchange carrier (LEC) viewpoint on the advantages of deploying SONET (synchronous optical network), the rate at which SONET will be deployed, some typical early applications and architectures, and the role SONET will play in the evolution of the LEC network of the future. The SONET deployment timeline and capabilities are examined. Aspects of SONET architecture are discussed, namely, the access network, the interoffice transport-network, and SONET operations and control. New network capabilities and services and evolution to broadband are considered     

建设ADSL接入网应注意的问题

ADSL系统对线对的要求苛刻,传输速率对传输距离、线径、铜线质量十分敏感。在前几年发展高峰中建设的铜缆线路,相当多的线路工程是在时间仓促的情况下建成的,全塑电缆未进行气闭验收、没有实行充气维护,电缆接头受潮的情况较为严重,交直流性能指标较低。另外,由于回波噪声、线路间串扰等因素的影响,目前国内市话电缆只有15%左右的线对可以开展ADSL业务。因此,在现有市话电缆上利用ADSL传送宽带业务应慎重。ADSL仅能应用在那些光纤接入网尚未形成、电缆传输质量较好的地区。ADSL只是宽带业务初期的一种过渡措施,一旦宽带业…     

Teletraffic modeling for personal communications services

This article presents a realistic teletraffic modeling framework for personal communications services. The framework captures complex human behaviors and has been validated through analysis of actual call and mobility data. Using the proposed framework, a large-scale simulation was performed on a model of the San Francisco Bay area. Simulation results showing the performance of IS-41 are presented     

Teletraffic Analysis for Single-Cell Mobile Radio Telephone Systems

Formulas are derived for the congestion in single-cell mobile radio systems in which there are both land-to-mobile and mobile-to-mobile calls and in which mobile-to-mobile calls go via the base station. Two approaches are used. The first yields modified forms of the familiar Erlang and Engset formulas. The second gives more complicated but more accurate formulas. The results of computer simulations to establish the accuracy of the formulas are described.     

Teletraffic Analysis for Multicell Mobile Radio Telephone Systems

New teletraffic formulas are derived for the congestion in multicell mobile radio telephone systems. Fixed, dynamic, and hybrid channel asignment are considered and "tromboning," where mobileto-mobile calls go via a base station, is taken into account. The formulas agree with previously published sumulation results.     

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     

Deregistration strategies for PCS networks

This paper studies three deregistration strategies (explicit, implicit, and timeout (TO) deregistration) for personal communication service (PCS) networks to determine the network conditions under which each strategy, gives the best performance. Two performance measures are considered: (1) the probability α that a portable cannot register (and receive service) and (2) the number of deregistration messages sent in a strategy. For the same database size, α is smaller for explicit deregistration (ED) than it is for TO or implicit deregistration (ID). On the other hand, ID does not create any deregistration message traffic. With an appropriate TO period, the deregistration message traffic for TO deregistration is much smaller than the traffic for ED. Suppose that there are N portables in a registration area (RA) on the average. To ensure that α<10^-3 our study indicates that if the database size is larger than 4N, then the implicit scheme should be selected (to eliminate deregistration traffic). If the database size is smaller than 1.5 N, then the explicit scheme should be selected. Otherwise, the TO scheme should be selected to achieve the best performance     

Multicarrier modulation for narrowband PCS

Investigation of multicarrier modulation has demonstrated the feasibility of using this modulation format to deliver relatively high channel bit rates (24 kbps) to a low cost, pager-like personal communications service (PCS) terminal that enjoys long battery life (e.g., one month on a few pen-light cells). This is to be compared to the 1200 bps carried by typical current paging systems or the 6250 bps attained by the new ERMES paging system. While more complex modulation formats, such as PSK and QAM, might achieve higher bit rates in less (power, size, cost) constrained environments, amplitude keying of the component subcarriers allows simple noncoherent energy detection that is found to be robust in this short message delivery application     

Teletraffic analysis of hierarchical cellular communication networks

The sustained increase of users and the request for advanced multimedia services are amongst the key motivations for designing new high-capacity cellular telecommunication systems. The proposals that are being pursued by several studies and field implementations consider hierarchical architectures and dynamic resource allocation. A hierarchical cellular communication network is analyzed, taking user mobility into account and exploiting dynamic channel-allocation schemes. In particular, a finite number of users has been considered, moving at different speeds in a geographical region covered by a finite number of cells structured in two hierarchical levels: micro- and macrocells. For such a system, mobility and traffic models have been developed, both based on queueing networks analyzing maximum packing (MP), a dynamic channel-allocation scheme. The obtained results, validated by simulation experiments, allow the evaluation of main system-performance parameters in terms of new-call and handoff blocking probabilities, and forced-termination probability as a function of load and system parameters.     

