A method comprises receiving a data signal on a data channel and a pilot signal on a pilot channel, demodulating the received data signal and the received pilot signal to obtain a demodulated data signal and a demodulated pilot signal, generating a data stream by decoding the demodulated data signal, generating a feedback signal by encoding the data stream, and performing a measurement of a coherent sum signal comprising the coherent sum of (1) the demodulated pilot signal and (2) the product of the demodulated data signal and the feedback signal.

In a physical broadcast channel sending/receiving method, after receiving two broadcast channel signals on two corresponding physical broadcast channels at two time-frequency resource locations, the terminal device determines that information other than an offset of a corresponding time-frequency resource location is the same in two pieces of broadcast information carried in the two broadcast channel signals, obtains a time offset difference between the foregoing two time-frequency resource locations, and generates a scrambling code sequence based on the time offset difference; and the terminal device separately descrambles the two broadcast channel signals based on the scrambling code sequence and a preset scrambling code sequence.

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.

Determination of a signal loss profile relative to a receiver based on measured signal power of a sounding signal from a sounding transmitter having a known signal power in free space relative to the receiver. The signal loss profile may include a plurality of signal loss values corresponding to a plurality of received sounding signals at the receiver. In an embodiment, the sounding signal may comprise a GNSS navigational signal (e.g., a GPS signal). The signal loss profile may be used to extrapolate signal loss for a transmitter collocated with the receiver. In turn, the signal loss profile may be used in conjunction with a shared spectrum system to model a signal propagation from the collocated transmitter when determining allocation of a shared spectrum resource of the shared spectrum system.

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.

A candidate arbitrary-phase spread spectrum modulation technique that offers similar performance to spread continuous phase modulation (CPM) waveforms and additional capabilities for programming a chosen frequency domain spectra into the resulting spread spectrum signal. The proposed chaotic-FSK waveform is derived from high-order sequence-based spread spectrum signals, with multi-bit resolution chaos-based sequences defining incremental phase words, enabling real-time efficient generation of practically non-repeating waveforms. A result of the C-FSK formulation is a parameterized hybrid modulation capable of acting like a traditional sequence-based spread spectrum signal or a traditional frequency shift keying signal depending on chosen parameters. As such, adaptation in this modulation may be easily implemented as a time-varying evolution, increasing the security of the waveform while retaining many efficiently implementable receiver design characteristics of traditional PSK modulations.

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.

The present invention is designed to reduce the decrease of spectral efficiency even when repetitious transmission is applied to communication by user terminals, in which the band to use is limited to a partial narrow band in a system band. According to one aspect of the present invention, a user terminal, in which the band to use is limited to partial narrow bands in a system band, has a receiving section that receives information related to spreading codes, a generation section that generates uplink signals, and a transmission section that repeats transmitting uplink signals in a plurality of subframes, and the generation section applies a predetermined spreading code to an uplink signal that is transmitted in part or all of the plurality of subframes, based on the information related to spreading codes.

Determination of a signal loss profile relative to a receiver based on measured signal power of a sounding signal from a sounding transmitter having a known signal power in free space relative to the receiver. The signal loss profile may include a plurality of signal loss values corresponding to a plurality of received sounding signals at the receiver. In an embodiment, the sounding signal may comprise a GNSS navigational signal (e.g., a GPS signal). The signal loss profile may be used to extrapolate signal loss for a transmitter collocated with the receiver. In turn, the signal loss profile may be used in conjunction with a shared spectrum system to model a signal propagation from the collocated transmitter when determining allocation of a shared spectrum resource of the shared spectrum system.