Personal Communication Services Research Articles

Stability and Optimization Analysis for the PRMA Protocol for Voice and Burst Data Integration in a Personal Communication Network

Personal Communication Networks (PCNs) have become an important filed of activity and they are expected to play a fundamental role in next-generation telecommunication systems. In particular, the emerging personal communication services, such as portable computing, paging, personal e-mail, etc. have led to the need of an efficient integration of voice and data traffic in a same PCN by means of a suitable multiple-access scheme. This paper considers stability and optimization issues for the Packet Reservation Multiple Access (PRMA) protocol used for integrating voice and burst data traffic in a PCN. An important result here devised is that the optimized PRMA protocol permits to be achieved good performance even under heavy traffic load conditions.

Seamless Support for Mobile Internet Protocol Based Cellular Environments

Cellular is the inevitable architecture for the Personal Communication Service system (PCS) in the coming future. Access to the Internet via cellular networks is expected to become an essential portion of future wireless service offerings. Providing seamless support for IP based packet switched services has become an important issue.

A location-based mobility tracking scheme for PCS networks

This paper introduces a location-based locating strategy for Personal Communication Services (PCS) systems. In the proposed scheme, location updates are based on the value of a movement counter. The update of the movement counter is based on information on the locations visited by a mobile terminal (MT) since the last location update. In particular, the cell identifiers and the corresponding movement counter values are maintained in the MT for a part of the visited cells since the last location update. When the MT enters a cell whose identifier is not stored in the MT, the movement counter increases by one. If the movement counter reaches the update threshold, a location update is triggered; otherwise, the cell identifier and the corresponding movement counter value are stored in the MT. When the MT enters a cell whose identifier is in the MT, the movement counter is assigned with the counter value kept in the MT for this cell, and all cells with greater counter values in the MT are removed. The proposed scheme allows the dynamic selection of the update threshold according to each user's calling and mobility patterns. Analytical and simulation models have been developed to compare the proposed scheme with both the movement-based scheme and the distance-based scheme. Results demonstrate that when the call-to-mobility ratio (CMR) is low, the proposed scheme can achieve a significant cost reduction compared to the movement-based scheme. For example, when the CMR is 0.01, a savings of around 25% in the optimal total cost per call arrival is achieved with the proposed scheme. Moreover, the proposed scheme is easier to implement than the distance-based scheme.

Mobility modeling and traffic analysis in three-dimensional high-rise building environments

To efficiently plan future personal communications services, we need to solve various mobility/traffic problems in one-dimensional (1-D), two-dimensional (2-D), and three-dimensional (3-D) micro- or pico-cell environments. Although many users exhibit vertical motion inside elevators in high-rise buildings, there have been no studies regarding cell planning which take into account vertical motion with elevators. We extend the previous 3-D indoor mobility modeling by considering the proper boundary conditions on each floor and vertical motions through elevators and modeling mobility in high-rise buildings in order to estimate the number of handoffs. We then propose a blocking probability model with mobility as a traffic model in 3-D indoor environments. Using this model, we can obtain the required number of channels per cell under the given blocking probability constraint. These results can be used in planning the networks of future personal communications services.

INTELLIGENT PAGING STRATEGIES FOR THIRD GENERATION PERSONAL COMMUNICATION SERVICES NETWORKS

We consider the problem of minimizing paging cost, subject to delay constraint, in Personal Communication Services Network (PSCN) and present two intelligent paging strategies for third generation systems. They are termed as sequential intelligent paging (SIP) and parallel-o-sequential intelligent paging (PSIP). Unlike the conventional blanket paging where all cells in a location area are polled at a time, in SIP (PSIP) one cell (a group of cells) is polled at a time. The proposed schemes lead to a decrease in paging signaling load at the cost of some extra processing power. When better discovery rate per cycle is expected irrespective of the incoming traffic PSIP is always preferred to other paging schemes primarily because of its less amount of polling delay. If the incoming traffic rate is low, SIP performs better than PSIP in terms of paging cost per cycle. However, the polling costs per cycle and the discovery rates for both the schemes become equal as number of paging requests per cycle increases. An improvement in respect of paging cost per cycle and discovery rate over conventional paging is shown with the help of simulation results.

