Complete alternative binary offset carrier modulated signals (AltBOC signals) with variable and constant envelopes for new-generation satellite radio navigation systems

The formation and structure of four- and eight-component complete alternative binary offset carrier modulated signals (AltBOC signals) for new-generation satellite radio navigation systems (SRNSs) (in particular, the Galileo and BeiDou-2 SRNSs) are considered. A four-component complete AltBOC signal has a time-variable envelope, while the envelope of an eight-component complete AltBOC signal is constant. The envelopes and phases of such AltBOC signals are analyzed for various values of the multiplicity coefficients of meander pulses. The combination components of an eight-component complete AltBOC signal are plotted, and the features of these components that ensure the time constancy of the envelope are revealed. A classification of AltBOC signals is proposed. Practical characteristics are analyzed on the basis of the AltBOC (15, 10) modulation, which is typical of the Galileo and Compass SRNSs.     

The spectral characteristics of navigation alternative binary offset carrier modulated signals (AltBOC signals)

Analytical expressions are obtained for spectral densities and energy spectra of single elements and single periods of modulating functions of alternative binary offset carrier modulated signals (AltBOC signals) for new-generation satellite radio navigation systems (SRNSs) (in particular, the Galileo system). The spectral characteristics are presented and analyzed for an elementary (two-component) AltBOC signal, a complete AltBOC with a time-variable envelope (a four-component complete AltBOC signal), and a complete AltBOC with a constant envelope (an eight-component complete AltBOC signal) in the case when the multiplicity coefficient of meander pulses has an arbitrary value. Plots are depicted, and the properties of energy spectra of single elements of modulating functions of all groups of AltBOC signals are discussed in the cases of the following modulation types: AltBOC(10, 10), AltBOC(15, 10), AltBOC(20, 10), and AltBOC(25, 10).     

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.     

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.     

Dual estimate receiver of binary offset carrier modulated signals for global navigation satellite systems

A dual estimate receiver of binary offset carrier (BOC) signals for GNSS applications is described. A unique estimate is derived solely from the code modulation. A more accurate but ambiguous estimate is derived solely from the subcarrier modulation. Any time difference between the two is rounded to the nearest subchip in order to correct the latter estimate. Implementation in the receiver is by a triple digital loop. The full potential accuracy of BOC is then reliably and unambiguously realised.     

The correlation functions of single elements of the modulating functions of double complex meander noise-like navigation signals (alternative binary offset carrier modulated signals)

The correlation characteristics of elements of complex meander pseudo-random sequences (PRSs) are analyzed. These sequences are the basis for forming double complex meander (DCM) noise-like signals (alternative binary offset carrier modulated signals—AltBOC signals) applied in new-generation satellite radio navigation systems (in particular, the European Galileo and Chinese Bei-Dou/Compass systems). Analytical expressions are obtained for the correlation functions (CFs) of single complex meander symbols (MSs) and for the cross CFs (CCFs) of the sine and cosine components of complex MSs. Formulas for the CFs of single elements of the modulating functions (MFs) of an elementary (two-component) AltBOC signal and a four-component AltBOC signal are derived for typical values of multiplicity coefficient N _m (N _m = 2 and 3). Plots of CFs and CCFs are depicted, and the properties of these functions are discussed. The Fourier transform is applied to obtain the energy spectra of single MSs of an elementary AltBOC signal and a complete four-component AltBOC signal. In the examples, the attention is focused on AltBOC signals with the AltBOC (15, 10) modulation and the repetition rate of PRS elements f _s = 10 f _ref = 10.23 MHz, where the reference frequency is f _ref = 1.023 MHz.     

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).     

Complex efficient carrier frequency offset estimation algorithm in OFDM systems

A new carrier frequency offset estimation scheme in the orthogonal frequency division multiplexing (OFDM) system is proposed. The proposed algorithm is an extension of the Michele Morelli (M&M) algorithm. By dividing one training symbol into L>1 identical small blocks, the carrier frequency offset estimation range up to /spl plusmn/L/2 times subcarrier spacing can be obtained. The proposed algorithm can utilize the correlativity among all small blocks of a training symbol more sufficiently than the M&M algorithm, and thus it is more accurate and robust. Without increasing the estimation errors, the computational complexity of the proposed algorithm can be further reduced by increasing parameters H/sub l/ and H/sub h/ with a positive value simultaneously.     

Use of pseudorandom binary sequences in the digital simulation of control systems subjected to random input signals

The application of pseudorandom binary sequences when simulating control systems subjected to smoothed random input signals is examined. If the sequence is assumed to be `white? noise, appreciable errors may occur in the computation of the input power to the system. However, if the system responds perfectly at low frequencies, the error in the computation of the system error power is negligible.     

