WO2012040899A1

WO2012040899A1 - Mechanism to support ack/nak bundling pattern flexible switching

Info

Publication number: WO2012040899A1
Application number: PCT/CN2010/077395
Authority: WO
Inventors: Peng Chen; Erlin Zeng
Original assignee: Nokia Corporation
Priority date: 2010-09-28
Filing date: 2010-09-28
Publication date: 2012-04-05

Abstract

A bundling pattern is selected that is indicated in a communication from a network to a user equipment LJE. For an uplink communication from the UE to the network which comprises a bundled bit sequence, the selected bundling pattern is used to map between an unbundled bit sequence and the bundled bit sequence such that each bit of the unbundled bit sequence corresponds to only one downlink resource on which the network communicated to the UE. In an exemplary embodiment each bundling pattern comprises an output sequence of bundled ACK/NAK bits, and the indication of the bundling pattern comprises an index corresponding to one of the output sequences of bundled ACK/NAK bits. In various embodiments this indication may be semi-statically signaled, or dynamically signaled in a PDCCH. The unbundled bit sequence implicitly corresponds to a configured component carrier.

Description

MECHANISM TO SUPPORT ACK/NAK BUNDLING PATTERN

FLEXIBLE SWITCHING

TECHNICAL FIELD:

[0001 ] The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer programs and, more specifically, relate to mapping uplink signaling such as ACK/NAK bits to their downlink communications, in which the ACK/NAK bits are arranged differently in different circumstances.

BACKGROUND:

[0002] This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section. [0003] The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3GPP third generation partnership project

ACK acknowledgement

CA carrier aggregation

CC component carrier

DAI downlink assignment index

DCI downlink control indication

DL downlink (eNB to UE)

DTX discontinuous transmission

eNB EUTRAN Node B (evolved Node B/base station)

E-UTRAN evolved UTRAN (LTE)

FDD frequency domain duplex

IMT international mobile telecommunications

1TU-R international telecommunication union - radio

LTE long term evolution

MIMO multiple input multiple output

M/MME mobility management/mobility management entity

NAK negative ACK PDCCH physical downlink control channel

PDSCH physical downlink shared channel

PUCCH physical uplink control channel

PUSCH physical uplink shared channel

RRC radio resource control

SC-FDMA single carrier, frequency division multiple access

TDD time domain duplex

UE user equipment

UL uplink (UE to eNB)

UTRAN universal terrestrial radio access network

[0004] In the communication system known as evolved UTRAN (E-UTRAN, also referred to as UTRAN-LTE, E-UTRA or 3.9G), the LTE Release 8 is completed, the LTE Release 9 is being standardized, and the LTE Release 10 is currently under development within the 3GPP. In LTE the downlink access technique is OFDMA, and the uplink access technique is SC-FDMA, and these access techniques are expected to continue in LTE Release 10. poos] Figure 1 shows the overall architecture of the E-UTRAN system, in which eNBs are interconnected with each other by means of an X2 interface and which provide the EUTRA user plane and control plane (RRC) protocol terminations towards the UE. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME and to a Serving Gateway.

[0006] Further releases of 3GPP LTE are targeted towards future IMT-Advanced systems, referred to herein for convenience simply as LTE-Advanced (LTE-A) which is expected to be part of LTE Release 10. LTE-A is expected to use a mix of local area and wide area optimization techniques to fulfill the ITU-R requirements for IMT-Advanced while keeping the backward compatibility with LTE Release 8. Topics that are included within the ongoing study item includes bandwidth extensions beyond 20 MHz, relays, cooperative MIMO and multi-user MIMO, and single user MIMO on the uplink.

[0007] The bandwidth extension beyond 20 MHz in LTE-Advanced is to be done via carrier aggregation CA, in which one or more Release 8 compatible component carriers CCs are aggregated together to form a larger bandwidth. This is shown by example at Figure 1 B in which there are 5 Release 8 compatible CCs aggregated to form one larger LTE-Advanced bandwidth. The purpose for aggregating individual 20 MHz Release 8 compatible component carriers (CCs) is that each existing Release 8 terminal can receive and/or transmit on one of the CCs, whereas future LTE-Advanced terminals could potentially receive/transmit on multiple CCs at the same time, thus having support for large bandwidth. Figure 1 B is exemplary; in practice there may be more or less than five CCs, they may not have equal bandwidths, and/or they may be frequency non-adjacent. The CCs could be aggregated in both TDD and FDD systems.

