IEEE Communications Letters

Issue 1 • Jan. 2002

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Displaying Results 1 - 15 of 15
  • Effects of multiple threshold values in double dwell DS-SS code acquisition systems

    Publication Year: 2002, Page(s):1 - 3
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (96 KB) | HTML iconHTML

    We describe a decision method using multiple threshold values for direct-sequence spread-spectrum (DS-SS) code acquisition systems. We apply this technique to a conventional double dwell serial search algorithm and analyze it in terms of mean code acquisition time. Numerical results show that our proposed scheme outperforms the conventional one by 0.2-0.5 sec with respect to the mean code acquisit... View full abstract»

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  • Rate control for wideband radios

    Publication Year: 2002, Page(s):4 - 6
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (66 KB) | HTML iconHTML

    We show a technique to control the data rate emitted by wideband radio terminals. This technique is designed for adapting terminals to channel capacity variations. The proposal is based on notifying the application layer of the channel status. This information is generated by the packet scheduler, which is designed for guaranteeing appropriate channel sharing to the traffic components. Results sho... View full abstract»

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  • Effects of bursty crosstalk in DSL

    Publication Year: 2002, Page(s):7 - 9
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (69 KB) | HTML iconHTML

    We propose a simple model for the bursty operation of digital subscriber line (DSL) modems. Based on this model, we derive the autocorrelation and the power spectrum density (PSD) of the bursty crosstalk. We analyze the effects of bursty operation in both the crosstalk PSD and the training of the DSL modem. This analysis suggests that both the duty cycle and the bursty activity rate must be optimi... View full abstract»

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  • A sensitivity matched multicarrier modulation

    Publication Year: 2002, Page(s):10 - 12
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (42 KB) | HTML iconHTML

    We develop a multicarrier modulation scheme for transmission of compressed data. The energy allocation among subcarriers is optimized by minimizing a modified symbol error function in either AWGN or Rayleigh fading channels. It is observed that our sensitivity matched multicarrier modulation significantly outperforms the conventional multi carrier modulation. The performance gain in Rayleigh fadin... View full abstract»

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  • On upper bounds of SIR-based call admission threshold in power-controlled DS-CDMA mobile systems

    Publication Year: 2002, Page(s):13 - 15
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (67 KB) | HTML iconHTML

    With signal-to-interference ratio (SIR) based call admission control, a newly arriving call is accepted only if the received SIR is greater than an admission threshold. Since a large threshold often leads to unnecessary denials of the admission requests, the threshold should be selected within a certain upper bound. In this paper, the upper bounds of the admission threshold is provided, which achi... View full abstract»

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  • On geometric properties of the decorrelator

    Publication Year: 2002, Page(s):16 - 18
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (68 KB) | HTML iconHTML

    We discuss the geometric properties of the multiuser decorrelator receiver. In particular we show that the prevalent geometric interpretation of the correlating vectors comprising the decorrelator receiver in terms of orthogonal projections of the signature vectors is incorrect. The correct interpretation established is that the correlating vectors are oblique projections of the signature vectors ... View full abstract»

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  • Estimating MIMO system performance using the correlation matrix approach

    Publication Year: 2002, Page(s):19 - 21
    Cited by:  Papers (53)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (64 KB) | HTML iconHTML

    The channel capacity of a multiple-input-multiple-output (MIMO) communication system depends substantially on correlation between individual receive branches. We investigate the MIMO capacity using the correlation matrix approach and the Salz-Winters (1994) spatial correlation model. It is shown that for a linear array, correlation has no impact on the MIMO channel capacity provided that the two-e... View full abstract»

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  • Optimal maximal ratio combining with correlated diversity branches

    Publication Year: 2002, Page(s):22 - 24
    Cited by:  Papers (36)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (46 KB) | HTML iconHTML

    It is proved that a maximal ratio combiner operating on correlated branches and weighting the branch signals as though they were independent is optimal. It is also proved that performance measures of maximal ratio combining operating with correlated Rayleigh or Ricean fading input branches are identical to performance measures of an equivalent diversity system operating with independent and, in ge... View full abstract»

