Wireless system, apparatus, and method for quantization of channel state information utilizing real and imaginary parts of a channel matrix

1 . A method comprising the steps of:

determining a maximum amplitude of real and imaginary parts of each element of a channel matrix for a channel;

converting each maximum amplitude to a fixed-point value within a predefined range;

determining a bit-shifting number for each maximum amplitude by comparing each fixed-point value with a series of predefined threshold values within the predefined range;

quantizing the real and imaginary parts of each element of the channel matrix to an integer; and

bit-shifting each of the quantized real and imaginary parts of each element of the channel matrix towards the most significant bit (MSB) by the corresponding bit-shifting number and truncating the bit-shifted result to a predefined number of bits for generating channel state information (CSI) for use in communication.

2 . The method of claim 1 , wherein the predefined range is a range between 2 (N p −R) and 2 (N p −2) , where N p is the number of bits in an internal fixed-point CSI representation and N p is greater than or equal to the predefined number of bits, and R is a maximum of the bit-shifting number.

3 . The method of claim 2 , wherein R=7.

4 . The method of claim 2 , wherein the series of predefined threshold values comprise 2 (N p −2) , 2 (N p −3) , . . . , 2 (N p −R−1) .

5 . The method of claim 2 , wherein said determining the bit-shifting number for each maximum amplitude comprises:

determining the bit-shifting number as zero if the maximum amplitude is greater than or equal to 2 (N p −2) ;

determining the bit-shifting number as i if the maximum amplitude is greater than or equal to 2 (N p −2−i) and smaller than 2 (N p −2−i+1) , where 1≤i≤R−1; and

determining the bit-shifting number as R if the maximum amplitude is smaller than 2 (N p −R−1) .

6 . The method of claim 5 , wherein said quantizing the real and imaginary parts of each element of the channel matrix to the integer comprises:

quantizing the real and imaginary parts of each element of the channel by multiplying each of the real and imaginary parts by (2 N p −1 −1) and then rounding the multiplication result to the nearest integer.

7 . The method of claim 1 , wherein the channel comprises a plurality of subcarriers;

wherein the channel matrix is for one of the plurality of subcarriers; and

wherein the method further comprises:

performing said determining the maximum amplitude, said converting each maximum amplitude, said determining the bit-shifting number, said quantizing the real and imaginary parts, and said bit-shifting for the plurality of subcarriers.

8 . A wireless apparatus comprising:

a processor for:

determining a maximum amplitude of real and imaginary parts of each element of a channel matrix for a channel;

converting each maximum amplitude to a fixed-point value within a predefined range;

determining a bit-shifting number for each maximum amplitude by comparing each fixed-point value with a series of predefined threshold values within the predefined range;

quantizing the real and imaginary parts of each element of the channel matrix to an integer; and

bit-shifting each of the quantized real and imaginary parts of each element of the channel matrix towards the most significant bit (MSB) by the corresponding bit-shifting number and truncating the bit-shifted result to a predefined number of bits for generating channel state information (CSI) for use in communication.

9 . The wireless apparatus of claim 8 , wherein the predefined range is a range between 2 (N p −R) and 2 (N p −2) , where N p is the number of bits in an internal fixed-point CSI representation and N p is greater than or equal to the predefined number of bits, and R is a maximum of the bit-shifting number.

10 . The wireless apparatus of claim 9 , wherein the series of predefined threshold values comprise 2 (N p −2) , 2 (N p −3) , . . . , 2 (N p −R−1) .

11 . The wireless apparatus of claim 9 , wherein said determining the bit-shifting number for each maximum amplitude comprises:

determining the bit-shifting number as zero if the maximum amplitude is greater than or equal to 2 (N p −2) ;

determining the bit-shifting number as i if the maximum amplitude is greater than or equal to 2 (N p −2−i) and smaller than 2 (N p −2−i+1) , where 1≤i≤R−1; and

determining the bit-shifting number as R if the maximum amplitude is smaller than 2 (N p −R−1) .

12 . The wireless apparatus of claim 11 , wherein said quantizing the real and imaginary parts of each element of the channel matrix to the integer comprises:

quantizing the real and imaginary parts of each element of the channel by multiplying each of the real and imaginary parts by (2 N p −1 −1) and then rounding the multiplication result to the nearest integer.

13 . The wireless apparatus of claim 8 , wherein the channel comprises a plurality of subcarriers;

wherein the channel matrix is for one of the plurality of subcarriers; and

wherein the method further comprises:

performing said determining the maximum amplitude, said converting each maximum amplitude, said determining the bit-shifting number, said quantizing the real and imaginary parts, and said bit-shifting for the plurality of subcarriers.

14 . One or more non-transitory computer-readable storage devices comprising computer-executable instructions, wherein the instructions, when executed, cause a processing structure to perform actions comprising:

determining a maximum amplitude of real and imaginary parts of each element of a channel matrix for a channel;

converting each maximum amplitude to a fixed-point value within a predefined range;

determining a bit-shifting number for each maximum amplitude by comparing each fixed-point value with a series of predefined threshold values within the predefined range;

quantizing the real and imaginary parts of each element of the channel matrix to an integer; and

bit-shifting each of the quantized real and imaginary parts of each element of the channel matrix towards the most significant bit (MSB) by the corresponding bit-shifting number and truncating the bit-shifted result to a predefined number of bits for generating channel state information (CSI) for use in communication.

15 . The one or more non-transitory computer-readable storage devices of claim 14 , wherein the predefined range is a range between 2 (N p −R) and 2 (N p −2) , where N p is the number of bits in an internal fixed-point CSI representation and N p is greater than or equal to the predefined number of bits, and R is a maximum of the bit-shifting number.

16 . The one or more non-transitory computer-readable storage devices of claim 15 , wherein R=7.

17 . The one or more non-transitory computer-readable storage devices of claim 15 , wherein the series of predefined threshold values comprise 2 (N p −2) , 2 (N p −3) , . . . , 2 (N p −R−1) .

18 . The one or more non-transitory computer-readable storage devices of claim 15 , wherein said determining the bit-shifting number for each maximum amplitude comprises:

determining the bit-shifting number as zero if the maximum amplitude is greater than or equal to 2 (N p −2) ;

determining the bit-shifting number as i if the maximum amplitude is greater than or equal to 2 (N p −2−i) and smaller than 2 (N p −2−i+1) , where 1≤i≤R−1; and

determining the bit-shifting number as R if the maximum amplitude is smaller than 2 (N p −R−1) .

19 . The one or more non-transitory computer-readable storage devices of claim 18 , wherein said quantizing the real and imaginary parts of each element of the channel matrix to the integer comprises:

quantizing the real and imaginary parts of each element of the channel by multiplying each of the real and imaginary parts by (2 N p −1 −1) and then rounding the multiplication result to the nearest integer.

20 . The one or more non-transitory computer-readable storage devices of claim 14 , wherein the channel comprises a plurality of subcarriers;

wherein the channel matrix is for one of the plurality of subcarriers; and

wherein the method further comprises:

performing said determining the maximum amplitude, said converting each maximum amplitude, said determining the bit-shifting number, said quantizing the real and imaginary parts, and said bit-shifting for the plurality of subcarriers.