CiteULike: dcastro's acquisition

Selection of the multiple-dwell hybrid-search strategy for the acquisition of Galileo signals in fading channels

ES Lohan — 2008-07-24T11:59:26-00:00

Personal, Indoor and Mobile Radio Communications, 2004. PIMRC 2004. 15th IEEE International Symposium on, Vol. 4 (2004), pp. 2352-2356 Vol.4.

The acquisition of CDMA signals in adverse mobile communication channels has been studied for more than five decades. However, the introduction of new standard proposals for the future European satellite system (i.e., Galileo) and for the modernized GPS has triggered new interest in fast and reliable acquisition strategies for CDMA systems with very high spreading factors (e.g., length of 10230 chips or higher). Typically, the double-dwell serial search strategies have been preferred for CDMA signal acquisition. Few papers have addressed also the problem of hybrid and parallel search strategies, but typically, the choice of the best number of dwells has not been discussed. The goal of this paper is to introduce a generic method for the computation of the mean acquisition time (MAT) for multiple-dwell hybrid-search acquisition blocks and to compare the performance of several multiple-dwell structures for CDMA systems with high spreading factors. It will be shown here that increasing the number of dwells does not always increase the performance from the point of view of the MAT. We also discuss the influence of various parameters on the selection of the multiple-dwell strategy and we present simulation results for a realistic Galileo signal.

Frequency acquisition and tracking for mobile LEO satellite communications

Yu Su — 2008-07-23T22:23:01-00:00

Vehicular Technology Conference, 1997 IEEE 47th, Vol. 3 (1997), pp. 1738-1742 vol.3.

A class of recursive frequency acquisition and tracking algorithms for use in high dynamic mobile low Earth orbit (LEO) satellite communication systems is proposed. The underlying principle of these algorithms is to apply the least-squares method to the reconstructed phase trajectories to estimate and predict the received frequency variations (Doppler frequency, Doppler rate, etc.). We consider both additive white Gaussian noise (AWGN) and Rician fading channels and analyze the corresponding mean squared errors (MSE). The numerical performance of the proposed algorithms demonstrates that the new frequency tracking algorithms not only has rapid acquisition times but also gives smaller tracking jitters

On DS-SS code acquisition time probability distribution-Serial search by multiple-dwell detector in fading channel

J Simsa — 2008-07-23T22:23:03-00:00

Spread Spectrum Techniques and Applications, 1998. Proceedings., 1998 IEEE 5th International Symposium on, Vol. 2 (1998), pp. 464-468 vol.2.

The complete description of code acquisition time is given by its probability distribution. In the contribution, serial search multiple-dwell code acquisition of a direct sequence spread spectrum receiver is analyzed and acquisition time probability distribution is derived using its moment generating function. The method is applied to a nonselective fading channel, which causes the amplitude of a random received signal. The probability distribution is expressed as an average over a given amplitude probability distribution

Frequency acquisition and tracking in high dynamic environments

Yu Su — 2008-07-23T22:23:20-00:00

Vehicular Technology, IEEE Transactions on, Vol. 49, No. 6. (2000), pp. 2419-2429.

This paper presents mean squared error (MSE) analysis of two classes of frequency acquisition and tracking algorithms. Additive white Gaussian noise as well as Rician fading channels are considered. The class of batch-processing algorithms is an extension of earlier least squares proposals used in more benign (lower dynamic) environments. These algorithms try to fit the phase trajectory of the down-converted samples of a received signal. Such a trajectory will depend on the histories of both the signal and the local frequency variations when the local frequency is updated recursively. We propose a method to solve this difficulty and present both first-order and second-order recursive algorithms. Numerical results demonstrate that the MSE performance predicted by our analysis is consistent with that estimated by computer simulation and that the proposed algorithms not only provide rapid acquisition times but also give small tracking jitters

Direct P-code Acquisition Based on FFT

Lian Baowang — 2008-06-15T13:46:35-00:00

Communication Technology, 2006. ICCT '06. International Conference on (2006), pp. 1-4.

This paper is a brief study of the Global Positioning System (GPS) P-code acquisition based on FFT. P-code has a higher chipping rate, better accuracy and anti-jamming property than C/A code. When C/A code is not available, direct P-code acquisition is useful. In this paper, the implementation on FPGA and DSP board proves that the technique using FFT (Fast Fourier Transform) has greatly reduced the acquisition times and calculations.

Fast direct GPS P-Code acquisition

Jing Pang — 2008-06-13T08:37:37-00:00

GPS Solutions, Vol. 7, No. 3. (1 December 2003), pp. 168-175.

