Downlink Specific Linear Equalization for Frequency Selective CDMA Cellular Systems

Krauss, T.P.; Hillery, W.J.; Zoltowski, M.D.

doi:10.1007/0-306-47322-4_10

Cited by 16 publications

(14 citation statements)

References 13 publications

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“…Chip-level equalization completely or partially restores the orthogonality and, hence, allows to suppress the MUI; see, e.g., [1] and [2]. However, this requires multiple receive antennas (two for chip rate sampling in a single-cell context) to guarantee a zero-forcing (ZF) solution for any set of well-conditioned channels [3].…”

Section: Space-time Block Coding For Single-carrier Blockmentioning

confidence: 99%

“…However, similar to all MC systems, single-user GMC-CDMA transmissions generally suffer from high peak-to-average-power-ratio (PAPR), which requires expensive radio frequency (RF) front-ends and/or additional signal processing to compensate for the nonlinear effects introduced by the front-end. 1 As opposed to [18], our transceiver is based on SCBT-DS-CDMA which allows for perfectly constant-modulus (CM) single-user transmissions, at least if we replace the zeros by known symbols [4], [20].…”

Section: Space-time Block Coding For Single-carrier Blockmentioning

confidence: 99%

“…At this point, it is important to note that all parallel symbol block sequences are spread by the same composite code sequence. For each of the parallel streams, the different user chip block sequences and the pilot chip block sequence are added, resulting into the th multiuser chip block sequence (1) For future discussions, we find it convenient to also define the th user's total data symbol block sequence (similarly for the total pilot symbol block sequence ) and the total multiuser chip block sequence . Unlike the traditional approach of performing ST encoding at the symbol level (see, e.g., [12] and [13]), we perform ST encoding at the block level (see also Fig.…”

Section: A Transmitter Designmentioning

confidence: 99%

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Space-time block coding for single-carrier block transmission DS-CDMA downlink

Petré

Leus

Deneire

et al. 2003

IEEE J. Select. Areas Commun.

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Abstract-The combination of space-time block coding (STBC) and direct-sequence code-division multiple access (DS-CDMA) has the potential to increase the performance of multiple users in a cellular network. However, if not carefully designed, the resulting transmission scheme suffers from increased multiuser interference (MUI), which dramatically deteriorates the performance. To tackle this MUI problem in the downlink, we combine two specific DS-CDMA and STBC techniques, namely single-carrier block transmission (SCBT) DS-CDMA and time-reversal STBC. The resulting transmission scheme allows for deterministic maximum-likelihood (ML) user separation through low-complexity code-matched filtering, as well as deterministic ML transmit stream separation through linear processing. Moreover, it can achieve maximum diversity gains of ( + 1) for every user in the system, irrespective of the system load, where is the number of transmit antennas, the number of receive antennas, and the order of the underlying multipath channels. In addition, it turns out that a low-complexity linear receiver based on frequency-domain equalization comes close to extracting the full diversity in reduced, as well as full load settings. In this perspective, we also develop two (recursive) least squares methods for direct equalizer design. Simulation results demonstrate the outstanding performance of the proposed transceiver compared to competing alternatives.Index Terms-Block transmission, direct-sequence code-division multiple access (DS-CDMA), equalizer design, frequency-selective fading channels, multiple-input-multiple-output (MIMO), space-time block coding (STBC).

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Section: Space-time Block Coding For Single-carrier Blockmentioning

confidence: 99%

Section: Space-time Block Coding For Single-carrier Blockmentioning

confidence: 99%

Section: A Transmitter Designmentioning

confidence: 99%

See 1 more Smart Citation

Space-time block coding for single-carrier block transmission DS-CDMA downlink

Petré

Leus

Deneire

et al. 2003

IEEE J. Select. Areas Commun.

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“…Other related approaches include the use of chip-level equalization. See, for example, [13], [14], and references therein.…”

Section: B Related Workmentioning

confidence: 99%

Blind decorrelating rake receivers for long-code WCDMA

Tong

Veen

Dewilde

et al. 2003

IEEE Trans. Signal Process.

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Abstract-The problem of blind and semiblind channel estimation and symbol detection is considered for long-code wideband code division multiple access (CDMA) systems, including systems with multirate and multicode transmissions. A decorrelating matched filter, implemented efficiently in state-space, eliminates multiaccess interference and produces a bank of vector processes. Each vector process spans a one-dimensional (1-D) subspace from which channel parameters and data symbols of one user are estimated jointly by least squares. A new identifiability condition is established, which suggests that channels unidentifiable in short-code CDMA systems are almost surely identifiable when aperiodic spreading codes are used. The decorrelating matched filter is implemented efficiently based on time-varying state-space realizations that exploit the structure of sparsity of the code matrix. The mean square error of the estimated channel is compared to the Cramér-Rao bound, and a bit error rate (BER) expression for the proposed algorithm is presented.Index Terms-Aperiodic spreading sequences/codes, blind and semiblind multiuser detection, channel estimation, decorrelating matched filter/RAKE receiver, fast algorithms, identifiability conditions, long-code wideband CDMA.

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“…Its effectiveness, however, has never been investigated under a fast fading channel. Performance of the proposed system is verified by simulations and is compared with a DS-CDMA system employing polynomial interpolation-based channel estimation [13] and Linear Minimum Mean Squared Error (LMMSE) chip-wise equalization [14] with block-wise equalizer update [1]. It is shown that our system can significantly outperform the DS-CDMA system from medium to high user populations under both low and high Doppler spread environments.…”

Section: Introductionmentioning

confidence: 99%

CS-CDMA/CP with the Chu Sequence: A Bandwidth-Efficient Multi-Access Scheme for Fast Fading Multipath Channels

Hashimoto

2011

2011 IEEE International Conference on Communications (ICC)

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In this paper, convolutional spreading CDMA with cyclic prefix (CS-CDMA/CP) employing the zero-correlation-zone (ZCZ) code generated from the Chu sequence is proposed as a novel multi-access scheme for fast fading multipath channels. Analysis results demonstrate that the system remains approximately multiuser interference (MUI)-free even when the system is heavily loaded and subject to severe Doppler spreads. An effective channel estimation method based on B-spline approximation is also proposed. Simulation results show, in combination with the Probabilistic Data Association (PDA) equalization, the system significantly outperforms the DS-CDMA system employing Linear Minimum Mean Squared Error (LMMSE) chip-wise equalization and polynomial interpolation-based channel estimation from medium to high user population.

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Downlink Specific Linear Equalization for Frequency Selective CDMA Cellular Systems

Cited by 16 publications

References 13 publications

Space-time block coding for single-carrier block transmission DS-CDMA downlink

Space-time block coding for single-carrier block transmission DS-CDMA downlink

Blind decorrelating rake receivers for long-code WCDMA

CS-CDMA/CP with the Chu Sequence: A Bandwidth-Efficient Multi-Access Scheme for Fast Fading Multipath Channels

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