System for generating a constant envelope and suppressed cyclic feature signal may include a transmission security (TRANSEC) function, a spread spectrum chip, an M-ary continuous phase modulator, and a pulse-shaped filter. The TRANSEC may generate a pseudorandom symbol by M-ary symbol generation selects a symbol with a signal phase, and the spread spectrum chip corresponding to the generated pseudorandom symbol or a phase rotation of the pseudorandom symbol. The M-ary continuous phase modulator with a delta-phase mapper maps the signal phase based at least in part on the selected symbol. The pulse-shaped filter of the M-ary modulator introduces inter-symbol interference from a previous and a subsequent symbol into a current symbol; the inter-symbol interference may be introduced by the main lobe of the signal phase being contained within a bandwidth of a chip rate of the spread spectrum chip for frequency modulation signal transmission of information by the generated signal.

System for generating a constant envelope and suppressed cyclic feature signal may include a transmission security (TRANSEC) function, a spread spectrum chip, an M-ary continuous phase modulator, and a pulse-shaped filter. The TRANSEC may generate a pseudorandom symbol by M-ary symbol generation selects a symbol with a signal phase, and the spread spectrum chip corresponding to the generated pseudorandom symbol or a phase rotation of the pseudorandom symbol. The M-ary continuous phase modulator with a delta-phase mapper maps the signal phase based at least in part on the selected symbol. The pulse-shaped filter of the M-ary modulator introduces inter-symbol interference from a previous and a subsequent symbol into a current symbol; the inter-symbol interference may be introduced by the main lobe of the signal phase being contained within a bandwidth of a chip rate of the spread spectrum chip for frequency modulation signal transmission of information by the generated signal.

A signal processing method is provided. Under the method, a first digital signal can be obtained by an optical transmitter. The first digital signal is a one-dimensional bipolar digital signal. A spectral compression and filtering can be performed by the optical transmitter on the first digital signal to generate a second digital signal. A frequency shift can be performed by the optical transmitter on the second digital signal such that a center location of a spectrum of the frequency-shifted second digital signal is at a frequency of 0.

A signal processing method is provided. Under the method, a first digital signal can be obtained by an optical transmitter. The first digital signal is a one-dimensional bipolar digital signal. A spectral compression and filtering can be performed by the optical transmitter on the first digital signal to generate a second digital signal. A frequency shift can be performed by the optical transmitter on the second digital signal such that a center location of a spectrum of the frequency-shifted second digital signal is at a frequency of 0.

Exemplary embodiments are disclosed of methods and devices (e.g., circuit, compensator, repeater, booster, signal amplifier device, etc.) for selectively amplifying multiple carriers in different frequency bands (e.g., 5G, 4G, etc.). In an exemplary embodiment, a circuit includes a detector configured for detecting carriers in different frequency bands, multiple signal paths respectively configured for amplifying multiple carriers in different frequency bands, and a control unit configured for controlling the detector and the multiple signal paths. The control unit is further configured to: select the carrier(s) to be compensated based on one or more first specified conditions and allow transmission of the selected carrier(s) along the corresponding signal path(s) for amplification; and lock the signal path(s) associated with the frequency band(s) of the unselected carrier(s) to prevent transmission of the unselected carrier(s) along the locked signal path(s) until one or more second specified conditions are satisfied.

Exemplary embodiments are disclosed of methods and devices (e.g., circuit, compensator, repeater, booster, signal amplifier device, etc.) for selectively amplifying multiple carriers in different frequency bands (e.g., 5G, 4G, etc.). In an exemplary embodiment, a circuit includes a detector configured for detecting carriers in different frequency bands, multiple signal paths respectively configured for amplifying multiple carriers in different frequency bands, and a control unit configured for controlling the detector and the multiple signal paths. The control unit is further configured to: select the carrier(s) to be compensated based on one or more first specified conditions and allow transmission of the selected carrier(s) along the corresponding signal path(s) for amplification; and lock the signal path(s) associated with the frequency band(s) of the unselected carrier(s) to prevent transmission of the unselected carrier(s) along the locked signal path(s) until one or more second specified conditions are satisfied.

A signal processing method is provided. Under the method, a first digital signal can be obtained by an optical transmitter. The first digital signal is a one-dimensional bipolar digital signal. A spectral compression and filtering can be performed by the optical transmitter on the first digital signal to generate a second digital signal. A frequency shift can be performed by the optical transmitter on the second digital signal such that a center location of a spectrum of the frequency-shifted second digital signal is at a frequency of 0.

Apparatus for encoding a plurality of received radio frequency (RF) analog signals. The apparatus includes a plurality of pseudo-noise (PN) encoders for performing analog signal spreading and down-conversion. Each PN encoder is configured to encode a respective received RF analog signal using a respective one of a plurality of mutually orthogonal PN complex codes and to output a respective PN-encoded analog signal. The apparatus also includes a PN complex code source configured to provide the mutually orthogonal PN complex codes to the plurality of PN encoders. The PN complex code source includes a code generator for generating multiple mutually orthogonal PN codes, and a complex modulator for modulating the mutually orthogonal PN codes.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit a frequency dependent residual side band (FDRSB) training signal on a first set of subcarriers that are lower than a carrier frequency and on a second set of subcarriers that are higher than the carrier frequency, a mirror of the first set of subcarriers about the carrier frequency being non-overlapping with the second set of subcarriers. The UE may receive an indication of FDRSB correction that is based at least in part on the FDRSB training signal. Numerous other aspects are described.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may transmit a frequency dependent residual side band (FDRSB) training signal on a first set of subcarriers that are lower than a carrier frequency and on a second set of subcarriers that are higher than the carrier frequency, a mirror of the first set of subcarriers about the carrier frequency being non-overlapping with the second set of subcarriers. The UE may receive an indication of FDRSB correction that is based at least in part on the FDRSB training signal. Numerous other aspects are described.