On the Teletraffic Capacity of Optical CDMA

The capacity of an optical CDMA (OCDMA) network has traditionally been defined as the number of continuously transmitting circuits supported by the network. In this paper, we use teletraffic models to determine the teletraffic capacity of a circuit-switched OCDMA network where circuits carry bursty traffic. Our analysis is independent of the OCDMA implementation or spreading code. In conventional networks, e.g., a wavelength-routed-network (WRN), new circuits are blocked when all wavelengths are occupied. In OCDMA, when the number of codewords exceeds the number of network subscribers, new circuits need not be blocked. Instead, capacity is limited by multiple-access interference: when the number of actively transmitting circuits becomes excessive, the bit-error rate of all circuits on the network degrades, causing an outage. We find that through statistical multiplexing, the capacity of OCDMA exceeds that of a WRN, except when circuit activity is very high, while the constraints on outages are more stringent than those blocking. In such cases, we show how OCDMA with call admission control can be used to match or exceed the capacity of a WRN. Overall, our analysis shows that OCDMA is well suited to applications when conventional blocking is undesirable, and/or circuits carry bursty traffic.      

Polling deregistration for unlicensed PCS

The FCC has allocated the spectrum between 1850-1910 and 1930-1990 MHz for licensed personal communications services (PCS) and the band between 1920-1930 MHz for unlicensed PCS (UPCS). This paper describes a polling deregistration protocol for a wireless access communications network which would support interoperability between licensed personal communications services (PCS) and unlicensed-PCS (UPCS). We show how the protocol can be efficiently implemented in the personal access communications system (PACS) for licensed PCS and in the PACS-Unlicensed Version B (PACS-UB). An analytical model is proposed to analyze the performance of the polling protocol. A cost function is derived, which can be used to estimate the optimal polling frequency     

Group deregistration strategy for PCS networks

This letter proposes a novel deregistration strategy-group deregistration-for PCS networks. In the proposed strategy, instead of deregistering a mobile terminal (MT) right after the MT leaves its registration area (RA), the home location register (HLR) keeps the MT's identification in a list associated with the RA. When the next registration from the RA arrives, the HLR sends the MT identification list to the RA along with the registration acknowledgment message. The RA then deregisters these MTs. Compared to the conventional deregistration strategy, the proposed strategy greatly reduces both the signaling traffic and the database load     

Comparison of signaling loads for PCS systems

We present a comparison of the control signaling load of two vastly different architectures for providing personal communication services (PCSs). One architecture is based on current cellular networks. The other architecture, called the wireless distributed call processing architecture (WDCPA), distributes processing from the mobile switching centers and cell sites and executes new procedures for tracking mobile users and locating mobile users to deliver calls. We determine the signaling load generated within each system to support mobility management and call control based on standard assumptions about the operating parameters of a cellular network. Our results show that, when compared to current cellular systems, for simple single-connection services, WDCPA has marginally reduced cross-network signaling loads. For multiconnection calls, WDCPA incurs 35% less total signaling load for mobility management, has reduced cross-network signaling load for mobility management by up to 65%, and depending on the user model (e.g., data or telecommunication), has reduced total cross-network signaling load, including procedures for call/connection and mobility management, by up to 55% when compared to current cellular systems, while more flexibly supporting services     

