一、BWP配置

1、BWP簡介

1.1、BWP概念和意義 [參考38211]

BWP就是資源柵格內的一段連續的CRB，其目的和意義主要就是以下幾點：

NR帶寬很大，UE沒必要強制性支持全部帶寬，只需要支持部分帶寬即可，這也是BWP這個名稱的由來（bandwidth part）；
在不必要的時候節省功耗，因為帶寬越大需要的功耗越高，所以沒必要讓UE時時刻刻都處在一個大帶寬的狀態；
實作靈活的調度，包括帶寬大小和頻帶位置，用于適應不同的業務需求以及克服頻率選擇性衰落等，

1.2、BWP配置 [參考38213]

BWP的配置分為幾種不同的情況：

1.初始BWP
初始上下行BWP，即Initial DL BWP和initial UL BWP會在SIB1中配置，如果initial BWP未配置，則默認為CORESET0，初始BWP主要用于初始接入程序，如SIB1的接收，隨機接入程序當中RAR、Msg4的接收以及preamble和Msg4的發送等，

2.激活BWP
激活BWP即active BWP是用于初始接入完成以后，為UE配置的BWP，初始接入完成以后，UE會有各種業務需求，所以一般active BWP的帶寬比初始BWP要大，

3.默認BWP
默認BWP即default BWP用于UE長時間沒有業務需求的情況下，讓UE從大帶寬的active BWP切換到一個默認的一般帶寬較小的BWP上，用于降低功耗，

一旦要配置BWP，則需要包含一些必要的引數，包括BWP的SCS和CP、BWP的頻域位置和大小（指示方式為RIV）、ID以及該BWP內的PDCCH和PDSCH的generic parameters and dedicate parameters，在該BWP內的PDCCH、PDSCH等的SCS和CP都和該BWP相同，BWP的帶寬可以是275RB以內的任意值，根據引數locationAndBandwidth指示一個RIV (Resource Indicator Value)，然后通過公式計算得到BWP的起始位置和RB數量，起始位置的參考點是Point A，
一個UE最多可以配置4個DL BWP和4個UL BWP，如果有SUL，則可以還有最多4個SUL上的BWP，在任意特定時刻，只能有一個激活上行BWP以及激活下行BWP，上下行資料信道、控制信道以及參考信號都不能在超出BWP的范圍以外傳輸，在NR FDD系統中，NR TDD系統中，上下行BWP為一個pair，具有相同的ID以及中心頻率，但是帶寬和子載波間隔可以不同，

2、BWP頻域資源

根據BWP計算公式：

其中 $N_{BWP}^{size} = 275$ ， $1\leq L_{RBs}<N_{BWP}^{size} - RB_{start}$

得出12928 = 275*(L-1)+RBstart = 275(48-1) + 3 => L = 48, RBstart = 3；

該范圍與CORESET0的頻域范圍一致，

BWP1的頻域資源為，表示整個小區帶寬，

1099 = 275*(276-L) +（274 – RBstart） L = 273 RBstart = 0

二、CORESET配置

controlResourceSetId	搜索空間關聯的CORESET,決定了搜索空間的物理資源
frequencyDomainResources	頻域占用的資源，每個bit對應BWP內一個6RB的組
duration	時域占用符號數
interleaved	專用于CCE-REG交織映射的引數
cce-REG-MappingType	CCE對應到具體的REG的映射關系
precoderGranularity	PDCCH預編碼相關的配置

ControlResourceSetId

The ControlResourceSetId IE concerns a short identity, used to identify a control resource set within a serving cell. The ControlResourceSetId = 0 identifies the ControlResourceSet#0 configured via PBCH (MIB) and in controlResourceSetZero (ServingCellConfigCommon). The ID space is used across the BWPs of a Serving Cell. The number of CORESETs per BWP is limited to 3 (including common and UE-specific CORESETs).

CORESET0在MIB中定義，或者在ServingCellConfigCommon的信元controlResourceSetZero中定義，

ControlResourceSetId定義了小區內唯一的控制資源集ID（跨BWP也不能重復），每個BWP的CORESET最多為3個（包括公共和UE特定的CORESET）

frequencyDomainResources

Frequency domain resources for the CORESET. Each bit corresponds a group of 6 RBs, with grouping starting from the first RB group (see 38.213, section 10.1) in the BWP. The first (left-most / most significant) bit corresponds to the first RB group in the BWP, and so on. A bit that is set to 1 indicates that this RB group belongs to the frequency domain resource of this CORESET. Bits corresponding to a group of RBs not fully contained in the bandwidth part within which the CORESET is configured are set to zero. Corresponds to L1 parameter 'CORESET-freq-dom' (see 38.211, section 7.3.2.2).