[0008] In LTE-Advanced, a single LTE-A compatible UE can be configured for more than one CC at once, and it may be that the ACK/NAK the UE sends for a PDSCH received on one CC can be sent on a PUCCH on a different CC. More complex, the UE may be scheduled in one PDCCH for PDSCHs on multiple CCs, all of which are ACK'd/NAK'd on only one PUCCH. Compared to Release 8, it follows that LTE-A needs to support more ACK/NAK bits per UL subframe. By example, for UL ACK/NAK feedback in LTE-A TDD, one UL subframe may be associated with multiple PDSCH transmission in a) multiple CCs in the frequency domain (depending on the UE's CC configuration); and b) multiple DL subframes in the time domain (depending on the configured TDD configuration).

[0009] Since there may be 4 DL subframes per one UL subframe in the time domain, if we assume there may be five configured CCs in the frequency domain for the UE (as shown at Figure 1 B), it is possible that twenty ACK NAK bits need to be fed back by the UE during a single UL subframe, even with ACK/NAK spatial bundling. To move toward this goal there have been two notable agreements in 3GPP RAN1 for UL ACK/NAK feedback for CA in the LTE-A TDD system: a) ACK/NAK multiplexing via channel selection (on PUCCH format 1b); and b) ACK/NAK multiplexing via joint encoding (on DFT-S-OFDM). For the former mode, channel selection which has been adopted in LTE Release 8 TDD is used to support up to 4-bit ACK/NAK feedback. For the latter mode, multiple ACK/NAK bits are multiplexed on a DFT-S-OFDM structure defined in LTE-A. It has also been agreed to re-use Reed- uller encoding for ACK NAK encoding, which in principle could support up to 12-bit ACK/NAK overhead.

[0010] Bundling of bits for signaling is a general technique known in the wireless arts, and in LTE-A TDD it appears some kind of bundling technique will be useful to make the above ACK/NAK modes workable. By example, the inventors have proposed in document R1 -103788 entitled UL ACK/NAK FEEDBACK FOR POWER LIMITED UE IN LTE-A TDD (3GPP TSG RAN WG1 Meeting #61 bis, Dresden, Germany; 28 June to 2 Jul 2010; by Nokia and Nokia Siemens Networks) that CC-domain ACK/NAK bundling is a promising way to compress related ACK NAK overhead. Following is one way in which this might be implemented within each DL subframe associated with a single UL subframe:

• Several CCs are formed into an ACK NAK bundle;

• A limited ACK/NAK (e.g. 1-bit) is generated per bundle, via a logical "AND" operation across the assignments within the bundle; and

• DAI is encoded as "the total number of assignments per bundle". A "MOD 4" operation may be used, for example if the DAI is only two bits wide. too ] These teachings relate primarily to the first bullet above and detail a mechanism by which the ACK/NAK bundling pattern can be switched based on various conditions. As will be detailed, such switching can be done by various types of signaling in LTE-A TDD.

SUMMARY:

[0012] The foregoing and other problems are overcome, and other advantages are realized, by the use of the exemplary embodiments of this invention.

[0013] In a first aspect thereof the exemplary embodiments of this invention provide a method, comprising: selecting one of a plurality of bundling patterns that is indicated in a communication from a network to a user equipment; and for an uplink communication from the user equipment to the network which comprises a bundled bit sequence, using the selected bundling pattern to map between an unbundled bit sequence and the bundled bit sequence such that each bit of the unbundled bit sequence corresponds to only one downlink resource on which the network communicated to the user equipment.

[oo ] In a second aspect thereof the exemplary embodiments of this invention provide an apparatus, comprising at least one processor and at least one memory including computer program code. The at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus at least to perform: selecting one of a plurality of bundling patterns that is indicated in a communication from a network to a user equipment; and for an uplink communication from the user equipment to the network which comprises a bundled bit sequence, using the selected bundling pattern to map between an unbundled bit sequence and the bundled bit sequence such that each bit of the unbundled bit sequence corresponds to only one downlink resource on which the network communicated to the user equipment. [0015] In a third aspect thereof the exemplary embodiments of this invention provide a memory storing a program of computer readable instructions that when executed by a processor result in actions comprising: selecting one of a plurality of bundling patterns that is indicated in a communication from a network to a user equipment; and for an uplink communication from the user equipment to the network which comprises a bundled bit sequence, using the selected bundling pattern to map between an unbundled bit sequence and the bundled bit sequence such that each bit of the unbundled bit sequence corresponds to only one downlink resource on which the network communicated to the user equipment.

