Paging strategy optimization in personal communication systems

Mobility tracking is concerned with finding a mobile subscriber (MS) within the area serviced by the wireless network. The two basic operations for tracking an MS, location updating and paging, constitute additional load on the wireless network. The total cost of updating and paging can be minimized by optimally dividing the cellular area into location registration (LR) areas. In current systems broadcast paging messages are sent within the LR area to alert the MS of an incoming call. In this paper we propose a selective paging strategy which uses the MS mobility and call patterns to minimize the cost of locating an MS within an LR area subject to a constraint on the delay in locating the MS. This revised version was published online in July 2006 with corrections to the Cover Date.     

Issues in satellite personal communication systems

In the paper various issues in personal satellite communications are addressed. Basic geostationary and non‐geostationary satellite constellations are considered. The narrowband and wideband characterization of the mobile satellite channel and related system implications are discussed. Satellite diversity is presented as a measure to overcome signal shadowing. The capacity of TDMA and CDMA multiple access is estimated, taking into account co‐channel interference. Various network issues, such as mobility management, radio resource management, call control, routing, and network integration are addressed. Finally, some regulatory and political issues are mentioned which may be most relevant for market development and financial success of satellite personal communication systems. This revised version was published online in June 2006 with corrections to the Cover Date.     

Emerging mobile and personal communication systems

The market demand for wireless communications has been demonstrated by the rapid growth of different second-generation wireless technologies that are optimized for particular applications and environments. Obvious examples include: digital cellular systems like GSM, ADC, PDC,and DCS1800 for widespread vehicular and pedestrian services, and cordless telecommunication systems based on CT2, DECT, and PHS standards for residential, business, and public cordless access applications. Efforts are also underway to consolidate the various radio environments and applications under a single standard for third generation wireless, i.e., FPLMTS. In the area of personal mobility, with the recent availability of “personal” numbers in various countries (e.g., 500 numbers in the United States), many fixed network operators are starting to offer such personal mobility services as “personal number service” and “number portability”. These services represent initial stages of full personal mobility that will be provided by UPT in both wireline as well as wireless environments. The expected heavy demand for PCS in the United States and the underlying market/regulatory forces are driving the standardization and business activity. A number of air interface standards for the 1900 MHZ PCS band are being considered, which are based on TDMA, CDMA, and FDMA technologies singly or in combination. Many are variations of existing digital cellular and cordless telecommunications technologies. PCS networking standards are also being developed; both for standalone systems and for systems that will utilize public switched network capabilities     

Satellite systems for personal communication networks

The paper addresses some issues related to Satellite Personal Communication Networks (S‐PCNs). The role of satellite communications in that scenario is discussed, and some characteristics of S‐PCNs are identified. In addition, the problem of the integration of S‐PCNs with the Universal Mobile Telecommunication System (UMTS) is considered. In this respect an original methodology for accomplishing such integration is proposed; such methodology aims at avoiding complex protocol conversions at the interfaces between the terrestrial and the satellite segment. The paper is partly based upon the work performed by the authors in the framework of the European Community INSURED Project “INtegrated Satellite UMTS Real Environment Demonstrator”. This revised version was published online in June 2006 with corrections to the Cover Date.     

Analysis of intelligent paging in personal communication systems

The authors quantify the paging cost for a specific form of intelligent paging in terms of the probability of a successful first paging step. When compared with the simultaneous and sequential paging schemes, the benefit of the intelligent scheme is found to be much more profound in pedestrian-dominated PCS environments     

Simulation of communication systems using personal computers

Two examples are provided of the use of microcomputer simulation for computer-aided design and analysis of communication systems: a fixed topology simulation program for digital data links written in Pascal; and a simulation of an analog link using Fortran. Such applications are reported to require a minimum of investment. The new 32-bit single-board computers and their potential impact on microcomputer simulation are discussed     

Handover mechanism and speed considerations in personal communication systems

In this paper, we discuss views concerning different approaches to the analysis of personal communication systems (PCSs): an outside observer's point of view, a user's point of view, and a base station's point of view. In these three approaches the paper focuses on the handover mechanism rather than on the data traffic modeling. In particular, we reexamine these different methods of analysis, combine these views with our approach, and propose a new queueing model. We take into account the speed factor and show that the ordinary measurements that are based on the state probabilities are not appropriate. In addition, we propose a layered queueing model in which low-speed and high-speed users are treated differently.     

