Rate matching for a wireless communications system
Apparatuses and methods are provided for generating a plurality of redundancy versions using various rate matching algorithms. In some embodiments, a rate matcher is provided that allocates systematic and parity bits to the redundancy versions in a manner that allows all of these bits to be transmitted in at least one redundancy version. In some embodiments, the rate matcher uses a first puncturing algorithm to generate both a first redundancy version and a third redundancy version, but allocates a different proportion of the systematic bits to these redundancy versions. In these embodiments, the second redundancy version may include only bits that were not transmitted in the first redundancy version.
1. A method of transmitting a message over a wireless communications network, the method comprising:
encoding the message using a Turbo code to produce encoded data, the encoded data comprising a plurality of systematic bits and a plurality of parity bits;
selecting, for transmission over the wireless communications network, a first subset of the systematic bits using a first puncturing algorithm and a first parameterized swap value;
generating a first redundancy version of the message that has a predetermined number of bit positions, the first redundancy version including the first subset of the systematic bits, wherein unused bit positions of the first redundancy version are allocated to a first subset of the parity bits;
selecting, for transmission over the wireless communications network, a second subset of the systematic bits that has substantially all of the systematic bits corresponding to the message that are not included in the first subset of the systematic bits;
generating a second redundancy version of the message that has the predetermined number of bit positions, the second redundancy version including the second subset of systematic bits, wherein unused bit positions of the second redundancy version are allocated to a second subset of parity bits that is generated from parity bits which are not included in the first subset of parity bits, and includes additional parity bits only if all of the parity bits are otherwise included in the first or second subsets; and
transmitting at least the first redundancy version.
2. The method of claim 1 , wherein selecting the first subset or the second subset of systematic bits comprises puncturing a portion of the systematic bits such that the portion is excluded from the that subset.
3. The method of claim 1 , further comprising:
selecting, for transmission over the wireless communications network, a third subset of the systematic bits using the first puncturing algorithm and a second parameterized swap value, wherein the second parameterized swap value is greater than the first parameterized swap value; and
generating a third redundancy version of the message that has the predetermined number of bit positions, the third redundancy version including the third subset of the systematic bits and a third subset of the parity bits.
4. The method of claim 3 , wherein the plurality of parity bits comprises a first plurality of parity bits and a second plurality of parity bits, the method further comprising:
allocating a portion of the first, second, and third subsets of parity bits to the first plurality of parity bits; and
allocating a remaining portion of the first, second, and third subsets of parity bits to the second plurality of parity bits.
5. The method of claim 1 , wherein the plurality of parity bits comprises a first plurality of parity bits and a second plurality of parity bits, the method further comprising:
allocating approximately half of the first and second subsets of parity bits to the first plurality of parity bits; and
allocating a remaining approximately half of the first and second subsets of parity bits to the second plurality of parity bits.
6. The method of claim 1 , wherein selecting the second subset of parity bits comprises:
excluding parity bits that are included in the first subset of the parity bits from the second subset of parity bits.
7. The method of claim 6 , wherein excluding the parity bits from being selected for the second subset is performed in response to determining that more than two redundancy versions are needed to transmit all bits of the encoded data.
8. The method of claim 1 , wherein including all of the parity bits in the second subset that have not been included in the first redundancy version is performed in response to determining that two redundancy versions are needed to transmit all bits of the encoded data stream.
9. A transmitter for transmitting a message over a wireless communications network, the transmitter comprising:
a Turbo encoder configured to encode the message to produce encoded data, the encoded data comprising a plurality of systematic bits and a plurality of parity bits;
a rate matcher configured to:
select, for transmission over the wireless communications network, a first subset of the systematic bits using a first puncturing algorithm and a first parameterized swap value;
generate a first redundancy version that has a predetermined number of bit positions, the first redundancy version including the first subset of the systematic bits, wherein unused bit positions of the first redundancy version are allocated to a first subset of the parity bits;
select, for transmission over the wireless communications network, a second subset of the systematic bits that has substantially all of the systematic bits corresponding to the message that are not included in the first subset of the systematic bits; and
generate a second redundancy version that has the predetermined number of bit positions, the second redundancy version including the second subset of the systematic bits, wherein unused bit positions of the second redundancy version are allocated to a second subset of parity bits that is generated from parity bits which are not included in the first subset of parity bits, and includes additional parity bits only if all of the parity bits are otherwise included in the first or second subsets; and
communications circuitry configured to transmit at least the first redundancy version over the wireless communications network.
