Personal Communication Services Research Articles

User's Profile Replication Tree and On Demand Replica Update in Wireless Communication

Replication strategy is mostly useful for replicating the called mobile user's profile at selected locations where some caller mobile users have higher calling rate. It plays important role in personal communication services (PCS) in order to reduce call setup cost and call setup time. In prior replication schemes, replicated sites (visitor location registers) have no inter relationship. We have proposed a novel and innovative replication tree which is buildup from replicated VLRs (visitor location registers). VLRs are replicated based on effective replication probability of caller mobile user. Home location register (HLR) keeps update replica at root VLR in the replication tree and root VLR forwards update replica to a VLR in the replication tree on demand. The main objective of the proposed scheme is to reduce call setup time and call setup cost by enabling replication of called mobile user's location profile at certain visitor location registers (VLRs) where caller mobile user roams. We have presented analytical modeling which shows that setting inter-relationship among the replicated sites helps in further reducing the call setup cost.

A compact dual-band RF front-end and board design for vehicular platforms

Modern vehicular platforms include several wireless systems that provide navigation, entertainment and road side assistance, among other services. These systems operate at different frequency bands and thus careful system-level design should be followed to minimise the interference between them. In this study, we present a compact dual-band RF front-end module for global positioning system (GPS) operating in the L1-band (1574.42–1576.42 MHz) and satellite digital audio radio system (SDARS) operating in the S-band (2320–2345 MHz). The module provides more than 26 dB of measured gain in both bands and low noise figure values of 0.9 and 1.2 dB in SDARS and GPS bands, respectively. The front-end has interference suppression capability from the advanced mobile phone system and personal communication service cellular bands. The module is designed on a low-cost FR-4 substrate material and occupies a small size of 62 × 29 × 1.3 mm3. It dissipates 235 mW in the SDARS section and 100 mW in the GPS section. Three prototypes have been built to verify a repeatable performance.

Design and implementation for location-based integrated GIS application provisioning platform

Mobile geographic information system (GIS) solutions and location-based services can be considered as the most rapid expanded field of the mobile communications domain that will play a major role in the future. The combination of position-fixing mechanisms with location and geographically dependent information can offer truly individualised personal communication services through the mobile phone or other type of devices. This paper aims to design, specify and implement an integrated GIS application provision platform, and focuses on the design of integrated service process language and geographic service description language as well as gives the implementation for the integrated GIS service execution container based on location-based service using service component architecture, which will cater for the full range of issues concerning the provision of location-based GIS value-added services. This platform will enable the specification, creation and deployment of such services, which can offer truly individualised personal communication services through mobile phone, and also make performance measurement and analysis. Finally, we give the conclusions and the plan for future work. Copyright © 2012 John Wiley & Sons, Ltd.

Electrically small tunable antennas using split ring resonators

Presented are tunable electrically small antennas composed of split ring resonators (SRRs), which are used to reduce antenna size. To control the resonance frequency, a lumped inductor is inserted between the SRRs and the ground. The proposed antenna operates within Korean personal communication services (PCS) frequency bands of 1750–1870 MHz, and the size of the antenna is 1/33λ0×1/33λ0 with an operating frequency of 1800 MHz. In spite of its small size, the radiation efficiency and −10 dB bandwidth were measured as 82% and 2.4%, respectively. Good agreement between the predicted and measured results ensures the validity of the design method to provide a frequency adjustment using lumped inductors in small SRR antennas.

An active tri-band (AMPS/PCS/GPS) antenna with enhanced cellular-to-GPS isolation for automotive applications

The design and performance of an active tri-band antenna for automotive applications that includes the global positioning system (GPS), analog mobile phone service (AMPS), and personal communication service (PCS) is presented. For automotive emergency applications, the close proximity of the GPS and cellular antenna elements demands stringent isolation requirements on the GPS low noise amplifier (LNA) design to prevent interference to GPS during cellular transmissions. The GPS low-noise amplifier designed in this letter exhibited a power gain of 26.4 dB, an out of band rejection in excess of 31 dB at +/-50 MHz around the center frequency, a noise figure of 1.5 dB, a 1dB power compression of 9.7 dBm, isolation over the AMPS band in excess of 62 dB, isolation over the PCS band in excess of 48 dB, an input 3rd order intercept of −6.5 dBm and an output 3rd order intercept of 20.6 dBm while operating at 5 volts with a current draw of 20mA. In addition, the antenna patterns measured on a ground plane are presented for the active GPS antenna, AMPS passive antenna and the PCS passive antenna. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26117

The Story of the EU and the Happily Roaming Consumers Case No. C58/08, Vodafone Ltd, et al. v. Secretary of State for Business, Enterprise and Regulatory Reform

