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Personal Wireless Communication, 1999 IEEE International Conference on

Date 17-19 Feb. 1999

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  • 1999 IEEE International Conference on Personal Wireless Communications (Cat. No.99TH8366)

    Publication Year: 1999
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    Freely Available from IEEE
  • Index of authors

    Publication Year: 1999 , Page(s): 506 - 507
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    Freely Available from IEEE
  • Sequential decoding of GMSK in a Rayleigh fading channel

    Publication Year: 1999 , Page(s): 481 - 485
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    By using sequential decoding techniques to detect the binary CPM signals, we develop a single stack algorithm detector when perfect channel estimation and coherent demodulation are assumed. The performance of sequential decoding of Gaussian minimum shift keying (GMSK) is evaluated in a frequency-selective fading channel. The fading channel is modeled as a two-ray Rayleigh fading channel. The performance is evaluated by computer simulation. Rate (BER) performance and computational complexity are compared with the conventional Viterbi algorithm View full abstract»

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  • Broadcasting in large unicyclic communication networks

    Publication Year: 1999 , Page(s): 19 - 23
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    Broadcasting is the process of information dissemination in communication networks (modelled as graphs) whereby a message originating at one vertex becomes known to all members given that at each unit of time a vertex can pass the message to at most one of its neighbours. A broadcast graph on n vertices is a network in which messages can be broadcast in the minimum possible (=[log2n]) number of steps regardless of the originator. In “Broadcasting in General Networks II: Unicyclic Graphs”, (Shastri, 1998) we continued our work initiated in, “Broadcasting in General Networks I: Trees”, (Shastri, 1995) by studying the problem of broadcasting in unicyclic graphs (connected graphs on n vertices having exactly n edges) as a second step towards studying broadcasting in general graphs, as opposed to the much studied problem of constructing broadcast graphs having the smallest number of edges. Unicyclic graphs of small order with the best possible broadcast time were constructed. In this paper, some of these constructions are generalised to obtain asymptotic bounds for large n and to obtain unicyclic graphs with best broadcast time of higher orders. The results make comparison with those obtained for trees in the above paper View full abstract»

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  • Performance issues in two-tier cellular networks

    Publication Year: 1999 , Page(s): 374 - 378
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    A two-tier cellular network consists of a number of small microcells overlayed by larger macro (umbrella) cells. Such a network can support improved quality of service (QoS), higher capacity, and larger coverage area than existing networks. In this work, we study the channel allocation problem for a two-tier cellular network for two types of calls (voice and data), under different degrees of handoff overheads. We also compare the impact of two typical call admission algorithms on network performance. We observe that, when minimal handoff overheads are present, allocating more channels to the microcell layer results in lower blocking and dropout probabilities. Second, there is an optimal orthogonal assignment of channels between the two tiers that minimizes the blocking and the dropout probabilities, when handoff overheads are significant, suggesting a hierarchical approach for designing handoff controllers. Finally, on comparing two typical call admission algorithms, we show that an algorithm that treats all calls identically performs better than an algorithm which tries to assign calls to different tiers based on their holding times View full abstract»

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  • Third generation (3G) mobile communications systems

    Publication Year: 1999 , Page(s): 39 - 43
    Cited by:  Papers (4)  |  Patents (4)
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    The International Telecommunication Union (ITU) began studies on globalization of personal communications in 1986 and identified long term spectrum needs for future “third generation” mobile wireless telecommunications systems. These 3G mobile telecommunications systems are expected to provide worldwide access and global roaming for a wide range of services. This paper describes the proposed 3G air interfaces of Europe, Japan, and North America. This paper highlights ETSI activities in the 3G arena and provides a brief description of the FRAMES (future radio wideband multiple access) multiple access (FMA) mode 1 and mode 2 air interfaces. Evolution of GSM and North American TDMA (TIA-IS-136) to wide-band code division multiple access (W-CDMA) via the EDGE system is also presented, as well as a discussion on industry trends View full abstract»

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  • Multi-spot diversity using OFDM for 60 GHz indoor wireless LAN

