Method and device enabling a dynamic bundle size HARQ mechanism
View Patent ↗A method, device and computer program product for transmitting data blocks in an LTE or similar wireless communication system supporting HARQ and TTI bundling, with dynamic TTI bundle sizing is provided. Each TTI bundle includes a number of redundancy versions of a data block, for example differently encoded versions of the data block which can be combined together in accordance with Type-II HARQ. Plural TTI bundles can be transmitted as necessary in accordance with HARQ, for example in response to a NACK. The present technology involves adjusting the TTI bundle size for a given HARQ process, wherein at least two TTI bundles have different sizes. In various embodiments, the TTI bundle size progressively decreases with retransmissions so that the last TTI bundle is not excessively large, thereby reducing resource waste. TTI bundle size adjustment may be implemented in the uplink, downlink, or both.
1. A method for transmitting a block of data from a transmitter to a receiver in a wireless communication system supporting HARQ and TTI bundling, the method comprising:
a) transmitting a TTI bundle from the transmitter to the receiver, the TTI bundle comprising a first number of redundancy versions indicative of the block of data as encoded using HARQ; and
b) following a determination at the transmitter that transmission of the TTI bundle failed to result in successful decoding of the block of data at the receiver, transmitting a second TTI bundle from the transmitter to the receiver, the second TTI bundle comprising a second number of redundancy versions indicative of the block of data as encoded using HARQ, the second number different from the first number,
wherein an initial size of the TTI bundle is configured based at least in part on latency requirements for transmission of the block of data, wherein determining the initial size of the TTI bundle comprises adjusting the initial size of the TTI bundle downward when the latency requirements are reduced.
2. The method according to claim 1 , wherein the second number of redundancy versions is less than the first number of redundancy versions.
3. The method according to claim 1 , wherein the second number of redundancy versions is about half of the first number of redundancy versions.
4. The method according to claim 1 , wherein the number of redundancy versions in successive TTI bundles is adjusted over time in accordance with a bundle size adjustment schedule.
5. The method according to claim 1 , wherein the TTI bundle size is caused to decrease monotonically over time in accordance with a bundle size adjustment schedule.
6. The method according to claim 1 , wherein the TTI bundle corresponds to an initial attempt to transmit the data block or a subsequent attempt to transmit the data block.
7. The method according to claim 1 , further comprising following a determination at the transmitter that transmission of the second TTI bundle failed to result in successful decoding of the block of data at the receiver, transmitting a third TTI bundle from the transmitter to the receiver, the third TTI bundle comprising a third number of redundancy versions indicative of the block of data as encoded using HARQ, the third number different from the first number, the second number, or both.
8. The method according to claim 1 , wherein a bundle size adjustment schedule is based at least in part on channel quality measurements, latency requirements, or both.
9. A communication device in a wireless communication system supporting HARQ and TTI bundling, the communication device configured to transmit a block of data to a receiver, the communication device comprising:
a) a transmission module configured to transmit at least a TTI bundle and a second TTI bundle from the transmitter to the receiver, the TTI bundle comprising a first number of redundancy versions indicative of the block of data as encoded using HARQ, the second TTI bundle comprising a second number of redundancy versions indicative of the block of data as encoded using HARQ;
b) a monitoring module configured to determine whether transmission of the TTI bundle failed to result in successful decoding of the block of data at the receiver, wherein the transmission module is configured to transmit the second TTI bundle in response to a determination that transmission of the TTI bundle has failed to result in successful decoding of the block of data at the receiver; and
c) a bundle size adjustment module configured to cause the second number of redundancy versions to be different from the first number of redundancy versions,
wherein an initial size of the TTI bundle is configured based at least in part on latency requirements for transmission of the block of data, wherein determining the initial size of the TTI bundle comprises adjusting the initial size of the TTI bundle downward when the latency requirements are reduced.
10. The communication device according to claim 9 , wherein the communication device is a wireless subscriber terminal.
11. The communication device according to claim 9 , wherein the communication device is a base station or eNB.
12. A computer program product comprising a non-transitory computer readable medium storing computer executable statements and instructions thereon that, when executed by a computer, perform operations for transmitting a block of data from a transmitter to a receiver in a wireless communication system supporting HARQ and TTI bundling, the operations comprising:
a) transmitting a TTI bundle from the transmitter to the receiver, the TTI bundle comprising a first number of redundancy versions indicative of the block of data as encoded using HARQ; and
b) following a determination at the transmitter that transmission of the TTI bundle failed to result in successful decoding of the block of data at the receiver, transmitting a second TTI bundle from the transmitter to the receiver, the second TTI bundle comprising a second number of redundancy versions indicative of the block of data as encoded using HARQ, the second number different from the first number,
wherein an initial size of the TTI bundle is configured based at least in part on latency requirements for transmission of the block of data, wherein determining the initial size of the TTI bundle comprises adjusting the initial size of the TTI bundle downward when the latency requirements are reduced.
13. The computer program product according to claim 12 , wherein the second number of redundancy versions is less than the first number of redundancy versions.
14. The computer program product according to claim 12 , wherein the second number of redundancy versions is about half of the first number of redundancy versions.
15. The computer program product according to claim 12 , wherein the number of redundancy versions in successive TTI bundles is adjusted over time in accordance with a bundle size adjustment schedule.
16. The computer program product according to claim 12 , wherein the TTI bundle size is caused to decrease monotonically over time in accordance with a bundle size adjustment schedule.
17. The computer program product according to claim 12 , wherein the TTI bundle corresponds to an initial attempt to transmit the data block or a subsequent attempt to transmit the data block.
18. The computer program product according to claim 12 , further comprising following a determination at the transmitter that transmission of the second TTI bundle failed to result in successful decoding of the block of data at the receiver, transmitting a third TTI bundle from the transmitter to the receiver, the third TTI bundle comprising a third number of redundancy versions indicative of the block of data as encoded using HARQ, the third number different from the first number, the second number, or both.
19. The computer program product according to claim 12 , wherein a bundle size adjustment schedule is based at least in part on channel quality measurements, latency requirements, or both.
20. The method according to claim 1 , wherein the TI bundle and the second TTI bundle convey data according to a common HARQ process.
21. The communication device according to claim 9 , wherein the TTI bundle and the second TTI bundle convey data according to a common HARQ process.
22. The method of claim 1 , wherein the initial size of the TTI bundle is further configured based on channel quality measurements.
23. The method of claim 1 , wherein the latency requirements are provided by a home subscriber service (HSS), a home location register (HLR), a wireless subscriber device, or a Policy Control and Charging (PCC) entity.
24. The method Of claim 1 , wherein the TTI bundle size is caused to change over time in accordance with a bundle size adjustment schedule, the method further comprising independently determining the bundle size adjustment schedule by the transmitter and the receiver.
25. The method of claim 1 , wherein the TTI bundle size is caused to change over time in accordance with a bundle size adjustment schedule, and wherein determination of the bundle size adjustment schedule is based at least in part on the initial size of the TTI bundle.