[0016] These and other aspects of the invention are detailed more fully below.

BRIEF DESCRIPTION OF THE DRAWINGS:

[0017] Figure 1A shows the overall architecture of the E-UTRAN system.

[0018] Figure 1 B is a diagram of a frequency spectrum using carrier aggregation in which five component carrier bandwidths are aggregated into a single LTE-Advanced bandwidth.

[0019] Figure 2 is a table showing number of ACK/NAK bits with spatial bundling needed to signal various combinations of CCs and DL/UL ratios.

[0020] Figure 3A is a mapping pattern of unbundled input bits to bundled output bits for the case of M=4 (DL:UL=4:1) and N=4 (4 CCs configured) shown at Figure 2, according to an exemplary embodiment of the invention. [0021] Figure 3B illustrate schematically the CC combinations supported by the mapping patterns of Figure 3A, according to an exemplary embodiment of the invention.

[0022] Figure 4A is similar to Figure 3A but for the case of M=3 (DL:UL=3:1) and N=5 (5 CCs configured) shown at Figure 2.

[0023] Figure 4B is similar to Figure 3B but showing the supported CC combinations for the mapping patterns of Figure 4A. [0024] Figure 5A is similar to Figure 3A but for the case of M=4 (DL:UL=4:1) and N=5 (5 CCs configured) shown at Figure 2.

[0025] Figure 5B is similar to Figure 3B but showing the supported CC combinations for the mapping patterns of Figure 5A.

[0026] Figure 6 shows a simplified block diagram of certain apparatus according to various exemplary embodiments of the invention.

[0027] Figure 7 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with the exemplary embodiments of this invention.

DETAILED DESCRIPTION:

[0028] The inventors have considered that it would be advantageous to be able to switch how the ACK/NAK bit bundling is done. This follows from the fact that a given UE may be configured with one CC set and re-configured to another CC set under the same eNB. Also, regardless of the configured CC set the UE may in one instance receive PDSCHs to ACK/NAK which are spread across one group of CCs and in another instance receive PDSCHs to ACK/NAK which are spread across a different group of CCs, even without having the eNB re-configure the UE's active CC set. An efficient bundling pattern for one situation may not be the most efficient for another situation, and so by switching the bundling patterns along the teachings set forth herein the overall signaling overhead can be kept low so long as the signaling for the switching is not excessive.

[0029] In conventional instances of ACK/NAK bundling, the pattern of which bits are bundled is pre-defined (i.e., there is only one pattern). But in the above scenario in which the UE can have its CC configured set re-configured and/or receive its PDSCHs which it ACKs/NAKs on different groupings of CCs., a single pre-defined pattern of how the bits are bundled gives no flexibility for the different CC variances; the pattern cannot be switched when a CC is activated or deactivated, nor can it be switched based on the dynamic scheduling status. This will result in potentially quite a large sacrifice in DL throughput. Additionally, this appears difficult in practice while LTE-A is under development since different members of the RAN community each have a different pre-defined pattern in mind and consensus for one pattern does not seem forthcoming.

[0030] Instead, according to exemplary embodiments of the invention, the bit bundling pattern may be switched. This may be effected in at least two different ways to reflect, as above, changes to the UE's configured CC set or to the dynamically scheduled PDSCHs which may lie across different groups of CCs for different PUCCH allocations. Pattern switches due to changes to the configured CC set may be triggered by higher layer signaling, whereas pattern switches due to specifics of the dynamic resource/PDSCH scheduling are dynamically effected. 10031] Switching the ACK/NAK bundling pattern by higher layer/semi-static signaling (e.g., the eNB or higher in the network) offers the advantage of some though limited flexibility. If the eNB switches the bundling pattern for a UE upon CC activation/de-activation, there is still loss of potential DL throughput when the dynamic scheduling over time for that same UE is across different CC groups while the UE's configured CC set remains unchanged. If instead the bundling pattern switching is carried out via RRC signaling, there is possibly a period of ambiguity during the RRC configuration period when the UE and the network may not understand identically which pattern is supposed to be in use.

