Binary‐offset‐carrier modulation techniques with applications in satellite navigation systems

Lohan, Elena Simona; Lakhzouri, Abdelmonaem; Renfors, Markku

doi:10.1002/wcm.407

Cited by 63 publications

(41 citation statements)

References 5 publications

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“…The typical notation for BOC modulation is BOC(m,n), where m and n are two positive indices (not necessarily integers, but with integer ratio 2m/n), satisfying the relationships m ¼ f sc =f ref and n ¼ f c =f ref , respectively, where f sc is the sub-carrier frequency, f c is the chip rate and f ref is a reference frequency (typically, f ref ¼ 1:023MHz) [4,6]. From the baseband point of view, the signal is fully characterized by twice the ratio between the sub-carrier frequency and the chip rate, denoted in what follows by BOC-modulation order N BOC [11,12]…”

Section: Background and Motivationmentioning

confidence: 99%

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Low‐complexity unambiguous acquisition methods for BOC‐modulated CDMA signals

Lohan

Burian

Renfors

2008

Satell Commun Network

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SUMMARYThe new M-code signals of GPS and the signals proposed for the future Galileo systems are of splitspectrum type, where the pseudorandom (PRN) code is multiplied with rectangular sub-carriers in one or several stages. Sine and cosine binary-offset-carrier (BOC) modulations are examples of modulations, which split the signal spectrum and create ambiguities in the envelope of the autocorrelation function (ACF) of the modulated signals. Thus, the acquisition of split-spectrum signals, based on the ambiguous ACF, poses some challenges, which might be overcome at the expense of higher complexity (e.g. by decreasing the step in searching the timing hypotheses). Recently, two techniques that deal with the ambiguities of the ACF have been proposed, and they were referred to as 'sideband (SB) techniques' (by Betz, Fishman et al.) or 'BPSK-like' techniques (by Martin, Heiries et al.), since they use SB correlation channels and the obtained ACF looks similar to the ACF of a BPSK-modulated PRN code. These techniques allow the use of a higher search step compared with the ambiguous ACF situation. However, both these techniques use SB-selection filters and modified reference PRN codes at the receivers, which affect the implementational complexity. Moreover, the 'BPSK-like' techniques have been so far studied for even BOC-modulation orders (i.e. integer ratio between the sub-carrier frequency and the chip rate) and they fail to work for odd BOC-modulation orders (or equivalently for split-spectrum signals with significant zero-frequency content). We propose here three reduced-complexity methods that remove the ambiguities of the ACF of the split-spectrum signals and work for both even and odd BOC-modulation orders. Two of the proposed methods are extensions of the previously mentioned techniques, and the third one is introduced by the authors and called the unsuppressed adjacent lobes (UAL) technique. We argue via theoretical analysis the choice of the parameters of the proposed methods and we compare the alternative methods in terms of complexity and performance.

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Section: Background and Motivationmentioning

confidence: 99%

“…The validity of the theoretical results has been also verified in multipath fading channels and for non-zero Doppler residual errors, via simulations. The received (modulated) signal rðtÞ can be written as [12]:…”

Section: Theoretical Analysismentioning

confidence: 99%

Low‐complexity unambiguous acquisition methods for BOC‐modulated CDMA signals

Lohan

Burian

Renfors

2008

Satell Commun Network

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“…where N B is BOC modulation order: N B = 1 for BPSK modulation (BPSK can be seen as a particular case of BOC modulation, as illustrated in [36] …”

Section: Signal and Channel Modelmentioning

confidence: 99%

“…In the above equations, R rx (τ) is the received downconverted correlation function, and R ideal (τ) is the ideal reference correlation function, the expression of which can be found in [36]. Generally speaking, RSSML performs a nonlinear curve fit on the input correlation function which finds a perfect match from a set of ideal reference correlation functions with certain amplitude(s), phase(s), and delay(s) of the multipath signal.…”

