Correlation functions of BOC and AltBOC signals as the inverse Fourier transforms of energy spectra

The navigation signals with sine binary offset carrier (sinBOC), cosine BOC (cosBOC), and alternative BOC (AltBOC) modulations are discussed. A technique for calculating the correlation functions (CFs) of the single components of modulating functions (MFs) inherent to the given signals, which is based on the inverse Fourier transform (IFT) of energy spectra, is proposed. This technique makes it possible to derive analytical expressions for the CFs characterizing the single components of the MFs of sinBOC and cosBOC signals and complete AltBOC waveforms with a constant envelope at the multiplicity coefficients N_m = 2?4. The graphs of CFs are constructed. Several illustrating examples, in which most attention is paid to sinBOC, cosBOC, and AltBOC signals employed in the Galileo satellite radio-navigation system and the global positioning system, are presented.     

BOC调制信号频谱特性及仿真分析

BOC调制技术是一种广泛应用于GPS的现代化以及伽利略系统中新型信号调制技术。为研究其频谱特性,分析了BOC调制技术的基本原理及信号的产生过程,应用Matlab软件对其频谱特性进行了仿真,阐述了这种信号调制方式的优点;此外对其扩展技术MBOC,CBOC,TMBOC以及AltBOC做了简要介绍,对进一步研究导航信号现代化具有一定意义。     

The statistical characteristics of navigation cosine binary offset carrier modulated signals (CosBOC signals)

The features and statistical characteristics of cosine binary offset carrier modulated signals (BOC signals) of new-generation satellite radio navigation systems, in particular the Galileo system, are considered. Analytical expressions for the correlation functions (CFs) of the cosine meander symbols (MSs) of the pseudorandom sequence of a ranging code are found for various values of the multiplicity coefficient of meander pulses. The energy spectra of cosine MSs are obtained with the help of the Fourier transform of the CFs. Plots are depicted, and the CFs and energy spectra of cosine MSs are analyzed for the following types of meander modulation: CosBOC (1,1), CosBOC (15,10), CosBOC (10,5), and CosBOC (5,2).     

Four novel quadrature overlapping modulations and their spectral efficiency analysis over band-limited non-linear channels

The power spectral density (PSD) analysis considering non-linearity is important in studying spectral efficiency of a digital modem for satellite systems. A general closed formula for numerical PSD calculation of quadrature overlapping modulations is derived in this paper. Four new quadrature overlapping modulation schemes are proposed because they have better spectral characteristics than those of conventional modulations, such as offset QPSK, MSK and staggered QORC, in both linear and nonlinear channels. The four new schemes are; overlapped minimum shift keying (OMSK), minimum shift keying triangular cosine (MSKTC), raised cosine triangular cosine (RCTC) and sinusoidal quadrature overlapped triangular cosine (SQOTC). The results show that for these new modulations, PSD side lobe regeneration caused by the channel non-linearity, is much less than that for the OQPSK, MSK and staggered QORC, a desirable feature enabling even tighter frequency band allocation in satellite communication systems. © 1997 John Wiley & Sons, Ltd.     

GALILEO E1B软件接收机设计实现

在全球各大卫星导航系统的导航信号中,E1/L1频段最为拥挤,也是系统间兼容性和互操作性研究的重点,其中Galileo试验星GIOVE-A率先发射了采用BOC调制方式的民用信号。该文研究并设计实现了完整的Galileo软件接收机。该接收机成功捕获、跟踪和解调了GIOVE-A信号,并得到了正确的定位结果。测试结果表明,在相同的模拟器配置和接收机参数下,其测距精度和定位精度均优于GPSL1C/A码接收机。     

Turbo‐coded APSK modulations design for satellite broadband communications

This paper investigates the design of power and spectrally efficient coded modulations based on amplitude phase shift keying (APSK) modulation with application to satellite broadband communications. APSK represents an attractive modulation format for digital transmission over nonlinear satellite channels due to its power and spectral efficiency combined with its inherent robustness against nonlinear distortion. For these reasons APSK has been very recently introduced in the new standard for satellite Digital Video Broadcasting named DVB‐S2. Assuming an ideal rectangular transmission pulse, for which no nonlinear inter‐symbol interference is present and perfect pre‐compensation of the nonlinearity, we optimize the APSK constellation. In addition to the minimum distance criterion, we introduce a new optimization based on the mutual information; this new method generates an optimum constellation for each spectral efficiency. To achieve power efficiency jointly with low bit error rate (BER) floor we adopt a powerful binary serially concatenated turbo‐code coupled with optimal APSK modulations through bit‐interleaved coded modulation. We derive tight approximations on the maximum‐likelihood decoding error probability, and results are compared with computer simulations. The proposed coded modulation scheme is shown to provide a considerable performance advantage compared to current standards for satellite multimedia and broadcasting systems. Copyright © 2006 John Wiley & Sons, Ltd.     