[0032] Switching the ACK/NAK bundling pattern by dynamic signaling alongside the PDCCH resource allocation which allocates the PDSCHs being ACK'd/NAK'd offers maximum flexibility which maximizes the potential DL throughput, at the cost of additional layerl signaling being required. Additionally, in the event the UE fails to receive or improperly decodes that L1 signaling there may be some ambiguity until the next PDCCH as to which pattern the UE should use. [0033] Exemplary embodiments of these teachings can be implemented so that the pattern switching is semi-statically triggered, or so that it is dynamically triggered, and further these can be combined so that in an implementation both semi-static triggering of pattern switching due to activating/de-activating a CC for a UE's configured set and dynamic triggering of pattern switching due to the UE's specific resource allocation are used.

[0034] By example, this concept can be generally stated as selecting one of a plurality of bundling patterns that is indicated in a communication from a network to a user equipment. This selection is done at both the UE and the eNB since each knows the full listing of patterns which can be used at any given time. From the eNB side it is the network which sends an indication of the selection; from the UE side it is the UE which gets the communication and which uses the indication to select which bundling pattern to use. In the different embodiments below this communication, which indicates the bundling pattern reflect the different manners of signaling, is semi-static or dynamic.

[0035] Further in this exemplary embodiment, for an uplink communication from the user equipment to the network which comprises a bundled bit sequence, the selected bundling pattern is used to map between an unbundled bit sequence and the bundled bit sequence. This mapping is such that each bit of the unbundled bit sequence corresponds to only one downlink resource on which the network communicated to the user equipment. From the eNB's perspective the mapping is from the bundled bit sequence on the uplink communication to the unbundled bit sequence, so the eNB can match all of the unbundled ACK/NAK bits to the PDSCHs which the UE is ACKing/NAKing. From the UE's perspective the mapping is from the unbundled bit sequence to the bundled bit sequence, which the UE sends on that uplink communication.

[0036] According to embodiments of this invention there is a flexible switching between different ACK/NAK bundling patterns, and that switching may be g semi-static switching effected by RRC signaling, and/or it may be dynamic switching effected by L1 signaling. In an embodiment the L1 signaling uses DCI bits in the resource grant or assignment (PDCCH) that are re-defined for the flexible switching purposes herein from their former use. In the following description it is assumed that the CC-index used to index the multiple CCs is visible in the physical layer. This helps assure that both the eNB and the UE have the same understanding of the ACK/NAK-to-CC mapping. [0037] In an exemplary embodiment each of the bundling patterns may be considered to have an input bit sequence and an output bit sequence. The input bit sequence corresponds to ACK/NAK bits which are yet to be bundled, and so there is one of these input bits for each PDSCH being ACK'd/NAK'd. The input ACK/NAK index is implicitly associated with the configured CC-index, meaning both eNB and UE have the same understanding of associations between any given input sequence index and configured CC index. The output ACK/NAK sequence corresponds to the bundled ACK/NAK bits. For convenience, each of the input and output bit sequences may be assigned an index. This also reduces signaling overhead since it is the output bit sequence that is explicitly signaled from the eNB to the UE.

[0038] According to an exemplary embodiment of the invention, there are two indices for each bit-mapping pattern. The index for the input ACK NAK bit sequence is implicitly associated with the CC-index noted above. This association is stored in a local memory of the eNB and the UE. The output bit sequence corresponds to the bundled bits, and is signaled by its index. Both the eNB and the UE have stored in their local memory a plurality of output bit sequences, each associated with an index. The mechanism to define mapping between an individual input ACK/NAK bit sequence and an individual output bundled ACK NAK bit sequence may in one embodiment be based on higher layer signaling (e.g., semi-static/RRC signaling), and in another embodiment the mechanism is based on dynamic signaling such as layer 1 signaling (e.g., the mapping is signaled with each PDCCH resource allocation for example).

[0039] Respecting the first embodiment of RRC signaling, in order to save on signaling overhead each DL subframe that is associated with single UL subframe has a similar ACK/NAK bundling pattern in the CC domain. For the ACK/NAK bits which the UE will generate for each configured CC, the eNB indicates the output ACK/NAK bit sequence index that the input ACK/NAK bit should be mapped to. Then, within each of those DL subframes associated with a single UL subframe, the generated ACK/NAK bits which are mapped to a similar output ACK/NAK bit sequence index should be bundled together,

[0040] Respecting the second embodiment of dynamic signaling, within each DL subframe that is associated with a single UL subframe, for the ACK/NAK bit which the UE is to generate for each resource assignment, the eNB indicates the output ACK/NAK bit sequence index that the input ACK/NAK bit should be mapped to. Like the first embodiment, in this second embodiment within each DL subframe that is associated with a single UL subframe, the ACK/NAK bits that are mapped to a similar output ACK NAK index should be bundled together.

