A method and system for multiple access in a system utilizing two-dimensional signal modulation. The method includes spreading data symbols arranged in a two-dimensional information domain onto sets of grid points respectively associated with different users in a time-frequency domain. The spreading is performed using two-dimensional basis functions uniquely associated with positions on a lattice in the information domain corresponding to the data symbols. A modulated signal is then generated using the sets of transformed symbols. The sets of grid points associated with the different users may be interleaved within the time-frequency domain or may form non-interleaved windows.

A data transmission and signaling method in a transmitter device configured for concurrent transmission of non-orthogonal independent downlink data streams to receiver devices in a wireless communication system comprises sending to all receiver devices control information that includes indices of receiver devices selected for transmission, code rates of selected receiver devices, a label bit-to-receiver device allocation, an index of an expanded constellation, and a number of resource elements used for transmission.

Upon detection of a trigger, such as the exceeding of an error threshold or the direction of a user, a diagnostic link system enters a diagnostic information transmission mode. This diagnostic information transmission mode allows for two modems to exchange diagnostic and/or test information that may not otherwise be exchangeable during normal communication. The diagnostic information transmission mode is initiated by transmitting an initiate diagnostic link mode message to a receiving modem accompanied by a cyclic redundancy check (CRC). The receiving modem determines, based on the CRC, if a robust communications channel is present. If a robust communications channel is present, the two modems can initiate exchange of the diagnostic and/or test information. Otherwise, the transmission power of the transmitting modem is increased and the initiate diagnostic link mode message re-transmitted to the receiving modem until the CRC is determined to be correct.

Methods, systems, and apparatus for receiving an input signal, where the input signal includes a carrier signal modulated with a first modulation signal and a second modulation signal, and where the second modulation signal is a TM signal. Demodulating the first modulation signal from the input signal. Modulating an un-modulated carrier signal with the first modulation signal to generate a third signal, where the third signal includes the carrier signal modulated by the first modulation signal. And, removing the first modulation signal from the input signal by subtracting the third signal from the input signal to extract the TM signal from the input signal.

A wireless communication device and a method for IQ calibration are provided. The device includes a transmitting unit for generating a set of RF transmitting signals based on a set of digital baseband signals, each of the set of RF transmitting signals has IQ components; a receiving unit for generating a set of digital feedback signals based on a set of RF receiving signals obtained from the set of RF transmitting signals; a processing unit for obtaining a first set of compensation coefficients for the transmitting unit and a second set of compensation coefficients for the receiving unit based on the set of digital baseband signals and the set of digital feedback signals with an IQ calibration model, the IQ calibration model includes a first high-order term set about a nonlinear error in the transmitting unit and a second high-order term set bout a nonlinear error in the receiving unit.