GPS P-Code has a higher chipping rate, better accuracy, and anti-jamming property than C/A code. Traditionally, GPS P-Code acquisition depends on handover from C/A code. This potentially needs long acquisition time. Moreover, when C/A code is not available, it is no longer possible to acquire GPS P-Code through handover from C/A code. The purpose of this paper is to describe a new overlap average method to facilitate hardware design of fast direct P-Code acquisition. It allows the rapid code phase search to acquire GPS P-Code signals, and also decreases the hardware resource requirement. The small size FFT in the proposed methods is very promising for fast FPGA hardware system design using FFT cores. The simulation results and theoretical analysis are included demonstrating the overall performance of the proposed method.

Corrections to, and comments on, "an improved approximation for the Gaussian Q-Function"

JS Dyer — 2008-06-11T20:27:13-00:00

Communications Letters, IEEE, Vol. 12, No. 4. (2008), pp. 231-231.

In a recent letter, Karagiannidis and Lioumpas (see ibid., vol.11, no.8, p.644-6, Aug. 2007) proposed a new approximation for the Gaussian Q-function. We provide corrections to two equations, corrected entries to a table, and an alternative to a figure in the letter, as well as a few comments.

DS-CDMA code acquisition in the presence of correlated fading-part II: application to cellular networks

C Caini — 2008-06-11T20:26:44-00:00

Communications, IEEE Transactions on, Vol. 52, No. 8. (2004), pp. 1397-1407.

This paper applies the theoretical framework for the evaluation of code acquisition in the presence of fading developed in the companion Part I paper. Code synchronization for code-division multiple-access (CDMA) cellular networks, such as IS-95 and cdma2000, is considered. A multidwell testing procedure is adopted. Notably, a procedure for the optimization of the multidwell parameters (number of dwells, dwell lengths, thresholds) to achieve minimum acquisition time is introduced and enforced. The effects of fading, interchip interference (ICI), frequency offset, multiple-access interference, and noise are taken into account in the determination of false alarm and detection probabilities. In particular, anomalous ICI despreading and internal interference-cancellation effects are described. Numerical and simulation results, in terms of time for correct acquisition, confirm the accuracy of the proposed approach and show how it can be effectively used in the design and evaluation of a code-acquisition subsystem.

DS-CDMA code acquisition in the presence of correlated fading - Part I: theoretical aspects

GE Corazza — 2008-06-11T20:26:05-00:00

Communications, IEEE Transactions on, Vol. 52, No. 7. (2004), pp. 1160-1168.

This paper deals with the analysis of the code-acquisition process performed by a mobile terminal in a code-division multiple-access cellular system. The fundamental contribution is the setting of a theoretical framework for code-acquisition analysis, accounting for the presence of fading and shadowing with specified coherence time. A multidwell architecture is considered, accounting for different verification strategies. The MAX/TC detection criterion is used, and the acquisition performance is analyzed, following both the direct and flow-graph approaches. Expressions for the acquisition time probability density function under different assumptions are given, as well as closed-form expressions for the mean and variance of the acquisition time. Practical applications and numerical results are reported in the Part II companion paper.

Comparison of generalized Q- function algorithms (Corresp.)

P Cantrell — 2008-06-11T20:18:08-00:00

Information Theory, IEEE Transactions on, Vol. 33, No. 4. (1987), pp. 591-596.

Several methods have been proposed for calculating the generalized<tex>Q</tex>-function<tex>Q_m(alpha, beta)</tex>, but only isolated comparisons of the various techniques have been reported. The accuracy, range, and execution time of prominent methods for computing the<tex>Q</tex>-function are compared, and limitations of the algorithms are identified.

Automated threshold control for acquisition in spread spectrum packet radio communication

ZL Shi — 2008-06-09T19:24:46-00:00

Communications, 1993. ICC 93. Geneva. Technical Program, Conference Record, IEEE International Conference on, Vol. 1 (1993), pp. 478-482 vol.1.

A novel automated threshold control (ATC) scheme for acquisition in direct-sequence spread-spectrum packet radio systems using a matched filter receiver is described. For received packets with different SNRs, the ATC algorithm is able to find a desired threshold value in one pseudonoise code period such that the probability of false acquisition is minimized and the probability of correct acquisition is maximized. It is shown that the proposed AT acquisition scheme is robust for receiving packets with a large amplitude dynamic range. Compared with the conventional constant threshold acquisition scheme, the new scheme only needs a few more logic units and a small memory unit for its implementation. A potential application of this algorithm is for code division multiple access (CDMA) systems where the equivalent SNRs of received packets fluctuate according to the amount of cochannel interference

Parallel acquisition of PN sequences in DS/SS systems

KK Chawla — 2008-06-09T19:24:39-00:00

Communications, IEEE Transactions on, Vol. 42, No. 5. (1994), pp. 2155-2164.

