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Universal Personal Communications, 1993. Personal Communications: Gateway to the 21st Century. Conference Record., 2nd International Conference on

Date 12-15 Oct 1993

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  • Narrowband propagation characteristics of 880 MHz and 1922 MHz radio waves in macrocellular environments

    Page(s): 610 - 615 vol.2
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    This paper describes narrowband propagation measurements at 880 MHz and 1922 MHz at four cell sites in the vicinity of Philadelphia, PA, USA. The objective of the measurements was to compare the large cell (macrocellular) propagation characteristics of 880 MHz and 1922 MHz radio waves in heavy-urban, urban, suburban, and semi-rural areas. Investigations include coverage, path loss, and shadowing comparisons, as well as analyses of slow and fast fading. Statistical comparisons include Level Crossing Rate (LCR), Average Duration of Fade (ADF), and Cumulative Distribution Functions (CDFs) of signal envelope fading. View full abstract»

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    Freely Available from IEEE
  • The N=9 frequency plan: A modified technique to enhance C/I performance and capacity

    Page(s): 718 - 722 vol.2
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    This paper presents a modified N=9 frequency plan for OMNI and 60-STSR (60 degree, Sector Transmit and Sector Receive) cell sites. It is based on dividing all the available channels into 9 or multiples of 9 groups. The basic N=9 cell cluster uses an ODD/EVEN channel distribution scheme which forms a 3 × 3 array of nine frequency groups. The proposed plan is free of adjacent channels and enhances channel capacity by a factor of 2.3 in AMPS, 6.9 in TDMA-3 and 13.8 in TDMA-6 View full abstract»

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  • A novel trellis coded modulation system without signal point expansion

    Page(s): 653 - 657 vol.2
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    In conventional trellis coded modulation (TCM), the number of signal points in the constellation is doubled by additional redundant bits. This paper proposes a novel TCM system without signal point expansion which employs 2m kinds of trellis paths depending upon m encoder input bits, instead of 2m+1 kinds of paths of conventional TCM. The number of cosets assigned to trellis paths and total number of signal points can be reduced to half of those in conventional TCM. Therefore, it is possible to implement a coded modulation systems without signal point expansion by additional redundant bits, and the effective bit rate becomes unity. This scheme achieves a considerable coding gain in comparison to the traditional uncoded systems, and to the conventional TCM system. Furthermore, as the proposed scheme needs only half the signal points of conventional TCM, the average power is lower and it is less sensitive to the carrier phase offset View full abstract»

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  • Cell shape for microcellular systems in residential and commercial environments

    Page(s): 723 - 727 vol.2
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    Personal Communication Services (PCS) will make use of low antennas and low radiated power to achieve base station coverage over microcells having radius of about 500 m. For such small cells the configuration of buildings surrounding the base station will have a major influence on the propagation in different directions, and hence on cell shape. This paper presents a theoretical approach to determining cell shape for residential and commercial regions, where the buildings are of a relatively uniform height, and are closely spaced in rows along the streets. Because it is based in theory, the model treats base station antenna height, location, and frequency as input parameters, in addition to area specific descriptors of the buildings, such as average height, location with respect to the streets, and street geometry. As an example, contour plots of signal level have been computed for an area having two story town houses located on a rectangular street grid, and for base station antennas located mid-block, at a street intersection, and in the backyards of the buildings View full abstract»

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  • Performance of orthogonal CDMA codes for quasi-synchronous communication systems

    Page(s): 995 - 999 vol.2
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    In this paper, the performance of quasi-synchronous direct-sequence CDMA communication systems based on different sets of orthogonal codes is investigated. The authors search for sets of sequences that minimize the probability of bit detection error, given that there is imperfect synchronization among the signals. Orthogonal sequences based on the Sylvester-type Hadamard matrices (Walsh functions) are shown to provide a large improvement over the case where an orthogonal set is chosen at random. For these sequences closed form expressions are derived for the average bit error rate. Computer searches indicate that this set of codes has special properties with respect to minimizing the average cross-correlations between the different signals for small errors in chip synchronization. It appears that these codes are optimal. A multi-carrier signalling scheme designed to help synchronize the CDMA signals at the chip level is also discussed View full abstract»