Once upon a time, there were roaming charges and disgruntled consumers. As a result of a preliminary ruling1 concerning the validity of a legislative measure2 on roaming on public mobile telephone networks within the European Union (hereinafter 'Union'), the regulation of roaming charges may have been changed forever. The reference had been made in proceedings between operators of public mobile telephone networks, including Vodafone Ltd, Telefónica O2 Europe plc, T-Mobile International AG, and Orange Personal Communications Services Ltd, and the Secretary of State for Business, Enterprise and Regulatory Reform. The roaming regulation aimed to cap the wholesale and retail charges mobile operators could charge for the provision of roaming services on public mobile networks for voice calls between Member States. The validity of the roaming regulation was challenged on three grounds, namely that its legal basis was inadequate, that it infringed the principle of proportionality, and that it offended the principle of subsidiarity. It was left to the Court of Justice to seal the fate of the roaming consumers.

Design of Optimized Multilayer PIFA With the EBG Structure for SAR Reduction in Mobile Applications

This paper proposes an optimized multilayer planar inverted-F antenna (PIFA) with an electromagnetic bandgap (EBG) at personal communication services band for specific absorption rate (SAR) reduction. The EBG structure, which has bandgap capability and acts as a perfect magnetic conductor surface, can suppress surface waves and reduce undesired radiation from an antenna. Thus, the EBG structure is capable of preventing electromagnetic (EM) fields being emitted in the direction of the human head. To optimize the multilayer PIFA structure for SAR reduction, the EBG structure between the printed circuit board and antenna layer is designed first. Second, a parameter study about the EBG cell numbers, height, and location of the PIFA with the EBG structure is performed. Finally, the optimized multilayer PIFA with the EBG is investigated and the S-parameters, radiation patterns, total radiated power values, and SAR values are presented. The results demonstrate the reduction of SAR values while maintaining the antenna performance. Thus, the human head can be protected from hazardous EM fields using the EBG structure.

Conditionally Optimal Minimum-Delay Scheduling for Bursty Traffic Over Fading Channels

Next-generation wireless networks for personal communication services should be designed to transfer delay-sensitive bursty-traffic flows over energy-limited buffer-equipped faded connections. In this application scenario, a still-open question concerns the closed-form design of scheduling policies minimizing the average transfer delay under constraints on both average and peak energies. Since, in this paper, both queue and link states may assume finite, countable infinite, or even uncountable infinite values, we cannot resort to dynamic programming to solve the aforementioned minimization problem. The key point of the (somewhat) novel approach that we follow consists of the minimization (on a per-step basis) of the queue length averaged over the fading statistics and conditioned on the queue occupancy at the previous step when two energy constraints are considered. The first one is on the allowed peak energy, and the second one is on the available average energy conditioned on the current queue occupancy. The resulting optimal scheduler operates cross layer, meaning that it allocates step-by-step energy on the basis of both current queue and link states. We prove that, under the considered energy constraints, the scheduler retains two optimality properties. First, its stability region is the maximal admissible one. Second, the scheduler also minimizes the unconditional average queue length. The numerical tests that have been carried out corroborate these optimality properties and give insight about scheduler performance under heavy-tailed distributed input traffic, such as that generated by variable-bit-rate (VBR) media encoders.

Multiband Meandered Monopole Antenna for Mobile Applications

A multiband meandered monopole antenna is proposed for digital video broadcasting handheld (DVB-H), global positioning system, personal communications service, wireless broadband (Wibro), and wireless local area network (WLAN) applications. The proposed antenna consists of a meandered line, a shorted length strip line, and a conductor strip between a meandered line and a microstrip feed line. By tuning a short strip and a conductor, a multiband impedance matching is achieved. The proposed antenna has an omnidirectional radiation and yields an antenna gain of greater than −3 dBi in the DVB-H band and 4.5 dBi in the Wibro and WLAN bands. Details of the proposed antenna design and experimental results are presented.

Impact of the Busy-Line Effect on the Interservice Time Distribution and Modeling of Portable Movements in PCS Networks

The distribution of the interservice time, which is the interval between the end of a call served and the start of the succedent call served by a portable, is a crucial parameter for modeling and cost analysis for location management in personal communication service (PCS) networks. The interservice time differs from the interarrival time due to the busy-line effect. However, in the literature, most of the cost analyses for location management were carried out by ignoring the busy-line effect, i.e., by identifying the interservice time with the interarrival time, because, so far, there is no analytical result for the interservice time distribution considering the busy-line effect. In this paper, we develop an analytical model to investigate the busy-line effect on the interservice time distribution. Closed-form analytical formulas for the interservice time are derived. A numerical study shows that a big discrepancy exists between the interarrival time and the interservice time. Based on the analytical results for the interservice time, the impact of the busy-line effect on modeling of portable movements in PCS networks is further evaluated. An analytical result for the distribution of the number of cell-boundary crossings during the interservice time is obtained. Both analytical results and numerical examples indicate that the busy-line effect has influence on the distribution of the number of cell-boundary crossings during the interservice time. Therefore, cost analysis for location management without considering the busy-line effect may lead to unreliable results. The results presented in this paper pave the way for modeling location management and portable movements in PCS networks.