The authors investigate methods for the parallel acquisition of a PN sequence in a baseband direct sequence spread spectrum system. Four different schemes are considered: the optimal estimation scheme, the maximum-likelihood estimation scheme, a hypothesis-testing scheme that searches over all shifts, and a locally optimum detection scheme. Approximate expressions for the probability of error are derived for the first and last of these schemes and compared with the actual error probabilities obtained via Monte Carlo simulation. Monte Carlo simulation is also used to obtain the error probabilities of the other two schemes and the results for all the schemes are compared. Since the obvious methods of implementing a parallel acquisition scheme require large amounts of hardware or excessive computation, they outline a technique that can be used to reduce the amount of computation

A novel up-link code-acquisition procedure based on a structured preamble sequence

M Villanti — 2008-06-09T13:56:48-00:00

Spread Spectrum Techniques and Applications, 2004 IEEE Eighth International Symposium on (2004), pp. 588-592.

A novel up-link one-shot code acquisition procedure is proposed based on a structured preamble sequence. The general strategy is applied to the context of third generation satellite networks. A multi-dwell approach is introduced to simplify the detection of a long preamble. The parallel detection of the two basic sequences forming the preamble is coordinated by a novel HLC (high level controller). Passive and active differential post detection integrations are selected to perform detection during the search and verification phases, respectively. Performance is evaluated and optimized with respect to the most significant system parameters.

Acquisition for Satellite UMTS with Large Frequency Offsets

MC Reed — 2008-06-03T18:59:20-00:00

This paper discusses the implementation of signal acquisition for Satellite UMTS, where the frequency offset is of similar size to that of the symbol rate. The entire frequency compensation and signal acquisition process is explained before an explanation of the correlating acquisition process is detailed. The resultant method provides low complexity while providing a very efficient implementation.

Acquisition Behavior of a First-Order Digital Phase-Locked Loop

W Lindsey — 2008-05-22T09:06:39-00:00

Communications, IEEE Transactions on [legacy, pre - 1988], Vol. 26, No. 9. (1978), pp. 1364-1370.

A general "phase-plane" technique for investigating the stability of nonlinear difference equation is described and applied to determine the stability criterion of a first-order digital phase-locked loop (DPLL). If the loop is stable, it is shown that acquisition behavior can be modeled as a first passage time problem. Using this model, one can evaluate the acquisition probability and the mean time to acquire, from the appropriate Chapman-Kolmogorov (C-K) equation describing the transition of the phase error sequence. This approach is verified by direct simulation.

Acquisition and Tracking

2008-05-21T09:32:52-00:00

Phase-Locked Loops for Wireless Communications (2002), pp. 113-137.

Properties Of The Half-Normal Distribution And Its Application To Quality Control

Chao-Yu Chou — 2008-05-19T19:39:02-00:00

The Official Electronic Publication of the National Association of Industrial Technology (1998)

GPS receiver search techniques

PW Ward — 2008-05-18T14:07:47-00:00

Position Location and Navigation Symposium, 1996., IEEE 1996 (1996), pp. 604-611.

GPS receivers must perform a two-dimensional sequential search process for the GPS signals. The two-dimensional search pattern consists of discrete search cells with each cell representing one code bin and one carrier Doppler bin. The code bin width is usually ½-half chip. The longer the dwell time per binary decision (the predetection integration time), the narrower the Doppler bin width and weaker GPS signals can be acquired, but the search time increases. The replica C/A-code generates larger than normal sidelobes if the Doppler bin is too wide (when predetection integration time is too short), False acquisition of the sidelobes can occur if the search threshold is set too low. At the heart of the receiver search process is the search detector. There are significant performance differences between search detector algorithms. This paper describes, analyzes and compares two powerful sequential search algorithms: the fixed-dwell-time M-of-N detector and the variable dwell time Tong detector (1973)

The Acquisition Process of a Maximum Likelihood GPS Receiver

Progri — 2008-05-18T12:45:37-00:00

Proc. Institute of Navigation GPS 2003 (2003)

Advanced Code Acquisition Techniques

2008-05-16T11:38:34-00:00

Scrambling Techniques for CDMA Communications (2002), pp. 41-82.

A noncoherent sequential PN code acquisition scheme in DS/SS receivers

Jia-Chin Lin — 2008-05-16T11:35:46-00:00

Global Telecommunications Conference, 1998. GLOBECOM 98. The Bridge to Global Integration. IEEE, Vol. 4 (1998), pp. 2168-2173 vol.4.

A noncoherent sequential PN code acquisition technique is proposed. Noncoherent detection is employed to handle the seriously noisy environments, while the carrier frequency offset and data modulation effects can be simultaneously taken care of. To realize the sequential acquisition, the out-of-phase and in-phase sequences are properly modeled to avoid the significantly high error probabilities caused by the conventional widely used zero sequence model. Extensive computer simulation results indicated that the proposed PN code acquisition outperforms the fixed-dwell-time counterparts by roughly 2-6 dB with much lower false alarm and miss probabilities, and the superiority of the proposed technique becomes more significant at lower SNR conditions

Rapid acquisition of PN sequences with a new decision logic

Jung Lee — 2008-05-15T18:51:28-00:00

Vehicular Technology, IEEE Transactions on, Vol. 53, No. 1. (2004), pp. 49-60.