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  • A novel approach to frequency synthesis and modulation using quadratic correlation

    Page(s): 658 - 661 vol.2
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    Due to the severe FM-TDMA constraints imposed in the established and emerging Personal Communication Systems, it is necessary to perform fast frequency channel switching. This feature, together with the modulation characteristic, that requires a bandwidth close to the interchannel switching ratio, make it difficult to merge both modulation and channelization in the same single loop structure. In fact, a PLL synthesizer damping factor has to be so low that it destroys the modulation if no special care is taken. The present paper shows some architecture and analytical studies, in order to obtain joined modulation and channelization, with a single loop synthesizer using a quadratic correlation loop View full abstract»

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  • Mobility models and biased sampling problem

    Page(s): 803 - 807 vol.2
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    In studies of cellular networks, such as the performance analysis of handoff or location update, mobility models for mobile terminals play a very important role. Several mobility models have been proposed in the previous studies, each of them depicts the terminal mobility by a simple method. In this paper, the authors studied Thomas's, Hong's and Guerin's mobility models. They find that Thomas's formula for outgoing terminals can be extended to the other two models. Thus, some system performance information derived from Thomas' model can also be used in the other two models. In the next analysis of a mobility model, the probability density function (PDF) of terminal speeds is a very important condition. For a given PDF for total terminals, a subset of terminals, such as the boundary-crossing terminals of the speed-renewing terminals (if the model requires speed-renewing), may have a different PDF, which follows the "Biased Sampling" formula. The PDF of moving directions at boundaries is also biased. The proposed formulas, boundary conditions and renewal conditions can be used as the basic components for the future studies of cellular systems View full abstract»

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  • Measurements and modelling of a microcellular advanced mobile system

    Page(s): 941 - 944 vol.2
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    The purpose of this paper is to present the results of propagation models for city center microcellular mobile communication systems. The results of the measurements and the proposed models will be used for the Planning Tools for Third Generation Mobile Radio Systems (project PLATON) View full abstract»

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  • Traffic performance of cellular communication systems with heterogeneous call and platform types

    Page(s): 690 - 695 vol.2
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    The proliferation of mobile, portable and personal communication systems will bring a variety of offered services. Practical systems must support different types of calls. These may include voice only, mixed voice and data, high speed data, low speed data, and image transmission. In addition there may be a mixture of platforms (such as persons, autos, and buses) having a range of mobility characteristics. In such environments, the bandwidth and/or resources needed for call sessions will not be identical. As a result, calls will generally encounter different blocking and hand-off constraints. These effects are in addition to differences in blocking and forced (call) termination probabilities that are attributable to differing platform mobilities and (resource) channel quotas View full abstract»

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  • RFICs for reduced size, cost and power consumption in handheld wireless transceivers

    Page(s): 919 - 925 vol.2
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    The high volume potential of existing and proposed wireless Personal Communications Systems in the 800-2500 MHz frequency range presents tremendous challenges and opportunities to designers and suppliers of RFICs. Amplifiers, oscillators, frequency converters and synthesizers are now required to operate from lower supply voltages, consume less current and reduce their physical size while meeting aggressive targets for performance, quality, cost and uniformity. This paper describes Silicon Bipolar and GaAs RFIC process technologies which are particularly well suited to this market. Furthermore, the roles of existing and future RFICs, hybrid modules and discrete devices for a typical RF system architecture in a half-duplex digital radio are discussed. Some key technical constraints that impact the performance of RFIC components at supply voltages of 3V or less are also illustrated in detail View full abstract»

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  • Performance of a UHF multimedia wireless LAN

    Page(s): 771 - 775 vol.2
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    This paper presents the results from simulation and tests of a UHF multimedia wireless Local Area Network (LAN). This wireless LAN supports simultaneous data and voice communications and image transfers. After a brief description of the wireless LAN testbed, the protocol stack used for the experiment and simulation is introduced. The simulation and experimental results on the measured voice quality, delays and throughput for simultaneous image and voice transfers are then presented and discussed. The results are also discussed from the point of view of the maximum number of users in such a network, its geographical spread and the maximum number of simultaneous user sessions View full abstract»