    Publication Year: 1999 , Page(s): 476 - 480
    Cited by:  Papers (3)
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    To realize high data rate wireless communication systems, much attention is being paid to millimeter-wave frequencies due to large bandwidth availability and cell planning flexibility. A directive antenna at the terminal side has been considered efficient both to suppress multipath delay and to compensate large path loss. However when the direct path is blocked by obstructions such as human bodies, the performance will be degraded seriously with a directive antenna. In the 60 GHz band, this shadowing problem has been considered as a severe problem to overcome. Therefore, multi-spot diversity is suggested as anti-shadowing scheme. In multi-spot diversity, multiple base stations (BS) transmit an identical information using an identical carrier frequency and a remote terminal (RT) composes the signals from multiple BS with OFDM modulation. This system realized by OFDM can be considered as a single frequency network (SFN) applied for indoor communications. We analyze theoretically the BER performance as a function of RT position using a simple three-dimensional ray tracing model with up to two reflections in an empty hypothetical room. We show the validity of the proposed system with multiple BS compared to that with a single BS View full abstract»

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  • Adaptive window random access algorithm with sequential detection capability for the capture environment

    Publication Year: 1999 , Page(s): 150 - 154
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    We propose an adaptive random access algorithm for mobile environments with capture. The algorithm has a dynamic window size which is updated according to the traffic intensity. The packet arrival rate is tracked by employing sequential detection procedures. Simulations indicate that changing the window size adaptively reduces the average delay under heavy load conditions View full abstract»

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  • Performance evaluation method of cellular networks with retrial

    Publication Year: 1999 , Page(s): 389 - 393
    Cited by:  Papers (1)
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    In cellular mobile communication networks, a proper modeling of call behavior is essential for network planning. Due to the increase of calls and network complexity, the retrial phenomenon may have a significant impact on the network performance. We focus on the effect of the call retrial phenomenon in a cellular mobile network. We formulate the dynamics of each cell as a three-dimensional Markov chain, and from which we approximately construct a one-dimensional Markov chain by aggregating auxiliary states to obtain numerically feasible formulas for performance measures. In numerical experiments, we show the analytical results are fairly accurate by comparing simulation results. We come to the conclusion that the proposed performance evaluation method is useful for cellular network planning View full abstract»

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  • Performance analysis of multimedia-capable wireless networks based on realistic traffic models

    Publication Year: 1999 , Page(s): 384 - 388
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    Two hybrid (reservation/random) medium access control protocols, which are based on code division multiple access are analyzed in the presence of multimedia traffic. The protocols contain a multi-priority mechanism. The priority mechanism is implemented and controlled explicitly by the user, with minimal involvement from the network. The performance analysis makes use of realistic traffic models View full abstract»

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  • Effect of azimuth angle probability distribution on interference between mobile satellite gateway station and terrestrial radio-relay link

    Publication Year: 1999 , Page(s): 130 - 134
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    MSS-feeder links and terrestrial radio-relay links will share the same spectrum of bandwidth. This requires proper and strict regulations for coordinating these services. The azimuth angle probability distribution of the MSS-gateway station antenna plays a significant role in the interference scenario between the gateway station and terrestrial radio-relay link. This paper shows that the probability distribution of azimuth angle is not equally likely as was suggested in some previous studies, but has stronger likelihood in certain directions, usually in the vicinity of inclination angle. The carrier-to-interference ratio shows a strong dependence on this unequal distribution. The planning of the gateway station should take this effect into consideration whenever terrestrial radio-relay links are situated in the nearby area View full abstract»

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  • ACTS FRAMES project towards IMT-2000/UMTS

    Publication Year: 1999 , Page(s): 44 - 49
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    Market expectations show an increasing demand for a wide range of services from voice, low up to high and advanced data rate services as mobile multimedia. This leads to technical requirements on third generation mobile radio systems (IMT-2000 in ITU and UMTS in ETSI in Europe), which are currently standardized worldwide. Circuit and packet oriented services will be supported. These systems will be operated in all radio environments to provide service to anyone, anytime and anywhere. In Europe the European Commission is partly funding research activities in the ACTS framework related to third generation systems. The ACTS FRAMES project has developed a spectrum efficient radio interface proposal for UMTS/IMT-2000. This paper briefly describes the original technical approach of the FRAMES project and the international standardization activities. Based on the decision of ETSI SMG on the UTRA (UMTS terrestrial radio access) radio concept FRAMES is investigating the UTRA radio interface for further improvement. The evaluation for the European contribution to the ITU for IMT-2000 was supported by FRAMES. The paper focuses on the UTRA concept and its performance View full abstract»

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  • Comparison of a logarithmic and a linear indoor lift car propagation model