10. The transmitter of claim 9 , wherein the rate matcher is further configured to:
select the first subset or the second subset of systematic bits by puncturing a portion of the systematic bits such that the portion is excluded from the that subset.
11. The transmitter of claim 9 , wherein the rate matcher is further configured to:
select, for transmission over the wireless communications network, a third subset of the systematic bits using the first puncturing algorithm and a second parameterized swap value, wherein the second parameterized swap value is different from the first parameterized swap value; and
generate a third redundancy version of the message that has the predetermined number of bit positions, the third redundancy version including the third subset of the systematic bits and a third subset of the parity bits.
12. The transmitter of claim 11 , wherein the second parameterized swap value is greater than the first parameterized swap value.
13. The transmitter of claim 11 , wherein the plurality of parity bits comprises a first plurality of parity bits and a second plurality of parity bits, the rate matcher further configured to:
allocate a portion of the first, second, and third subsets of parity bits to the first plurality of parity bits; and
allocate a remaining portion of the first, second, and third subsets of parity bits to the second plurality of parity bits.
14. The transmitter of claim 9 , wherein the plurality of parity bits comprises a first plurality of parity bits and a second plurality of parity bits, the rate matcher further configured to:
allocate a portion of the first and second subsets of parity bits to the first plurality of parity bits; and
allocate a remaining portion of the first and second subsets of parity bits to the second plurality of parity bits.
15. The transmitter of claim 9 , wherein the rate matcher is further configured to:
select the second subset of parity bits by excluding parity bits that are included in the first subset of the parity bits from the second subset of parity bits.
16. The transmitter of claim 9 , wherein the rate matcher is configured to include all of the parity bits in the second subset that have not been included in the first redundancy version in response to determining that two redundancy versions are needed to transmit all bits of the encoded data stream.
17. A method of generating redundancy versions of a message having associated systematic bits and parity bits, the method comprising:
selecting a first subset of the systematic bits using a first puncturing algorithm and a first parameterized swap value;
generating a first redundancy version of the message that has a predetermined number of bit positions, the first redundancy version including the first subset of the systematic bits, wherein unused bit positions of the first redundancy version are allocated to a first subset of the parity bits;
selecting a second subset of the systematic bits that has substantially all of the systematic bits corresponding to the message that are not included in the first subset of the systematic bits; and
generating a second redundancy version of the message that has the predetermined number of bit positions, the second redundancy version including the second subset of systematic bits, wherein unused bit positions of the second redundancy version are allocated to a second subset of parity bits that is generated from parity bits which are not included in the first subset of parity bits, and includes additional parity bits only if all of the parity bits are otherwise included in the first or second subsets.
18. The method in claim 17 , further comprising:
selecting a third subset of the systematic bits using the first puncturing algorithm and a second parameterized swap value, wherein the second parameterized swap value is different from the first parameterized swap value; and
generating a third redundancy version of the message that has the predetermined number of bit positions, the third redundancy version including the third subset of the systematic bits and a third subset of the parity bits.
19. The method in claim 18 , wherein the second parameterized swap value is greater than the first parameterized swap value.
20. A rate matcher for generating redundancy versions of a message having associated systematic bits and parity bits, the rate matcher configured to:
select a first subset of the systematic bits using a first puncturing algorithm and a first parameterized swap value;
generate a first redundancy version that has a predetermined number of bit positions, the first redundancy version including the first subset of the systematic bits, wherein unused bit positions of the first redundancy version are allocated to a first subset of the parity bits;
select a second subset of the systematic bits that has substantially all of the systematic bits corresponding to the message that are not included in the first subset of the systematic bits; and
generate a second redundancy version that has the predetermined number of bit positions, the second redundancy version including the second subset of the systematic bits, wherein unused bit positions of the second redundancy version are allocated to a second subset of parity bits that is generated from parity bits which are not included in the first subset of parity bits, and includes additional parity bits only if all of the parity bits are otherwise included in the first or second subsets.
21. The rate matcher in 20 , wherein the rate matcher is further configured to:
select the first subset or the second subset of systematic bits by puncturing a portion of the systematic bits such that the portion is excluded from the that subset.
22. The rate matcher in 20 , wherein the rate matcher is further configured to:
select a third subset of the systematic bits using the first puncturing algorithm and a second parameterized swap value, wherein the second parameterized swap value is different from the first parameterized swap value; and
generate a third redundancy version of the message that has the predetermined number of bit positions, the third redundancy version including the third subset of the systematic bits and a third subset of the parity bits.