For each CORESET in a DL BWP of a serving cell, a respective frequencyDomainResources provides a bitmap. The bits of the bitmap have a one-to-one mapping with non-overlapping groups of 6 consecutive PRBs, in ascending order of the PRB index in the DL BWP bandwidth of $N_{RB}^{BWP}$ PRBs with starting common RB position $N_{BWP}^{start}$ where the first common RB of the first group of 6 PRBs has common RB index $6\left \lceil N_{BWP}^{start}/6 \right \rceil$ .

RB group在38.213, 10.1節定義，每bit表示6個RB，從該BWP的第一個RB group開始，

frequencyDomainResources提供了bitmap，bitmap中每個位元映射一個6 RB group，組與組之間PRB連續但不重疊，PRB按升序排列，總數為 $N_{RB}^{BWP}$ ，起始RB為 $N_{BWP}^{start}$ ，第一組中第一個PRB索引為 $6\left \lceil N_{BWP}^{start}/6 \right \rceil$ ，Bitmap中位元值為1標識對應的6個PRB屬于該CORESET，值為0標識對應的6個PRB不屬于該CORESET，

注意frequencyDomainResources第一個bit對應的RB并不一定從該BWP的第一個RB開始，比如 $N_{RB}^{BWP} = 3$ ，則第一個bit表示的PRB為PRB索引6，則PRB索引為3~5的RB不可能用于CORESET，

根據前面一節的計算，下圖中BWP頻域資源為L = 273，RBstart = 0，

ControlResourceSetId = 1的frequencyDomainResources前面有9個0，表示前面54個（0~53）PRB都不是該CORESET的頻域資源，

CORESET1頻域上為54~149PRB，總共96個RB，時域為1個符號，

CORESET2頻域上為54~77PRB，總共24個RB，時域上為1個符號，

三、PDCCH-ConfigCommon和PDCCH-Config

PDCCH-ConfigCommon

The IE PDCCH-ConfigCommon is used to configure cell specific PDCCH parameters provided in SIB as well as during handover and PSCell/SCell addition.

PDCCH-ConfigCommon信元用于配置小區級別的PDCCH引數，在小區SIB訊息和切換訊息，以及PSCell/SCell添加時使用，主要包含CORESET0定義，以及指示該BWP接收尋呼、SIB1、SIBs、RAR的搜索空間，

PDCCH-ConfigCommon field descriptions

commonControlResourceSet

An additional common control resource set which may be configured and used for RAR/paging/system information. If the network configures this field, it uses a ControlResourceSetId other than 0 for this ControlResourceSet.

附加的CORESET，用于RAR/paging/system information，如果網路配置了該域，則使用該附加的CORESET，

commonSearchSpaceList

A list of additional common search spaces. If the network configures this field, it uses the SearchSpaceIds other than 0.

附加的公共搜索空間，如果網路配置了該域，則使用該附加的公共搜索空間，否則使用CORESET0，

controlResourceSetZero

Parameters of the common CORESET#0. The values are interpreted like the corresponding bits in MIB pdcch-ConfigSIB1. Even though this field is only configured in the initial BWP (BWP#0) controlResourceSetZero can be used in search spaces configured in other DL BWP(s) than the initial DL BWP if the conditions defined in 38.213, section 10 are satisfied.

CORESET0配置引數，該引數與MIB pdcch-ConfigSIB1的含義一致，盡管該引數只在初始BWP配置，該引數也可以用于其他BWP的其它搜索空間，

pagingSearchSpace

ID of the Search space for paging. Corresponds to L1 parameter 'paging-SearchSpace' (see 38.213, section 10). If the field is absent, the UE does not receive paging in this BWP (see 38.213, section 10).

尋呼訊息所用搜索空間，如果不配置該域，表示UE在該BWP不接收尋呼訊息，

ra-SearchSpace

ID of the Search space for random access procedure. Corresponds to L1 parameter 'ra-SearchSpace' (see 38.214?, section FFS_Section) If the field is absent, the UE does not receive RAR in this BWP. This field is mandatory present in the DL BWP(s) if the conditions described in TS 38.321 [3], subclause 5.15 are met.

隨機接入所用搜索空間，如果不配置該域，表示UE在該BWP不接收RAR訊息，

searchSpaceOtherSystemInformation

ID of the Search space for other system information, i.e., SIB2 and beyond. Corresponds to L1 parameter 'osi-SearchSpace' (see 38.213, section 10) If the field is absent, the UE does not receive other system information in this BWP.

接收其它SIB（SIB2及其它）訊息所用搜索空間，如果不配置該域，表示UE在該BWP不接收其它SIB訊息，

searchSpaceSIB1

ID of the search space for SIB1 message. If the field is absent, the UE does not receive SIB1 in this BWP. (see 38.213, section 10)

接收SIB1所用搜索空間，如果不配置該域，表示UE在該BWP不接收SIB1訊息，

searchSpaceZero

Parameters of the common SearchSpace#0. The values are interpreted like the corresponding bits in MIB pdcch-ConfigSIB1. Even though this field is only configured in the initial BWP (BWP#0) searchSpaceZero can be used in search spaces configured in other DL BWP(s) than the initial DL BWP if the conditions described in Spec38.213 [13], section 10 are satisfied.

