For the 5 MHz channel bandwidth:

PBCH transmission bandwidth is 20 PRBs.

CORESET #0 transmission bandwidth is to be decided by RAN1.

Other details (including sync raster details) are to be progressed in the work groups.

Based on the current agreement, for 3 MHz channel bandwidth, the 12 & 15 PRB CORESET operation is supported. specifically,

- For 3 MHz channel bandwidth in all bands (max channel utilization 15 PRBs as already agreed in RAN1/RAN4):
  - PBCH transmission bandwidth is 12 PRBs.
  - For CORESET #0 transmission bandwidth, both 12 PRBs and 15 PRBs are supported.
    - In Case of 12 PRBs, the legacy interleaved (R=2) CORESET CCE-to-REG mapping is used with N_RB^CORESET=12, i.e., 12PRBs are indicated without puncturing.
    - In Case of 15 PRBs, the N_RB^CORESET=24 CORESET #0 is punctured.
      - Both interleaved (legacy interleaver size of R=2) and non-interleaved mapping are supported,
      - Some entries in the table are related with interleaved mapping and some are non-interleaved mapping.
    - A single table of up to 16 entries to accommodate both cases:
      - Maximum number of CORESET #0 symbols is 3. Minimum number of CORESET #0 symbols is 2.
      - SSB and CORESET #0 multiplexing pattern 1 is used (pattern 1 means that SSB and CORESET #0 are time multiplexed”)
    - REG bundle size=6.

As described above, i.e., one of the objectives of the work item may be “identify and specify necessary minimum changes to PDCCH for functional support based on existing design, without optimization. During system information acquisition, UE monitors PDCCH on resources spanning at least 4.32 MHz (i.e., 24 RBs), i.e., exceeding the targeted transmission bandwidths of 20, 15 and 12 RBs. The PDCCH changes that are necessary to support NR in narrow spectrum allocations should therefore be focused on these PDCCH resources. Another PDCCH aspect requiring attention is the PDCCH frequency domain location with respect to SSB.

The PDCCH can be mapped to sets of physical resources known as CORESETs, which in turn is comprised of control channel elements (CCEs). A control-channel element consists of 6 resource-element groups (REGs) where a resource-element group equals one resource block during one OFDM symbol.

CORESETs can be flexibly configured to the UE after the initial access. However, there are limited configuration options available for the CORESET #0 that are used e.g., for the PDCCH that schedules the transmission of System Information Block 1 (SIB1), known as Type0-PDCCH.

First, the CORESET #0 frequency domain location can be considered with respect to SSB. FIG. 2 shows an example of CORESET #0 frequency domain resource allocation.

As shown in FIG. 2, after the UE has detected Primary synchronization signal (PSS) 201 and Secondary synchronization signal (SSS) 203 and demodulated the PBCH 202, the UE has acquired the Master Information Block (MIB) on the PBCH 202. Next the UE needs to acquire the remaining minimum system information, carried by the SIB1. The UE reads the CORESET #0 configuration index from the MIB on the PBCH 202, which indicates time and frequency resource allocation parameters for the CORESET 205. One of the parameters defines the frequency domain offset 204 between the first RB in which the SSB is located and the first RB of CORESET #0.

Similar to the PBCH transmission, puncturing may be needed to constrain CORESET #0 within the available spectrum. This may lead to situations where the constrained CORESET #0 would contain some partial CCEs. For example, when the available spectrum is not an integer multiple of CCE size and is less than 24 RBs (for our specific case: 20 RBs), there would be at least one partial CCE.

However, if the puncturing of PBCH is not taken into account on the CORESET #0 frequency domain allocation, there would be unnecessarily two CCEs that are punctured. As a CCE is used as the basic resource unit in channel estimation, partial CCEs can degrade channel estimation.

Although the use of partial CCEs is unavoidable, it makes sense to minimize the number of partial CCEs. Thus, the CORESET #0 frequency domain allocation may require re-consideration to keep CORESET #0 aligned at the CCE level with the non-punctured RBs of the SSB or in case of 20 RBs to keep the unpunctured part of the CORESET #0 aligned at the CCE level with RBs of the SSB.

In this situation, how to configure a narrower bandwidth for CORESET #0 (especially for Type0_PDCCH) with 20RB CORESET #0 design when operating with 5 MHz channel bandwidth (targeting especially band n100) may need to be further discussed to minimize the additional complexity, while provide the sufficient flexibility.