A new framework for performance analysis of emerging personalized communication services

The emergence of new communication services with anytime access to content, such as personalized time-shifted television (TV) programming, requires a combination of unicast and multicast content distribution, and possibly caching, for efficient support of user requests. We present a general framework for the analysis and design of such delivery systems that takes into account network resource constraints, time constraints, content features, user preferences, and service availability requirements. In this framework, the time-shifted content delivery system is modeled via the well-known probabilistic urn model with novel occupancy probabilities reflecting actual content popularity. New approximations to occupancy distributions are derived which enable fast computation of various system performance measures, such as likelihood of access to requested programs. We illustrate the utility of this analytical framework via a prototypical scenario in emerging personalized wireless video services.

Personal multimedia services over a common home and access networking environment

This article presents a new end-to-end architecture model that will enable the deployment of a plethora of different multimedia services from diverse suppliers competitively coexisting over a common access and home networking environment. The model is focused on personal multimedia communication services and terminals. The proposed model is a segmentation of the end-to-end multimedia chain into several business segments. The interfaces among segments and functional entities inside each segment are identified and defined in the work. In order to study the impact level of the results achieved, a comparison with the approximation to NGN provided by current standardization bodies in the field (3GPP and TISPAN) is also included in the article. This comparison highlights the advantages of using this model as a solution to offer PMC services.

Compact PIFA for Mobile Terminals Supporting Multiple Cellular and Non-Cellular Standards

A novel multiband planar inverted-F antenna (PIFA) covering ten frequency bands has been proposed for personal wireless communications terminals. The design is based on the combination of various techniques that are used for designing multiband/broadband antennas. We used a shorted parasitic patch efficiently coupled to the driven patch, a quarter-wave resonator connected to the feed strip in parallel with the main patch, and four slits in the main radiator to excite various current modes in the antenna structure. The antenna is designed within a volume of 4.0 times 2.0 times 0.8 cm3 and it can be used to serve the following wireless communication systems: Global System for Mobile Communications (GSM-900), Digital Communications System (DCS), Personal Communication Service (PCS), Universal Mobile Telecommunications System (UMTS), WiBro at 2.35 GHz, Bluetooth, Satellite-Digital Multimedia Broadcasting (SDM-B) at 2.65 GHz, WiMAX at 3.5 GHz, and the two bands (5.15-5.35 GHz and 5.725-5.875 GHz) for the wireless Local Area Network (WLAN) standards. A prototype antenna was fabricated and tested for input reflection coefficient and radiation performances. The measured and simulated results have been presented and discussed. Important geometrical parameters determining the multiband performances of the antenna have been explained in the paper.

Surface Acoustic Wave Duplexer Composed of SiO2/Cu Electrode/LiNbO3 Structure Having Convex and Concave Portions

The transition bandwidth of 20 MHz between the transmission (Tx: 1850–1910 MHz) and the receiving (Rx: 1930–1990 MHz) bands of personal communication service (PCS) handy phones in the United States (US) is very narrow compared with those of other systems. We have already realized surface acoustic wave (SAW) duplexers with sizes of 5.0×5.0×1.7 and 3.0×2.5×1.2 mm3 for PCS handy phones in the US with an excellent temperature coefficient of frequency (TCF) by using a shear horizontal (SH) wave on a flattened SiO2/Cu electrode/36–48° YX-LiTaO3 structure and a Rayleigh wave on a SiO2/Cu electrode/120–128° YX-LiNbO3 structure. Although the surface of the above-mentioned structures is flattened SiO2, we have also studied the shape of the SiO2 surface. As a result, in addition to increasing the stop-band width, which corresponds to the reflection coefficient, the TCF and power durability have been improved by forming convex portions on the surface of the SiO2 over the interdigital transducer (IDT) gaps.

Location update cost of distance-based scheme for PCS networks with CTRW model

This letter concerns the optimization of the dynamic location-update area (LA) for the per-user distance-based scheme in personal communication service (PCS) networks. We have two main contributions: (1) under the general and popular one-dimensional (1-D) continuous-time random walk (CTRW) mobility model, we propose a novel framework to analyze the location update cost; (2) with this framework, we investigate the impact of call arrivals and the initial position of the mobile terminal (MT) on the position of the LA, which was neglected by previous work. Simulation shows that our theoretical model is very accurate.