Correlation functions of single symbols of meander signals in new-generation satellite radio navigation systems

Mathematical models of meander noise-like signals (binary offset carrier modulated signals (BOC signals)) of new-generation satellite radio navigation systems (SRNSs), in particular, the modernized GPS, the Galileo system, and the QZSS are presented. An analytic expression for the correlation function (CF) of single symbols of meander pulses is obtained for the arbitrary value of the multiplicity coefficient. The properties of CFs of various meander symbols are analyzed. The features of CFs are revealed for the even and odd values of the multiplicity coefficient. Examples of CFs are considered, and CFs of single symbols of BOC signals applied in new-generation SRNSs are plotted.     

BOC调制技术研究

伽利略卫星导航系统是欧洲自主的、独立的全球多模式卫星定位导航系统，提供高精度、高可靠性的定位服务，同时它实现完全非军方控制、管理。伽利略系统采用BOC调制方式。现介绍BOC调制的性质及和BPSK调制方式相比较的优点。     

Performance of optimum wavelet waveform for DS‐CDMA chip waveform over QS‐AWGN channel

In this paper, we search for a better chip waveform based on orthogonal wavelets for direct sequence‐code division multiple access (DS‐CDMA) signals to improve the probability of error (P_e) performance with minimal signal bandwidth variations. First, we derive the P_e expression over a quasi‐synchronous additive white Gaussian noise channel for DS‐CDMA signals, which use various pulse shaping waveforms including orthogonal wavelets as chip waveforms. It is observed that this expression depends on the chip waveform. Then, we design an optimum wavelet by using the relationship between wavelets and filter coefficients to reduce the probability of error. The DS‐CDMA system using the optimum wavelet waveform results in a lower probability of error than those using the conventional chip waveforms such as raised cosine, half‐sine and rectangular waveforms. Especially, the P_e of the optimum wavelet‐based scheme becomes significantly better than those of the conventional chip waveforms‐based schemes under the heavy loading that is the case for commercial wireless systems. When the systems work with full load (i.e. the number of users equals the processing gain), the optimum wavelet‐based system results in 0.5, 2.1 and 4 dB better SNR values than those of the raised cosine, half‐sine and rectangular‐based systems, respectively, for a P_e value of 10^?3. Copyright © 2005 John Wiley & Sons, Ltd.     

An architecture for amplify‐and‐forward cooperative systems with real modulations

This paper proposes a simple architecture for half‐duplex cooperative systems which use amplify‐and‐forward (AF) as a relay strategy and one‐dimensional modulations for source messages. The proposed solution uses the two orthogonal channels of quadrature modulation in order to allow a node to behave simultaneously as a source and a relay. We demonstrate that the new scheme has a similar performance to the conventional orthogonal amplify‐and‐forward protocol without suffering from bandwidth loss, and avoids error propagation problems of previously reported AF superposition schemes. The proposed technique is suitable for applications with low spectral efficiencies and practical adaptive systems where real modulations are implemented based on a quadrature modulation core. Copyright © 2009 John Wiley & Sons, Ltd.     

卫星导航系统中的BOC调制和接收技术分析

BOC调制是一种新的调制方式,能够实现频谱分离并能够充分利用整个频带,比传统的BPSK调制拥有更好的自相关特性,以至于能够改善定位精度。由于BOC调制信号在载波频率点处有较低的功率谱密度,因而,在未来的卫星导航系统中使用BOC调制信号将能够减少信号间的干扰。本文详细地分析了BOC调制信号的特点,通过对功率谱密度函数、自相关函数、Gabor带宽和码跟踪精度等参数的分析和仿真,验证了BOC调制信号在相关特性、抗干扰能力和码跟踪精度方面的优越性。并针对BOC调制信号自相关峰的多峰带来的跟踪不确定性会使捕获复杂度增加和带来跟踪误差的问题,本文介绍了几种BOC调制信号的接收技术,可为我国自主研发的导航系统的信号体制设计和系统优化提供技术支撑。     

Performance of the Proposed Galileo CBOC Modulation in Heavy Multipath Environment