According to some example embodiments of the present disclosure, there is provided a solution for controlling the CORESET #0 puncturing. In this solution, the first apparatus 110 detects a synchronization signal block, received from a second apparatus, on a specific frequency location and determine whether a CORESET of a specific type is punctured based on the detection. If the first apparatus 110 determines that the CORESET of the specific type is punctured, the first apparatus 110 determines the portion of resources punctured in the CORESET at least based on the CORESET puncturing pattern.

Based on the solution, a flexible selection between punctured vs. non-punctured CORESET #0 and corresponding puncturing options can be supported.

Example embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

Reference is now made to FIG. 3, which shows a signaling chart 300 for communication according to some example embodiments of the present disclosure. As shown in FIG. 3, the signaling chart 300 involves the first apparatus 110 and the second apparatus 120. For the purpose of discussion, reference is made to FIG. 1 to describe the signaling chart 300. It is to be understood that the process shown in FIG. 3 may also be adopted by other terminal devices and network devices shown in FIG. 1.

The first apparatus 110 may perform an initial access to a channel associated with a specific bandwidth (e.g., n100, 5 MHz channel bandwidth (CBW)). As shown in FIG. 1, the second apparatus 120 may transmit (305) an SSB. It is to be understood that the SSB used herein may include a ‘Synchronization Signal’ (SS) block and a PBCH block, and the SS block may be replaced by a synchronization signal, a primary synchronization signal, or a secondary synchronization signal.

Based on the detection of the SSB, the first apparatus 110 determines CORESET #0 parameters such as CORESET multiplexing pattern, number of RBs, number of symbols, the offset (RBs) from table 1, entries 0-5.

TABLE 1

set of resource blocks and slots symbols of CORESET for

Type0-PDCCH search space set when {SS/PBCH block, PDCCH}

SCS is {15, 15} kHz for frequency bands with minimum

channel bandwidth 5 MHz or 10 MHz or with minimum channel

bandwidth 3 MHz and channel bandwidth larger than 3 MHz

SS/PBCH block
number
number of

and CORESET
of RBs
symbols
offset

index
multiplexing pattern
N_RB^CORESET
N_symb^CORESET
(RBs)

0
1
24
2
0

1
1
24
2
2

2
1
24
2
4

3
1
24
3
0

4
1
24
3
2

5
1
24
3
4

6
1
48
1
12

7
1
48
1
16

8
1
48
2
12

9
1
48
2
16

10
1
48
3
12

11
1
48
3
16

12
1
96
1
38

13
1
96
2
38

14
1
96
3
38

15
reserved

If the first apparatus 110 detects the SSB on a specific frequency location, the first apparatus 110 may determine (315) that a CORESET of a specific type is punctured. The term “a CORESET of a specific type” used herein may be referred to as CORESET #0 that are used e.g., for the PDCCH that schedules the transmission of SIB1, known as Type0-PDCCH.

The term “specific frequency location” used herein may be referred to as a location of a sync raster point in a frequency domain such as, e.g., 921.45 MHz. This sync raster point could be set based on n100 lower band edge which is at 919.4 MHz. This means that the lowest channel raster point having the channel BW within the band is at 919.4 MHz+2.5 MHz=921.9 MHz. 5 MHz CBW means 25 RBs so lowest RB edge is 12.5 RBs below channel raster point. The sync raster point with the lowest RB aligned with the lowest RB of the channel (common raster) is then 12.5−10=2.5 RB (=450 kHz) below the channel raster point, i.e. 921.9−0.45=921.45 MHz. So in short, the 921.45 is the sync raster point that allows SSB to be placed as low as possible within the band with 5 MHz CBW but limited to 20 PRB transmission bandwidth. It is also a sync raster point that is not part of regular/legacy sync raster otherwise used for 5 MHz CBW with the regular 25 PRB transmission bandwidth on n100.

For example, if the first apparatus 110 determines that a primary synchronization signal or a secondary synchronization signal is detected on the specific frequency location, the first apparatus 110 may determine that a CORESET of a specific type is punctured.

The CORESET #0 is operated without puncturing with the remaining synch raster points for 5 MHz CBW.

Furthermore, an additional confirmation for a CORESET puncturing may be obtained by the first apparatus from another way, such as from MIB.