Efficient location area planning for personal communication systems

A central problem in personal communication systems is to optimize bandwidth usage, while providing Quality of Service (QoS) guarantees to mobile users. Network mobility management, and in particular, location management, consumes a significant portion of bandwidth, which is a necessary overhead for supporting mobile users. We focus our efforts on minimizing this overhead. Unlike previous works, we concentrate on optimizing existing schemes, and so the algorithms we present are easily incorporated into current networks. We present the first polynomial time approximation algorithms for minimum bandwidth location management. In planar graphs, our algorithm provably generates a solution that uses no more than a constant factor more bandwidth than the optimal solution. In general graphs, our algorithm provably generates a solution that uses just a factor O (log n) more bandwidth than optimal where n is the number of base stations in the network. We show that, in practice, our algorithm produces near-optimal results and outperforms other schemes that are described in the literature. For the important case of the line graph, we present a polynomial-time optimal algorithm. Finally, we illustrate that our algorithm can also be used for optimizing the handoff mechanism.     

Wideband rectangular slot antenna for personal wireless communication systems

Antenna designs are achieved for wideband operation by the use of a coplanar patch-slot antenna, fed by a coplanar waveguide. This design is easily tuned to operate at 2.45 and 5.75 GHz, with wide bandwidth for wireless systems. The operating frequency is controlled by modifying the patch dimensions. The return loss, input impedance, radiation pattern, directivity, gain, and efficiency of the proposed designs are computed and presented. A parametric study of the antenna is also introduced.     

Three-dimensional cellular systems for air/ground personal communication

A new three-dimensional (3-D) cellular system is proposed for air/ground (A/G) personal communications. The proposed system extends the Global System for Mobile Communication (GSM) to enable its subscribers to send and receive calls while traveling in the air using the same subscriber identity module (SIM)-the same mobile number-that is used for the ground network. Modifications to the GSM system architecture to develop the A/G system architecture are outlined. A multilayer service volume is proposed in which the coverage volume is divided into three coaxial cylindrical layers (cells) with each layer serving a limited part of the airspace. Capacity of the new proposed system based on the standard GSM concept is analyzed and compared to other alternative systems: Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA).     

Analysis and optimization of wavelet-coded communication systems

Since its advent, wavelet coding has been recognized as a promising technique for wireless transmission systems, especially due to its low decoding complexity and good performance over multipath fading. However, this technique requires unusual modulation schemes in order to be fully exploited. A BER analysis of wavelet-coded transmission systems over Rayleigh fading channels is presented in this work. This analysis is used in the design of novel signal constellations for wavelet-coded systems by means of numerical performance optimization. Numerical results obtained from analysis and simulations show that the wavelet-coded systems derived herein have very good performance characteristics over fading channels.     

Paging area optimization based on interval estimation in wireless personal communication networks

We consider an optimum personal paging area configuration problem to improve the paging efficiency in PCS/cellular mobile networks. The approach is to set up the boundaries of a one-step paging area that contain the locations of a mobile user with a high probability and to adjust the boundaries to gain a coverage that is matched to the mobile user's time-varying mobility pattern. We formulate the problem as an interval estimation problem. The objective is to reduce the paging signaling cost by minimizing the size of the paging area constrained to certain confidence measure (probability of locating the user), based on a finite number of available location observations of the mobile user. Modeling user mobility as a Brownian motion with the drift stochastic process and by estimating the parameters of the location probability distribution of the mobility process, the effects of the mobility characteristics and the system design parameters on the optimum paging area are investigated. Results show: (1) the optimum paging area expands with the time elapsed after the last known location of the user; (2) it also increases with the length of a prediction interval and the location probability; (3) the relative change in the paging area size decreases with the increase in the number of location observations. This revised version was published online in June 2006 with corrections to the Cover Date.     

Paging area optimization based on interval estimation in wireless personal communication networks

We consider an optimum personal paging area configuration problem to improve the paging efficiency in PCS/cellular mobile networks. The approach is to set up the boundaries of a one-step paging area that contain the locations of a mobile user with a high probability and to adjust the boundaries to gain a coverage that is matched to the mobile user's time-varying mobility pattern. We formulate the problem as an interval estimation problem. The objective is to reduce the paging signaling cost by minimizing the size of the paging area constrained to certain confidence measure (probability of locating the user), based on a finite number of available location observations of the mobile user. Modeling user mobility as a Brownian motion with the drift stochastic process and by estimating the parameters of the location probability distribution of the mobility process, the effects of the mobility characteristics and the system design parameters on the optimum paging area are investigated. Results show: (1) the optimum paging area expands with the time elapsed after the last known location of the user; (2) it also increases with the length of a prediction interval and the location probability; (3) the relative change in the paging area size decreases with the increase in the number of location observations. This revised version was published online in June 2006 with corrections to the Cover Date.     