[0041] In a LTE-A specific implementation of the second embodiment, there is one DAI bit that is re-used according to these teachings for pattern switching/signaling purposes. Specifically, two DAI bits in the PDCCH are used to indicate:

• The output ACK/NAK sequence index that the current ACK/NAK, corresponding to the current assignment, should be mapped to.

• The total number of assignments within the current bundle, or the number of ACK/NAK bits having an output ACK/NAK sequence index similar to the current ACK/NAK output sequence index.

[0042] Consequently, the eNB sets the DAI bit values according to a) the output ACK/NAK sequence index that the corresponding ACK/NAK input sequence should be mapped to; and b) the total number of assignment within the current bundle. Once the UE receives a PDCCH with its resource assignment, the UE should read the DAI bits and check a) the output ACK/NAK sequence index that the current ACK/NAK input sequence to be generated should be mapped to; and b) the total number of assignments within the current bundle and whether or not there is a PDCCH missing. By checking the output sequence which the UE will map to, the UE can know exactly how to map the current ACK/NAK sequence it is to generate (the unbundled bits) to the output ACK/NAK sequence which is the bundled bits.

[0043] From the above examples it can be seen that for both described embodiments, the eNB signals the index for the bundling pattern that gives the output bit sequence, and the input bit sequence is known from implicit mapping from the configured CC on which the UE receives data on the PDSCHs which are being ACK'd/NAK'd.

[0044] The background section above detailed two agreements in the LTE-A development, one of which multiplexes multiple ACK/NAK bits on the DFT-S-OFD structure and uses Reed Muilen encoding which in principle can support up to twelve bits for UL ACK/NAK signaling. Using the parameter N to denote the number of CCs configured for a UE in the frequency domain, and the parameter M to denote the DL/UL ratio in the time domain, the number of ACK/NAK bits that the UE generates can vary from two to twenty as shown at Figure 2. Because the above-cited agreed techniques will support up to twelve bits, the following examples are directed solely to the three cases of Figure 2, offset by shading, which generate more than 12 ACK/NAK bits but which must use (at least partial) bundling so that there are no more than twelve actual bits signaled UL from the UE. They are:

· Case 1 : M=4, N=4; sixteen ACK NAK bits generated.

• Case 2: =3, N=5; fifteen ACK/NAK bits generated.

• Case 3: M=4, N=5; twenty ACK/NAK bits generated.

[0045] Note that the techniques described herein may also be extended to other entries in the table of Figure 2 which generate twelve or less unbundled bits. The three examples below for the entries of Figure 2 which generate more than twelve unbundled ACK/NAK bits are merely exemplary. [0046] Assume for simplicity that the bundled ACK/NAK overhead is distributed evenly among the DL subframes which are associated with a single UL subframe. Then considering that above twelve-bit signaling is the upper bound for the ACK/NAK signaling overhead, the three example cases will result in the following bundling per DL subframe:

· For Case 1 (M=4, N=4): 12/4=3 ACK/NAK bits per DL subframe are generated via partial bundling.

• For Case 2 (M=3, N=5): 12/3=4 ACK/NAK bits per DL subframe are generated via partial bundling.

• For Case 3 (M=4, N=5): 12/4=3 ACK/NAK bits per DL subframe are generated via partial bundling.

[0047] Within each DL subframe, designate ¾, ...,a_s _,_. as the input ACK/NAK sequence (prior to any ACK/NAK partial bundling), where a_n is generated from the assignment on CC n Further designate &_0t .... ^ as the output ACK/NAK sequence (after the ACK/NAK partial bundling). The ACK NAK overhead for the input sequence ..., a_N_, before bundling per DL subframe is the integer N, and the ACK/NAK overhead for the output sequence b_0t ... . b_L__! after bundling per DL subframe is the integer L. [0048] Further assuming that two DAI bits are re-used for the pattern switching/mapping purposes described herein, as detailed above in an exemplary implementation one of those DAI bits is used to indicate the output ACK/NAK sequence index that the current ACK/NAK sequence to be generated by the UE should be mapped to, and the other is used to indicate the total number of assignments within the current bundle. Figures 3-5 detailed below illustrate specifically the three cases from Figure 2 where more than twelve unbundled ACK/NAK bits are generated, using the second embodiment of dynamic signaling of the bundling pattern index for the bundled output bit sequence.