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  • Advanced CDMA scheme for PCS based on interference cancellation

    Page(s): 1000 - 1003 vol.2
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    This paper describes the configuration and characteristics of the advanced CDMA scheme. The scheme realizes the Interference Cancellation (IC) with a Walsh code and a Viterbi decoder using a full soft-decision. The interference signal of other users has been reduced and the Bit Error Rate (BER) performance of this scheme has been improved, bringing the number of simultaneous access users per cell to 64 View full abstract»

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  • Multi carrier modulation for indoor wireless communications

    Page(s): 674 - 678 vol.2
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    This paper discusses Multi Carrier Modulation (MCM) with application to broadband Frequency Selective Fading (FSF) channels. The first part of the paper discusses the capacity of such channels subject to the assumption that the channel bandwidth is much larger than the coherence bandwidth. Under this condition, it is shown that for a given spectral efficiency, in terms of C/W (Bits/S/Hz), the FSF channel requires 2.5dB more power by comparison to the ideal AWGN channel in high Signal to Noise Ratio (SNR). The extra power requirement decreases to less than 2dB for SNR below 10dB. The second part of the paper discusses the performance of a differentially detected MCM system. It is shown that the average Bit Error Rate (BER) performance is at best similar to the performance achievable over flat Rayleigh fading channels if no channel coding is used. Block error rate results are also presented and used in predicting the average performance improvement due to linear block codes View full abstract»

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  • The highly shortened conical helix

    Page(s): 914 - 918 vol.2
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    The highly shortened conical helix antenna is a leaky wave antenna that is inherently small yet displays high directional gain and good return loss, bandwidth, and circular polarization characteristics. As a consequence it can be used in lieu of the microstrip patch antenna, especially within confined spaces and in small arrays. This paper discusses the characteristics and details the effect of various physical variables on the performance of the highly shortened conical helix. Examples of successful designs which have found application in L-Band mobile satellite communications terminals are provided View full abstract»

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  • Traffic forwarding by radio relay in personal communication networks

    Page(s): 808 - 813 vol.2
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    Base stations for personal wireless communications are ordinarily connected to switching facilities through a wired network. This paper examines applications for radio relay of traffic among base stations, particularly as a protective fallback or startup alternative to wired base station networks. We presume that a portion of the PCN access channels are used instead for base station-to-base station links. We show, for a simple serving area model, that roughly fifteen percent of the traffic capacity of a wired base station network can be salvaged through radio relay if the wired network fails View full abstract»

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  • Simulation of radio wave propagation in urban microcellular environments

    Page(s): 595 - 599 vol.2
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    A powerful and versatile software was developed to investigate the radio wave propagation in urban microcellular environments. The two dimensional layout of the buildings and streets is given to the software in terms of segments which define the building walls. The propagation through and over the buildings is neglected. After having chosen the location of a transmitter, the various rays which reach a receiver are determined and the received wave field is computed. Currently, the rays considered include the effects of specular reflections and diffraction. The results show the limitations of models based only on specular reflections. The software is used to investigate various combinations of reflected and diffracted rays in several building layouts and transmitter locations View full abstract»

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  • FPLMTS satellite component: Service roles

    Page(s): 849 - 853 vol.2
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    Recent advances in satellite techniques have allowed FPLMTS to incorporate a personal pocket satellite terminal into its configuration. The forms of FPLMTS, both terrestrial and satellite, are described and analysed in network and service terms. The latter analysis is used to show how the hybrid terrestrial/satellite pocket terminal provides a new role for the satellite mode of FPLMTS which will act as an enabler, or pathfinder, for subsequent exploitation by the terrestrial mode. Outline discussion is given on the implications of this for the technical design of FPLMTS and the commercial/regulatory arrangements necessary for its running View full abstract»

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  • Integration of micro and macro cellular networks for future land mobile communications