Capacity optimization in wireless communication systems with mixed platforms

A mobility-aware call admission control (CAC) strategy for capacity optimization in mobile wireless communication systems is proposed. In the strategy, calls by slow moving users are intentionally dropped in a controlled manner to increase channel utilization. Results show that our CAC achieves 23.3% and 5.56% capacity gain relative to the Non Priority and Fractional Channel Reservation (FCR) strategies, respectively.     

Enhanced reserved polling multiaccess technique for multimedia personal communication systems

This article describes a multiaccess technique which allows the transport of multimedia information across global personal communication systems (PCS). Impressive growth in the application of wireless technologies to telecommunications has sparked active research on a new generation of mobile radio networks projected to handle heterogeneous traffic types. One of the key requirements of these advanced systems is the multiaccess protocol which must guarantee quality of service and provide efficient access to multirate broadband applications that combine voice, video and data communications. In addition, the protocol is required to operate with the demanding constraints imposed by moving users, dynamic traffic load variations and highly sensitive wireless links. To this end, a multiaccess scheme called enhanced reserved polling is proposed. The scheme is designed to execute many PCSrelated functions including radio resource assignment, connection control and mobility management. It accommodates a diverse mixture of delay classes/message priorities and can also enhance the bandwidth sharing among different cells in the network.     

An algorithm for global optimization of optical communication systems

We present a global optimization algorithm especially appropriate for the optimization of optical communication systems. It is independent of external parameters and converges to the global optimum, considerably reducing the simulation time. The algorithm is used to optimize the fiber launch powers and dispersion map of a single-channel OOK, DPSK and DQPSK at several data rates.     

Improved ADPCM voice signal transmission employing click-noisedetection scheme for TDMA-TDD personal communication systems

In personal communication systems, better voice quality and lower terminal price are essential requirements, and adaptive differential pulse-code modulation (ADPCM) codecs are one of the voice codec candidates that have good voice quality and reasonable cost. However, in slow fading environments, burst errors induce click noise in ADPCM voice signal transmission. This paper proposes a novel error-concealment scheme to improve the ADPCM voice signal transmission quality of time division multiple access time division duplex (TDMA-TDD) personal communication systems in slow fading environments. The proposed scheme employs an improved error-detection technique with PCM differential detection and overflow detection coupled with a cyclic redundancy check (CRC) code. To compensate for residual click noise, an expanded CRC error-detection signal is used. Erroneous PCM signals are adaptively suppressed according to the click-noise detection information. Hardware simulation results show that these techniques significantly improve ADPCM voice signal transmission quality by 0.5 points and 1.0 compared to that of the conventional ADPCM muting scheme and no processing, respectively, with the mean opinion scoring (MOS) test in the slow fading environments typical of personal communication systems     

On the capacity of packet reservation multiple access with capturein personal communication systems

A new Markovian model is developed to analyze the packet reservation multiple access (PRMA) protocol over Rician fading channels with lognormal shadowing. The packet dropping probability and the voice user capacity are defined as the performance measures. A new formula is derived to evaluate the dropping probability in the fading environment. The analytical results from our new formula show close agreement with those from computer simulations. The capture effect on the PRMA system performance is also studied. We found that, with capture, the user capacity will be improved and the service quality will degrade gracefully when the number of active users in the system increases. Using the dropping probability as the criterion, we also determine the optimal permission probability in a microcellular environment     

Location management for next-generation personal communicationsnetworks

This article presents a survey on location management algorithms for next-generation personal communications networks. We first describe different static and dynamic location update algorithms. Then we discuss various selective paging strategies. We also present various modeling techniques that have been used for the performance analysis of location update and terminal paging. We conclude by stating a number of open problems that need to be addressed for the deployment of next-generation PCNs     

Adaptive importance sampling for performance evaluation andparameter optimization of communication systems

We present new adaptive importance sampling techniques based on stochastic Newton recursions. Their applicability to the performance evaluation of communication systems is studied. Besides bit-error rate (BER) estimation, the techniques are used for system parameter optimization. Two system models that are analytically tractable are employed to demonstrate the validity of the techniques. As an application to situations that are analytically intractable and numerically intensive, the influence of crosstalk in a wavelength-division multiplexing (WDM) crossconnect is assessed. In order to consider a realistic system model, optimal setting of thresholds in the detector is carried out while estimating error rate performances. Resulting BER estimates indicate that the tolerable crosstalk levels are significantly higher than predicted in the literature. This finding has a strong impact on the design of WDM networks. Power penalties induced by the addition of channels can also be accurately predicted in short run-times