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Communications Letters, IEEE

Issue 9 • Date Sept. 1999

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Displaying Results 1 - 8 of 8
  • Minimum cost traffic shaping

    Page(s): 257 - 259
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (89 KB)  

    We propose a minimum-cost method for traffic shaping in the context of quality of service (QoS)-based networks. Given the user's desired QoS and the network's resource availability, our method determines the least cost parameters for a shaper while guaranteeing access to the network and satisfying the QoS requirements. View full abstract»

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  • Concatenated prime codes

    Page(s): 260 - 262
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (160 KB)  

    This letter presents a new construction of frequency-hopping (FH) patterns, here designated as concatenated prime codes, for a multilevel frequency-shift-keying/frequency-hopping code-division multiple-access (MFSK/FH-CDMA) system. The concatenated prime codes are constructed by modifying prime codes and they possess ideal autocorrelation and nearly ideal cross-correlation properties. Furthermore, these concatenated prime codes can be partitioned into P+1 groups, of which the maximum cross-correlation between any two FH patterns in the same group is at most one. View full abstract»

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  • Bandwidth allocation for TDMA-based wireless local loops

    Page(s): 263 - 265
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (57 KB)  

    Wireless local loops are of interest due to their many advantages over the wireline systems. However, the bandwidth allocation schemes in wireless local loops are different from that of the cellular networks in some aspects since the terminals are fixed. In this paper, we propose a strategy of bandwidth allocation for time-division multiple-access based wireless local loops. We align the sectors assigned the same channels such that the cochannel interference is reduced. In the performance evaluation, we demonstrate that the proposed scheme improves the bandwidth efficiency and increases system capacity with minimal loss of signal-to-interference ratio. View full abstract»

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  • An error bound for reduced-state Viterbi decoding of TCM codes

    Page(s): 266 - 268
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    An upper bound is given on the error event rate of reduced-state Viterbi decoding of trellis-coded modulation (TCM) codes. Such reduced-state decoding could form the heart of an adaptive-complexity approach that saves substantially on required decoding power consumption, an important consideration in handheld portable communications. The bound is based on a difference-state formulation utilizing the uniform error properties of the codes. It fully includes the effect of finite decoding depth L, and is efficiently computed with a single forward pass through the encoder trellis. View full abstract»

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  • On the minimum distance of composite-length BCH codes

    Page(s): 269 - 271
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (135 KB)  

    We derive a theorem which generalizes Theorem 3 in Chapter 9 of the book "The Theory of Error-Correcting Codes" by F.J. MacWilliams and N.J.A. Sloane (North-Holland, 1977). By this theorem, we are able to give several classes of BCH codes of composite length whose minimum distance does not exceed the BCH bound. Moreover, we show that this theorem can also be used to determine the true minimum distance of some other cyclic codes with composite-length. View full abstract»

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  • Iterative decoding of serially concatenated convolutional codes and MSK

    Page(s): 272 - 274
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (59 KB)  

    The performance of iterative decoding and demodulation of serially concatenated convolutional codes and minimum shift keying (MSK) is studied. It is shown that by appropriately combining the trellises of MSK and the inner code, a high performance coded modulation system can be achieved. Simulation results also confirms that recursive inner codes are essential for a serially concatenated system. View full abstract»

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  • Pitch synchronous extended excitation in multimode CELP

    Page(s): 275 - 276
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (43 KB)  

    This letter proposes a 4-kb/s multimode code-excited linear prediction (CELP) coder with pitch synchronous extended excitation. Three modes are used for the short-term excitation, namely algebraic, extended, or stochastic excitations, together with an adaptive codebook for the long-term excitation. Comparisons with the FS-1016 and ITU-T G.723.1 coders show a performance level between these standards. View full abstract»

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  • UVoD: An unified architecture for video-on-demand services

    Page(s): 277 - 279
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (49 KB)  

    Existing video-on-demand (VoD) systems can be classified into two categories: true-VoD (TVoD) and near-VoD (NVoD). TVoD systems allocate a dedicated channel for every user to achieve short latency. NVoD systems make use of multicast technologies to enable multiple users to share a single channel to reduce system cost. This paper proposes a VoD architecture called UVoD that unifies the existing TVoD and NVoD architectures by integrating unicast with multicast transmissions. A performance model of the system is derived and numerical results show that one can achieve significant performance gain over TVoD (over 500%) under the same latency constraints. 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