Various puncturing patterns may be obtained/determined by the first apparatus 110. For example, the puncturing patterns may be configured by the second apparatus 120 and transmitted to the first apparatus 110 or pre-configured/pre-defined in the specification.

After determining that a CORESET of a specific type is punctured, the first apparatus 110 may determine the corresponding puncturing pattern for the CORESET puncturing. Various puncturing patterns are described in detail with respective to FIGS. 4A-4F as below.

As an option (hereinafter may be referred as to option 1), RBs below the lowest RB of PBCH (i.e., RB #0) are punctured. In some embodiment, the lowest subcarrier of PBCH (i.e., RB #0) can be seen as puncturing_threshold_low.

FIG. 4A shows an example of CORESET puncturing when using the MIB informed Table 1 according to some example embodiments of the present disclosure. As shown, for index 0 or 3, index 1 or 4 and index 2 or 5 of Table 1 RBs below the RB #0 of PBCH are to be punctured.

In another option (hereinafter may be referred as to option 2), RBs above the highest RB of PBCH (i.e., RB #19) are punctured. In some embodiment, the highest subcarrier of PBCH (i.e., RB #19) can be seen as puncturing_threshold_high.

In a further option (hereinafter may be referred as to option 3), RBs below the lowest RB of PBCH (i.e., RB #0) and above the highest RB of PBCH (i.e., RB #19) are punctured to align the transmission bandwidth with PBCH.

FIG. 4B shows an example of CORESET puncturing when using the MIB informed Table 1 according to some example embodiments of the present disclosure. As shown on the basis of option 3, for index 0 or 3, index 1 or 4 and index 2 or 5 of Table 1 RBs below the RB #0 and above the RB #19 of PBCH are to be punctured.

Furthermore, on the basis of options 1-3 as described above, only those indexes that contain up-to 20RBs after puncturing operation may be considered as valid indexes. The first apparatus 110 may also not expect to receive an invalid index. Additionally or optionally, puncturing is additionally applied with a granularity of full a CCE (rather than RB). In other words, if at least one RB of a CCE needs to be punctured, the whole CCE (i.e., all RBs part of that CCE) will be punctured (hereinafter may be referred as to option 4). In this option the non-punctured resources comprise an integer multiple of 6 REGs.

FIG. 4C shows an example of CORESET puncturing when using the MIB informed Table 1 according to some example embodiments of the present disclosure. On the basis of option 1, i.e., RBs below the lowest RB of PBCH (i.e., RB #0) are punctured, FIG. 4C shows a puncturing pattern (index 1 or 4) according to option 4 with only full CCEs transmitted. In FIG. 4C, option 1 pattern is shown as reference (index 1 or 4) for the option 4 patterns (one is for index 4 with 3 OFDM symbols (OS) and the other is for index 1 with 2 OS shown below the option 1 pattern) that are derived from the option 1 pattern.

FIG. 4D shows an example of CORESET puncturing when using the MIB informed Table 1 according to some example embodiments of the present disclosure. On the basis of option 3, i.e., both RBs below the lowest RB of PBCH (i.e., RB #0) and above the highest RB of PBCH (i.e., RB #19) are punctured, FIG. 4D shows a puncturing pattern (for indices 0-5 of Table 1) according to option 4 with only full CCEs transmitted.

In some variants, there is a threshold of a share of the RBs of a CCE based on which it's determined whether the whole CCE will be punctured. For example, if the threshold is 0.5 (50%) the whole CCE is punctured if at least half of the RBs of the CCE needs to be punctured.

FIG. 4E shows an example of CORESET puncturing when using the MIB informed Table 1 according to some example embodiments of the present disclosure. On the basis of option 3, i.e., both RBs below the lowest RB of PBCH (i.e., RB #0) and above the highest RB of PBCH (i.e., RB #19) are punctured, FIG. 4E shows a puncturing pattern according to option 4, i.e., only PRBs transmitted in case of more than 50% of PRBs of a CCE.

Furthermore, on the basis of options 1-4 as described above, the IEs puncturing_threshold_low and/or puncturing_threshold_high may be determined with a predefined offset with respect to the lowest RB of PBCH (i.e., RB #0) and the highest RB of PBCH (i.e., RB #19) (hereinafter may be referred as to option 5).

