IEE Proceedings - Communications
Volume 150, Issue 2, April 2003
Volumes & issues:
Volume 150, Issue 2
April 2003
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- Author(s): G. Feng ; C.K. Siew ; K.L. Yeung
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 69 –79
- DOI: 10.1049/ip-com:20030179
- Type: Article
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69
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Local loss recovery for reliable multicast can provide significant performance improvement in terms of loss recovery latency, bandwidth consumption and network throughput. Active reliable multicast (ARM) is a novel loss recovery scheme for large-scale reliable multicast. When sufficient active resources of active routers (ARs) and associated cache are available, ARM gives good loss recovery latency performance. The authors build an analytical model for studying the optimal active resource allocation for ARM. They propose a top-down layering analysis (TDLA) approach to derive the expected loss recovery latency (ELRL). For a given multicast tree, the ELRL is derived as a function of the active resource allocation pattern. Simulation experiments reveal that high performance gains can be attained with limited active resources, which are properly allocated. It is also shown that simulation results have a good match with the analytical results. The analytical framework developed can be used for further investigation of various active resource allocation schemes and caching policies. - Author(s): F.Y. Long and K.T. Lo
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 80 –84
- DOI: 10.1049/ip-com:20030178
- Type: Article
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80
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The effectiveness of adaptive modulation is affected by the accuracy of channel quality estimation. The authors attempt to find a simple way to measure the performance degradation of adaptive modulation schemes caused by channel quality estimation error without considering the details of specific multimedia information to be transmitted. With their approach, the effect of channel quality estimation error on the performance of the adaptive modulation scheme is analysed using four proposed parameters: extra bit-error-rate cost (EBC), potential theoretical channel capacity loss (PTCCL), average system EBC and average system PTCCL. Experiments are performed using a 4-mode adaptive modulation scheme and the trade-off between the proposed parameters is discussed. It is shown that the effects of channel quality estimation error on average system performance are not apparent. However, it is still necessary to keep the estimation error small in order to keep a good instantaneous performance of the system. - Author(s): J. Zhang ; W. Ser ; J. Zhu
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 85 –90
- DOI: 10.1049/ip-com:20030172
- Type: Article
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85
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In OFDM systems, a pre-filter can be used to shorten the channel impulse response when the order of the impulse response is longer than the length of the cyclic prefix (CP) of the system. The authors propose an effective optimisation method for determining the coefficients of the channel-shortening pre-filter (CSP). This method is designed in the time domain completely and it does not require the channel length to be subject to any constraint. It is optimum in the sense that it maximises the signal-to-interference-plus-noise ratio (SINR) of the pre-filter output. Compared with existing methods, the proposed method takes into account the effect of noise, thereby making the optimisation criterion more accurate and allowing the pre-filter developed to not only mitigate intersymbol interference (ISI) but also suppress noise effectively. Computer simulation results show that the proposed method outperforms some existing methods. - Author(s): C.-C. Lee ; M.-S. Hwang ; W.-P. Yang
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 91 –95
- DOI: 10.1049/ip-com:20030290
- Type: Article
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91
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An extension of the authentication protocol for GSM is proposed to improve some drawbacks of the current GSM authentication protocol including: not supporting bilateral authentication; huge bandwidth consumption between VLR and HLR; stored space overhead in VLR; and overloaded HLR with authentication of mobile stations. As a result, this new extension of the authentication protocol not only improves these drawbacks but also achieves the requirements: mutual authentication, reduction of bandwidth consumption, less storage of VLR database, security, and efficiency. The merit of the proposed protocol is that it does not cause problems and alter the existing architecture of GSM at all. The robustness of the new protocol is also based on security algorithms A3, A5 and A8. - Author(s): S. Buzzi ; E. Conte ; A. De Maio
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 96 –100
- DOI: 10.1049/ip-com:20030176
- Type: Article
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96
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The use of polarisation diversity techniques in conjunction with nonorthogonal multipulse modulation is considered for a multiuser communication system operating on a single-path Rayleigh fading channel. Indeed, in mobile environments multiple reflections and scattering phenomena introduce polarisation rotation of the transmitted power, and polarisation diversity is a suitable means of taking advantage of this effect. Several different two-stage receiving structures, each one relying on different amounts of a priori information on the channel status, are introduced. The performance of the proposed detectors is analysed through Monte Carlo counting techniques. It is seen that these receivers yield a remarkable performance improvement with respect to those not exploiting polarisation diversity. - Author(s): T.C. Chuah ; B.S. Sharif ; O.R. Hinton
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 101 –107
- DOI: 10.1049/ip-com:20030168
- Type: Article
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p.
101
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Direction of arrival estimation schemes based on multiuser detection for CDMA signals are investigated. The paper reports performance improvements achieved by the linear decorrelator and the nonlinear M-regression decorrelator over the conventional matched filter scheme combined with the subspace-based MUSIC algorithm. The near–far resistant properties of the decorrelators show improved bearing estimation performance in the presence of strong interference. In particular, the minimax M-regression decorrelator combined with the MUSIC algorithm achieves an excellent performance trade-off by performing satisfactorily over the entire range of noise distributions, which, on the other hand, is unattainable by the ROC-MUSIC scheme. - Author(s): Y. Wu
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 109 –114
- DOI: 10.1049/ip-com:20030170
- Type: Article
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p.
