Rate-matching scheme for control channels using polar codes
Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to methods and apparatus for rate-matching control channels using polar codes. An exemplary method generally includes encoding a stream of bits using a polar code, determining a size of a circular buffer for storing the encoded stream of bits based, at least in part, on a minimum supported code rate and a control information size, and performing rate-matching on stored encoded stream of bits based, at least in part, on a mother code size, N, and a number of coded bits for transmission, E.
1. A method of wireless communications by a first wireless communication device, comprising:
encoding a stream of bits using a polar code;
storing the encoded stream of bits in a circular buffer, wherein a size of the circular buffer is based on a minimum supported code rate (R min ) and a number of information bits (K);
performing rate-matching on the encoded stream of bits stored in the circular buffer based on a code size (N) and a number of coded bits for transmission (E); and
transmitting the rate-matched encoded stream of bits in a wireless network to a receiving device.
2. The method of claim 1 , wherein performing rate-matching on the stored encoded stream of bits comprises puncturing a first number of stored encoded bits if E is less than N.
3. The method of claim 2 , wherein the puncturing is performed according to a defined pattern starting at a location of N in the circular buffer and proceeding in a counter-clockwise fashion.
4. The method of claim 3 , wherein puncturing according to the defined pattern comprises:
generating a vector of E ones followed by N-E zeros; and
performing one of:
puncturing bits in a location of the N-E zeros in the circular buffer; or
puncturing bits in locations in the circular buffer according to a bit-reversal of the vector.
5. The method of claim 1 , wherein performing rate-matching on the stored encoded stream of bits comprises repeating a second number of stored encoded bits if E is greater than N.
6. The method of claim 5 , wherein the repeating is performed according to a defined pattern starting at a location of N in the circular buffer and proceeding in a counter-clockwise fashion.
7. The method of claim 6 , wherein repeating according to the defined pattern comprises:
generating a vector of E-N ones followed by 2N-E zeros; and
performing one of:
repeating bits in a location of the E-N ones in the circular buffer; or
repeating bits in locations of the circular buffer according to a bit-reversal of the vector.
8. The method of claim 1 , wherein the minimum supported code rate is one of 1/6 or 1/8.
9. The method of claim 1 , further comprising:
determining a parameter (N M ), where N M is the minimum power of 2 which is not less than E; and
determining another parameter (N 1 ), according to:
N
1
=
{
N
M
2
if
E
≤
β
N
M
N
M
otherwise
wherein β is a real value in the range of [1, 2].
10. The method of claim 9 , wherein N=min(N 1 , N 2 ).
11. The method of claim 9 , wherein β is equal to 1.125.
12. A non-transitory computer-readable medium, comprising:
instructions that, when executed by a processor of a first wireless communication device, cause the first wireless communication device to:
encode a stream of bits using a polar code;
store the encoded stream of bits in a circular buffer, wherein a size of the circular buffer is based on a minimum supported code rate (R min ) and a number of information bits (K);
perform rate-matching on the encoded stream of bits stored in the circular buffer based on a code size (N) and a number of coded bits for transmission (E); and
transmit the rate-matched encoded stream of bits in a wireless network to a receiving device.
13. The non-transitory computer-readable medium of claim 12 , wherein, in order to cause the first wireless communication device to perform rate-matching on the stored encoded stream of bits, the instructions cause the first wireless communication device to puncture a first number of stored encoded bits if E is less than N.
14. The non-transitory computer-readable medium of claim 13 , wherein the instructions cause the first wireless communication device to puncture the first number of stored encoded bits according to a defined pattern starting at a location of N in the circular buffer and proceeding in a counter-clockwise fashion.
15. The non-transitory computer-readable medium of claim 14 , wherein, in order to cause the first wireless communication device to puncture the first number of stored encoded bits according to the defined pattern, the instructions cause the first wireless communication device to:
generate a vector of E ones followed by N-E zeros; and
one of:
puncture bits in a location of the N-E zeros in the circular buffer; or
puncture bits in locations in the circular buffer according to a bit-reversal of the vector.
16. The non-transitory computer-readable medium of claim 12 , wherein, in order to cause the first wireless communication device to perform rate-matching on the stored encoded stream of bits, the instructions cause the first wireless communication device to repeat a second number of stored encoded bits if E is greater than N.
17. The non-transitory computer-readable medium of claim 16 , wherein the instructions cause the first wireless communication device to repeat the second number of stored encoded bits according to a defined pattern starting at a location of N in the circular buffer and proceeding in a counter-clockwise fashion.
18. The non-transitory computer-readable medium of claim 17 , wherein, in order to cause the first wireless communication device to repeat the second number of stored encoded bits according to the defined pattern, the instructions cause the first wireless communication device to:
generate a vector of E-N ones followed by 2N-E zeros; and
one of:
repeat bits in a location of the E-N ones in the circular buffer; or
repeat bits in locations of the circular buffer according to a bit-reversal of the vector.
19. The non-transitory computer-readable medium of claim 12 , wherein the minimum supported code rate is one of 1/6 or 1/8.
20. The non-transitory computer-readable medium of claim 12 , wherein the instructions further cause the first wireless communication device to:
determine a parameter (N M ), where N M is the minimum power of 2 which is not less than E; and
determine another parameter (N 1 ), according to:
N
1
=
{
N
M
2
if
E
≤
β
N
M
N
M
otherwise
wherein β is a real value in the range of [1, 2].