[0049] For each of Figures 3-5, first the UE receives from the eNB some resource assignment on the PDCCH which carries those two re-used DAI bits. The UE checks one of those DAI bits to select from the mapping table stored in its memory the bundled output bit sequence. The UE knows the unbundled input bit sequence implicitly from the CC on which the PDSCHs are scheduled since the CC corresponds to a specific input bit sequence. At this point the UE knows exactly what mapping it will use. The UE also checks the other re-used DAI bit to check whether or not a PDCCH missing exists within the current bundle. This check controls errors, since the mapping will be incorrect if the eNB sends a PDCCH which the UE does not correctly receive. In LTE-A, it is anticipated that there will be a maximum of two assignments (PDCCHs) per bundle and so this single (second) re-used DAI bit is sufficient. If the UE's check of the second re-used DAI bit shows that no PDCCH missing exists, then the UE will map the unbundled ACK/NAK bits which it generates from the PDSCHs in the assignment(s) to the indicated bundled output bit sequence that the UE derived from the first re-used DAI bit.

[0050] Figure 3A is a table of input bit sequence indices and output bit sequence indices. Each input bit sequence is a string of four ACK/NAK bits, since M=4 corresponds to a DL:UL ratio of 4:1. From the Case 1 summary above, each of these 4 unbundled input ACK/NAK bits per subframe will be bundled into 3 output bits. As above, for simplicity we assume in Figure 3B that there is one PDSCH on each of the four illustrated CCs that are configured for the UE (N=4 for Figures 3A-B). Each column of Figure 3B illustrates a bundling pattern, which from left to right correspond to output ACK/NAK sequence indices (0,0,1 ,2), (0,1 ,1 ,2) and (0,1 ,2,2) respectively, as indicated at Figure 3B.

[0051] Since one DAI bit of each assignment gives the output bundling sequence index, then for the leftmost column of Figure 3B the assignment bits from the four assignments tell the UE that the output indices will be {0,0, 1 ,2), meaning in each of the four DL subframes the ACK/NAK bits for the PDSCHs on CC#s 0 and 1 are bundled and the ACK/NAK bits for the PDSCHs on CC#s 2 and 3 remain unbundled. If instead that DAI bit of each assignment gives the output bundling sequence indices as (0,1 , 1 ,2), then the center column of Figure 3B is invoked for the output sequence and in each of the four DL subframes the ACK/NAK bits for the PDSCHs on CC#s 1 and 2 are bundled and the ACK/NAK bits for the PDSCHs on CC#s 0 and 3 remain unbundled. Finally, if the relevant DAI bit of each assignment gives the output bundling sequence indices as (0, 1 ,2,2), then the rightmost column of Figure 3B is invoked for the output sequence and in each of the four DL subframes the ACK/NAK bits for the PDSCHs on CC#s 2 and 3 are bundled and the ACK/NAK bits for the PDSCHs on CC#s 0 and 1 remain unbundled.

[0052] In all cases for the four PDSCHs in the four different CCs there is generated four unbundled ACK/NAK bits per DL subframe which by the output index mapping are bundled to three bits per DL subframe which are signaled. For each assignment there is another DAI bit which tells the total number of assignments within the current bundle, so by example the above output sequence indices may be signaled by four assignments each giving one output index and each indicating one assignment per bundle.

[0053] In all there are sixteen PDSCHs across four DL subframes and four CCs in Figures 3A-B, which the UE will signal to the eNB using exactly twelve bits, which fall within what can be signaled using the LTE-A Reed Muller encoding noted above.

