Techniques for processing a received multi-code code-division multiple-access (CDMA) signal to detect unused spreading codes are disclosed. An example method includes, for each of a plurality of observation time intervals and for each of one or more candidate spreading codes, determining a detection threshold for use in detecting whether the candidate spreading code is unused in the received multi-code CDMA signal, based on a target detection sensitivity and at least one of an estimate of received signal quality and an estimate of channel estimation quality. Estimated signal power for the candidate spreading code is compared to estimated noise and interference power corresponding to a spreading code that is known to be unused or corresponding to a spreading code that carries known symbol values, using the calculated detection threshold. Whether or not the candidate spreading code is unused is then determined, based on the comparison.

Digital mobile communications devices and methods for processing, modulation and demodulation, transmission and reception of spread spectrum signals, Orthogonal Frequency Division Multiplexed (OFDM) signals and conversion of spread spectrum signals into OFDM signals. Received spread spectrum signals from 3G cellular systems are converted into OFDM signals and transmitted in a Wi-Fi network. Received OFDM signals, received in a cellular system in a first RF frequency band, are demodulated and in a repeater mode are re-transmitted in a cellular system in a second OFDM radio frequency band. One or more receivers and demodulators for receiving demodulating and processing received signals into location finder information. A video camera in mobile device generates video signal and transmits video signal with location finder information signal.

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.

A system and apparatus are disclosed for a method and apparatus for equalizing signals. An apparatus that incorporates teachings of the present disclosure may include, for example, an equalizer having a channel estimation calculator for calculating a time domain channel estimation from a baseband signal, a Fast Fourier Transform processor for translating the time domain channel estimation to a frequency domain channel estimation, a tap weight calculator for calculating a frequency domain tap weight according to the frequency domain channel estimation, an inverse Fast Fourier Transform processor for translating the frequency domain tap weight calculation to a time domain tap weight calculation, and a filter for equalizing the baseband signal according to the time domain tap weight calculation.

Methods and devices are disclosed for receiving and decoding sparsely encoded data sequences using a message passing algorithm (MPA) or maximum likelihood sequence estimation (MLSE). Such data sequences may be used in wireless communications systems supporting multiple access, such as sparse code multiple access (SCMA) systems. The Methods and devices reduce the number of states in a search space for each received signal and associated function node based on a search threshold based on a characteristic related to the received signal and/or to a quality of a resource element over which the received signal is transmitted.

There is provided with a method for enabling a user equipment to perform a random access procedure in a wireless communication system. The method includes transmitting a random access preamble and receiving a random access response as a response to the random access preamble. The random access response is addressed by a random access identifier. The random access identifier is mapped to radio resources used for transmitting the random access preamble. The user equipment can immediately confirm its random access response and perform further efficient random access procedure.