In the framework of the modernization plans of Global Navigation Satellite Systems (GNSS) a new Multiplexed Binary Offset Carrier (MBOC) modulation has been proposed as a possible Signal-In-Space (SIS) with improved performance with respect to the robustness against external sources of degradation. Discussion around such signal format are still on-going at the time of writing, anyway it is the most probable candidate signal that will be adopted by both GPS L1C and the Galileo E1 Open Service (OS) signals [(, 2004)] as modernization of the present BOC(1,1). In the context of the integration between wireless communication and satellite navigation, one of the major problems is that usually the GNSS receiver has to work in a critical environment characterized by a heavy presence of multipath or interference sources. Some examples are urban canyons or light indoor spaces. These are also typical situations for the usage of personal communications systems. The new MBOC modulation have been studied with the specific goal to create a signal more robust with respect to multipath, bringing the high performance of Galileo in situations in which the present BOC(1,1) shows limitations. In this sense, future Location Based Services (LBS) provided on the basis of the GNSS OS will benefits from this intrinsic robustness of the signal. Throughout the paper a review of the MBOC structure will be presented, specifying that in the Galileo framework such a structure has been proposed in a version named Composite BOC (CBOC). In particular, the paper presents the simulation of the CBOC behavior in presence of multipath showing the extreme improvement with respect to other BOC solutions.

Bandwidth‐efficient turbo coding over Rayleigh fading channels

Introduced in 1993, turbo codes can achieve high coding gains close to the Shannon limit. In order to design power and bandwidth‐efficient coding schemes, several approaches have been introduced to combine high coding rate turbo codes with multilevel modulations. The coding systems thus obtained have been shown to display near‐capacity performance over additive white Gaussian noise (AWGN) channels. For communications over fading channels requiring large coding gain and high bandwidth efficiency, it is also interesting to study bit error rate (BER) performance of turbo codes combined with high order rectangular QAM modulations. To this end, we investigate, in this paper, error performance of several bandwidth‐efficient schemes designed using the bit‐interleaved coded modulation approach that has proven potentially very attractive when powerful codes, such as turbo codes, are employed. The structure of these coding schemes, termed ‘bit‐interleaved turbo‐coded modulations’ (BITCMs), is presented in a detailed manner and their BER performance is investigated for spectral efficiencies ranging from 2 to 7 bit/s/Hz. Computer simulation results indicate that BITCMs can achieve near‐capacity performance over Rayleigh fading channels, for all spectral efficiencies considered throughout the paper. It is also shown that the combination of turbo coding and rectangular QAM modulation with Gray mapping constitutes inherently a very powerful association, since coding and modulation functions are both optimized for operation in the same signal‐to‐noise ratio region. This means that no BER improvement is obtainable by employing any other signal constellation in place of the rectangular ones. Finally, the actual influence of the interleaving and mapping functions on error performance of BITCM schemes is discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

Galileo系统中MBOC调制信号及性能分析

MBOC(Multiplexed Binary Offset Carrier)调制是GalileoE1频段以及GPS L1C频段推荐使用的一种优化调制方式。与BOC调制相比,MBOC调制方式的功率谱密度函数提供了更为丰富的高频分量,因此具有更高的伪码跟踪精度和抗多径性能。Galileo E1 OS采用了CBOC(6,1,1/11)(Composite Binary Offset Carrier)的方式实现MBOC调制。通过MATLAB仿真,对该信号的自相关函数、频谱特性进行了研究,并且通过与BOC调制信号的比对,证明了MBOC在码跟踪特性和抗多径性能方面的优越性。     

Navigational cosGBOC Signals in Promising Satellite Radio-Navigation Systems

The formation and structure of the modulation function (MF) of cosine generalized binary offset carrier (cosGBOC) signals applied in promising satellite radio-navigation systems, such as Galileo (European Union), global positioning system (GPS) (USA), and BeiDou/Compass (China), are discussed. Analytical expressions for the spectral density and energy spectrum characterizing the single components of cosGBOC-signal MFs are derived at the different values of pulse multiplicity coefficients N_R (N_R=2, 4, 6, …) and duty cycles ρ (ρ ∈ [0, 1]). The obtained general formulas for cosGBOC signals are employed to analyze spectra in the important particular cases of cosGBOC and BPSK signals. With the help of the Mathcad software package, the graphs of the energy spectra of the single components entering into the cosGBOC-signal MF are constructed for the following types of modulation: cosGBOC(1, 1, ρ), cosGBOC(2, 2, ρ), and cosGBOC(10, 5, ρ). The properties of the given energy spectra are investigated.     

