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Communications Letters, IEEE

Issue 1 • Date Jan. 1999

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Displaying Results 1 - 7 of 7
  • Logical and diversity combining in FH/SSMA packet radio networks

    Publication Year: 1999 , Page(s): 1 - 3
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB)  

    We propose the logical and diversity combining in slotted frequency-hopped spread spectrum multiple access (FH/SSMA) packet radio networks. The proposed diversity scheme employs the symbol-by-symbol logical AND operation between the currently received packet and the previously combined packet. Our results show that the proposed low-complexity diversity combining scheme provides a significant performance improvement over existing diversity combining schemes. View full abstract»

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  • Clipping noise mitigation for OFDM by decision-aided reconstruction

    Publication Year: 1999 , Page(s): 4 - 6
    Cited by:  Papers (88)  |  Patents (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (91 KB)  

    Clipping is often used to reduce the large peak-to-mean envelope power ratio of orthogonal frequency-division multiplexing (OFDM) signals. However, it introduces additional noise that degrades the system performance. A technique called decision-aided reconstruction (DAR) is proposed for mitigating the clipping noise. The performance of the proposed technique is evaluated for additive white Gaussian noise and static intersymbol interference channels. The effect of using a realistic channel estimate is also examined. Results show that the DAR technique can mitigate the clipping noise significantly for OFDM systems that have large block sizes. View full abstract»

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  • Cryptanalysis of an authentication and key distribution protocol

    Publication Year: 1999 , Page(s): 7 - 8
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (61 KB)  

    We point out that a previously proposed authentication and key distribution protocol is not secure from both the viewpoints of authentication and key distribution requirements. View full abstract»

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  • Convolutional spectral shaping

    Publication Year: 1999 , Page(s): 9 - 11
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (73 KB)  

    A new spectral shaping technique, convolutional spectral shaping (CSS), is introduced. In CSS, equivalence classes of possible sign bit sequences are represented by a coset of a convolutional code and a search through the trellis of the code is used to pick a sequence from the selected coset to approximate a target spectral shape for transmission. Simulation results are included to illustrate the performance of CSS. A version of CSS has been adopted by the International Telecommunication Union (ITU) in the pulse code modulation (PCM) modem standard V.90. View full abstract»

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  • L-band land mobile satellite (LMS) amplitude and multipath phase modeling in urban areas

    Publication Year: 1999 , Page(s): 12 - 14
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (57 KB)  

    A study is presented of the amplitude and multipath phase variations found in the land mobile satellite channel at L-band (1.820 GHz) in urban areas. The received time-series are split into three categories or "states" according to the degree of shadowing experienced: line-of-sight, light shadow, and deep shadow. Statistical models and their corresponding parameters (extracted from experimental data) are provided for a wide range of elevation angles (10/spl deg/-70/spl deg/) both for the amplitude and for the phase variations due to multipath. View full abstract»

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  • Spectral overlay of multicarrier CDMA on existing CDMA mobile systems

    Publication Year: 1999 , Page(s): 15 - 17
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (86 KB)  

    A spectral overlay of a narrow-band code division multiple access (CDMA) system and a wide-band multicarrier CDMA system is considered as a means for existing CDMA mobile networks to evolve into a future CDMA network. The achievable joint capacity of the overlaid system is provided and compared with that of another network evolution strategy of spectrally overlaying wide-band single-carrier CDMA to the existing CDMA systems. View full abstract»

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  • Augmented APP (A2P2) module for a posteriori probability calculation and channel parameter tracking

    Publication Year: 1999 , Page(s): 18 - 20
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (114 KB)  

    The augmented a posteriori probability (APP) module, denoted by A/sup 2/P/sup 2/, comprises two mutually supporting algorithms: (1) a soft-input soft-output (SISO) APP module, adjusted to output edge metric information and (2) a recursive estimator for the channel parameters that benefits from this information at each step of the recursion. The thus-estimated parameters appropriately transform, in turn, the channel output signals that feed the SISO module. When applied to decoding a parallel concatenated convolutional code (PCCC) transmitted by binary phase-shift keying through a channel with frequency offset (0.08/T/sub s/ Hz) and phase jitter (0.23-rad RMS), concentrated at 0.01/T/sub s/ Hz, (T/sub s/-symbol duration), the degradation compared to fully coherent reception is a small fraction of 1 dB, without use of a preamble. View full abstract»

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IEEE Communications Letters  is aimed at satisfying the need for rapid dissemination of information, offering a vehicle for authors to expose their results to be used in future developments. This ensures early recognition of work. 

 

 

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Editor-in-Chief
George K. Karagiannidis
Aristotle University of Thessaloniki
Greece