Training sequence based multiuser channel identification for cochannel interference cancellation in GSM

Trigui, Hafedh; Slock, Dirk

doi:10.1109/spawc.1999.783029

Cited by 8 publications

(4 citation statements)

References 8 publications

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“…In [60][61][62], the authors develop an interference cancelling matched filter by using known training sequences. In [63], the authors investigate the cancellation of unwanted interfering signals based on second-order statistics.…”

Section: Filtering Methodsmentioning

confidence: 99%

Joint Demodulation of Low-Entropy Narrowband Cochannel Signals

Meehan¹,

Kragh²,

Clark³

2007

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government.Approved for public release; distribution is unlimited.Reception of one or more signals, overlapping in frequency and time with the desired signal, is commonly called cochannel interference. Joint detection is the optimal minimum probability of error decision rule for cochannel interference. This dissertation investigates the optimum approach and a number of suboptimum approaches to joint detection when a priori information based in fields, or sets of transmitted symbols, is available. In the general case the solution presents itself as a time-varying estimation problem that may be efficiently solved with a modified Bahl, Cocke, Jelinek and Raviv (BCJR) algorithm. The low-entropy properties of a particular signal of interest, the Automatic Identification System (AIS), are presented. Prediction methods are developed for this signal to be used as a priori information for a joint field-based maximum a posteriori (MAP) detector. Advanced joint detection techniques to mitigate cochannel interference are found to have superior bit error rate (BER) performance than can be obtained compared to traditional methods. ABSTRACTReception of one or more signals, overlapping in frequency and time with the desired signal, is commonly called cochannel interference. Joint detection is the optimal minimum probability of error decision rule for cochannel interference. This dissertation investigates the optimum approach and a number of suboptimum approaches to joint detection when a priori information based in fields, or sets of transmitted symbols, is available. In the general case the solution presents itself as a time-varying estimation problem that may be efficiently solved with a modified Bahl, Cocke, Jelinek and Raviv (BCJR) algorithm.

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Section: Filtering Methodsmentioning

confidence: 99%

Joint Demodulation of Low-Entropy Narrowband Cochannel Signals

Meehan¹,

Kragh²,

Clark³

2007

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“…Recall that our receiver assumes arbitrary offset, and thus considers the symbols that interfere with the training sequence initially unknown. Under the constraint of jN rel j45, the receiver can be further improved by exploiting the knowledge of the N m À jN rel j overlapping symbols of known training sequences [18]. Initial channel estimates can be obtained by applying the least squares method (Equation 5) on the overlapping parts of midambles.…”

Section: Bit Error Rate Performancementioning

confidence: 99%

“…We consider a scenario in which two mobile users are served on the same physical channel. A similar problem has been addressed in [18], where it was assumed that co-channel users are served by different interfering base stations, which are synchronized and cover cells small enough so that the two signals are almost completely aligned in time. In current GSM systems, however, no synchronization among base stations is employed [19].…”

Section: Introductionmentioning

confidence: 99%

Co‐channel interference mitigation in GSM networks by iterative estimation of channel and data

Loncar

Mecklenbräuker

Müller

2003

Trans Emerging Tel Tech

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SUMMARYIn multiple-access communication systems several users share the system resources, thus creating cochannel interference to each other. Multiuser detection, applied at the receiver side, is a powerful technique to combat co-channel interference, in contrast to single-user approaches that treat the interference as additive noise. In this paper, we investigate the feasibility of achieving increased spectral efficiency in GSM-like TDMA networks by applying multiuser detection. We focus on downlink operation and consider two mobile users that share the same physical channel within the same cell or in two adjacent cells. No synchronization between the base stations is assumed. Mobile terminals exploit multiple receiving antennas. We propose a simple iterative receiver algorithm that performs joint channel and data estimation. Results of simulations that evaluate the receiver's performance are presented.

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“…The channel estimation is the critical part in the ICMF and especially in the second branch (i.e. blocking equalizers branch) where we used a linear parameterization of the noise subspace in terms of the unstructured channel impulse response coefficients [3,4]. When the quality of the channel estimate is not good enough (in a high interference scenarios such as the soft handover) because only a short training sequence is available at the mobile terminal, the blocking equalizers passes a significant part of the desired signal which degrades significantly the performance of the Wiener filter.…”

Section: Interference-canceling Matched Filter (Icmf) Introduced In [2]mentioning

confidence: 99%

Semi-blind downlink inter-cell interference cancellation for FDD DS-CDMA systems

Trigui¹,

Fischer²,

Slock³

Conference Record of the Thirty-Fourth Asilomar Conference on Signals, Systems and Computers (Cat. No.00CH37154)

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We adress the problem of downlink interference rejection in a DS-CDMA system Periodic orthogonal WalshHadamard sequences spread different users' symbols followed by scrambling by a symbol aperiodic base-station specific overlay sequence. The point-to-point propagation channel from the cell-site to a certain mobile station is the same for all downlink signals (desired user as well as the intracell interference). The intercell interference (which can be seen as co-channel interference) degrades signif icantly the performance of the receiver when the mobile approaches the edge of its cell and the situation becomes more critical at the so# handovel: We propose to simultaneously equalize the user of interest while canceling (or reducing) the intercell inte ferers by the Interference Canceling Matched Filter (ICMF) receiver which we introduced previously. We can get ride of the intracell interference by the maximum SINR receiver following the ICME The ICMF depends on the common channel for the cell of interest, to be estimated with a pilot sequence, and contains a blind interference cancellation part. The critical part is the channel estimation. The usual correlation method may lead to poor estimates in high interference environments. Signifcant improvements result from the exploitation of the sparceness of the propagation channel model.

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Training sequence based multiuser channel identification for cochannel interference cancellation in GSM

Cited by 8 publications

References 8 publications

Joint Demodulation of Low-Entropy Narrowband Cochannel Signals

Joint Demodulation of Low-Entropy Narrowband Cochannel Signals

Co‐channel interference mitigation in GSM networks by iterative estimation of channel and data

Semi-blind downlink inter-cell interference cancellation for FDD DS-CDMA systems

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