[005 ] At the eNB side, the eNB knows the CC configuration of what it scheduled and does the mapping in reverse of the UE, going from bundled bits received on the uplink to unbundled bits which it matches one-to-one to the PDSCHs the eNB sent to the UE. [0055] The same principle detailed above for Figures 3A-B follows for Figures 4A-B, in which the DL:UL ratio is 3:1 and there are five configured CCs for the UE. There are thus three in time DL subframes each having one PDSCH on each of five CCs, thereby generating a total of fifteen unbundled ACK/NAK bits. Each of those three subframes generate five unbundled bits which are bundled according to Figures 4A-B to four bundled bits per subframe, yielding exactly twelve bundled bits for the UE to signal on the UL to the eNB. As shown at Figures 4A-B, for the case in which the signaled output index is (0,0,1 ,2,3) the leftmost column of Figure 4B shows the ACK/NAK bits for the PDSCHs on CC#s 0 and 1 are bundled while the ACK/NAK bits for the PDSCHs on CC#s 2, 3 and 4 remain unbundled. Different partial bundling patterns are shown at other columns of Figure 4B for the other output sequence indices shown at Figure 4A. [0056J Figures 5A-B are for the case of the DL:UL ratio being 4:1 like Figures 3A-B, but in which there are five configured CCs for the UE like Figures 4A-B. There are thus four in time DL subframes each having one PDSCH on each of five CCs, thereby generating a total of twenty unbundled ACK/NAK bits. Each of those four subframes generate five unbundled bits which are bundled according to Figures 5A-B to three bundled bits per subframe, again yielding exactly twelve bundled bits for the UE to signal on the UL to the eNB. Unlike Figures 3-4 in which the bundling per subframe is one instance of two bits being bundled to one bit, at Figures 5A-B since the reduction per subframe is from five to three bits the bundling is two instances of two bits being bundled to one bit in each DL subframe. Specific examples are shown at the different columns of Figure 5B for the indicated output sequence indices.

[0057] Reference is made to Figure 6 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. In Figure 6 a wireless network 1 is adapted for communication over a wireless link 1 with an apparatus, such as a mobile communication device which above is referred to as a UE 10, via a network access node, such as a Node B (base station), and more specifically an eNB 12. The network 1 may include a network control element (NCE) 14 that may include the M E/S-GW functionality shown in Figure 1A, and which provides connectivity with a network, such as a telephone network and/or a data communications network (e.g., the internet). The UE 10 includes a controller, such as a computer or a data processor (DP) 10A, a computer-readable memory medium embodied as a memory (MEM) 10B that stores a program of computer instructions (PROG) 10C, and a suitable radio frequency (RF) transmitter and receiver 10D for bidirectional wireless communications with the eNB 12 via one or more antennas. The eNB 12 also includes a controller, such as a computer or a data processor (DP) 12A, a computer-readable memory medium embodied as a memory (MEM) 12B that stores a program of computer instructions (PROG) 12C, and a suitable RF transmitter and receiver 12D for communication with the UE 10 via one or more antennas. The eNB 12 is coupled via a data / control path 13 to the NCE 14. The path 13 may be implemented as the S1 interface shown in Figure 1A. The eNB 12 may also be coupled to another eNB via data / control path 15, which may be implemented as the X2 interface shown in Figure 1A. [0058] At least one of the PROGs 10C and 12C is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with the exemplary embodiments of this invention, as will be discussed below in greater detail. [0059] That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP 0A of the UE 10 and/or by the DP 12A of the eNB 12, or by hardware, or by a combination of software and hardware (and firmware). [0060] For the purposes of describing the exemplary embodiments of this invention the UE 10 may be assumed to also include a stored listing of bundling patterns and corresponding indices 10E, and the eNB 12 .may include a stored listing of bundling patterns and corresponding indices 12E. [0061] In general, the various embodiments of the UE 10 can include, but are not limited to, cellular telephones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

[0062] The computer readable MEMs 10B and 12B may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs 10A and 12A may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples.

[0063] Figure 7 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with the exemplary embodiments of this invention. In accordance with these exemplary embodiments at block 702 there is selected one of a plurality of bundling patterns that is indicated in a communication from a network to a user equipment. For an uplink communication from the user equipment to the network which comprises a bundled bit sequence, the method follows at block 704 with using the selected bundling pattern to map between an unbundled bit sequence and the bundled bit sequence such that each bit of the unbundled bit sequence corresponds to only one downlink resource on which the network communicated to the user equipment.

[0064] The various blocks shown in Figure 7 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s).

[0065] In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the exemplary embodiments of this invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as nonlimiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0066] It should thus be appreciated that at least some aspects of the exemplary embodiments of the inventions may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry {as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

[0067] Various modifications and adaptations to the foregoing exemplary embodiments of this invention may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-iimiting and exemplary embodiments of this invention.

