Wireless communication system and method using grouping maximum likelihood detection

Abstract

Disclosed is a method for increasing a data transfer rate without an increase in the whole bandwidth using intrinsic spreading codes and orthogonal codes. The method uses interleaving, OFDM modulation/demodulation, and maximum likelihood detection (MLD) to overcome the effects of multipath fading or signal interference, determines grouped optimal values by a grouping method of dividing the intrinsic spreading codes in series, and calculates an integrated optimal value for all the intrinsic spreading codes using the grouped optimal values, thereby reducing the complexity of MLD according to the length of the intrinsic spreading code and acquiring an improved performance.

1. A wireless communication system comprising:
 a transmitter including an orthogonal encoder for converting serially input binary signals to parallel binary signals and orthogonally encoding the parallel binary signals, a first multiplier for multiplying the orthogonally encoded binary signals by an intrinsic spreading code to spread the orthogonally encoded binary signals, and an OFDM (Orthogonal Frequency Division Multiplexing) modulator for OFDM-modulating the spread signals; and 
 a receiver including an OFDM demodulator for demodulating the OFDM-modulated signals, and a maximum likelihood detector for performing a maximum likelihood detection of the demodulated spread signals, 
 the maximum likelihood detector grouping the OFDM-demodulated signals into a predetermined number of blocks, and performing maximum likelihood detection for each of the blocks to get a predetermined number of maximum likelihood detection values, and performing maximum likelihood detection for all of the predetermined number of maximum likelihood detection values. 
 
     
     
       2. The wireless communication system as claimed in  claim 1 , wherein the transmitter further includes:
 a first serial-to-parallel converter for serial-to-parallel converting the signals spread with the intrinsic spreading code; and 
 an interleaver for interleaving the serial-to-parallel converted signals and sending the interleaved signals to the OFDM modulator, 
 the receiver further including: 
 a deinterleaver for deinterleaving the OFDM-demodulated signals; and 
 a first parallel-to-serial converter for parallel-to-serial converting the deinterleaved signals and sending the parallel-to-serial converted signals to the maximum likelihood detector. 
 
     
     
       3. The wireless communication system as claimed in  claim 1 , wherein the maximum likelihood detector comprises:
 a second multiplier for multiplying the OFDM-demodulated signals by the intrinsic spreading code; 
 a grouping section for grouping the multiplied signals into the predetermined number of blocks; 
 a grouping maximum approximation detector for performing a maximum likelihood detection for each of the blocks to get the predetermined number of maximum likelihood detection values; 
 an integrated maximum approximation detector for performing maximum likelihood detection for the predetermined number of maximum likelihood detection values; 
 an orthogonal despreader for orthogonally despreading a sequence having a maximum approximation value to output parallel signals; and 
 a second parallel-to-serial converter for converting the parallel output signals to serial signals. 
 
     
     
       4. The wireless communication system as claimed in  claim 3 , wherein the grouping section groups an interval length of the intrinsic spreading code into blocks having a bit interval length of the orthogonal code. 
     
     
       5. A wireless communication method comprising:
 orthogonally encoding serial binary signals; 
 multiplying the orthogonally encoded serial binary signals by an intrinsic spreading code to spread the orthogonally encoded binary signals; 
 OFDM-modulating the spread signals; 
 OFDM-demodulating the OFDM-modulated signals: 
 grouping the demodulated signals into a predetermined number of blocks; 
 performing maximum likelihood detection for each of the predetermined number of blocks to get a predetermined number of maximum likelihood detection values; and 
 performing maximum likelihood detection for all of the predetermined number of 
 maximum likelihood detection values. 
 
     
     
       6. The wireless communication method as claimed in  claim 5 , further comprising:
 serial-to-parallel converting the signals spread with the intrinsic spreading code, and 
 interleaving the serial-to-parallel converted signals; and 
 deinterleaving the OFDM-demodulated signals; and parallel-to-serial converting the deinterleaved signals and sending the parallel-to-serial converted signals to a maximum likelihood detector. 
 
     
     
       7. The wireless communication method as claimed in  claim 6 , wherein said grouping the demodulated signals further comprises
 multiplying the OFDM-demodulated signals by the intrinsic spreading code, 
 grouping the multiplied signals into the predetermined number of blocks. 
 