In this paper, a fast acquisition scheme of pseudonoise (PN) sequences for direct-sequence spread-spectrum systems is proposed. The scheme exploits a new decision logic not only to estimate chip values, but also to check the reliability of the chip estimates. As a result, the internal state of a PN sequence generator is estimated more accurately. We derive the probability of finding a correct state estimate and show that the proposed scheme can reduce the average number of chips for acquisition when compared with the conventional scheme. It is also shown that the performance improvement is more noticeable in the moderate signal-to-noise-ratio range.

Noncoherent hybrid acquisition of DS/CDMA signals

GS Hosangadi — 2008-05-15T18:51:26-00:00

Military Communications Conference, 1996. MILCOM '96, Conference Proceedings, IEEE, Vol. 3 (1996), pp. 988-992 vol.3.

A noncoherent signal acquisition scheme using hybrid active correlation for a direct sequence code division multiple access (DS/CDMA) receiver is presented. A test based on sequential hypothesis testing called the M-ary sequential probability ratio test (MSPRT) and several fixed sample size (FSS) tests are considered for the testing stage. Continuous integration of in-phase and quadrature signal components is used to minimize noncoherent combining losses. The MSPRT is adapted accordingly to accommodate dependent samples from the integrator output. Results of analysis and simulation show that the IMSPRT provides significantly better performance than the FSS schemes. It has been found that use of the IMSPRT with continuous integration results in negligible noncoherent implementation loss (compared to coherent acquisition) when a moderate number of correlators are used

Pipelined sequential acquisition in a direct sequence spread spectrum communication system

GS Hosangadi — 2008-05-15T18:51:24-00:00

Personal Wireless Communications, 1997 IEEE International Conference on (1997), pp. 189-193.

Direct sequence spread spectrum (DS/SS) technology has been proven very useful in various mobile communication and global positioning systems. In order to exploit the advantages of a DS/SS signal the receiver must first be to able synchronize the local pseudonoise (PN) code with the received PN code. This is usually done in two steps: acquisition and tracking. First, the acquisition process coarsely aligns the two PN codes to within a fraction of a chip duration. The tracking circuit then takes over and performs fine adjustment until the desired accuracy is achieved. Hybrid acquisition schemes have been shown to provide a useful tradeoff between the low complexity of serial schemes and the high speed of parallel schemes. We compare two hybrid active schemes both using sequential tests at the testing stage. The first scheme uses a test based on the M-ary sequential probability ratio test (MSPRT), while the second scheme uses a test based on the sequential probability ratio test (SPRT) that utilizes M SPRTs operating independently. The latter scheme can be viewed as a form of pipelining. Both coherent and noncoherent acquisition are considered. The system and channel models are presented, and the sequential decision rules and numerical results are given

An FFT-Based Approach for Fast Acquisition in Spread Spectrum Communication Systems

Sascha Spangenberg — 2008-05-15T18:51:07-00:00

Wireless Personal Communications, Vol. 13, No. 1. (1 May 2000), pp. 27-55.

This paper describes a non-coherent technique forfast acquisition of direct sequence spread spectrum(DS/SS) signals in low earth orbit (LEO) satellitecommunication scenarios. Large Doppler offsets areinherent to such environments and are likely to causemajor problems during the code acquisition phase dueto the introduced frequency ambiguity. In the presentpaper we discuss the use of a set of partialcorrelators for code phase acquisition, combined witha fast Fourier transform (FFT) for the purpose of simultaneous Doppler estimation. We will show that theuse of this architecture largely accelerates thesynchronisation process compared to conventionaltechniques over a wide range of Doppler offsets.Furthermore we discuss the implementation of azero-padded FFT that increases the frequencyresolution to such an extent, that acquisition timesidentical to scenarios without existing Doppler offsetcan be achieved.

Parallel acquisition of PN sequences in Rayleigh fading channel and the application to the multi-carrier CDMA systems

June Moon — 2008-05-15T18:49:52-00:00

Personal, Indoor and Mobile Radio Communications, 2001 12th IEEE International Symposium on, Vol. 2 (2001), pp. G-6-G-10 vol.2.