In some embodiments, the predefined offset is [offset_low, offset_high]=[x,y] subcarriers (x, y are positive or negative integers). In some other embodiments, the predefined offset is [offset_low, offset_high]=[x,y] RBs (x,y are positive or negative integers).

In a further option, assuming that CORESET #0 and PBCH are in subcarrier offset with respect to each other. This option (hereinafter may be referred as to option 6) is a variant of options 1-3, where puncturing is applied with the granularity of subcarrier. In this case, partial RB (for CORESET #0) is considered to be a punctured RB. The partial RB may be considered as a portion of symbols or subcarriers in an RB (hereinafter may be referred as to option 6). A partial RB can be called also a punctured RB, where a partial RB has punctured subcarriers and the number of punctured subcarriers of the partial RB is greater than 0 and less than 12.

Moreover, on the basis of options 1-5 as described above, puncturing may require additional implicit or explicit signaling or confirmation (otherwise UE interprets error in MIB content and continues searching other PSS/SSSs or, alternatively UE does not apply puncturing without additional confirmation). The additional confirmation can be e.g., certain value in k_SSB (an indicated gap between Subcarrier 0 of SS/PBCH block and Common Resource Block), e.g., 0 or a k_SSB value that is predefined to correspond to the indicated CORESET table index (hereinafter may be referred as to option 7). The k_SSB may indicate the frequency domain offset between SSB and the common resource block in number of subcarriers. k_SSB is indicated by the MIB.

In another option, certain indexes (e.g., Index 0 and/or Index 3) are considered as the only valid options for the cases when the detected synch raster point relates to n100, 5 MHz CBW (hereinafter may be referred as to option 8).

FIG. 4F an example of CORESET puncturing when using the MIB informed Table 1 according to some example embodiments of the present disclosure. As shown on the basis of option 8, in a case where one predefined synch raster point is 921.45 MHz, in some embodiments, for index 0 or index 3, RBs 20-23 are punctured (Alt. 1). In some other embodiments denoted with Alt. 2, RBs 18-23 are punctured for index 0 (with 20S CORESET) and RBs 20-23 are punctured for index 3 (with 30S CORESET), hence, limiting puncturing to the granularity of whole CCEs.

As described above, with the CORESET puncturing pattern, the first apparatus 110 may determine the portion of resources punctured in the CORESET. Now the reference is back to FIG. 3, the first apparatus 110 may decode (320) the PBCH and monitor the PDCCH based on the determined portion of resources punctured in the CORESET.

In another case where PSS/SSS is found from another synch raster point defined for 5 MHz CBW on the specific channel and the CORESET is determined as not being punctured, the first apparatus 110 may decode the PBCH and obtain information from PBCH/MIB to determine Index addressing a row (0-5) in Table 1. Then the first apparatus 110 may perform detection for Type0_PDCCH assuming that reception does not involve puncturing.

In this way, the original Table for CORESET #0 (i.e., Table 1) can be reused. Furthermore, a flexible selection between punctured vs. non-punctured CORESET #0 and corresponding puncturing options can be supported.

FIG. 5 shows a flowchart of an example method 500 of CORESET #0 puncturing controlling according to some example embodiments of the present disclosure. The method 500 may be implemented at the first apparatus 110 (which may be implemented as a terminal device) as shown in FIG. 1. For the purpose of discussion, the method 500 will be described with reference to FIG. 1.

At block 510, the first apparatus 110 determines, based at least on a detection of a synchronization signal block, received from a second apparatus, on a specific frequency location, whether a CORESET of a specific type is punctured, wherein a portion of resources punctured in the CORESET of the specific type are incapable of carrying downlink control information.

If the first apparatus 110 determines the CORESET of the specific type is punctured, at block 520, the first apparatus 110 obtains a CORESET puncturing pattern.

At block 530, the first apparatus 110 determines the portion of resources punctured in the CORESET at least based on the CORESET puncturing pattern.

In some example embodiments, the CORESET of the specific type is CORESET #0.

In some example embodiments, the method 500 further comprises: in accordance with a determination that at least one of the following: a primary synchronization signal or a secondary synchronization signal is detected on the specific frequency location, or additional confirmation for a CORESET puncturing is obtained from a master information block, determining that the CORESET of the specific type is punctured.

In some example embodiments, the specific frequency location is associated with a location of a sync raster point in a frequency domain.