A new random walk model for PCS networks

This paper proposes a new approach to simplify the two-dimensional random walk models capturing the movement of mobile users in personal communications services (PCS) networks. Analytical models are proposed for the new random walks. For a PCS network with hexagonal configuration, our approach reduces the states of the two-dimensional random walk from (3n/sup 2/+3n-5) to n(n+1)/2, where n is the layers of a cluster. For a mesh configuration, our approach reduces the states from (2n2-2n+1) to (n/sup 2/+2n+4)/4 if n is even and to (n/sup 2/+2n+5)/4 if n is odd. Simulation experiments are conducted to validate the analytical models. The results indicate that the errors between the analytical and simulation models are within 1%. Three applications (i.e., microcell/macrocell configuration, distance-based location update, and GPRS mobility management for data routing) are used to show how our new model can be used to investigate the performance of PCS networks.

Portable movement modeling for PCS networks

In this paper, we propose a new model for the portable movement in personal communications services (PCSs) networks. Based on this model with general interservice time and registration area residence time distributions, an analytic expression for the probability that a portable moves across K registration areas (RAs) is obtained. The busy-line effect on this quantity is also studied and an analytic expression is presented. The result given in this paper is very useful for cost analysis for location updating and paging.

Reducing database sizes in implicit deregistration for personal communication networks

Mobility management schemes that reduce signaling traffic load and connection setup time play a pivotal role in designing future personal communication services (PCS) network. It concerns users' Quality of Service (QoS) requirements and the efficient use of network resources. In recent years, many mobility management schemes have been proposed for the reduction of signaling traffic and network load. Regardless of the specific protocol, all such technologies must support two fundamental mechanisms. One is location management (knowing where the users are) and the other is handover management (making the transition between cells smooth). In location management, a mobile user has to register when entering a new registration area (RA) and to deregister when leaving. To reduce the signaling cost in registration and deregistration, Lin and Noerpel proposed an implicit deregistration scheme. That is, a mobile will not perform deregistration when leaving a RA. As a result, there are two consequences. First, we need a large registration database. Second, even with a large database, it will become full eventually. Then we have to select a record to delete when a new mobile moves into the RA. In the original implicit deregistration scheme, the oldest record is deleted. In this paper, we propose two more reasonable and effective criteria to determine which record should be deleted from the database when a new mobile moves into an RA and the database is full. The purpose is to decrease the database size and ensure a low probability that a valid record will be replaced at the same time. The two parameters used are call-to-mobility ratio (CMR) and average call arrival interval. When the database is full, the proposed method will delete the record that has the lowest CMR or that will have to wait for the longest time for an expected call arrival. Simulation results show that the modified approach has significant improvements on the database sizes.

Performance analysis of queueing strategies for multiple priority calls in multiservice personal communications services

Supporting multiple priority calls, we propose the queueing strategies which efficiently manage the queue to reduce the blocking probability with multiclass calls in multiservice personal communications services (MPCS). The two queueing schemes are proposed and are shown the analytic model with ( n+1) class calls. Numerical results demonstrate that the two proposed schemes show the improved performance compared to the previous scheme with two types of traffic in terms of the blocking probability. The proposed schemes are flexibly adaptable to MPCS.

An innovative monopole antenna for mobile-phone handsets

An innovative monopole antenna with a parasitic helix mounted on the ground plane is designed for installation on mobile-phone handsets. Unlike the conventional monopole antenna, measurements showed that the added parasitic helix could result in a wider bandwidth for the whole antenna. The radiation patterns and the polarization properties of the monopole antenna are also shown to be relatively unchanged. Results at 1.8 GHz,which is the operating frequency of PCS (personal communications services) or GSM1800, will be presented. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 119–121, 2000.

An innovative monopole antenna for mobile-phone handsets

An innovative monopole antenna with a parasitic helix mounted on the ground plane is designed for installation on mobile-phone handsets. Unlike the conventional monopole antenna, measurements showed that the added parasitic helix could result in a wider bandwidth for the whole antenna. The radiation patterns and the polarization properties of the monopole antenna are also shown to be relatively unchanged. Results at 1.8 GHz,which is the operating frequency of PCS (personal communications services) or GSM1800, will be presented. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 119–121, 2000.