    Publication Year: 1999 , Page(s): 115 - 120
    Cited by:  Papers (5)
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    In indoor cellular coverage planning, the lift shaft and the associated lift car create one of the most difficult propagation environments. In this paper the radiowave propagation in such an environment was studied and new empirical propagation models were introduced. The new models were adjusted by using multiple linear regression to the results of the measurements performed at 900 MHz and at 1800 MHz. The calculated RMS error for the new logarithmic empty lift car model was 2.15 dB and for its extension with persons in the lift car it was 2.02 dB. The results for the corresponding new linear models were 2.94 dB and 2.56 dB. These results combined with the new information of the lift car attenuation are valuable progressions concerning indoor radio network planning and radiowave propagation knowledge in a lift car View full abstract»

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  • A low-deviation digital modulation scheme for mobile communication

    Publication Year: 1999 , Page(s): 193 - 197
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    This paper proposes a modulation scheme that can be applied to severely bandlimited channels such as land-mobile and satellite-mobile radio channels. A simple demodulation scheme is discussed and its BER performance analysis in AWGN channels is carried out. The spectral characteristics are analysed through computer simulation and its error performance are tested for different values of Eb/N0 View full abstract»

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  • Revenue-based call admission control for wireless cellular networks

    Publication Year: 1999 , Page(s): 486 - 490
    Cited by:  Papers (2)
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    Call admission control (CAC) schemes in wireless cellular networks attempt to reduce call dropping probability possibly at the expense of increased call blocking probability. We propose using channel reassignments in a controlled manner to minimize call dropping while maintaining high spectrum utilization. Guard channels are used to control the number of reassignments. The number of guard channels is dynamically determined using reassignment frequency as feedback. A simple scheme that attempts to maintain the number of reassignments under a specified target is described. A revenue-based CAC scheme is then presented which attempts to maximize income by balancing the penalty for reassignments against the reward for serviced calls. Simulation results confirm and validate the ideas discussed View full abstract»

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  • An analysis of the weaknesses of the MBE coding scheme

    Publication Year: 1999 , Page(s): 419 - 422
    Cited by:  Papers (1)  |  Patents (2)
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    This paper explores the deficiencies in the multiband-excitation (MBE) model (proposed by Griffin and Lim (1988) for very-low-bitrate speech coding, and incorporated in the INMARSAT-M standard (1991)) that restricts its application in commercial telephone and mobile applications. The pitch frequency has been found to be the most crucial parameter in the MBE scenario. The errors occurring in the estimation of this parameter get reflected in the estimation of other parameters such as voiced/unvoiced decision and the spectral shape, since the estimation techniques of these parameters implicitly assume accurate knowledge of the pitch frequency for the spectral harmonic matching techniques they employ. Thus the output quality of 8 kHz-sampled speech suffers from a set of audible distortions which result in the degradation of the decoded speech quality. This paper is an attempt to analyse the weaknesses of this coding scheme under telephone-channel conditions View full abstract»

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  • Impact of random user motion on locating subscribers in mobile networks

    Publication Year: 1999 , Page(s): 491 - 495
    Cited by:  Papers (1)
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    The impact of random user motion on intelligent paging schemes is examined and quantified. It is shown that, depending on the size of the location area (LA), the random user motion can increase the cost of locating subscribers in mobile networks substantially View full abstract»

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  • A MINBLOCK approach for resource allocation in wireless networks supporting soft handover

    Publication Year: 1999 , Page(s): 326 - 330
    Cited by:  Papers (1)
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    In this paper we define a call admission control (CAC) strategy, based on the MINBLOCK problem for wireless networks using soft-handover. According to this approach, the call admission controller, decides whether to accept new-calls or not, respecting a hard constraint over the handover drop probability and a hard constraint over the admission waiting time of the handover requests, with the objective of minimizing the mean waiting time for the new-call admission requests. An analytical Markov-based model is proposed to achieve the solution of this problem, that is, to calculate the parameters of the admission controller View full abstract»

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  • Audio coding using parametric piecewise modeling

    Publication Year: 1999 , Page(s): 414 - 418
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    We study the application of parametric piecewise modeling (PPM), a novel coding technique, for audio coding. PPM is based on either the polynomial, Bezier or Chebyshev parametric representation. It has already been proposed for curve and surface modeling use in computer graphics and has been recently proposed for source and channel coding. PPM speeds up the process of generating graphics, has increased compression capability and to a certain extent can predict missing parts of the signal. Results show that high compression of audio signals is achieved using PPM. Further we can see that error correction, to a certain extent, can be achieved using PPM due to its prediction capabilities View full abstract»