We propose an improved scheme for parallel acquisition of PN sequences of multi-carrier direct-sequence spread spectrum systems in the Rayleigh fading channel. Unlike conventional parallel acquisition schemes, the search region of each searcher in the proposed scheme is modified so that it is overlapped with that of other searchers. The use of the proposed search scheme enables us to obtain multiple information on the same code phase at different time instants, providing the time diversity effect. This effect results in acquisition performance robust to fading. The performance of the proposed acquisition scheme is analytically evaluated in terms of the detection probability and the mean acquisition time in the Rayleigh fading channel. Numerical results show that the proposed scheme can provide acquisition performance robust to channel conditions, including fading and correlation between the subchannels

Noncoherent sequential PN code acquisition using sliding correlation in DS/SS

Jia-Chin Lin — 2008-05-15T18:49:50-00:00

Communications, 2000. ICC 2000. 2000 IEEE International Conference on, Vol. 1 (2000), pp. 341-345 vol.1.

Noncoherent sequential PN code acquisition using sliding correlation is proposed. Noncoherent detection and chip asynchronization is taken into consideration, while frequency offset and data modulation can be simultaneously taken care of. To realize the sequential detection, the integrate/dump (I/D) cross-correlation under out-of-lock has to be modeled as a Gaussian random sequence to avoid the significantly high false alarm probabilities caused by the conventional zero sequence model. Extensive computer simulation results indicated that the proposed PN code acquisition can achieve low false alarm and missing probabilities

New Code Acquisition Techniques in Spread-Spectrum Communication

A Elhakeem — 2008-05-15T18:49:48-00:00

Communications, IEEE Transactions on [legacy, pre - 1988], Vol. 28, No. 2. (1980), pp. 249-257.

New techniques for acquiring the codes used in frequency hopping (FH), hybrid frequency hopping/time hopping (FH/TH), and frequency hopping/direct sequence (FH/DS) spread-spectrum systems are presented. Autoregressive spectral estimation is employed to recover the FH code, quadrature processing is used for the DS code, while the TH gating code is recovered by a simple threshold test used in conjunction with the adaptive filter used for the spectral estimation. A wide margin of spectral estimation errors can be tolerated since an acquisition logic is used to estimate the FH code phase. The proposed techniques require acquisition times only of the order of the shift-register generator lengths, whereas other schemes of serial and parallel search require acquisition times of the order of the code lengths. Detailed simulation results will identify the working carrier-to-noise ratio (CNR) range for the different techniques presented as well as the various thresholds involved.

Doppler estimation for fast acquisition in spread spectrum communication systems

PM Grant — 2008-05-15T18:49:47-00:00

Spread Spectrum Techniques and Applications, 1998. Proceedings., 1998 IEEE 5th International Symposium on, Vol. 1 (1998), pp. 106-110 vol.1.

This paper describes a non-coherent technique which employs a fast Fourier transform (FFT) for the fast acquisition of direct sequence spread spectrum signals in the presence of large Doppler shifts. The application of an FFT to code acquisition results in decreased acquisition time and can improve the probability of detection. The technique discussed in this paper uses a set of partial correlators and a zero-padded FFT to reduce the search region for code acquisition whilst maintaining good frequency resolution for Doppler offset. This approach will prove most pertinent in future re-configurable terminals

Direct sequence spread spectrum parallel acquisition in a fading mobile channel

E Sourour — 2008-05-15T18:37:52-00:00

Vehicular Technology Conference, 1989, IEEE 39th (1989), pp. 774-779 vol.2.

The acquisition performance of a direct-sequence spread-spectrum system is investigated in a fading mobile environment. A parallel acquisition scheme is applied to make up for the effect of the fading environment on key parameters such as the probability of detection, the probability of false alarm, and the mean acquisition time. An expression for the mean acquisition time is derived in terms of detection, false alarm, and missing probabilities. These probability expressions are derived in both a nonfading and fast-fading AWGN (additive white Gaussian noise) channels, and the mean acquisition time is shown for nonfading, slow-fading, and fast-fading channels. It is shown that in a nonfading channel, the designer should choose the MF (matched filter) length as large as practically possible and then cover the rest of the uncertainty region with parallel MFs. The same applies for the slow-fading channel. In fast-fading channels the contrary is the right choice; for better performance the designer needs to increase parallelism at the cost of MF length

Variable dwell-time code acquisition for direct-sequence spread-spectrum systems on time-variant Rayleigh fading channels

Huan-Chun Wang — 2008-05-15T18:37:51-00:00

Communications, IEEE Transactions on, Vol. 48, No. 6. (2000), pp. 1037-1046.

Variable dwell-time code acquisition based on multiple-dwell or sequential linear tests is investigated for direct-sequence spread-spectrum systems on time-variant Rayleigh fading channels. Unlike in the conventional additive white Gaussian noise channels, the channel memory incurred by fading renders the exact analysis of the acquisition systems extremely difficult, if not impossible. In this paper, a novel method is developed to evaluate the mean acquisition time of the acquisition systems very accurately. The effects of Rayleigh fading are evaluated, and comparisons are made between double-dwell and sequential linear tests. Numerical results show that Rayleigh fading may result in 1-4-dB loss in performance, and the sequential linear test can outperform double-dwell test by a margin of 1-2 dB. The analytical results are verified by computer simulations

Direct sequence spread spectrum serial acquisition in a nonselective and frequency selective Rician fading channel

E Sourour — 2008-05-15T18:37:48-00:00

Military Communications Conference, 1990. MILCOM '90, Conference Record, A New Era. 1990 IEEE (1990), pp. 171-175 vol.1.