Fast recovery from database/link failures in mobile networks

An important issue in the design of future Personal Communication Services (PCS) networks is the efficient management of location information. The current IS-41 standard PCS architecture uses a centralized database, the Home Location Register (HLR), to store service and location information of each mobile registered in the PCS network. If the HLR fails, all incoming calls to a mobile from hosts which are not in the same location area as the mobile are lost. Location updates from mobiles to the HLR are also lost. Once the HLR is functional it cannot direct calls to mobiles immediately as mobiles could have changed their location during the HLR's failure. Fast recovery from a failure of the HLR is hence important. A link failure in the network could partition the network resulting in a loss of location updates from mobiles affected by the failed link. We present a new protocol for fast recovery of the HLR after a HLR failure or an intermediate link failure. The protocol does not require use of wireless bandwidth during the recovery process, has a bounded recovery period and is simple to implement making it an appealing choice in the design of future mobile networks. We analyze the protocol in order to find a medium between protocol cost and the recovery interval. We use the protocol to recover from VLR failures. We then use the protocol to recover from database failures in a distributed database architecture.

Performance analysis for voice/data integration on a finite-buffer mobile system

Personal communication service (PCS) networks offer mobile users diverse telecommunication applications, such as voice, data, and image, with different bandwidth and quality-of-service (QoS) requirements. This paper proposes an analytical model to investigate the performance of an integrated voice/data mobile network with finite data buffer in terms of voice-call blocking probability, data loss probability, and mean data delay. The model is based on the movable-boundary scheme that dynamically adjusts the number of channels for voice and data traffic. With the movable-boundary scheme, the bandwidth can be utilized efficiently while satisfying the QoS requirements for voice and data traffic. Using our model, the impact of hot-spot traffic in the heterogeneous PCS networks, in which the parameters (e.g., number of channels, voice, and data arrival rates) of cells can be varied, can be effectively analyzed. In addition, an iterative algorithm based on our model is proposed to determine the handoff traffic, which computes the system performance in polynomial-bounded time. The analytical model is validated by simulation.

A Simple Heuristic for Assignment of Cells to Switches in a PCS Network

This work deals with a design problem for a network of Personal Communication Services (PCS). The goal is to assign cells to switches in a PCS Network (PCSN) in an optimum manner so as to minimize the total cost which includes two types of cost, namely handoff cost between two adjacent cells, and cable cost between cells and switches. The design is to be optimized subject to the constraint that the call volume of each switch must not exceed its call handling capacity. In the literature, this problem has been conventionally formulated as an integer programming problem. However, because of the time complexity of the problem, the solution procedures are usually heuristic when the number of cells and switches are more. In this paper, we have proposed an assignment heuristic which is faster and much simpler than the existing algorithms. Despite its simplicity, experimental results show that it performs equally well in terms of solution quality, and, at the same time, it is faster than its predecessors. We present the algorithm as well as comparative results to justify our claim.

An architecture of ATM-based PCS network: Signaling traffic and capacity

In this paper, we propose an ATM?based Personal Communication Service (PCS) network architecture with ring?based access networks. We also propose a simple ring management scheme using ATM Add?Drop?Multiplexers (ADM). The ring has a Virtual Star topology, and we manage its bandwidth at two levels: Virtual Path (VP) level and Virtual Channel (VC) level. We consider four different types of configurations according to the locations of visitor location register (VLR) and mobile switching center (MSC) functions, and obtain signaling load and processing load. A 150 Mb/s?dual ring can support about 5,500 homogeneous ON---OFF voice sources. This ring capacity corresponds to covering approximately 180 cells in the case of 30 connections per cell. Even though we are here concerned with evaluating the proposed network for voice traffic, we can extend this study to the analysis of the proposed ATM?based PCS network accommodating various types of multimedia traffic as a further study.