[0068] For example, while the exemplary embodiments have been described above in the context of the LTE-Advanced system, it should be appreciated that the exemplary embodiments of this invention are not limited for use with only this one particular type of wireless communication system that uses carrier aggregation.

[0069] It should be noted that the terms "connected," "coupled," or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are "connected" or "coupled" together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be "connected" or "coupled" together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical {both visible and invisible) region, as several non-limiting and non-exhaustive examples.

[0070] Further, the various names used for the described parameters and channels (for example, PDCCH, PDSCH/PUSCH, etc.) are not intended to be limiting in any respect, as these parameters may be identified by any suitable names. Further, the formulas and expressions that use these various parameters may differ from those expressly disclosed herein.

[0071] Furthermore, some of the features of the various non-limiting and exemplary embodiments of this invention may be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.

Claims

What is claimed is:

1. A method, comprising:

selecting one of a plurality of bundling patterns that is indicated in a communication from a network to a user equipment; and

for an uplink communication from the user equipment to the network which comprises a bundled bit sequence, using the selected bundling pattern to map between an unbundled bit sequence and the bundled bit sequence such that each bit of the unbundled bit sequence corresponds to only one downlink resource on which the network communicated to the user equipment.

2. The method according to claim 1 , in which and at least two bits of the unbundled input bit sequence correspond to downlink resources on different component carriers.

3. The method according to claim 1 , in which each of the plurality of bundling patterns comprise an output sequence of bundled ACK/NAK bits, and the indication of the bundling pattern in the communication from the network to the user equipment comprises an index corresponding to one of the output sequences of bundled ACK/NAK bits.

4. The method according to claim 3, in which the unbundled bit sequence implicitly corresponds to a configured component carrier.

5. The method according to claim 1 , in which the selected one of the plurality of bundling patterns is indicated dynamically in a physical downlink control channel from the network to the user equipment.

6. The method according to claim 1 , in which the selected one of the plurality of bundling patterns is indicated semi-statically via radio resource control signaling from the network to the user equipment.

7. The method according to any one of claims 1 through 6, in which the method is executed by the user equipment;

in which the user equipment selects the bundling pattern from the indication which the user equipment receives in the communication; and

in which the user equipment uses the selected bundling pattern to map from the unbundled bit sequence to the bundled bit sequence. 8. The method according to any one of claims 1 through 6, in which the method is executed by an access node of the network;

in which the access node selects the bundling pattern and sends to the user equipment the indication in the communication; and

in which the access node uses the selected bundling pattern to map from the bundled bit sequence to the unbundled bit sequence.

9. An apparatus, comprising:

at least one processor; and

at least one memory including computer program code;

the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus at least to perform:

10. The apparatus according to claim 9, in which and at least two bits of the unbundled input bit sequence correspond to downlink resources on different component carriers.

11. The apparatus according to claim 9, in which each of the plurality of bundling patterns comprise an output sequence of bundled ACK/NAK bits, and the indication of the bundling pattern in the communication from the network to the user equipment comprises an index corresponding to one of the output sequences of bundled ACK/NAK bits.

12. The apparatus according to claim 11 , in which the unbundled bit sequence implicitly corresponds to a configured component carrier.

13. The apparatus according to claim 9, in which the selected one of the plurality of bundling patterns is indicated dynamically in a physical downlink control channel from the network to the user equipment. 14. The apparatus according to claim 9, in which the selected one of the plurality of bundling patterns is indicated semi-statically via radio resource control signaling from the network to the user equipment.

15. The apparatus according to any one of claims 9 through 14, in which the method is executed by the user equipment;

in which the user equipment uses the selected bundling pattern to map from the unbundled bit sequence to the bundled bit sequence.

16. The apparatus according to any one of claims 9 through 14, in which the method is executed by an access node of the network;

17. A memory storing a program of computer readable instructions that when executed by a processor result in actions comprising:

18. The memory according to claim 17, in which each of the plurality of bundling patterns comprise an output sequence of bundled ACK/NAK bits, and the indication of the bundling pattern in the communication from the network to the user equipment comprises an index corresponding to one of the output sequences of bundled ACK/NAK bits. 9. The memory according to claim 17, in which the selected one of the plurality of bundling patterns is indicated dynamically in a physical downlink control channel from the network to the user equipment.

20. The memory according to claim 17, in which the selected one of the plurality of bundling patterns is indicated semi-statically via radio resource control signaling from the network to the user equipment.