Aspects of the subject disclosure may include, for example, a system for modulating a first electrical signal to generate first modulated electromagnetic waves, and transmitting the first modulated electromagnetic waves on a waveguide located in proximity to a transmission medium. In one embodiment, the first electromagnetic waves can induce second electromagnetic waves that propagate on an outer surface of the transmission medium. The second electromagnetic waves can have a first spectral range that is divided into, contains or otherwise includes a first control channel and a first plurality of bands. Other embodiments are disclosed.

The invention discloses a method for receiving TD-AltBOC signal, which belongs to the field of global satellite navigation. The method of the invention includes steps of: converting a TD-AltBOC radio-frequency signal into an medium frequency, performing a band-pass filtering and sampling on the signal, and peeling off a sampled signal carrier by using a local carrier to obtain a sampled baseband signal; correlating on a local waveform with the sampled baseband signal chip-by-chip in a time division manner; performing a data demodulation according to correlated output signals, and obtaining a carrier phase deviation estimated value and a code phase deviation estimated value according to the correlated output signals; generating the local waveform according to the code phase deviation estimated value; generating the local carrier according to the carrier phase deviation estimated value. The invention also provides an apparatus for receiving TD-AltBOC signal.

To obtain a high-quality enhanced signal, there is provided an apparatus including a transformer that transforms a mixed signal, in which a first signal and a second signal coexist, into a phase component for each frequency and one of an amplitude component and a power component for each frequency, a change amount generator that generates a change amount of the phase component at a predetermined frequency by using a series of data with a cross-correlation weaker than that of the phase components and randomness lower than that of random numbers, a phase controller that controls the phase component by using the change amount provided from the change amount generator, and an inverse transformer that generates an enhanced signal by using the phase component having undergone control processing by the phase controller.

Aspects of the subject disclosure may include, for example, a system for modulating a first electrical signal to generate first modulated electromagnetic waves, and transmitting the first modulated electromagnetic waves on a waveguide located in proximity to a transmission medium. In one embodiment, the first electromagnetic waves can induce second electromagnetic waves that propagate on an outer surface of the transmission medium. The second electromagnetic waves can have a first spectral range that is divided into, contains or otherwise includes a first control channel and a first plurality of bands. Other embodiments are disclosed.

The present invention relates to a device and a method for detecting a transmission signal in a wireless communication system, and a reception device in a wireless communication system comprises: a transceiver for receiving a signal from a transmitting end; a first correlator for performing a first correlation and outputting a real part among the results of the first correlation; a second correlator for performing a second correlation and outputting an imaginary part among the results of the second correlation; and a control unit for controlling the first correlator and the second correlator on the basis of a channel change rate so as to detect a transmission signal.

Example communication systems and methods are described. In one implementation, a method receives a first chaotic sequence of a first temporal length, and a second chaotic sequence of a second temporal length. The method also receives a data symbol for communication to a destination. Based on the data symbol, the second chaotic sequence is temporally shifted and combined with the first chaotic sequence to generate a composite chaotic sequence. The first chaotic sequence functions as a reference chaotic sequence while the second chaotic sequence functions as a data-carrying auxiliary chaotic sequence.

A wireless device detects a synchronization signal by obtaining (210), from a received signal, a sequence of samples, and calculating (220) a differentially decoded sequence from the obtained sequence of samples. The wireless device correlates (230) the calculated differentially decoded sequence with a first reference sequence corresponding to the synchronization signal, at each of a plurality of time offsets, and identifies which of the plurality of time offsets results in a largest correlation result. In response to determining (240) that the largest correlation result does not meet a predetermined reliability criterion, the wireless device correlates (250) the obtained sequence of samples with a second reference sequence, at each of a plurality of time and frequency offsets, and identifies which combination of time offset and frequency offset results in a largest correlation result. The first reference sequence comprises a differentially decoded version of the second reference sequence.

A Global Navigation Satellite System receiver for position determination receives from a multitude of satellites a respective GNSS code signal, which are correlated with a reference code signal to obtain an autocorrelation function. A multitude of function values of the autocorrelation function at different discrete chip spacings (chosen asymmetrically with respect to a prompt chip spacing) are analyzed and used in obtaining a test metric. Using the test metric, a decision is made whether the received GNSS code signal is suitable or unsuitable (thereafter excluded) for a position determination due to multipath signal components. A bias removal is performed taking into account corresponding function values of an autocorrelation function that would result from a received GNSS code signal of the satellite unaffected by multipath signal components. This provides a simple method for operating a GNSS receiver minimizing errors in position determination caused by multipath signal components.

A radio frequency (RF) communications system may include a first RF node that transmits data, including a new frequency of operation, and a sequence of pilot symbols spread with a complex spreading code sequence. A second RF node may receive an incoming signal from the first RF node and perform despreading for N sample offset delays to generate N despreading sequences for the sequence of pilot symbols. The second RF node may perform a cross-correlation to select a desired despreading sequence from the N despreading sequences, determine a phase offset and timing offset, process the incoming signal based upon the desired despreading sequence, phase offset and timing offset, and switch to the new frequency of operation.

Methods, systems, and devices for wireless communications are described. In some wireless systems, different wireless devices may communicate using different radio access technologies (RATs) in a shared radio frequency spectrum. Prior to communicating on a channel in the shared radio frequency spectrum, a wireless device may transmit a training field as part of a preamble in a transmission on the channel to reserve the channel for the transmission. As described herein, a training field transmitted by a wireless device using one RAT may be transmitted with an autocorrelation property associated with training fields of another RAT. As such, a wireless device configured to communicate using the other RAT may be able to receive and identify the training field (e.g., based on the autocorrelation property), and the wireless device may use the additional techniques described herein to determine an availability of the channel based on the training field.