Integrated Services over ATM/MAN-Based Personal Communication Networks

IEEE 802.6 metropolitan area networks (MANs) provide an efficient architecture for supporting wireless personal communication services (PCSs) over metropolitan areas by interconnecting wireless base stations into personal communication networks (PCNs). They also serve as peripheral gathering networks to transport PCS traffic over a wide area broadband integrated services digital network employing asynchronous transfer mode (ATM), enabling integration of PCNs in different cities into a global PCN. By combining the various access methods and employing a dynamic bandwidth integration scheme, a MAN can function as a powerful distributed switch for integrating different types of local traffic. Simulation results are presented to illustrate the advantages of the integration scheme. To provide ubiquitous PCS, we also propose a simple suffix-dialing method for integrating telephone, fax, paging and email services over the ATM/MAN-based PCNs using a single personal telecommunication number. With this method, the current practice of printing a long list of phone numbers on one's business card will no longer be necessary.

Determining the Source of Inter-License Synergies in Two-Way Paging Networks

In the Federal Communication Commission’s (FCC) regional narrowband personal communications services (PCS) license auction (auction #3), bidders paid a premium to provide advanced paging services on a nationwide basis as opposed to a regional scale. This paper investigates the potential source of inter-license synergy for two-way paging, the intended narrowband PCS application. Three sources of inter-license synergy are identified as possible candidates. One source, boundary interference, occurs when two distinct carriers operate in the same frequency in neighboring regions. Another source of synergy derives from the fact that neighboring regions may share common resources. A final source of synergy is the ability to offer seamless roaming.

Performance analysis for dual band PCS networks

In a dual band personal communications services (PCS) network, heavy traffic areas are covered by microcells which overlay macrocells. In such a network, microcells and macrocells utilize different frequency bands. We propose an analytic model to study the performance of a dual band PCS architecture. Our model assumes that a PCS subscriber has a general residence time distribution in a microcell and the macrocell residence time distribution is derived from the microcell residence time distribution. An iterative algorithm is used to compute the overflow traffic from a microcell to its overlaid macrocell. Then, the call incompletion probability is computed by a macrocell model based on the overflow traffic. Our study indicates that the variance of the microcell residence time distribution and the number of microcells covered by a macrocell have significant effects on the call incompletion probability.

Chain authentication in mobile communication systems

Digital mobile telecommunication systems have become a future trend in personal communications services (PCS) networks. To satisfy the demand for high quality services, security functions, including the authentications of communication parties and the confidentiality of communication channels, must be embedded into mobile communication systems. This work presents an authentication scheme to support the security functions. The proposed protocol significantly improves the performance of authentications and ensures the security of mobile communications in a large-scale communication network with multiple service providers.

Analysis and Comparison of Location Strategies for Reducing RegistrationCost in PCS Networks

In mobile environments, a personal communication service (PCS) network must keep track of the location of each mobile user in order to correctly deliver calls. A basic scheme used in the standard IS-41 and GSM protocols is to always update the location of a mobile user whenever the mobile user moves to a new location. The problem with this approach is that the cost of location update operations is very high especially when the mobile user moves frequently. In recent years, various location management strategies for reducing the location update cost have been proposed. However, the performance issue of these proposed algorithms remains to be investigated. In this paper, we develop two Markov chains to analyze and compare the performance of two promising location update strategies, i.e., the two location algorithm (TLA) and the forwarding and resetting algorithm (FRA). By utilizing the Markov chain, we are able to quickly answer what-if questions regarding the performance of PCS networks under various workload conditions and also identify conditions under which one strategy can perform better than the others. Using the cost due to location update and search operations between two successive calls to a mobile user as a performance measure, we show that when the mobile user exhibits a high degree of locality and the mobile user‘s call-to-mobility ratio (CMR) is low, TLA can significantly outperform both FRA and IS-41. On the other hand, when CMR is high, FRA is the winner. Furthermore, unlike TLA which may perform worse than IS-41 at high CMR values, FRA at identified optimal conditions can always perform at least as good as IS-41, suggesting that FRA over TLA should be used as a generic scheme in reducing the location cost in the PCS network to cover all possible per-user CMR values.