21. The non-transitory computer-readable medium of claim 20 , wherein N=min(N 1 , N 2 ).
22. The non-transitory computer-readable medium of claim 20 , wherein β is equal to 1.125.
23. A first wireless communication device, comprising:
a memory comprising executable instructions;
a processor in data communication with the memory and configured to execute the executable instructions and cause the first wireless communication device to:
encode a stream of bits using a polar code;
store the encoded stream of bits in a circular buffer, wherein a size of the circular buffer is based on a minimum supported code rate (R min ) and a number of information bits (K);
perform rate-matching on the encoded stream of bits stored in the circular buffer based on a code size (N) and a number of coded bits for transmission (E); and
transmit the rate-matched encoded stream of bits in a wireless network to a receiving device.
24. The first wireless communication device of claim 23 , wherein in order to perform rate-matching on the stored encoded stream of bits, the processor is further configured to cause the first wireless communication device to puncture a first number of stored encoded bits if E is less than N.
25. The first wireless communication device of claim 24 , wherein the processor is further configured to cause the first wireless communication device to puncture the first number of stored encoded bits according to a defined pattern starting at a location of N in the circular buffer and proceeding in a counter-clockwise fashion.
26. The first wireless communication device of claim 25 , wherein in order to puncture according to the defined pattern, the processor is further configured to cause the first wireless communication device to:
generate a vector of E ones followed by N-E zeros; and
perform one of:
puncture bits in a location of the N-E zeros in the circular buffer; or
puncture bits in locations in the circular buffer according to a bit-reversal of the vector.
27. The first wireless communication device of claim 23 , wherein in order to perform rate-matching on the stored encoded stream of bits, the processor is further configured to cause the first wireless communication device to repeat a second number of stored encoded bits if E is greater than N.
28. The first wireless communication device of claim 27 , wherein the processor is further configured to cause the first wireless communication device to repeat the second number of stored encoded bits according to a defined pattern starting at a location of the mother code size, N, in the circular buffer and proceeding in a counter-clockwise fashion.
29. The first wireless communication device of claim 28 , wherein in order to repeat according to the defined pattern, the processor is further configured to cause the first wireless communication device to:
generate a vector of E-N ones followed by 2N-E zeros; and
perform one of:
repeat bits in a location of the E-N ones in the circular buffer; or
repeat bits in locations of the circular buffer according to a bit-reversal of the vector.
30. The first wireless communication device of claim 23 , wherein the minimum supported code rate is one of 1/6 or 1/8.
31. The first wireless communication device of claim 23 , wherein the processor is further configured to cause the first wireless communication device to:
determine a parameter (N M ), where N M is the minimum power of 2 which is not less than E; and
determine another parameter (N 1 ), according to:
N
1
=
{
N
M
2
if
E
≤
β
N
M
N
M
otherwise
wherein β is a real value in the range of [1, 2].
32. The first wireless communication device of claim 31 , wherein N=min(N 1 , N 2 ).
33. The first wireless communication device of claim 31 , wherein β is equal to 1.125.
34. A first wireless communication device, comprising:
means for encoding a stream of bits using a polar code;
means for storing the encoded stream of bits in a circular buffer, wherein a size of the circular buffer is based on a minimum supported code rate (R min ) and a number of information bits (K);
means for performing rate-matching on the encoded stream of bits stored in the circular buffer based on a code size (N) and a number of coded bits for transmission (E); and
means for transmitting the rate-matched encoded stream of bits in a wireless network to a receiving device.
35. The first wireless communication device of claim 34 , wherein the means for performing rate-matching on the stored encoded stream of bits comprise means for puncturing a first number of stored encoded bits if E is less than N.
36. The first wireless communication device of claim 35 , wherein the means for puncturing the first number of stored encoded bits comprise means for puncturing the first number of stored encoded bits according to a defined pattern starting at a location of N in the circular buffer and proceeding in a counter-clockwise fashion.
37. The first wireless communication device of claim 36 , wherein means for puncturing the first number of stored encoded bit according to the defined pattern comprise:
means for generating a vector of E ones followed by N-E zeros; and
one of:
means for puncturing bits in a location of the N-E zeros in the circular buffer; or
means for puncturing bits in locations in the circular buffer according to a bit-reversal of the vector.
38. The first wireless communication device of claim 34 , wherein the means for performing rate-matching on the stored encoded stream of bits comprise means for repeating a second number of stored encoded bits if E is greater than N.
39. The first wireless communication device of claim 38 , wherein the means for repeating the second number of stored encoded bits comprise means for repeating the second number of stored encoded bits according to a defined pattern starting at a location of N in the circular buffer and proceeding in a counter-clockwise fashion.
40. The first wireless communication device of claim 39 , wherein the means for repeating the second number of stored encoded bits according to the defined pattern comprise:
means for generating a vector of E-N ones followed by 2N-E zeros; and
one of:
means for repeating bits in a location of the E-N ones in the circular buffer; or
means for repeating bits in locations of the circular buffer according to a bit-reversal of the vector.
41. The first wireless communication device of claim 34 , wherein the minimum supported code rate is one of 1/6 or 1/8.
42. The first wireless communication device of claim 34 , further comprising:
means for determining a parameter (N M ), where Nu is the minimum power of 2 which is not less than E; and
means for determining another parameter (N 1 ), according to:
N
1
=
{
N
M
2
if
E
≤
β
N
M
N
M
otherwise
wherein β is a real value in the range of [1, 2].
43. The first wireless communication device of claim 42 , wherein N=min(N 1 , N 2 ).
44. The first wireless communication device of claim 42 wherein β is equal to 1.125.