The mean acquisition time performance of a straight, serial-search direct-sequence spread spectrum (DS-SS) acquisition system, operating in nonselective and frequency-selective Rician fading channels is analyzed. The system was proposed by Polydoros and Weber (1984), and its performance is analyzed for a nonfading channel, at which all the cells that fall under hypothesis <e1>H</e1>o are statically identical. This is not the case for the Rician fading channel. A signal flow graph for which the <e1>H</e1>o cells are not identical is used to derive an expression for the mean acquisition time in terms of the probabilities of detection and false alarm. These probabilities are then derived for the nonselective and frequency selective Rician fading channels. The results show the effect of the channel and system parameters on the mean acquisition time performance

Optimal decision strategies for acquisition of spread-spectrum signals in frequency-selective fading channels

RR Rick — 2008-05-15T18:37:39-00:00

Communications, IEEE Transactions on, Vol. 46, No. 5. (1998), pp. 686-694.

The focus of this paper is on the initial acquisition of a direct sequence (DS) spread-spectrum signal utilizing a purely parallel search strategy. A parallel search strategy is utilized because it reduces the acquisition time compared to either serial or partially parallel strategies. In particular, the purpose of this paper is to derive the optimal decision rule, based on the maximum-likelihood criterion, for frequency-selective fading channels. The performance of the conventional decision rule, optimized for additive white Gaussian noise and flat-fading channels, the optimal decision rule derived, and a suboptimal decision rule, also presented in this paper, are compared. It is shown that the optimal and suboptimal decision rules for Rayleigh-fading channels outperform the conventional decision rule. For Rician-fading channels, it is shown both that the optimal decision rule outperforms the conventional decision rule, and that the optimum decision rule for Rayleigh-fading channels, when implemented on a Rician-fading channel, yields approximately optimum performance

Multiple Dwell Serial Search: Performance and Application to Direct Sequence Code Acquisition

D Dicarlo — 2008-05-15T18:32:43-00:00

Communications, IEEE Transactions on [legacy, pre - 1988], Vol. 31, No. 5. (1983), pp. 650-659.

The technique of multiple dwell serial search is described and analyzed. The advantage of the multiple dwell procedure is that the examination interval need not be fixed, allowing incorrect cells to be quickly discarded, which in turn results in a shorter search time than is possible with a fixed dwell time procedure. This type of search scheme is particularly useful for direct sequence code acquisition in a spread-spectrum communication system. An expression for the generating function is obtained from a flow graph representation of the multiple dwell technique. The generating function is used to develop expressions for the mean and variance of the search time in terms of the following parameters: the dwell times, the detection probability, the false alarm probability, and the false alarm penalty time. Coherent detector characteristics are then used to investigate the performance of the multiple dwell technique for direct sequence code acquisition. It is shown that the multiple dwell procedure can significantly reduce the expected acquisition time from that obtained with a single dwell system. The most significant improvement is obtained by using a two-dwell system. Additional but nominal improvement is gained when more than two dwells are employed.

CDMA downlink code acquisition performance in frequency-selective fading channels

M Latva-Aho — 2008-05-15T18:22:24-00:00

Personal, Indoor and Mobile Radio Communications, 1998. The Ninth IEEE International Symposium on, Vol. 3 (1998), pp. 1476-1480 vol.3.

In this paper, the performance of some code acquisition schemes are studied in the downlink of DS-CDMA systems. The conventional matched filter, the minimum variance method, the MUSIC algorithms and the eigenvector method based delay acquisition schemes are studied in a frequency-selective fading channel. The three last algorithms are based on different estimation schemes for the inverse of the sample-covariance matrix. Based on the results, the minimum variance based method can be used to improve the acquisition performance in comparison to the conventional non-coherent matched filter method. The MUSIC algorithm becomes useless in highly loaded systems. The best performance, however, was obtained by using a longer despreading interval in the conventional delay estimator. Unfortunately, it would require either unmodulated pilot channel or a control channel with lower data rate, which may not be available in all applications

Adaptive PN code acquisition using instantaneous power-scaled detection threshold under Rayleigh fading and pulsed Gaussian noise jamming

Kwonhue Choi — 2008-05-15T18:22:20-00:00

Communications, IEEE Transactions on, Vol. 50, No. 8. (2002), pp. 1232-1235.