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  • Peak-to-average power ratio reduction in multicarrier communication systems

    Publication Year: 1999 , Page(s): 204 - 206
    Cited by:  Papers (2)
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    The demand for high data rates has been continuously increasing in wireless applications, with requirements such as support for multimedia applications. Multicarrier modulation techniques have been proposed for achieving high bit rate transmission in severe multipath and fading channels. This paper presents two peak-to-average power ratio (PAR) reduction techniques for multicarrier communication systems. The advantage of the methods is that they are transparent to the receiver and no bandwidth is lost while performing PAR reduction. Simulation studies are presented for the two proposed techniques in order to demonstrate their efficacy View full abstract»

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  • Multi-carrier DS-CDMA using frequency spread coding

    Publication Year: 1999 , Page(s): 244 - 248
    Cited by:  Papers (5)  |  Patents (3)
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    A multi-carrier direct sequence code division multiple access (MC-DS-CDMA) system combined with frequency spread coding is proposed and investigated for the downlink. The proposed system exploits frequency diversity without additional redundancy by using frequency spread coding in a frequency-selective fading channel. Computer simulation results show its effectiveness in terms of average bit error rate and bandwidth efficiency. Furthermore, the proposed system is compared with a multi-carrier (MC)-CDMA system and a single-carrier (SC)-DS-CDMA system using a RAKE receiver View full abstract»

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  • Cost-effective allocation of radioports under constant offered load

    Publication Year: 1999 , Page(s): 316 - 320
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    Determining the most cost-effective allocation of resources in wireless network infrastructures is a difficult combinatorial problem when only the general case is considered. A significant class of wireless networks comprises those serving dense user populations with approximately uniform spatial distribution of offered load. In such networks, it is shown that analytical solutions for optimal radioport power and cost are feasible. Mathematical proof of the above is presented, as well as examples for different levels of offered load. It is also demonstrated that, for the cost model used, cost is not highly sensitive to quality of service View full abstract»

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  • A system architecture for mobile broadband access using wireless ATM

    Publication Year: 1999 , Page(s): 274 - 278
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    We present a system level architecture for supporting mobility in an ATM-based wireless personal communication network (PCN). The proposed architecture uses a networking scheme based on intelligent, multicast-based trees with distributed mobility management and predictive resource allocation at the base stations. The addressed functionalities include connection admission, location management and tracking and handoff procedure with QoS support. The associated protocols for implementing these functions are outlined and the architecture is compared vis-a-vis currently existing proposals in the literature. In doing so we discuss key design issues, and speculate on future directions in the development of broadband wireless packet communications systems View full abstract»

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  • An extension of the TCP flow control algorithm for wireless networks

    Publication Year: 1999 , Page(s): 207 - 210
    Cited by:  Papers (2)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    Reliable transport protocols such as the transmission control protocol (TCP) are tuned to perform well in traditional wireline networks where packet losses occur mostly because of congestion. However, networks with wireless and lossy links also suffer from significant packet losses due to bit errors and handoffs. TCP responds to all the packet losses by invoking congestion control and avoidance algorithms and this results in degraded end-to-end performance in wireless and lossy systems. We propose a simple strategy to determine the cause of packet drops in a network running the TCP protocol. Our method is based on observing the slow start threshold value and the number of packets successfully transmitted between two consecutive drops. We then show that the additive increase and multiplicative decrease algorithm of TCP results in unfair allocation of bandwidth to wireless connections. Thus, it needs to be modified to take into account the wireless drops. We present the performance of one such strategy which takes corrective action once a drop is identified as a wireless drop View full abstract»

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  • Capacity improvement in CDMA and FDMA cellular mobile communication systems using adaptive antennas

    Publication Year: 1999 , Page(s): 75 - 77
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    A simulation study of the possibility of capacity improvement in multi-cell CDMA and FDMA cellular systems by using adaptive antennas at the base stations is presented. Phased arrays that form steerable, fixed-pattern, narrow beams towards the users, have been assumed to approximate the performance of the adaptive antennas in a multipath-free environment. Simulation results for BER improvements in CDMA systems by assuming only distance-dependent path loss are given. Further improvements by considering the voice activity factor are also presented. Then, simulation results for improvements in the outage probability in CDMA and FDMA systems and degradation caused by power control errors assuming distance-dependent path loss and log-normal shadowing are presented View full abstract»

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