Multiple access interference suppression with linear chip equalizers in WCDMA downlink receivers

Hooli, K.; Latva-aho, Matti; Juntti, Markku

doi:10.1109/glocom.1999.831683

Cited by 66 publications

(20 citation statements)

References 15 publications

(6 reference statements)

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“…Adaptive beamforming employing finite length, transversal filters is one technique that can be used in the suppression of multiple access interference in synchronous WCDMA channels when transmitted through a frequency selective multipath medium [6]. This is particularly so if long scrambling PN sequences overlay the coded information bearing signals transmitted by a basestation, which render the more traditional and computationally exhaustive Minimum Mean Square Error receiver [7] impractical to implement in real time communication.…”

Section: The Single User Lmmse Receivermentioning

confidence: 99%

Logarithmic Codecs for Adaptive Beamforming in WCDMA Downlink Channels

Litchfield

Lee

Langley

et al. 2007

2007 IEEE International Symposium on Circuits and Systems (ISCAS)

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This paper presents a comparison of two logarithmic codecs for low-medium resolution (6-12 bit) adaptive beamforming in WCDMA terminals. The two different logarithmic coding techniques are based on the utilization of a look up table (LUT), where one method employs a direct LUT conversion, and the other uses linear interpolation requiring a multiplier and a comparatively small LUT. The two logarithmic converters are analyzed with Matlab simulation, where the address precision is varied to generate observations on the adaptive filter misadjustment and its effect on the probability of error. The results indicate that both algorithms cause relatively small mean square error for address precision above 9 bits for the direct LUT conversion and 5 bits for the interpolative conversion. Both techniques render low cost alternatives to a fixed-point implementation while yielding an improved probability of error metric.

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Section: The Single User Lmmse Receivermentioning

confidence: 99%

Logarithmic Codecs for Adaptive Beamforming in WCDMA Downlink Channels

Litchfield

Lee

Langley

et al. 2007

2007 IEEE International Symposium on Circuits and Systems (ISCAS)

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“…Hence, it is important to use other techniques suitable for multicode operation and also multilevel modulation over frequency-selective channels. Various time-domain and frequency-domain equalization techniques [5]- [12] have been proposed to improve the DS-CDMA transmission performance.…”

Section: Introductionmentioning

confidence: 99%

Packet access using DS-CDMA with frequency-domain equalization

Garg

Adachi

2006

IEEE J. Select. Areas Commun.

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Abstract-The next-generation mobile communications system is anticipated to support very high-speed data rates exceeding several tens megabits per second. In this paper, we consider high-speed downlink packet access for direct-sequence code-division multiple access (DS-CDMA) as in third-generation wideband code-division multiple-access systems. Adaptive modulation and coding (AMC), multicode operation and hybrid automatic repeat request (HARQ) will be the enabling technologies. With such high-speed data transmissions, however, multicode operation severely suffers from the loss of orthogonality among the spreading codes since the wireless channel becomes severely frequency-selective. In this paper, we apply frequency-domain equalization (FDE) based on minimum mean-square error (MMSE) criterion instead of conventional rake combining for receiving the packet.

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“…This idea can also be applied in the multipath channel case but since users within a cell are no longer orthogonal there will be some loss of optimality. Note that even if the orthogonality between the users within a particular cell is restored using the equalization techniques described in [3], [4], [5], [6], [7], [8], [9], [10], [11], the resulting matched filter bank outputs will contain noise terms that are correlated across the users.…”

Section: Reduced Complexity Optimum Detectionmentioning

confidence: 99%

Multiuser Detection for Out-of-Cell Cochannel Interference Mitigation in the IS-95 Downlink

Brown¹,

Poor²,

Verdú³

et al. 2002

Information Technology: Transmission, Processing and Storage

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This paper considers the application of multiuser detection techniques to improve the quality of downlink reception in a multi-cell IS-95 digital cellular communication system. In order to understand the relative performance of suboptimum multiuser detectors including the matched filter detector, optimum multiuser detection in the context of the IS-95 downlink is first considered. A reduced complexity optimum detector that takes advantage of the structural properties of the IS-95 downlink and exhibits exponentially lower complexity than the brute-force optimum detector is developed. The Group Parallel Interference Cancellation (GPIC) detector, a suboptimum, low-complexity multiuser detector that also exploits the structure of the IS-95 downlink is then developed. Simulation evidence is presented that suggests that the performance of the GPIC detector may be near-optimum in several cases. The GPIC detector is also tested on a snapshot of on-air data measured with an omnidirectional antenna in an active IS-95 system and is shown to be effective for extracting weak downlink transmissions from strong out-of-cell cochannel interference. The results of this paper suggest that the GPIC detector offers the most performance gain in scenarios where weak downlink signals are corrupted by strong out-of-cell cochannel interference.

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Multiple access interference suppression with linear chip equalizers in WCDMA downlink receivers

Cited by 66 publications

References 15 publications

Logarithmic Codecs for Adaptive Beamforming in WCDMA Downlink Channels

Logarithmic Codecs for Adaptive Beamforming in WCDMA Downlink Channels

Packet access using DS-CDMA with frequency-domain equalization

Multiuser Detection for Out-of-Cell Cochannel Interference Mitigation in the IS-95 Downlink

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