ATM-based TH-SSMA network for multimedia PCS

Personal communications services (PCS) promise to provide a variety of information exchanges among users with any type of mobility, at any time, in any place, through any available device. To achieve this ambitious goal, two of the major challenges in the system design are: (i) to provide a high-speed wireless subsystem with large capacity and acceptable quality-of-service (QoS) and (ii) to design a network architecture capable of supporting multimedia traffic and various kinds of user mobility. A time-hopping spread-spectrum wireless communication system called ultra-wide bandwidth (UWB) radio is used to provide communications that are low power, high data rate, fade resistant, and relatively shadow free in a dense multipath environment. Receiver-signal processing of UWB radio is described, and performance of such communications systems, in terms of multiple-access capability, is estimated under ideal multiple-access channel conditions. A UWB-signal propagation experiment is performed using the bandwidth in excess of 1 GHz in a typical modern office building in order to characterize the UWB-signal propagation channel. The experimental results demonstrate the feasibility of the UWB radio and its robustness in a dense multipath environment. A ATM network is used as the backbone network due to its high bandwidth, fast switching capability, flexibility, and well-developed infrastructure. To minimize the impact caused by user mobility on the system performance, a hierarchical network-control architecture is postulated. A wireless virtual circuit (WVC) concept is proposed to improve the transmission efficiency and simplify the network control in the wireless subsystem. The key advantage of this network architecture and WVC concept is that the handoff can be done locally most of the time, due to the localized behavior of PCS users     

Modeling techniques for large-scale PCS networks

There has been rapid growth in the demand for mobile communications that has led to intensive research and development of complex PCS (personal communication services) networks. Capacity planning and performance modeling are necessary to maintain a high quality of service to the PCS subscriber while minimizing costs. Effective and practical performance models for large-scale PCS networks are available. Two new performance models are presented in this article which can be solved using analytical techniques. The first is the so-called portable population model, based on the flow equivalent assumption (the rate of portables into a cell equals the rate of portables out of the cell). The model provides the steady-state portable population distribution in a cell that is independent of the portable residual time distribution, which can be used by simulations to reduce the necessary execution time by reaching the steady state more rapidly. Additionally, this model can be used to study the blocking probability of a low (portable) mobility PCS network and the performance of portable deregistration strategies. The second model is the so-called portable movement model which can be used to study location tracking and handoff algorithms. The model assumes that the arriving calls to a portable form a Poisson process, and portable residual times have a general distribution. This model can be used to study location-tracking algorithms and handoff algorithms. It is shown that under some assumptions, the analytic techniques are consistent with the simulation model     

Call performance for a PCS network

It is well known that, due to the mobility of a portable and limited channel availability, calls of portables may not be completed due to being blocked or terminated during the call initiation or the handover process. The characteristics of the call-completion and call-holding times for both a complete call and an incomplete call are of critical importance for establishing the actual billing process in the PCS network. We derive the call-completion probability (hence, call-dropping probability) and the effective call-holding time distributions for complete/incomplete calls with a general cell-residence time and a general call-holding time are analyzed, and general computable formulas are obtained. We show that when call-holding times are Erlang distributed, easy-to-compute formulas for the probability of a call completion and the expected effective call-holding times for both a complete call and an incomplete call can be derived     

Architecture for interworking data over PCS

This article presents a new approach for wireless service providers to offer data services by taking advantage of the existing infrastructure for voice services and interworking with existing wireline-based data services. The article presents a framework: for interworking between any wireless radio system and any data application on the wireline network. The interworking is provided by a common interworking function that uses a generic interworking control protocol (ICP). Any radio system capable of using the ISDN-based C-interface and implementing ICP can take advantage of the proposed approach. ICP is a generic protocol and can be implemented using different networks. The article considers an ISDN network for the lower-layer transport of ICP. Though the article focuses on interworking with the PSTN and the Internet, the architecture also allows access to other data networks     

Teletraffic implications of database architectures in mobile andpersonal communications

Intelligent networks (INs) will allow wide area roaming and location of individuals so that true anytime, anywhere, any form communications can take place. Personal communications will put new demands on INs. The architectures of existing INs may need to be modified to accommodate the new capabilities required to support such services. In particular, the databases that put the “intelligence” in IN will have many more demands placed upon them due to the changes in scope and content. We identify some of the teletraffic and architectural issues associated with the support of personal and mobile communications by IN databases. We first provide some context by reviewing IN architecture, personal communications, and the data required to support it. We then look at a pseudoservice example to better understand the implications for query and update traffic that must be handled by the databases. We also identify same of the most important issues that must be addressed by database manufacturers and IN providers to realize the promise of truly transparent personal and terminal mobility