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  • Robust transmission based on variable-rate error control and genetic programming

    Publication Year: 2002, Page(s):25 - 27
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (65 KB) | HTML iconHTML

    This paper presents a novel variable-rate error control design algorithm matched to full-search vector quantizers (VQs) for robust transmission. In the algorithm, different locations of binary strings obtained from VQ encoders are protected by channel codes with different protection levels. The degree of protection at each location is determined by a genetic programming technique minimizing the en... View full abstract»

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  • Transition probabilities of coded BPSK signals for hard-decision decoding with k-bit CSI in Nakagami-m fading channels

    Publication Year: 2002, Page(s):28 - 30
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (129 KB) | HTML iconHTML

    We evaluate a closed form expression of the transition probabilities used for calculating metric values and pairwise error probabilities of convolutional codes, equipped with coherent BPSK signals, for hard-decision decoding with k-bit channel state information (CSI) in slow varying frequency nonselective Nakagami-m fading channels. It is noted that 1-bit CSI is sufficient to take advantage of cha... View full abstract»

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  • Performance of RCPC codes with soft-decision decoding over Nakagami-m fading channels

    Publication Year: 2002, Page(s):31 - 33
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (127 KB) | HTML iconHTML

    The analytical upper bounds on the pairwise error probability of rate compatible punctured convolutional (RCPC) codes, using coherent BPSK signals over slow frequency nonselective Nakagami-m fading channels with AWGN, are evaluated. With perfect channel state information (CSI) assumption, we use a direct integral with the Nakagami-m probability density function to obtain a closed form upper bound.... View full abstract»

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  • A new equalizer for multitone systems without guard time

    Publication Year: 2002, Page(s):34 - 36
    Cited by:  Papers (13)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (61 KB) | HTML iconHTML

    We propose a new, low-complexity frequency-domain equalizer, which, in the absence of a guard interval, utilizes redundancy in the frequency domain to completely eliminate intersymbol and interchannel interference. Simulation results show that the new equalization scheme has at least the same potential compared to conventional DMT/OFDM while offering the shortest possible latency at a reasonable c... View full abstract»

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  • On the relationship between absolute and relative fairness bounds

    Publication Year: 2002, Page(s):37 - 39
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (71 KB) | HTML iconHTML

    The fairness of scheduling disciplines used in communication networks has frequently been evaluated using one of two fairness measures: the absolute fairness bound (AFB) and the relative fairness bound (RFB). We present a tight bounded relationship between these measures of fairness. The bounds established are exactly reached in the case of many real scheduling disciplines, thus leading to an easy... View full abstract»

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  • Adaptive random channel allocation scheme in HIPERLAN type 2

    Publication Year: 2002, Page(s):40 - 42
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (38 KB) | HTML iconHTML

    The MAC protocol of HIPERLAN type 2 is based on TDMA/TDD and resources in one MAC frame can be allocated dynamically by the access point (AP). We propose an adaptive random channel (RCH) allocation scheme for HIPERLAN type 2. The AP scheduler controls the number of RCHs in one MAC frame according to the transmission results of the previous MAC frame. The simulation results show that the proposed s... View full abstract»

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  • Dynamic reblocking RSA-based multisignatures scheme for computer and communication networks

    Publication Year: 2002, Page(s):43 - 44
    Cited by:  Papers (9)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (40 KB) | HTML iconHTML

    This investigation utilized dynamic reblocking to enhance the RSA-based multisignatures scheme and solve the moduli clashes problem. In contrast to other RSA-based multisignature schemes, the proposed scheme has fewer modular exponentiations operations, overcomes the signing order problem, and minimizes the keys requirements. Consequently, the proposed scheme is suitable for application to all com... View full abstract»

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IEEE Communications Letters publishes letters on the frontiers of research within the field of interest of the IEEE Communications Society in a timely manner.

 

 

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Meet Our Editors

Editor-in-Chief
Octavia Dobre
Memorial University, Canada