In some example embodiments, the obtaining of the CORESET puncturing pattern comprises: determining of at least one puncturing threshold associated with a location of a set of broadcasting channel resource blocks; in accordance with a determination that the portion of resources in the CORESET do not satisfy the at least one puncturing threshold, determining that the portion of resources are punctured.

In some example embodiments, the portion of resources in the CORESET do not satisfy the at least one puncturing threshold comprises at least one of the following: one or more resource blocks of the CORESET are located below the lowest broadcasting channel resource block; or one or more resource blocks of the CORESET are located above the highest broadcasting channel resource block.

In some example embodiments, the at least one puncturing threshold is determined based on an offset with respect to at least one of: a lowest broadcasting channel resource block, or a highest broadcasting channel resource block.

In some example embodiments, the method 500 further comprises: in accordance with a determination that the puncturing threshold is determined based on an offset with respect the location of the set of broadcasting channel resource blocks and the offset has a granularity of subcarrier, determine that the portion of resources punctured in the CORESET comprises at least one partial resource block.

In some example embodiments, the method 500 further comprises: in accordance with a determination that the CORESET puncturing pattern requires that the CORESET is punctured with a granularity of a control channel element, CCE, and at least one resource block in the CCE is punctured, determining that a second portion of further resource blocks in the CCE is punctured.

In some example embodiments, whether the further resource blocks in the CCE are punctured is determined based on a threshold value.

In some example embodiments, the method 500 further comprises: in accordance with a determination that the sync raster point relates to at least one of the following: a specific bandwidth, or a specific band, determining that only at least one specific index associated with the CORESET of the specific type is valid; and determining that one or more specific resource blocks associated with the at least one specific index are punctured, wherein the at least one specific index is indicated by a master information block.

In some example embodiments, the method 500 further comprises: determining that the at least one specific index associated with the CORESET of the specific type is valid when the related CORESET contains up-to 20RBs after puncturing operation.

In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

FIG. 6 shows a flowchart of an example method 600 of CORESET puncturing controlling according to some example embodiments of the present disclosure. The method 600 may be implemented at the second apparatus 120 (which may be implemented as a network device) as shown in FIG. 1. For the purpose of discussion, the method 600 with be described with reference to FIG. 1.

At block 610, indicating, to a first apparatus, that a CORESET of a specific type is punctured by transmitting a synchronization signal block on a specific frequency location; and

At block 620, transmitting, to the first apparatus, downlink control information at least based on a portion of resources of the CORESET which is not punctured.

In some example embodiments, the CORESET of the specific type is CORESET #0.

In some example embodiments, the apparatus is caused to indicating that the CORESET of the specific type is punctured by additional information in a master information block.

In some example embodiments, the specific frequency location is associated with a location of a sync raster point in a frequency domain.

In some example embodiments, the first apparatus comprises a terminal device and the second apparatus comprises a network device.

In some example embodiments, a first apparatus capable of performing any of the method 500 (for example, the first apparatus 110 in FIG. 1) may comprise means for performing the respective operations of the method 500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module. The first apparatus may be implemented as or included in the first apparatus 110.

In some example embodiments, the first apparatus comprises means for determining, based at least on a detection of a synchronization signal block, received from a second apparatus, on a specific frequency location, whether a CORESET of a specific type is punctured, wherein a portion of resources punctured in the CORESET of the specific type are incapable of carrying downlink control information; means for, in accordance with a determination that the CORESET of the specific type is punctured, obtaining a CORESET puncturing pattern; and means for determining the portion of resources punctured in the CORESET at least based on the CORESET puncturing pattern.

In some example embodiments, the CORESET of the specific type is CORESET #0.

In some example embodiments, the first apparatus further comprises: means for in accordance with a determination that at least one of the following: a primary synchronization signal or a secondary synchronization signal is detected on the specific frequency location, or additional confirmation for a CORESET puncturing is obtained from a master information block, determining that the CORESET of the specific type is punctured.

In some example embodiments, the specific frequency location is associated with a location of a sync raster point in a frequency domain.

In some example embodiments, the means for obtaining of the CORESET puncturing pattern comprises: means for determining of at least one puncturing threshold associated with a location of a set of broadcasting channel resource blocks; means for in accordance with a determination that the portion of resources in the CORESET do not satisfy the at least one puncturing threshold, determining that the portion of resources are punctured.