System and methods for ACK/NAK feedback in TDD communications
View Patent ↗Systems and methods for providing an efficient mechanism for transmitting encoded downlink assignment index (DAI) and for signaling the ACK/NAK information corresponding to downlink grant allocations in an over the air radio telecommunications network with time division duplex (TDD) capability, where aggregation of component carriers (CCs) is used. Downlink control messages containing encoded DAI information are transmitted with downlink allocation grants. A receiver observes the encoded DAI and the downlink allocation grants and forms corresponding ACK/NAK signals. Method embodiments for forming the ACK/NAK signals for CC groups and frames or subframes are provided. The ACK/NAK signals are then encoded using method embodiments and transmitted over parallel channels for each CC group to the transmitter. By using method embodiments for selecting resources for use in the transmission, the last observed DL grant can be identified by the transmitter and the transmitter can detect an error at the receiver.
1. A method, comprising:
identifying groups of information frames or subframes to be transmitted in parallel over a plurality of aggregated component carriers to a communications terminal over an air interface;
indexing a downlink assignment index counter by counting downlink allocation grant signals to be transmitted in the groups of information frames or subframes;
encoding the downlink assignment index counter into a downlink assignment index value by performing a modulo operation on the downlink-assignment-index counter; and
transmitting, over the plurality of aggregated component carriers, the groups of information frames or subframes including the downlink allocation grant signals and the downlink assignment index value to a receiver within the communications terminal.
2. The method of claim 1 , wherein indexing the downlink assignment index counter further comprises incrementing a counter.
3. The method of claim 2 , wherein incrementing the counter comprises performing a function DAICounter=0, 1, 2, . . . N i −1; where N i =number of downlink grants in the ith group, for each group.
4. The method of claim 2 , wherein incrementing the counter further comprises incrementing the counter first in a frequency domain and then in a time domain.
5. The method of claim 2 , wherein incrementing the counter comprises performing a function DAICounter=0, 1, 2 . . . N−1; where N is the total number of downlink grants in the receiver reception window.
6. The method of claim 1 , wherein encoding the downlink assignment index comprises performing a function MOD 4 on the value of the downlink assignment index counter.
7. The method of claim 1 , wherein transmitting the groups of frames or subframes including the downlink allocation grant signals and the downlink assignment index value further comprises:
forming a physical downlink control channel;
modulating the signals to be transmitted; and
transmitting the modulated signals over the air interface.
8. The method of claim 1 , further comprising:
receiving over the air interface an uplink message from the receiver;
decoding the uplink message; and
recovering for each downlink allocation grant in the transmitted message one of an acknowledgement signal, a not acknowledgement signal, and a discontinuous transmission signal.
9. The method of claim 8 , wherein receiving the uplink message further comprises receiving over the air interface a physical uplink control channel message.
10. The method of claim 9 , further comprising: determining from an implicit selection of a transmission method for the uplink message the last of the transmitted downlink allocation grants that was correctly received by the receiver.
11. The method of claim 10 , wherein the determining is performed based on the channel selected for the physical uplink control channel message.
12. A method, comprising:
forming a predetermined grouping of component carriers and frames or subframes to form subgroups of frames or subframes within each group;
forming a bundled information signal comprising at least one of an acknowledgement signal, a not acknowledgement signal and a discontinuous transmission message signal for each frame or subframe within each group; and
transmitting in parallel the bundled information signal on an uplink channel;
wherein the transmitting in parallel the bundled information signal comprises transmitting over an air interface using aggregated component carriers, and wherein transmitting in parallel the bundled information signal comprises:
forming information, comprising at least part of the bundled information signal, to be carried on a physical uplink control channel;
selecting from a plurality of channel resources a channel resource available to carry the information on the physical uplink control channel; and
transmitting the information on the selected channel resource.
13. The method of claim 12 , wherein selecting the channel available for transmitting further comprises:
selecting the channel based on a last downlink allocation grant correctly received from a transmitter.
14. The method of claim 12 , wherein the forming is based at least in part on a downlink allocation grant and a downlink assignment index value.
15. The method according to claim 14 , wherein the downlink allocation grant and the downlink assignment index value are received in groups of frames or subframes.
16. The method of claim 12 wherein the transmitting in parallel comprises transmitting using a physical uplink control channel format 1b.
17. An apparatus, comprising:
at least one processor; and
at least one memory including computer program instructions, where the at least one memory and the computer program instructions are configured, with the at least one processor, to cause the apparatus to at least:
receive and transmit signals over an air interface;
receive downlink allocation grants;
form at least one of an acknowledgement signal, a not acknowledgement signal and a discontinuous transmission message signal in response to received signals and the downlink allocation grants;
form a predetermined grouping of component carriers and frames or subframes to form subgroups of frames or subframes within each group;
form a bundled information signal comprising the at least one of the acknowledgement signal, the not acknowledgement signal and the discontinuous transmission message signal for each frame or subframe within each group; and
transmit in parallel the bundled information signals on an uplink channel over the air interface, wherein the transmitting in parallel the bundled information signal comprises transmitting over the air interface using aggregated component carriers, and wherein transmit in parallel the bundled information signal comprises:
forming information, comprising at least part of the bundled information signal, to be carried on a physical uplink control channel;
selecting from a plurality of channel resources a channel resource available to carry the information on the physical uplink control channel; and
transmitting the information on the selected channel resource.