Application of generalized binary offset carrier modulation in BeiDou satellite navigation system

As quickly growing of global navigation satellite system community, there is increasing interest in new signals for military and civilian uses. New signals must provide more robustness, higher performance, and greater capacity than already-existing signals and compliant with the radio frequency compatibility rule with existing and planned signals. This paper presents a class of particularly attractive modulations called Generalized Binary Offset Carrier (GBOC) modulations, and demonstrates their essential characteristics and performance in the signal design of BeiDou system. The GBOC modulations can offer additional degrees of freedom for shaping the signal’s spectrum and provide superior performance in code tracking, multipath and compatibility than other BPSK and BOC modulations. The results show that the proposed modulation can provide potential opportunities for BeiDou satellite navigation system modernization and construction.     

Cross‐layer packet scheduler for QoS support over Digital Video Broadcasting‐Second Generation broadband satellite systems

This article presents a cross‐layer packet scheduler to provide end‐to‐end QoS guarantees for Digital Video Broadcasting‐Second Generation (DVB‐S2) broadband satellite systems. The scheduler design is based on a cross‐layer mechanism defined between the physical and the network layer. It includes an algorithm to guarantee the required QoS specifications established in the service level agreement. The algorithm calculation depends basically on two parameters: the available bandwidth present in a DVB‐S2 satellite link and the QoS requirements of each traffic class defined by the satellite operator. The cross‐layer scheduler's operation is demonstrated using the NS‐2 simulator tool. The results show that the proposed mechanism maximizes the bandwidth utilization while enforcing the priority level of each service class when an extreme reduction of bandwidth caused by rain events is experienced. Copyright © 2012 John Wiley & Sons, Ltd.     

Leveraging multiuser diversity for adaptive hybrid satellite‐LTE downlink scheduler (H‐MUDoS) in emerging 5G‐satellite network

In order to achieve ubiquitous coverage and service continuity in future 5G network, satellite‐based access is the best solution to complement the terrestrial LTE‐A. In light of this, we introduce a channel‐aware hybrid scheduling technique on the basis of satellite‐LTE spectrum sharing. According to the user‐experienced channel, base stations (eNodeB) and the satellite will work cooperatively. The eNodeB mainly provides service in urban area for high density population. Meanwhile, the satellite will perform either offloading, providing service for under‐served users, or extra coverage for users in rural and remote areas having no coverage of eNodeB. Leveraging the multiuser diversity, we implement a new metrics computation method for hybrid satellite‐LTE downlink scheduler (H‐MUDoS). Compared with other existing schedulers, simulation results clearly demonstrate the high performance of H‐MUDoS in terms of spectral efficiency in addition to improvement of the quality‐of‐service requirements and capacity maximization.     

Unambiguous and precise correlation receiver for binary offset carrier modulated signal

The binary offset carrier (BOC) modulated signal can improve the positioning accuracy and increase the multipath resistance in global navigation satellite system (GNSS), and it may cause potential ambiguity in the process of signal acquisition and code tracking. In this paper, a simple but efficient unambiguous receiver is firstly proposed for multiple side‐peaks mitigation by implementing correlation of the received BOC signal with local sine wave instead of square wave used at the transmitter. Moreover, the potential degradation of sharpness of the nonlinear correlation induced by the sine wave is well compensated by optimizing the early‐to‐late spacing. The other reason leading to ambiguity is the multipath propagation, so we further propose a maximum likelihood (ML) estimator with Newton iteration method, where the received GNSS signal is modeled via the line‐of‐sight (LOS) component and the first‐arrived non‐line‐of‐sight (NLOS) component. Finally, the analytical expression of multipath propagation Cramer‐Rao bound is derived for the designed ML estimator. Simulation results indicate that compared with the conventional BOC modulation, the proposed sine wave receiver can achieve unambiguous and more precise code tracking performance and thus turns out to be more robust to multipath propagation.     

Applying a BOC-PRN discriminator to cosine phased BOC(fs, fc) modulation

The extended binary offset carrier-pseudorandom noise (BOC-PRN) discriminator is shown to work efficiently for the new cosine phased BOC (fs,fc) signals defined for global navigation satellite systems, where n (=2fs/fc) is an arbitrary even integer. The new unambiguous code discriminator provides good multipath mitigation performance for medium delays.