Section: Reduced Search Space Maximum Likelihood Delaymentioning

confidence: 99%

Advanced Multipath Mitigation Techniques for Satellite-Based Positioning Applications

Bhuiyan

Lohan

2010

International Journal of Navigation and Observation

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Multipath remains a dominant source of ranging errors in Global Navigation Satellite Systems (GNSS), such as the Global Positioning System (GPS) or the future European satellite navigation system Galileo. Multipath is generally considered undesirable in the context of GNSS, since the reception of multipath can make significant distortion to the shape of the correlation function used for time delay estimation. However, some wireless communications techniques exploit multipath in order to provide signal diversity though in GNSS, the major challenge is to effectively mitigate the multipath, since we are interested only in the satellitereceiver transit time offset of the Line-Of-Sight (LOS) signal for the receiver's position estimate. Therefore, the multipath problem has been approached from several directions in order to mitigate the impact of multipath on navigation receivers, including the development of novel signal processing techniques. In this paper, we propose a maximum likelihood-based technique, namely, the Reduced Search Space Maximum Likelihood (RSSML) delay estimator, which is capable of mitigating the multipath effects reasonably well at the expense of increased complexity. The proposed RSSML attempts to compensate the multipath error contribution by performing a nonlinear curve fit on the input correlation function, which finds a perfect match from a set of ideal reference correlation functions with certain amplitude(s), phase(s), and delay(s) of the multipath signal. It also incorporates a threshold-based peak detection method, which eventually reduces the code-delay search space significantly. However, the downfall of RSSML is the memory requirement which it uses to store the reference correlation functions. The multipath performance of other delay-tracking methods previously studied for Binary Phase Shift Keying-(BPSK-) and Sine Binary Offset Carrier-(SinBOC-) modulated signals is also analyzed in closed loop model with the new Composite BOC (CBOC) modulation chosen for Galileo E1 signal. The simulation results show that the RSSML achieves the best multipath mitigation performance in a uniformly distributed two-to-four paths Rayleigh fading channel model for all three modulated signals.

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“…Moreover, BOC modulation represents another major disadvantage which is related to the existence of secondary peaks in its Correlation Function (CF) that can create ambiguity in the tracking process [9]. Several methods have been proposed for side peaks cancelation and true Delay Locked Loop (DLL) zerocrossing detection [10] [11] [12] [13] [14].…”

Section: Introductionmentioning

confidence: 99%

GNSS Multipath Reduction Using GPS and DGPS in the Real Case

Titouni¹,

Rouabah²,

Atia³

et al. 2017

POS

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In Global Navigation Satellite System (GNSS) like Global Positioning System (GPS) and future Galileo, space signal reception in urban environment seems to be one of most significant. The urban environment is characterized by the presence of an excessive number of obstacles that produce Multiple Path (MP) in positioning the receiver. Consequently, it is of primary importance to characterize and ameliorate the performances of GNSS receiver for this type of application. In this paper, a method to mitigate MP in GNSS applications was proposed. Its principle is based on the addition, to the geographic map of a city or a neighborhood, of a supplementary information that consists of the correction of error caused by the MPs. The latter one was carried out by the comparison of the measurements, realized by Differential GPS (DGPS) and GPS, between two different sites with the same form. The first one was characterized by the presence of the MPs and the second one was completely clear of any type of obstacle. As a consequence, the measurements comparison has allowed us to deduce the GNSS MPs errors. This information can subsequently be used to make the corrections of the errors caused by MPs and it can be generalized by a measurement company to any entire city in order to identify errors in any neighborhood.

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Binary‐offset‐carrier modulation techniques with applications in satellite navigation systems

Cited by 63 publications

References 5 publications

Low‐complexity unambiguous acquisition methods for BOC‐modulated CDMA signals

Low‐complexity unambiguous acquisition methods for BOC‐modulated CDMA signals

Advanced Multipath Mitigation Techniques for Satellite-Based Positioning Applications

GNSS Multipath Reduction Using GPS and DGPS in the Real Case

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