An adaptive serial search pseudonoise (PN) code acquisition scheme is proposed, in which the detection threshold is scaled by the instantaneous received power measured prior to PN code correlation. We observe that the proposed scheme achieves significantly improved mean acquisition times compared to the conventional nonadaptive schemes under Rayleigh fading and pulsed Gaussian noise jamming. Furthermore, the proposed scheme is shown to be optimum under pulsed Gaussian noise jamming in the sense that it forces the worst case jamming fraction to unity.

Spread-spectrum signal acquisition: Methods and technology

S Rappaport — 2008-05-15T18:22:18-00:00

Communications Magazine, IEEE, Vol. 22, No. 6. (1984), pp. 6-21.

A PN Code Acquisition Scheme in the Presence of Data Modulation and Doppler Shift

Zhi-Jun Chen — 2008-05-15T18:22:16-00:00

Machine Learning and Cybernetics, 2007 International Conference on, Vol. 5 (2007), pp. 2653-2656.

A PN (pseudo noise) code acquisition scheme for direct sequence spread spectrum (DSSS) systems is developed in this paper, which is especially suitable for the simultaneous presence of various rate data modulation and wide Doppler shift range at low signal-to-noise ratio. The technique is based on FFT and noncoherent integration, and can be implemented easily with less hardware cost. Some computer simulation results are given, which show that the technique can achieve fast PN acquisition and obtain carrier Doppler frequency estimation.

A New DS/CDMA Code Acquisition Scheme for Reducing the Effect of Residual Code Phase Offset

Seokho Ju — 2008-05-15T18:22:13-00:00

When the code phase offset between two sequences is within one chip duration, the sum of two successive matched filter outputs has a constant value regardless of the residual code phase offset if the noise is absent. Based on this observation, we propose a new code acquisition scheme, which is robust to the variation of the residual code phase offset and outperforms the conventional scheme. Numerical results are also given to show that the proposed scheme is more robust to the variation of the...

Note on `The calculation of the probability of detection and the generalized Marcum Q-function'

DA Shnidman — 2008-05-15T17:57:15-00:00

Information Theory, IEEE Transactions on, Vol. 37, No. 4. (1991), 1233.

The author presents corrections to his original paper (see ibid., vol.35, no.2, p.389-400, 1989). The corrections concern computational cases using the steepest descent integration technique. It is pointed out that, for certain specific parameter ranges, the calculation error is too large to be accounted for by accumulated round-off error

Analysis of a multicarrier DS-CDMA code-acquisition system

Dongwook Lee — 2008-05-15T17:57:12-00:00

Communications, IEEE Transactions on, Vol. 47, No. 8. (1999), pp. 1233-1244.

We present two code-acquisition schemes for a multicarrier direct-sequence code-division multiple-access system, one that uses equal gain combining and the other that uses selection combining. The code-acquisition performance of the two multicarrier systems, as well as that of a single-carrier system, are analyzed in both nonfading and Rayleigh fading channels under the assumption that the receiver is chip-synchronized; the effect of partial-band interference (PBI) on the performance is also included. It is demonstrated that in an additive white Gaussian noise channel, the single-carrier system has a better code-acquisition performance than both multicarrier systems. However, in a Rayleigh fading channel, the code-acquisition performance of a multicarrier system with equal gain combining is better than that of the single-carrier system, while a multicarrier system with selection combining has the same performance as the single-carrier system. Further, the presence of PBI more severely affects the code-acquisition performance of the single-carrier system than those of both multicarrier systems. Finally, the code-acquisition performance of a multicarrier system with equal gain combining is always better than that of the selection combining system

A new twist on the Marcum Q-function and its application

MK Simon — 2008-05-15T17:57:01-00:00

Communications Letters, IEEE, Vol. 2, No. 2. (1998), pp. 39-41.

A new form of the Marcum (1950) Q-function is presented that has both computational and analytical advantages. The new form is particularly useful in simplifying and rendering more accurate the analysis of the error probability performance of uncoded and coded partially coherent, differentially coherent, and noncoherent communication systems in the presence of fading. It also enables simple upper and lower bounds to be found analogous to the Chernoff bound on the Gaussian Q-function

New bounds for the Marcum Q-function

GE Corazza — 2008-05-15T17:56:58-00:00

Information Theory, IEEE Transactions on, Vol. 48, No. 11. (2002), pp. 3003-3008.

New bounds are proposed for the Marcum Q-function, which is defined by an integral expression where the 0th-order modified Bessel function appears. The proposed bounds are derived by suitable approximations of the 0th-order modified Bessel function in the integration region of the Marcum Q-function. They prove to be very tight and outperform bounds previously proposed in the literature. In particular, the proposed bounds are noticeably good for large values of the parameters of the Marcum Q-function, where previously introduced bounds fail and where exact computation of the function becomes critical due to numerical problems

Integral representation and bounds for Marcum Q-function

M Chiani — 2008-05-15T17:56:57-00:00

Electronics Letters, Vol. 35, No. 6. (1999), pp. 445-446.