Ionospheric and plasmaspheric effects in satellite navigation systems

A satellite navigation concept requires determination of time (or phase) delays that satellite-emitted signals experience when traversing the distance between satellite and observer. A pulse propagating this distance is slowed down somewhat from its free space velocity-by an amount directly proportional to the total number of free electrons (TEC) along its path. Ranging accuracy requirements mandate compensation for this additional signal delay. The total electron content for high-orbit satellites includes the ionospheric as well as the plasmaspheric electron content. The Radio Beacon Experiment (RBE) aboard the geostationary ATS-6 Satellite provides the opportunity to determine the ionospheric content (up to heights ofsim 1500km), the total electron content (from observer to satellite), and the plasmaspheric content (the difference of the two). Observations of ionospheric contents were carried out at Fort Monmouth from the launch of the ATS-6 in May 1974 to its planned drift eastward in June 1975. Diurnal, day-to-day, and seasonal variations of the contents were observed. Diurnal plasmaspheric changes were smaller in percent and in absolute terms than ionospheric changes. While, in general, ionospheric contents were larger during the fall than during the spring, the plasmaspheric contents exhibited the opposite behavior. The diurnal behavior of the ratio of plasmaspheric-to-total contents exhibited variations fromsim 45percent at night togsim 10percent during the day, with rapid changes after local sunrise and after local sunset.     

Subjective evaluation of companded frequency modulation and continuously variable slope delta modulation single channel per carrier satellite communication systems

A comprehensive series of subjective tests are carried out on narrow-band companded F.M. and continuously controlled delta modulation SCPC satellite systems. In order to resolve discrepancies reported in the literature both Youden square and mean opinion scale listening tests have been applied. Both white noise and modulated noise reference conditions are employed and the performance of the systems, in terms of signal to noise and equivalent Q factor are given for various C/N₀ fixed and mobile-maritime performance requirements.     

Standardizable low-pass voice band hybrid circuit filters for pulse code modulation (PCM) communication systems

A standardizable design approach to realize the voice band low-pass filters for a variety of pulse code modulation (PCM) communications systems is described. This design concept incorporates cascaded RC active filter sections, thick and thin film hybrid technologies, and functional tuning to allow the use of the same hybrid design for both transmit and receive filters, for a range of input and output requirements. Tuning, sensitivity analyses, and implementation tradeoffs are described. Thick film implementations, using NPO chip capacitors, with the new high stability resistor inks as well as thin film implementation, using the usual tantalum integrated thin film technology are presented. Very stringent requirements have been successfully met using state-of-the-art hybrid technologies.     

Blind carrier frequency offset estimation in SISO, MIMO, and multiuser OFDM systems

Relying on a kurtosis-type criterion, we develop a low-complexity blind carrier frequency offset (CFO) estimator for orthogonal frequency-division multiplexing (OFDM) systems. We demonstrate analytically how identifiability and performance of this blind CFO estimator depend on the channel's frequency selectivity and the input distribution. We show that this approach can be applied to blind CFO estimation in multi-input multi-output and multiuser OFDM systems. The issues of channel s, multiuser interference, and effects of multiple antennas are addressed analytically, and tested via simulations.     

Complex chaotic discrete signals in telecommunications, radar, and navigation systems

Discrete chaotic signals with a high information capacity are developed and studied on the basis of nonlinear chaotic dynamic systems. The structural and fractal complexity of pseudorandom integer and binary sequences is analyzed. A model digital spread-spectrum radio channel is used to show experimentally that the chaotic algorithms developed can be applied efficiently in various radio facilities, such as telecommunications, radar, and navigation systems. A technique is developed for forming a reproducible irregular fractal structure involved in frequency-independent fractal antennas with a given fractal dimension. An integer chaotic algorithm with retardation is employed to generate a pseudorandom sequence.     

Subcarrier allocation based compensation for carrier frequency offset and I/Q imbalances in OFDM systems

We propose a novel subcarrier allocation (SCA) based approach for compensating carrier frequency offset (CFO) and I/Q imbalances in direct-conversion OFDM receivers. From the matrix representation of OFDM signals with CFO and I/Q imbalances, maximum likelihood CFO estimation and the associated SCA are given. Then, an SCA-based algorithm is proposed for the I/Q imbalances compensation. Moreover, the proposed approach is extended to a blind compensation scheme for OFDM signals with asymmetric SCA.     

空时码及其在移动通信中的应用

总结了空时码的分类，分析了各类空时码的性能特点和在移动通信中的应用，并对其研究方向和发展前景进行了探讨。     

Interleaved 5B20 code for insertion of carrier and clock pilots in 64-QAM systems

An interleaved 5-binary to 2-octonary (5B20) block code is proposed to insert carrier and clock pilots in 64-QAM systems with a spectrum efficiency of about 4.5 bit/s/Hz. Its design is based on the rotated and scaled 64-QAM signal constellation. The spectral components of symbol sequences from this encoder are completely suppressed at DC and at the Nyquist frequency (NF).<>     

Channel capacity and minimum probability of error in large dual antenna array systems with binary modulation

Uncoded bit error probability with maximum-likelihood detection and channel capacity is derived for binary signaling on the dual antenna array channel with constrained scattering in the large system limit making use of the replica method. Examples are discussed in case of equal power for all propagation paths. In case of poor scattering (or high load), a waterfall behavior of the uncoded bit error probability is observed.