109
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RS-CDMA (rotated spectrum code division multiple access) is designed to yield a novel multiple access concept termed RS-CTDMA (rotated spectrum code time division multiple access) for mobile radio systems. The concept exploits the principle of CTDMA (code time division multiple access) to combine the advantages of the good user separation of TDMA and the spread spectrum of CDMA. Moreover, the concept allows multicode transmission, and thus high spectrum efficiency. Owing to its having the inherent features of both CDMA and TDMA, RS-CTDMA preserves maximum commonality with other air interfaces, and thus has the potential to be compatible with UMTS. - Author(s): Y. Xue and X. Zhu
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 115 –120
- DOI: 10.1049/ip-com:20030169
- Type: Article
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115
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The use of the second-order LMS (SOLMS) algorithm for wireless channel tracking is explored. A frequency domain approach is presented to optimise the steady-state mean performance of SOLMS-based wireless channel tracking. It is shown that in comparison to the LMS algorithm, the benefit provided by the SOLMS algorithm is evident in tracking the wireless channel. However, such an optimisation is based on knowledge of the fading channel, which is usually not obtainable in practice. To deal with this problem, a self-tuning implementation of SOLMS-based wireless channel tracking is proposed. Performing online parameter optimisation using the technique of gradient descent, the proposed method can be used to implement high-performance wireless channel tracking without any a priori knowledge. These developments are supported by Monte Carlo simulations. - Author(s): R.A. Carrasco and R. Uribeetxeberria
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 121 –128
- DOI: 10.1049/ip-com:20030174
- Type: Article
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121
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Multicarrier CDMA is a major candidate to fulfil the requirements of 3G mobile systems. A novel scheme is developed combining modulo-S ring TCM with RNN-based adaptive space diversity for multicarrier CDMA systems with single-antenna transmitter and multiple-antenna receiver. The nonlinear RTRL algorithm for antenna diversity combining combats the distortive effects of the communication channel and reduces the interference. Ring TCM channel coding and RNN space diversity are evaluated in 16-QAM multicarrier CDMA systems transmitting over Rician and Rayleigh fast fading channels with a maximum Doppler frequency of 96 Hz. Modulo-4 ring TCM codes of 16 and 64 states have been designed. The RNN system is shown to be superior to the linear algorithms in channels dominated by multipath fading, inter-symbol interference and multiple access interference. The complexity of the RNN structure is comparable to that of the linear techniques. The joint utilisation of RNN based diversity, ring TCM and binary TCM coding schemes has been implemented. Whereas coding and space diversity do not provide sufficient benefit separately, the combination of both produces an increase in performance. - Author(s): S. Shin ; A. Ahmad ; K. Kim
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 129 –133
- DOI: 10.1049/ip-com:20030175
- Type: Article
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129
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Since interference is related to the capacity and performance of DS/CDMA systems, it is necessary to investigate other-cell-interference characteristics according to the location of a user. The ratio of the intercell interference to the total power received from the user's own cell in a downlink, defined as the other-cell-interference factor, as a function of normalised distance is specifically analysed. Additionally, the maximum transmission rate under uniform user distribution throughout the cell is simulated when TDX mode packet scheduling is applied. The results show that a maximum transmission rate up to 7.6 Mbit/s for the privileged user could be supported under the following conditions: when the bandwidth is 1.2288 MHz, the orthogonality factor is 0.9, the path loss is 4 and the normalised distance is 0.1. - Author(s): L. Lv ; S. Zhu ; S. Dong
- Source: IEE Proceedings - Communications, Volume 150, Issue 2, p. 134 –140
- DOI: 10.1049/ip-com:20030173
- Type: Article
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134
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The authors present a distributed power control algorithm for wideband code division multiple access (WCDMA) third generation mobile communications systems. In the algorithm, a new exponential type of power update function is defined. By altering the parameter α in the update function, the system can satisfy different performance requirements. The major properties of the algorithm are revealed and the convergence condition is investigated. Simulation results show that the new algorithm has faster convergence speed and better system stability compared to most existing distributed power control algorithms.
Active resource allocation for active reliable multicast
Measurements for performance degradation of adaptive modulation scheme caused by channel quality estimation error
Effective optimisation method for channel shortening in OFDM systems
Extension of authentication protocol for GSM
Polarisation diversity reception of nonorthogonal multipulse signals in multiuser Rayleigh fading channels
Robust direction of arrival estimation for CDMA signals in impulsive noise
RS-CTDMA: a novel concept of multiple access design
Wireless channel tracking based on self-tuning second-order LMS algorithm
Neural network space diversity combination and ring coding for multicarrier CDMA over fast fading channels
Performance of packet data transmission using the other-cell-interference factor in DS/CDMA downlink
Fast convergence distributed power control algorithm for WCDMA systems
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