Patent ID: 9641274
Date: 2017-05-02
CPC Classifications: H04J,H04L

Claim:
1. An OFDM receiving apparatus for estimating a Signal to Noise Ratio, SNR, of a first sounding signal associated with a first user, the first sounding signal being transmitted along with a second sounding signal associated with a second user, over a wide channel of a wireless communication system, the first and second sounding signals being code-division multiplexed in the frequency domain based on a phase rotated version of a known code exhibiting constant-amplitude zero autocorrelation, CAZAC, property, the receiving apparatus comprising: a receiving unit comprising a plurality of antennas and arranged to receive and convert the first and second sounding transmission signals into first and second frequency-domain sounding signals, respectively; a complex multiplying unit operably coupled to the receiving unit and arranged to multiply, in the frequency domain, the first and second frequency-domain sounding signals with a complex conjugate of the known CAZAC code, thereby generating first and second phase rotated frequency-domain sounding signals, respectively; an Inverse Fast Fourier Transform, IFFT, unit operably coupled to the multiplying unit and arranged to transform the first and second phase rotated frequency-domain sounding signals from the frequency domain to the time domain, thereby generating first and second cyclically shifted time-domain sounding signals; a power delay profile, PDP, estimation unit operably coupled to the IFFT unit and arranged to estimate a power delay profile of the wide channel based on the first and second cyclically shifted time-domain sounding signals, thereby generating a power delay profile estimate comprising first and second energy regions associated with first and second propagation delays occurring in the wide channel, respectively; and, a processing unit such as a processor, operably coupled to the receiving unit and the PDP estimation unit, the processing unit being arranged to: