Patent Description:
At the RAN plenary meeting #<NUM>, a new Work Item (WI) entitled "Rel-<NUM> enhancements for NB-IoT and LTE-MTC" was agreed. One of its objectives consists in specifying for LTE-MTC the introduction of <NUM> HARQ processes in DL as stated in the Work Item Description (WID): Support additional PDSCH scheduling delay for introduction of <NUM>-HARQ processes in DL, for HD-FDD Cat M1 UEs. [LTE-MTC] [RAN1].

The WID's objective for LTE-MTC targets HD-FDD Cat M1 UEs, which peak data rate can be achieved through the combined usage of <NUM> HARQ processes and HARQ-ACK bundling as depicted in <FIG>.

In <FIG>, the solid and dotted arrows illustrate examples of the "Scheduling delay for PDSCH" (encompassing <NUM> subframes) and "HARQ-ACK delay" (encompassing <NUM> subframes) respectively.

The Rel-<NUM> enhancement for LTE-MTC aims at increasing the peak data rate through the "Support of additional PDSCH scheduling delay for introduction of <NUM>-HARQ processes in DL, for HD-FDD Cat M1 UEs", which, as shown in <FIG>, is intended to be done by using the framework depicted in <FIG>.

In relation to the introduction of <NUM> HARQ processes in DL, it reads as: <NPL>.

Although the increase in peak data rate is estimated using <NUM> HARQ processes, there are <NUM> HARQ processes in total. As can be seen in <FIG>, the reason for having <NUM> HARQ processes (i.e., spanning from #<NUM> to #<NUM>) is that the HARQ processes #<NUM> and #<NUM> (tied to MPDCCH <NUM> and <NUM>) need to wait for the ACK bundling that follows the upcoming set of MPDCCHs ending with HARQ processes #<NUM> and #<NUM> (tied to MPDCCH <NUM> and <NUM>).

From <FIG>, it can be seen that the introduction of <NUM> HARQ process in DL would require adding new values for both the "Scheduling delay for PDSCH" and "HARQ-ACK delay".

In legacy when there are <NUM>-HARQ processes, the "Scheduling delay for PDSCH" uses a value of <NUM>. That is, the PDSCH starts on the second subframe after the end of the MPDCCH used to schedule the corresponding DL data. On the other hand, when there are <NUM> HARQ processes the "Scheduling delay for PDSCH" requires a value equal to <NUM> in addition to the legacy value that is equal to <NUM> (See <FIG>).

In R1-<NUM>, "<NPL>, it has been proposed that the "Scheduling delay for PDSCH" can support the value of <NUM> in addition to the legacy value of <NUM>, whereas for the "HARQ-ACK delay" it has been proposed to use the following values: <NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>.

Regarding HARQ-ACK delay, it is described in the current 3GPP specifications. In particular, HARQ-ACK delay for BL/CE UE in CE ModeA is shown in Table <NUM> as below:.

For details, please refer to 3GPP specification TS <NUM>, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures", version <NUM>. The current specification allows at most <NUM> HARQ processes in FDD, and as can be seen from the table above the maximum HARQ-ACK delay for 'ce-HARQ-AckBundling' is <NUM>.

One of the objectives of the WI on "Rel-<NUM> enhancements for NB-IoT and LTE-MTC" is to introduce "<NUM>-HARQ processes in DL, for HD-FDD Cat M1 UEs", the problems envisioned towards its support are listed below:.

According to one aspect of the present disclosure, a selective HARQ-ACK delay counting strategy has been described in the form of Tables providing delays associated to PUCCH (e.g., PUCCH #<NUM>, PUCCH #<NUM> and PUCCH #<NUM>) when the "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE" is in presence of:.

In the present disclosure, the term "invalid BL/CE DL subframes" corresponds to the term "non-BL/CE DL subframes" in the 3GPP technical specifications.

The solutions as described in the present disclosure are backward compatible with the 3GPP standard since they utilize existing framework (e.g., BL/CE DL subframes) to create the selective HARQ-ACK delay counting strategy.

According to one embodiment, there is provided a method as defined in claim <NUM>.

According to another embodiment, there is provided a method as defined in claim <NUM>.

According to another embodiment, there is provided a UE as defined in claim <NUM>.

According to another embodiment, there is provided an apparatus as defined in claim <NUM>.

According to another embodiment, there is provided a computer program product as defined in claim <NUM>.

The foregoing and other objects, features, and advantages would be apparent from the following more particular description of preferred embodiments as illustrated in the accompanying drawings in which:.

As used herein, the term "processor" refers to one or more devices, circuits, and/or processing cores configured to process data, such as computer program instructions. It will be further understood that the terms "comprises" "comprising," "includes" and/or "including" when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Also, use of ordinal terms such as "first," "second," "third," etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood.

The scope of the invention is limited only by the appended claims.

A flowchart of a method <NUM> for scheduling delay associated with HARQ processes in LTE-MTC according to one embodiment of the present invention is shown in <FIG>.

As shown in <FIG>, the flowchart comprises the following steps performed, e.g., at NodeB side:
Step <NUM>: in response to presence or non-presence of PUCCH repetition, invalid BL/CE DL subframe, invalid BL/CE UL subframe, and measurement gap, determining a HARQ-ACK scheduling counting strategy.

Step <NUM>: scheduling a HARQ-ACK delay value in accordance with the HARQ-ACK scheduling counting strategy.

In this embodiment, preferably, the flowchart further comprises the step of transmitting DCI including the HARQ-ACK delay value to a UE.

In this embodiment, preferably, the HARQ-ACK delay value is represented as one of a plurality of multi-bit values which are stored in a HARQ-ACK delay table.

In this embodiment, preferably, the determining of the HARQ-ACK scheduling counting strategy comprising the step of selecting one of a plurality of candidate HARQ-ACK delay counting strategies as the HARQ-ACK scheduling counting strategy on the basis of presence or non-presence of PUCCH repetition, invalid BL/CE DL subframe, invalid BL/CE UL subframe, and measurement gap.

In this embodiment, preferably, in the presence of PUCCH repetition, invalid BL/CE DL subframe, and invalid BL/CE UL subframe, in the case of <NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE, the scheduling is carried out follows:
for HARQ-ACK delay between HARQ #n and HARQ-ACK bundle <NUM>, the HARQ-ACK delay value is set as:.

In this embodiment, preferably, in the presence of PUCCH repetition, invalid BL/CE DL subframe, invalid BL/CE UL subframe and measurement gap, in the case of <NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE, the scheduling is carried out follows:
for an average of HARQ-ACK delay between HARQ #n and HARQ-ACK bundle <NUM>, the HARQ-ACK delay value is set as:.

In this embodiment, preferably, in the non-presence of PUCCH repetition, invalid BL/CE DL subframe, invalid BL/CE UL subframe and measurement gap, in the case of <NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE, the scheduling is carried out in accordance with procedure as specified in 3GPP TS <NUM>.

In this embodiment, preferably, the definition of BL/CE DL subframe and BL/CE UL subframe remain the same as legacy, whereas the definition of absolute subframe refers to any type of subframe.

In this embodiment, preferably, an invalid BL/CE DL subframe is used for performing a DL-to-UL switching or UL-to-DL switching, or transmitting in UL.

In this embodiment, preferably, an invalid BL/CE UL subframe is used for performing a DL-to-UL switching or UL-to-DL switching, or transmitting in DL.

<FIG> is a block diagram illustrating an apparatus for scheduling delay associated with HARQ processes in LTE-MTC according to another embodiment.

With reference to <FIG>, the apparatus <NUM> comprises a storage device <NUM> and a processor <NUM> coupled to the storage device <NUM>. The storage device <NUM> is configured to store a computer program <NUM> comprising computer instructions. The processor <NUM> is configured to execute the computer instructions to perform some or all of the method steps as shown in <FIG>.

A flowchart of a method <NUM> for scheduling delay associated with HARQ processes in LTE-MTC according to another embodiment of the present invention is shown in <FIG>.

As shown in <FIG>, the flowchart comprises the following steps performed at UE side:
Step <NUM>: receiving a HARQ-ACK delay value.

Step <NUM>: transmitting a PUCCH subframe for HARQ-ACK or HARQ-NACK with the HARQ-ACK delay value.

In this embodiment, the HARQ-ACK delay value is scheduled in accordance with the HARQ-ACK scheduling counting strategy, which is determined in response to presence or non-presence of PUCCH repetition, invalid BL/CE DL subframe, invalid BL/CE UL subframe, and measurement gap, determining a HARQ-ACK scheduling counting strategy.

In this embodiment, preferably, the HARQ-ACK delay value is included in DCI from a NodeB.

The Rel-<NUM> objective on introducing "<NUM>-HARQ processes in DL, for HD-FDD Cat M1 UEs" fails to consider further delays caused when the feature happens to coexist with PUCCH repetitions, invalid BL/CE DL subframes, invalid BL/CE UL subframes, and measurement gaps, which will impact the HARQ-ACK delays. In the present disclosure, methods for supporting the introduction of "N-HARQ processes in DL, for HD-FDD Cat M1 UEs" in presence of PUCCH repetitions, invalid BL/CE DL subframes, invalid BL/CE UL subframes, and measurement gaps are described. For illustrative purpose and to stay aligned with the Rel-<NUM> WID, the methods are described using <NUM> HARQ processes as a basis, but they can be applied to an N number of HARQ processes.

Throughout the present disclosure, the term "invalid BL/CE DL subframes" used herein may correspond to the term "non-BL/CE DL subframes" in the 3GPP technical specifications.

In general, in presence of MG, invalid BL/CE DL subframes, invalid BL/CE UL subframes, and PUCCH repetitions, the HARQ-ACK delay values available are insufficient and thus will limit the number of HARQ processes that can be used. The examples below illustrate that even with <NUM> HARQ processes in DL using HARQ-ACK bundling, the set of HARQ-ACK delay values available results insufficient to deal with the required HARQ-ACK delays.

Example <NUM>: "Downlink subframe bitmap <NUM>, which denotes the invalid BL/CE DL subframes with '<NUM>' " is described with reference to <FIG>.

In Example <NUM>, not all the <NUM> HARQ processes can be scheduled, as there are no available HARQ-ACK delay values for HARQ process <NUM>, <NUM>, and <NUM>. That is, in <FIG>, only the delay values highlighted with a "diagonal dash" pattern are available in HARQ-ACK delay set for 'ce-HARQ-AckBundling' (See Table <NUM>).

Example <NUM>: "Measurement gaps. The measurement gap duration and its periodicity are defined through the variable Measurement Gap Length (MGL) and the Measurement Gap Repetition Period (MGRP) as defined in 3GPP specification TS <NUM>" is described with reference to <FIG>.

The +<NUM> subframe is because it is assumed that Cat-M1 UEs cannot transmit anything in UL in the subframe after the measurement gap. In Example <NUM>, not all the <NUM> HARQ processes can be scheduled, as there are no available HARQ-ACK delays for HARQ process <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>.

Example <NUM>: "This example illustrates the presence of PUCCH repetitions for the case when the number of PUCCH repetitions = <NUM>" is described with reference to <FIG>.

In Example <NUM>, not all the <NUM> HARQ processes can be scheduled, as there are not sufficiently many available HARQ-ACK delay values. It is known that PUCCH <NUM>, <NUM>, and <NUM> can respectively handle up to <NUM> HARQ processes each. Thus, in Example <NUM>:.

In Rel-<NUM>, the introduction of "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE" will require additional HARQ-ACK delay values and will limit even more the number of HARQ processes that can be used.

As described above, for <NUM> HARQ processes, at most <NUM> HARQ processes can be handled by a given HARQ-ACK bundling set consisting of <NUM> PUCCHs. Although there are <NUM> HARQ processes in total, the increase in peak data rate is estimated using <NUM> HARQ processes due that <NUM> out of <NUM> processes require cross UL transmissions (see <FIG>). The term "cross UL transmission" is used for describing the case of DL data scheduling for a particular DL HARQ process where an UL (PUCCH) transmission takes place between the MPDCCH carrying the DL grant and the associated PDSCH carrying the DL data.

In one embodiment for the introduction of "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE", the HARQ-ACK delays in presence of invalid BL/CE DL subframes, invalid BL/CE UL subframes, and PUCCH repetitions (i.e., the number of PUCCH repetitions, and it is referred to as "Rpucch") is handled according to the following HARQ-ACK scheduling counting strategy:.

Assuming the HARQ process with max HARQ-ACK delay is HARQ #n and that the delay counting starts after the last subframe in which the PDSCH is transmitted, then.

In one embodiment, the sign "+" means "followed by" as to account for the order in which the delays are counted.

In one embodiment, the definition of BL/CE DL subframe and BL/CE UL subframe remain the same as legacy, whereas the definition of absolute subframe refers to any type of subframe.

In one embodiment, it is assumed that an invalid BL/CE DL subframe can be used to perform either a DL-to-UL switching, UL-to-DL switching, or to transmit in UL (e.g., PUCCH).

In one embodiment, it is assumed that an invalid BL/CE UL subframe can be used to perform either a DL-to-UL switching, UL-to-DL switching, or to transmit in DL (e.g., MPDCCH, or PDSCH).

In one embodiment, the presence of measurement gaps is incorporated to the HARQ-ACK scheduling counting strategy as follows:.

Assuming a fraction x% of invalid BL/CE DL subframes, a fraction y% of invalid BL/CE UL subframes, and that the measurement gap length is <NUM> or <NUM>:.

The equations under the three sub-bullets below describe the average HARQ-ACK delay from the farthest HARQ process (described below as "HARQ #n") that can be bundled to either PUCCH <NUM>, <NUM>, or <NUM> respectively. The HARQ-ACK delay starts from the subframe after the end of the PDSCH till the subframe used to transmit either PUCCH <NUM>, <NUM>, or <NUM>. The equations below incorporate percentagewise the presence of invalid subframes and measurement gaps. The no presence of invalid subframes nor measurement gaps can be used as a starting point to understand the equations below, since such a case leads to an average HARQ-ACK delay from the farthest HARQ process to PUCCH <NUM>, <NUM> and <NUM> equal to <NUM>, <NUM>, and <NUM> respectively, which resembles <FIG> where the farthest HARQ process is "HARQ #<NUM>" (See also in the upper part of Table <NUM> the column corresponding to a <NUM>% for x and y).

In one embodiment, the definition of BL/CE DL subframe, BL/CE UL subframe, and measurement gaps remain the same as legacy, whereas the definition of absolute subframe refers to any type of subframe.

Table <NUM> illustrates the presence in different percentages of invalid BL/CE DL subframes, invalid BL/CE UL subframes, several cases of PUCCH repetitions and their impact on the HARQ-ACK delay.

In relation to the example in Table <NUM>, if PDSCH scheduling encounters MG, then the HARQ-ACK delay for HARQ #n is increased by <NUM> or <NUM> subframes.

In one embodiment for the introduction of "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE", the HARQ-ACK scheduling counting strategy is made compatible with the set of HARQ-ACK delay values in 3GPP specification TS <NUM>, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures", version <NUM>. by increasing the "HARQ-ACK delay" field size by <NUM> bit in DCI Format <NUM>-1A (i.e., to use <NUM> bits instead of <NUM> bits), which increases the number of HARQ-ACK delay values from <NUM> to <NUM>. Alternatively, a new <NUM>-bit field in DCI Format <NUM>-1A is introduced to provide the HARQ-ACK delays when "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE" is configured.

In one embodiment, the "HARQ-ACK delay for BL/CE UE in CE ModeA" is updated similarly to Table <NUM> below to handle the HARQ delays in presence of PUCCH repetitions, invalid BL/CE DL subframes, invalid BL/CE UL subframes, and Measurement gaps when "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE" is configured.

In Table <NUM>, the largest step in 'HARQ-ACK delay' is <NUM> (e.g., from <NUM> to <NUM>). With HARQ-ACK bundling, the channel condition is basically good, so only a small number of PUCCH repetitions need to be covered for most cases, e.g. <NUM><NUM> or even <NUM> repetitions. When MG is for RSTD, the MGL is usually very large, which will result in a large HARQ-ACK delay, so only relatively small MGL needs to be covered, e.g. MGL = <NUM>.

In dependent embodiment when the "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE" is configured and the "HARQ-ACK delay" field uses <NUM> bits:.

Some examples are shown in <FIG> for illustrating the HARQ-ACK scheduling counting strategy using Table <NUM> when "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE" is configured.

Example <NUM>: "HARQ-ACK scheduling counting strategy using Table <NUM> when "<NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE" is subject to the presence of invalid BL/CE DL subframes, invalid BL/CE UL subframes, and Measurement gaps" is described with reference to <FIG>.

The delay values highlighted with a "diagonal dash" pattern are available in HARQ-ACK delay set of Table <NUM>.

In example <NUM>, with the 'HARQ-ACK delay' based on Table <NUM>, still not all the <NUM> HARQ processes can be used as HARQ process #<NUM>, #<NUM>, #<NUM>, #<NUM>, #<NUM> and #<NUM> can only use HARQ-ACK bundle <NUM> (recall that the number of PDSCH transmissions bundled in one HARQ-ACK cannot exceed <NUM>). Thus, in this example, with new 'HARQ-ACK delay' table, the max number of HARQ process that can be scheduled is <NUM> instead of <NUM>.

Example <NUM>: "The scenario is the same as Example <NUM> except that the measurement gap is shifted to subframes the right, which results in different HARQ-ACK delay requirements" is described with reference to <FIG>.

In Example <NUM>, with a 'HARQ-ACK delay' based on Table <NUM>, all the <NUM> HARQ processes can be scheduled at the same time.

Example <NUM>: "This example represents a scenario with no presence of measurement gap, which results in different HARQ-ACK delay requirements" is described with reference to <FIG>.

In Example <NUM>, with a 'HARQ-ACK delay' based on Table <NUM>, even though there is no MG not all the <NUM> HARQ processes can be used (Note that for HARQ process #<NUM> and #<NUM>, there is no available HARQ-ACK delay). Thus, as mentioned earlier the set of HARQ-ACK delay values in Table <NUM> do not cover all possible scenarios that may arise from having individual or simultaneous presence of PUCCH repetitions, invalid BL/CE DL subframes, invalid BL/CE UL subframes, and Measurement gaps, reason why the set of HARQ-ACK delays should account for the most common scenarios foreseen in real deployments.

In one embodiment the HARQ-ACK delay counting strategies for the support of <NUM> HARQ processes in DL can be described as set of rules or any other form/format other than the Table format, e.g., Table <NUM>.

Claim 1:
A method performed by a UE (<NUM>) for HARQ-ACK delay associated with HARQ processes in LTE MTC, the method comprising:
receiving (<NUM>) downlink control information indicating a HARQ-ACK delay value associated with a HARQ process in LTE-MTC; and
transmitting (<NUM>) a Physical Uplink Control Channel., PUCCH, including HARQ-ACK or HARQ-NACK with a delay in accordance with the HARQ-ACK delay value,
the method being characterized in that the HARQ-ACK delay value is scheduled in accordance with a HARQ-ACK scheduling counting strategy, which is determined in response to presence or non-presence of PUCCH repetition, invalid BL/CE downlink, DL, subframe, invalid BL/CE uplink, UL, subframe, and measurement gap,
wherein, in the case of <NUM> HARQ processes in DL using HARQ-ACK bundling for a Cat M1 HD-FDD UE:
for HARQ-ACK delay between HARQ #n and HARQ-ACK bundle <NUM>, the HARQ-ACK delay value is
<NUM> BL/CE DL subframes + <NUM> subframe + <NUM> BL/CE UL subframe;
for HARQ-ACK delay between HARQ #n and HARQ-ACK bundle <NUM>, the HARQ-ACK delay value is
<NUM> BL/CE DL subframes + <NUM> subframe + (<NUM>* Rpucch + <NUM>) BL/CE UL subframes; and
for HARQ-ACK delay between HARQ #n and HARQ-ACK bundle <NUM>, the HARQ-ACK delay value is
<NUM> BL/CE DL subframes + <NUM> subframe + (<NUM>* Rpucch + <NUM>) BL/CE UL subframes,
wherein HARQ #n represents a HARQ process with max HARQ-ACK delay, wherein Rpucch represents a number of PUCCH repetitions, and wherein a delay counting for the HARQ-ACK delay value starts after the last subframe in which PDSCH is transmitted.