A new expression for the Marcum Q-function involving an integral over a fixed interval is given. Tight upper and lower bounds are then derived and applied to the performance evaluation of noncoherent and differentially coherent detection of digital modulation over Nakagami fading channels

A new method of calculating the generalized Q function (Corresp.)

S Parl — 2008-05-15T17:56:39-00:00

Information Theory, IEEE Transactions on, Vol. 26, No. 1. (1980), pp. 121-124.

A recursion relationship for the modified Bessel function is used to develop recursive formulas for functions which are expressed as a Neumann series expansion. The method is applied to devise an algorithm for calculating the generalized<tex>Q</tex>function. Comparisons with some alternative schemes are discussed and an error analysis is presented.

Computing the generalized Marcum <e1>Q</e1>-function

CW Helstrom — 2008-05-15T17:53:10-00:00

Information Theory, IEEE Transactions on, Vol. 38, No. 4. (1992), pp. 1422-1428.

A modified version of the method of saddlepoint integration is shown to compute the generalized Marcum <e1>Q</e1>-function accurately over a broad range of parameters. Bounds on the truncation error incurred by stopping the numerical quadrature at a certain point are presented

Exponential-type bounds on the generalized Marcum Q-function with application to error probability analysis over fading channels

MK Simon — 2008-05-15T17:53:06-00:00

Communications, IEEE Transactions on, Vol. 48, No. 3. (2000), pp. 359-366.

Strict upper and lower bounds of exponential-type are derived for the generalized (mth order) Marcum Q-function which enable simple evaluation of a tight upper bound on the average bit-error probability performance of a wide class of noncoherent and differentially coherent communication systems operating over generalized fading channels. For the case of frequency selective fading with arbitrary statistics per independent fading path, the resulting upper hound on performance is expressed in the form of a product of moment generating functions of the instantaneous power random variables that characterize these paths

The calculation of the probability of detection and the generalized Marcum <e1>Q</e1>-function

DA Shnidman — 2008-05-15T17:53:02-00:00

Information Theory, IEEE Transactions on, Vol. 35, No. 2. (1989), pp. 389-400.

A highly reliable, accurate, and efficient method of calculating the probability of detection, <e1>P</e1>N(<e1>X</e1>,<e1>Y </e1>), for <e1>N</e1> incoherently integrated samples, where <e1>X</e1> is the constant received signal-to-noise ratio of a single pulse and <e1>Y</e1> is the normalized threshold level, is presented. The useful range of parameters easily exceeds most needs. On a VAX/11 computer with double precision calculations, better than 13-place absolute accuracy is normally achieved. There is a gradual loss of accuracy with increasing parameter values. For example, for <e1>N</e1>=109, and with both <e1>NX</e1> and <e1>Y</e1> near 107, the accuracy can drop to ten places. The function <e1>P</e1>N(<e1>X</e1>,<e1>Y </e1>) can be equated to the generalized Marcum <e1>Q</e1>-function, <e1>Q</e1>m(α,β). The corresponding limits on α and β are roughly 4500 for the 13-place accuracy and 60000 for ultimate (INTEGER×4) limit

Serial acquisition techniques for DS-CDMA signals in frequency-selective multi-user mobile channels

Lie-Liang Yang — 2008-05-15T17:46:50-00:00

Vehicular Technology Conference, 1999 IEEE 49th, Vol. 3 (1999), pp. 2398-2402 vol.3.

This paper compares the mean acquisition time performance of two serial search acquisition schemes over frequency-selective multipath Rayleigh fading channels. Both the conventional cell-by-cell detection and the novel joint twin-cell detection are characterised. In contrast to the majority of published results considering only one correct timing state (Hi cell) in the uncertainty region of the pseudo noise (PN) sequence, this paper aims to analyse the mean acquisition time performance of a serial search so acquisition scheme considering multiple timing states in the uncertainty region. The mean acquisition time performance comparison between the conventional cell-by-cell detection and the joint twin-cell detection shows that the latter can achieve significantly improved acquisition time performance at almost the same complexity

DS-SS serial search code acquisition in time-variant channel

J Simsa — 2008-05-15T17:46:47-00:00

Spread Spectrum Techniques and Applications Proceedings, 1996., IEEE 4th International Symposium on, Vol. 2 (1996), pp. 771-775 vol.2.

The serial search DS code acquisition in time-variant channel is analyzed. The stationary random signal amplitude is supposed to be constant during each single/multiple dwell test interval and independent of that on any other test interval. The dependence of the acquisition time PDF as well as its mean value on the random amplitude is eliminated by averaging over the given amplitude distribution. As an example of the general concept application the mean acquisition time of the double-dwell coherent detector at Rayleigh distributed signal amplitude is evaluated