     
     
       8. The wireless communication method as claimed in  claim 7 , wherein the grouping comprises grouping an interval length of the intrinsic spreading code into the blocks having a bit interval length of the orthogonal code. 
     
     
       9. A wireless communication transmitter, comprising:
 an orthogonal encoder to convert serially input binary signals into a first number of parallel binary signals and to orthogonally encode the binary signals; and   an OFDM (Orthogonal Frequency Division Multiplexing) modulator to OFDM-modulate the spread signals,   wherein the OFDM-modulated signals are transmitted such that a receiver to receive the OFDM-modulated signals is configured to demodulate the OFDM-modulated signals and to perform a maximum likelihood detection by grouping the OFDM-demodulated signals into a second number of blocks, performing grouped maximum likelihood detection for each block to determine grouped maximum likelihood detection values, and performing integrated maximum likelihood detection to determine an integrated maximum likelihood detection value.   
     
     
       10. The wireless communication transmitter of claim 9, further comprising:
 an interleaver to interleave the binary signals and to send the interleaved signals to the OFDM modulator.   
     
     
       11. The wireless communication transmitter of claim 9, wherein the first number of parallel binary signals is the same number as the second number of blocks. 
     
     
       12. A method for wireless communication transmission, comprising:
 converting serially input binary signals into a first number of parallel binary signals;   orthogonally encoding the binary signals;   OFDM (Orthogonal Frequency Division Multiplexing)-modulating the binary signals; and   transmitting the OFDM-modulated signals,   wherein a receiver to receive the OFDM-modulated signals is configured to demodulate the OFDM-modulated signals and to perform a maximum likelihood detection by grouping the OFDM-demodulated signals into a second number of blocks, performing grouped maximum likelihood detection for each block to determine grouped maximum likelihood detection values, and performing integrated maximum likelihood detection to determine an integrated maximum likelihood detection value.   
     
     
       13. The method of claim 12, further comprising:
 interleaving the binary signals.   
     
     
       14. The method of claim 12, wherein the first number of parallel binary signals is the same number as the second number of blocks. 
     
     
       15. A wireless communication receiver to receive OFDM-modulated signals, comprising:
 an OFDM (Orthogonal Frequency Division Multiplexing) demodulator to demodulate the OFDM-modulated signals; and   a maximum likelihood detector to perform a maximum likelihood detection of the OFDM-demodulated signals,   wherein the maximum likelihood detector groups the OFDM-demodulated signals into a first number of blocks, performs grouped maximum likelihood detection for each block to determine grouped maximum likelihood detection values, and performs integrated maximum likelihood detection to determine an integrated maximum likelihood detection value.   
     
     
       16. The wireless communication receiver of claim 15, wherein the receiver further comprises:
 a deinterleaver to deinterleave the OFDM-demodulated signals.   
     
     
       17. The wireless communication receiver of claim 15, wherein the first number of blocks corresponds to a second number of parallel binary signals orthogonally encoded by a transmitter configured to transmit the OFDM-modulated signals. 
     
     
       18. The wireless communication receiver of claim 15, wherein the maximum likelihood detector comprises:
 a grouping section to group the OFDM-demodulated signals into the first number of blocks;   a grouping maximum approximation detector to perform the grouped maximum likelihood detection for each block to determine the grouped maximum likelihood detection values;   an integrated maximum approximation detector to perform the integrated maximum likelihood detection to determine the integrated maximum likelihood detection value;   an orthogonal despreader to orthogonally despread a sequence having a maximum approximation value, and to output parallel signals; and   a parallel-to-serial converter to convert the parallel output signals to serial signals.   
     
     
       19. A method for wireless communication reception, comprising:
 receiving OFDM (Orthogonal Frequency Division Multiplexing)-modulated signals;   OFDM-demodulating the OFDM-modulated signals:   grouping the OFDM-demodulated signals into a first number of blocks;   performing grouped maximum likelihood detection for each of the first number of blocks to determine grouped maximum likelihood detection values; and   performing integrated maximum likelihood detection to determine an integrated maximum likelihood detection value.   
     
     
       20. The method of claim 19, further comprising:
 deinterleaving the OFDM-demodulated signals.   
     
     
       21. The method of claim 19, wherein the first number of blocks corresponds to a second number of parallel binary signals orthogonally encoded by a transmitter configured to transmit the OFDM-modulated signals.