18. The apparatus of claim 17 , wherein the at least one memory including the computer program instructions is configured with the at least one processor to cause the apparatus to select the physical uplink control channel for transmission based on a last downlink allocation grant correctly received from a transmitter.
19. An apparatus, comprising:
at least one processor; and
at least one memory including computer program instructions, where the at least one memory and the computer program instructions are configured, with the at least one processor, to cause the apparatus to at least:
receive and transmit signals on channels over an air interface to one or more second apparatus;
identify groups of frames or subframes to be transmitted in parallel over a plurality of aggregated component carriers to the one or more second apparatus over the air interface;
index a downlink assignment index counter by counting downlink allocation grant signals to be transmitted in the groups of frames or subframes;
encode the downlink assignment index counter into a downlink assignment index value by performing a modulo operation on the downlink assignment index counter; and
transmit, over the plurality of aggregated component carriers, the groups of frames or subframes including the downlink allocation grant signals and the downlink assignment index value over the air interface to a receiver within the one or more second apparatus.
20. The apparatus of claim 19 , wherein the at least one memory including the computer program instructions is configured with the at least one processor configured to cause the apparatus to index the downlink assignment index counter by incrementing a counter.
21. The apparatus of claim 20 , wherein the at least one memory including the computer program instructions is configured with the at least one processor to cause the apparatus to increment the counter first in a frequency domain and then in a time domain.
22. An apparatus, comprising:
at least one processor; and
at least one memory including computer program instructions, where the at least one memory and the computer program instructions are configured, with the at least one processor, to cause the apparatus to at least:
identify groups of information frames or subframes to be transmitted in parallel over a plurality of aggregated component carriers to a communications terminal over an air interface;
index a downlink assignment index counter by counting downlink allocation grant signals to be transmitted in the groups of information frames or subframes;
encode the downlink assignment index counter into a downlink assignment index value by performing a modulo operation on the downlink assignment index counter; and
transmit, over the plurality of aggregated component carriers, the groups of information frames or subframes including the downlink allocation grant signals and the downlink assignment index value to a receiver within the communications terminal.
23. The apparatus of claim 22 , wherein indexing the downlink assignment index counter comprises incrementing a counter.
24. The apparatus of claim 23 , wherein incrementing the counter comprises performing a function DAICounter=0, 1, 2, . . . N i −1; where N i =number of downlink grants in the ith group, for each group.
25. The apparatus of claim 23 , wherein incrementing the counter further comprises incrementing the counter first in a frequency domain and then in a time domain.
26. The apparatus of claim 23 , wherein incrementing the counter comprises performing a function DAICounter=0, 1, 2 . . . N−1; where N is the total number of downlink grants in the receiver reception window.
27. The apparatus of claim 22 , wherein encoding the downlink assignment index comprises performing a function MOD 4 on the value of the downlink assignment index counter.
28. The apparatus of claim 22 , wherein transmitting the groups of information frames or subframes including the downlink allocation grant signals and the downlink assignment index value further comprises:
forming a physical downlink control channel;
modulating the signals to be transmitted; and
transmitting the modulated signals over the air interface.
29. The apparatus of claim 22 , wherein the at least one memory including the computer program instructions are configured with the at least one processor to cause the apparatus to:
receive over the air interface an uplink message from the receiver;
decoding the uplink message; and
recover for each downlink allocation grant in the transmitted message one of an acknowledgement signal, a not acknowledgement signal, and a discontinuous transmission signal.
30. The apparatus of claim 29 , wherein receiving the uplink message further comprises receiving over the air interface a physical uplink control channel message.
31. The apparatus of claim 30 , wherein the at least one memory including the computer program instructions are configured with the at least one processor to cause the apparatus to determine from an implicit selection of a transmission method for the uplink message the last of the transmitted downlink allocation grants that was correctly received by the receiver.
32. The apparatus of claim 31 , wherein the determining is performed based on the channel selected for the physical uplink control channel message.
33. An apparatus comprising,
at least one processor; and
at least one memory including computer program instructions, where the at least one memory and the computer program instructions are configured, with the at least one processor, to cause the apparatus to at least:
form a predetermined grouping of component carriers and frames or subframes to form subgroups of frames or subframes within each group;
form a bundled information signal comprising at least one of an acknowledgement signal, a not acknowledgement signal and a discontinuous transmission message signal for each frame or subframe within each group; and
transmit in parallel the bundled information signal on an uplink channel, wherein the transmitting in parallel the bundled information signal comprises transmitting over an air interface using aggregated component carriers, and wherein transmit in parallel the bundled information signal comprises:
forming information, comprising at least part of the bundled information signal, to be carried on a physical uplink control channel;
selecting from a plurality of channel resources a channel resource available to carry the information on the physical uplink control channel; and
transmitting the information on the selected channel resource.
34. The apparatus of claim 33 , wherein selecting the channel available for transmitting further comprises:
selecting the channel based on a last downlink allocation grant correctly received from a transmitter.
35. The apparatus of claim 33 , wherein the forming the predetermined grouping is based at least in part on a downlink allocation grant and a downlink assignment index value.
36. The apparatus of claim 35 , wherein the downlink allocation grant and the downlink assignment index value are received in groups of frames or subframes.
37. The apparatus of claim 33 , wherein the transmitting in parallel comprises transmitting using a physical uplink control channel format 1b.