A communication receiving apparatus, a signal receiving method thereof, a signal processing method, and a signal transmitting method based Code Division Multiple Access (CDMA) technology are provided. The signal processing method includes the following steps: the communication transmitting apparatus encodes an original data sequence based on a perfect Gaussian integer sequence (PGIS) to generate a spread signal and transmits a radio frequency (RF) signal including the spread signal. An autocorrelation function of the PGIS conforms to an impulse characteristic, and the PGIS has a spectrum with equal magnitude. The communication receiving apparatus obtains the RF signal from the communication transmitting apparatus and transforms the RF signal into a baseband signal. The baseband signal is de-modulated into a data stream by the communication receiving apparatus. The data stream is recovered into at least one data value of the original data sequence based on the PGIS by the communication receiving apparatus.

A receiver receives signals and noise over a frequency spectrum of a desired received signal. The desired received signal is spread using code division multiple access. The received signals and noise are demodulated to produce a demodulated signal. The demodulated signal is despread using a code uncorrelated with a code associated with the desired received signal. A power level of the despread demodulated signal is measured as an estimate of the noise level of the frequency spectrum.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a configuration of a feedback resource associated with a sidelink feedback channel, wherein the feedback resource is associated with an eight-level code division multiplexing (CDM) scheme. The UE may transmit a feedback communication associated with a sidelink data communication using the feedback resource, wherein transmitting the feedback communication is based at least in part on using the eight-level CDM scheme to generate the feedback communication. Numerous other aspects are described.