Combinations of an adaptive array antenna and a canceller of interference for direct-sequence spread-spectrum multiple-access system

Kohno, Ryuji; Imai, Hideki; Hatori, Mitsutoshi; Pasupathy, S.

doi:10.1109/49.54463

Cited by 233 publications

(60 citation statements)

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“…Asymptotic efficiency of user , with energy , and bit-error rate of the user in the multiuser environment, as a function of the background noise power , is defined as [8] ( 18) where . Then the near-far resistance is defined as [8] ( 19) It is well known that the asymptotic efficiency of an MMSE receiver is equal to the asymptotic efficiency of a decorrelating (zero-forcing) receiver [8]. Therefore, in order to study the asymptotic efficiencies of the unconstrained and constrained MMSE receivers (OTSF and CTSF, respectively), we will study the asymptotic efficiencies of the unconstrained and constrained (to rank 1 matrix space) decorrelating receivers.…”

Section: Performance Of the Temporal-spatial Mmse Filtersmentioning

confidence: 99%

Interference management for CDMA systems through power control, multiuser detection, and beamforming

Yener

Yates

Ulukuş

2001

IEEE Trans. Commun.

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Abstract-Among the ambitious challenges to be met by the third-generation systems is to provide high-capacity flexible services. Code-division multiple access (CDMA) emerges as a promising candidate to meet these challenges. It is well known that CDMA systems are interference-limited, and interference management is needed to maximally utilize the potential gains of this access scheme. Several methods of controlling and/or suppressing the interference through power control, multiuser detection (temporal filtering), and receiver beamforming (spatial filtering) have been proposed to increase the capacity of CDMA systems up to date. We investigate the capacity increase that is possible by combining power control with intelligent temporal and spatial receiver filter design. The signal-to-interference ratio maximizing joint temporal-spatial receiver filters in unconstrained and constrained filter spaces are derived. Two-step iterative power control algorithms that converge to the optimum powers and the joint temporal and spatial receiver filters in the corresponding filter domains are given. A power control algorithm with a less complex filter update procedure is also given. We observe that significant savings in total transmit power are possible if filtering in both domains is utilized compared with conventional power control and joint optimal power control and filtering in only one domain.Index Terms-Code-division multiple access (CDMA), interference suppression, MMSE receivers, multiuser detection, power control, receiver beamforming.

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Section: Performance Of the Temporal-spatial Mmse Filtersmentioning

confidence: 99%

Interference management for CDMA systems through power control, multiuser detection, and beamforming

Yener

Yates

Ulukuş

2001

IEEE Trans. Commun.

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“…Adaptive arrays are typically designed for either utilizing spatial diversity for mitigating the effect of fading or for using the inherent angle diversity in the received signals for CCI reduction. In [17], an adaptive array receiver configured as the cascade of a beamformer and matched filter (MF) detector is presented. The update of the beamformer weights in this structure is rather cumbersome, especially over fading channels.…”

Section: B Multichannel Cdma Receptionmentioning

confidence: 99%

Adaptive multiuser detection and beamforming for interference suppression in CDMA mobile radio systems

Kapoor

Gollamudi

Nagaraj

et al. 1999

IEEE Trans. Veh. Technol.

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Abstract-This paper considers the problem of interference suppression in direct-sequence code-division multiple-access (DS-CDMA) systems over fading channels. An adaptive array receiver is presented which integrates multiuser detection, beamforming, and RAKE reception to mitigate cochannel interference and fading. The adaptive multiuser detector is formulated using a blind constrained energy minimization criterion and adaptation is carried out using a novel algorithm based on set-membership parameter estimation theory. The proposed detector overcomes the shortcomings of conventional LMS-and RLS-type algorithms, namely, that of slow convergence and large computational load, respectively. This is especially the case when strong interferers are present or when the number of adaptive weights is relatively large. DS-CDMA systems can have a relatively large number of spatially distributed interferers. Thus beamforming is based on direction-of-arrival (DOA) estimates provided by an approximate maximum-likelihood estimator (DOA-MLE). Unlike previous approaches, the DOA-MLE exploits the structure of the DS-CDMA signaling scheme resulting in robust performance and simple implementation in the presence of angle spreading. The overall method is suitable for real-time implementation and can substantially improve the interference suppression capabilities of a CDMA system. Index Terms-Adaptive filters, array signal processing, code division multiaccess, direction of arrival estimation, interference suppression, mobile communication.