Novel dual‐band Fabry‐Pérot cavity antenna with low‐frequency separation ratio

AbstractA new dual‐band Fabry‐Pérot cavity (FPC) antenna consisting of a partially reflective surface (PRS) superstrate and an artificial magnetic conductor (AMC) substrate is proposed for low‐frequency separation ratio. The main purpose of this antenna is to introduce more than −20 dB rejection band in between two very closely located service bands (up‐ and downlink bands) of Korean personal communication service (PCS). Additionally, with the help of metallic side walls enclosing all the openings between the superstrate and the substrate, we can obtain more than 10 dB realized gain throughout the two operation bands. Moreover, the selective behavior of the gain near the pass bands is highly increased and the back radiation is reduced remarkably. The effect of attaching the superstrate to the side walls on antenna performance is also analyzed. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1869–1872, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24509

Design and analysis of a TDMA call assignment scheme for cellular networks

In this paper, we introduce a TDMA channel assignment scheme suitable for personal communication services (PCS) networks. This scheme, called Handoff TDMA (H-TDMA), assumes three type of traffic: new voice calls, handoff voice calls and data packets, all competing for a finite number of channels. In the present scheme, priority is given to handoff voice calls over data calls, while a number of channels is exclusively dedicated to data calls. The performance of the scheme is analyzed using a Markov chain model. We evaluate major performance metrics such as forced termination probability, blocking probability, and data packets loss probability. The analytical results obtained are validated by simulation and good agreement is obtained.

Modeling and Analysis of Mobile Terminal Power on/off-State Management Considering User Behavior

Mobile terminals (MTs) in real personal communication service (PCS) environments are turned off due to limited battery lifetime, avoidance of unwanted incoming calls, and undesirable subscriber behaviors. Since the probability that an MT is in the off-state may be significant, MT power on/off-state transition behavior and the effect of state management on mobile communication networks require analysis. Two MT power on/off-state management schemes are introduced based on the level of location registers (LRs) for managing MT state information. Effects are investigated from the aspects of a radio interface, a network, and a database based on the modeling of the state transition behavior of an MT for varying values of MT and mobile communication network parameters. These values include the MT on/off duration and the incoming call arrival rate. Although additional database processing overhead exists, the management of MT power on/off-states provides a significant reduction in overhead from the aspects of the radio interface and the network. There is a tradeoff between the two management schemes as the MT on/off ratio varies.

Modeling and Cost Analysis of Movement-Based Location Management for PCS Networks With HLR/VLR Architecture, General Location Area and Cell Residence Time Distributions

Location management plays a central role in guaranteeing the effective operation of personal communication service (PCS) networks. In current PCS networks, a two-tier system of home location register (HLR) and visitor location register (VLR) databases is commonly used for location management. To improve the performance of PCS networks, several dynamic location management schemes have been proposed. Among the existing dynamic schemes, the movement-based location management may be the most practical due to its effectiveness and easy implementation under the framework of current PCS networks. To implement location management in PCS networks, cost analysis is a crucial aspect. However, most of the existing cost analyses for the movement-based scheme are too simple and not available for PCS networks with the HLR/VLR architecture. One reason for this is the complexity and the difficulty associated with the problem. Li et al. and Rodriguez-Dagnino et al. challenged this task by considering the HLR/VLR architecture. However, the cost analysis developed by Li et al. was carried out under the assumption that the cell and location area (LA) residence times are exponentially distributed. Rodriguez-Dagnino et al. furthered Li et al.'s work by assuming that the LA residence time follows a hyperexponential distribution and that the cell residence time is generally distributed. However, Li et al. and Rodriguez-Dagnino et al. failed to consider VLR location updates that are caused by terminal movements between LAs. In this paper, we relax the restrictions imposed on the distributions of the cell and LA residence times and propose an analytical model to study the movement-based scheme with HLR/VLR architecture. The issue of VLR location updates that are caused by movements between LAs is addressed carefully and successfully. Analytical formulas for the costs of HLR and VLR location updates are derived using a unified approach. Numerical study suggests that the total cost is a convex function of the movement threshold and is sensitive to the variances of the cell and LA residence times. The result presented in this paper can serve as a guideline for the system design and the implementation of the movement-based scheme for PCS networks.

Compact Spatial Triple-Band-Stop Filter for Cellular/PCS/IMT-2000 Systems

We propose a novel spatial multi-band-stop filter using modified multiple loop array elements to block electromagnetic waves or signals of mobile phones in public facilities. It operates at the following frequency bands: Korean cellular (824 MHz to 894 MHz), Personal Communication Service (PCS) (1.75 GHz to 1.87 GHz), and IMT-2000 (1.92 GHz to 2.17 GHz). Two frequency selective surfaces with modified multiple-loop elements are printed on the top and bottom of a pair-glass pane, which is a pair of glass panes with an air gap between them. A modified multiple-loop element with a meander line is used to make the size of the filter compact. The simulated and measured results show good agreement, which confirms the usefulness of the proposed tri- band spatial filter.