Digital communication receiver using partial knowledge of the channel state information

Abstract

The present invention proposes a demodulator device, a receiver and a demodulation method for M-ary amplitude shift keying systems (MASK) that requires partial knowledge of the CSI, namely, the channel attenuation coefficient. Therefore, the new demodulator, receiver and demodulation method do not require the knowledge of the channel phase shift. Consequently, no complicated channel estimation techniques are required, and the system will be very robust to the system impairments such as phase noise, I-Q imbalance, etc. In this sense, the new technique is denoted as semi-coherent demodulation (SCD). To reduce the complexity of the new SCD, a suboptimal demodulator is derived which has much lower complexity than the optimal while providing almost the same error probability.

1 . A digital communication receiver for detecting signals transmitted by a digital transmitter through a communication channel, the channel having a channel attenuation |h| and a channel phase shift having a multipath fading effect on the transmitted signals, the receiver comprising a demodulator configured to demodulate signals received by the receiver using channel coefficients representing the channel attenuation only without any knowledge of the channel phase shift. 
     
     
         2 . The digital communication receiver as claimed in  claim 1 , wherein the demodulator is robust to phase noise, large phase variations and time-varying I-Q imbalance. 
     
     
         3 . The digital communication receiver as claimed in  claim 2 , wherein the demodulator uses a M-ary amplitude shift keying technique, the transmitted signals being modulated by the transmitter using said same technique before transmission using a modulation order M equal or superior to 2. 
     
     
         4 . The digital communication receiver as claimed in  claim 3 , wherein the detected signals have a symbol Error Rate (SER) intermediate in terms of performance between a coherent detection and a non-coherent detection assuming a same spectral efficiency. 
     
     
         5 . The digital communication receiver as claimed in  claim 4 , wherein the demodulator is less complex than a coherent demodulator, and wherein the SER performance of the detected signals using the demodulator is substantially similar to a SER performance obtained using a coherent demodulator. 
     
     
         6 . The digital communication receiver as claimed in  claim 5 , wherein the channel is a multi-path fading channel. 
     
     
         7 . A computer-implemented demodulation method comprising:
 receiving from a digital communication receiver signals transmitted by a digital transmitter through a communication channel, the channel having a channel attenuation |h| and a channel phase shift having a multipath fading effect on the transmitted signals; and   demodulating the signals received by the receiver using only channel coefficients representing the channel attenuation without any knowledge of the channel phase shift for detecting the transmitted signals.   
     
     
         8 . The demodulation method as claimed in  claim 7 , wherein the demodulation method is robust to phase noise, large phase variations and time-varying I-Q imbalance. 
     
     
         9 . The demodulation method as claimed in  claim 8 , wherein the demodulation method uses a M-ary amplitude shift keying technique, the transmitted signals being modulated by the transmitter using said same technique before transmission using a modulation order M equal or superior to 2. 
     
     
         10 . The demodulation method as claimed in  claim 9 , wherein the detected signals have a symbol Error Rate (BER) intermediate in terms of performance between a coherent detection and a differentially coherent detection assuming a same spectral efficiency. 
     
     
         11 . The demodulation method as claimed in  claim 10 , wherein the demodulation method is less complex than a coherent demodulation, and wherein the SER performance of the detected signals using the demodulation method is substantially similar to a SER performance obtained using a coherent demodulation. 
     
     
         12 . The demodulation method as claimed in  claim 11 , wherein the channel is a multi-path fading channel. 
     
     
         13 . A demodulator device for detecting signals transmitted by a digital transmitter to a digital receiver through a communication channel, the channel having a channel attenuation |h| and a channel phase shift having a multipath fading effect on the transmitted signals, the demodulator device being configured to communicate with the digital receiver for demodulating signals received by the receiver using channel coefficients representing the channel attenuation only without any knowledge of the channel phase shift. 
     
     
         14 . The demodulator device as claimed in  claim 13 , wherein the demodulation is robust to phase noise, large phase variations and time-varying I-Q imbalance. 
     
     
         15 . The demodulator device as claimed in  claim 14 , wherein the demodulator device uses a M-ary amplitude shift keying technique, the transmitted signals being modulated by the transmitter using said same technique before transmission using a modulation order M superior to 2. 
     
     
         16 . The demodulator device as claimed in  claim 15 , wherein the detected signals have a Bit Error Rate (BER) intermediate in terms of performance between a coherent detection and a differentially coherent detection assuming a same spectral efficiency. 
     
     
         17 . The demodulator device as claimed in  claim 16 , wherein the demodulator device is less complex than a coherent demodulator, and wherein the BER performance of the detected signals using the demodulator is substantially similar to a BER performance obtained using a coherent demodulator. 
     
     
         18 . The demodulator device as claimed in  claim 17 , wherein the channel is a multi-path fading channel.