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“…Research efforts invested in the area of AAA include, among others, the investigations carried out by Thompson et al [27], [28]; Naguib and Paulraj [29]; Godara [30]; as well as Kohno et al [31]. However, the area of AAAs is beyond the scope of this article, and the reader is referred to the references cited for further discussions.…”

Section: B Multiuser Equalizer Conceptsmentioning

confidence: 99%

Burst-by-burst adaptive multiuser detection cdma: a framework for existing and future wireless standards

Kuan

Hanzo

2003

Proc. IEEE

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This paper provides a broad overview of the multiuser detection literature of the past few years in a nonmathematical, easily accessible approach. The treatment is then extended to the comparative study of channel-quality controlled burst-by-burst (BbB) adaptive code division multiple access (CDMA) detection such as parallel interference cancellation, successive interference cancellation, and joint detection (JD I. MOTIVATIONMobile propagation channels exhibit time-variant propagation properties [1]. Although, apart from simple cordless telephoneschemes,mostmobileradiosystemsemploypowercontrol for mitigating the effects of received power fluctuations, rapid channel quality fluctuations cannot be compensated by practical, finite reaction-time power control schemes. Furthermore, the ubiquitous phenomenon of signal dispersion due to the multiplicity of scatering and reflecting objects cannot be mitigated by power control. Similarly, other performance lim- iting factors, such as adjacent-channel and cochannel intereference as well as multiuser interference (MUI) vary as a function of time. The ultimate channel quality metric is the bit-error rate (BER), regardless of the specific channel impairments encountered. The channel quality variations are typically higher near the fringes of the propagation cell or when moving from an indoor scenario to an outdoor cell due to the high standard deviation of the shadow fading and fast fading [1] encountered, even in conjunction with agile power control. Furthermore, the bit errors typically occur in bursts due to the time-variant channel quality fluctuations; hence, it is plausible that a fixed transceiver mode cannot achieve a high flexibility in such environments. The design of powerful and flexible transceivers [2]-[4] has to be based on finding the best compromise among a number of contradicting design factors [2]- [4]. Some of these factors are low power consumption, high robustness against transmission errors among various channel conditions, high spectral efficiency, low-delay for the sake of supporting interactive real-time multimedia services, high-capacity networking, and so forth [5]. In this paper, we will address a few of these issues in the context of direct sequence code division multiple access [6] (DS-CDMA) systems, 1 since CDMA is the solution standardized in all three recently ratified global mobile 1 The simple philosophy of DS-CDMA is that a binary bit of a user is signaled to the receiver with the aid of a unique, user-specific signature sequence. The DS spreading sequences may be chosen such that they are orthogonal to each other; hence, the individual users' signals do not interfere with each other, provided that the transmission channel does not destroy the orthogonality of the DS spreading sequences. When the orthogonality of the DS spreading codes is retained at the receiver, no MUI is inflicted; hence, a simple correlator is capable of detecting the codes of the users conveying the information with the aid of the code's polarity. By contrast, if the...

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Combinations of an adaptive array antenna and a canceller of interference for direct-sequence spread-spectrum multiple-access system

Cited by 233 publications

References 4 publications

Interference management for CDMA systems through power control, multiuser detection, and beamforming

Interference management for CDMA systems through power control, multiuser detection, and beamforming

Adaptive multiuser detection and beamforming for interference suppression in CDMA mobile radio systems

Burst-by-burst adaptive multiuser detection cdma: a framework for existing and future wireless standards

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