    Page(s): 737 - 742 vol.2
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    This paper proposes a system of integrating micro and macrocell for future land mobile communications which allows the user to enjoy mobile communications services, regardless of terminal speed, using one terminal. Current and developing digital land mobile communications systems are classified into two categories according to their differences in cell size, operating environments, service requirements and terminal speeds. One is a microcell system offering cordless telephone services for the user moving at low speeds and the other is a macrocell system offering vehicle telephone services for the user moving at high speeds. In order to access these two systems, the user needs to prepare two different terminals and use the appropriate one according to the operating environment, service requirements and terminal speed. This paper proposes a land mobile communication systems in which the user can place a call without any of the inconvenience described above. This system consists of multi-layered macrocells each of which is composed of a number of microcells. This paper presents the detailed structure of this system and evaluates its channel capacity based on computer simulation results View full abstract»

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  • Influence of antenna radiation patterns on MM-wave indoor radio channels

    Page(s): 631 - 635 vol.2
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    In millimeter-wave indoor radio systems the radiation patterns of the applied antennas at the remote and base station have considerable impact on received power and channel dispersion and therefore on the performance of indoor radio communication systems. This influence is examined by simulating the high frequency propagation behavior in a typical indoor environment by using a propagation model according to Geometrical Optics. First, the accuracy of this propagation model is tested by comparing initial simulation results with measurement data obtained from a large scale measurement campaign which has been carried out in various buildings of the Eindhoven University of Technology. Next, sectoral horn antennas as well as biconical horn antennas are considered in different setups and the dependence of normalised received power and RMS delay spread on beam directivity, pointing error and wall reflectivity under both line-of-sight and non-line-of-sight conditions is determined View full abstract»

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  • Traffic management strategies in an integrated satellite/cellular network for mobile services

    Page(s): 839 - 843 vol.2
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    After a survey on the historical reasons for the current configuration of incompatible terrestrial and satellite mobile networks, the paper compares the classical traffic channel assignment in cellular networks with a more enhanced strategy, suitable to an integrated configuration that exploits the concept of sharing, peculiar to satellite resources. The impact on network management and planning is pointed out and the results of a simulation model allow a quantitative assessment. The paper also illustrates how the corresponding procedures respect the terrestrial cellular network protocols View full abstract»

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  • Characterization of time-varying cellular signals in buildings: Application to packet retry schemes

    Page(s): 945 - 949 vol.2
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    In this paper, a characterization of the temporal variation of cellular signals at fixed locations inside urban buildings is presented through measurements and analysis. The signals fluctuate on several time scales due to the varying presence and number of scatterers in the environment. The measurement data are used to examine the viability of network performance enhancement techniques e.g., packet retry, and the improvement from such techniques is examined as a function of the various packet and network parameters which can be varied, including packet length and number of retries View full abstract»

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  • Personal communications initiatives in Canada

    Page(s): 533 - 538 vol.2
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    This paper describes the facilitative role undertaken by the Canadian federal Department of Communications in respect of the regulatory and licensing process for the 900 MHz digital cordless telephone service that is being implemented in Canada. It recounts the progress that has been made to date and outlines the steps that will be taken before the service becomes fully operational. The paper also considers possible future developments that might see the introduction of personal communications services in the 1.8 GHz range and the establishment of a common Canada-U.S. digital cordless telephone service View full abstract»

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  • Multiplexing protocol for the WACS system broadcast channel

    Page(s): 580 - 584 vol.2
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    A protocol is described which allows a wireless access communication system (WACS) to dynamically allocate bandwidth on its system-wide broadcast radio channel among the alerting, system information, and priority access request subchannels. These subchannels each have different requirements with respect to the message length and position within the framing structure; the described protocol meets each of their requirements. The protocol efficiently accommodates a wide range of alerting traffic levels, and provides for efficient downloading of system information to subscriber units by using excess capacity when alerting traffic is low. It has error detection capabilities above that provided by the radio channel alone, and is easily extendible to accommodate other services such as paging and low bandwidth broadcast messaging. This work is targeted towards understanding the implications to local exchange networks of wireless system alternatives that could provide access to those networks View full abstract»

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