CORESET0的引數，該引數與MIB pdcch-ConfigSIB1的含義一致，盡管該引數只在初始BWP配置，該引數也可以用于其他BWP的其它搜索空間，

PDCCH-Config

The PDCCH-Config IE is used to configure UE specific PDCCH parameters such as control resource sets (CORESET), search spaces and additional parameters for acquiring the PDCCH.

PDCCH-Config信元用于配置UE專用PDCCH引數，例如CORESET、搜素空間，以及獲取PDCCH的其它引數，

PDCCH-Config field descriptions

controlResourceSetToAddModList

List of UE specifically configured Control Resource Sets (CORESETs) to be used by the UE. The network configures at most 3 CORESETs per BWP per cell (including UE-specific and common CORESETs).

controlResourceSetToAddModList指示了UE專用的CORESET，對于每個小區的每個BWP，網路最多配置3個CORESET（包括UE專用和公用CORESET）

downlinkPreemption

Configuration of downlink preemption indications to be monitored in this cell. Corresponds to L1 parameter 'Preemp-DL' (see 38.214, section 11.2)

FFS_RAN1: LS R1-1801281 indicates this is "Per Cell (but association with each configured BWP is needed)" => Unclear, keep on BWP for now.

searchSpacesToAddModList

List of UE specifically configured Search Spaces. The network configures at most 10 Search Spaces per BWP per cell (including UE-specific and common Search Spaces).

UE專用搜索空間，對于每小區的每個BWP，網路最多配置10個搜索空間，（包括UE專用和公共搜索空間）

四、搜索空間

searchSpaceId

Identity of the search space. SearchSpaceId = 0 identifies the searchSpaceZero configured via PBCH (MIB) or ServingCellConfigCommon and may hence not be used in the SearchSpace IE. The searchSpaceId is unique among the BWPs of a Serving Cell.

搜索空間ID，PBCH(MIB)或者ServingCellConfigCommon配置的搜索空間ID為0，searchSpaceId在一個小區的所有BWP中唯一，

controlResourceSetId

The CORESET applicable for this SearchSpace. Value 0 identifies the common CORESET#0 configured in MIB and in ServingCellConfigCommon. Values 1..maxNrofControlResourceSets-1 identify CORESETs configured in System Information or by dedicated signalling. The CORESETs with non-zero controResourceSetId locate in the same BWP as this SearchSpace.

該搜索空間所用的CORESET，0指示為PBCH(MIB)或者ServingCellConfigCommon配置的CORESET#0，其他數值指示為SIB或者專用信令配置的CORESET，非0的CORESET與該搜索空間在同一個BWP中，

common

Configures this search space as common search space (CSS) and DCI formats to monitor.

ue-Specific

Configures this search space as UE specific search space (USS). The UE monitors the DCI format with CRC scrambled by C-RNTI, CS-RNTI (if configured), and SP-CSI-RNTI (if configured)

搜索空間有common和ue-Specific兩種，common表示公共搜索空間，ue-Specific表示UE專用搜索空間，此時DCI用C-RNTI，CS-RNTI、或SP-CSI-RNTI進行CRC加擾，

monitoringSlotPeriodicityAndOffset、duration、monitoringSymbolsWithinSlot引數確定了該搜索空間在CORESET中的周期和持續時間，

duration

Number of consecutive slots that a SearchSpace lasts in every occasion, i.e., upon every period as given in the periodicityAndOffset. If the field is absent, the UE applies the value 1 slot. The maximum valid duration is periodicity-1 (periodicity as given in the monitoringSlotPeriodicityAndOffset).

搜索空間持續的時隙數量，如果沒有該引數，表示持續1個時隙，最大持續時隙數量比周期少1個時隙，

monitoringSlotPeriodicityAndOffset

Slots for PDCCH Monitoring configured as periodicity and offset. If UE is configured to monitor DCI format 2_1, only the values 'sl1', 'sl2' or 'sl4' are applicable. Corresponds to L1 parameters 'Montoring-periodicity-PDCCH-slot' and 'Montoring-offset-PDCCH-slot' (see 38.213, section 10)

以時隙為單位的PDCCH監測周期和偏移，如果UE監測DCI format 2_1 ，則只有'sl1', 'sl2' or 'sl4'可以使用，

monitoringSymbolsWithinSlot

The first symbol(s) for PDCCH monitoring in the slots configured for PDCCH monitoring (see monitoringSlotPeriodicityAndOffset and duration). The most significant (left) bit represents the first OFDM in a slot. The least significant (right) bit represents the last symbol. The bit(s) set to one identify the first OFDM symbol(s) of the control resource set within a slot. Corresponds to L1 parameter 'Montoring-symbols-PDCCH-within-slot' (see 38.213, section 10)

PDCCH監測時隙中監測的第一個符號，最左邊（最大一位）的bit表示時隙中第一個符號，最右邊（最小一位）的bit表示時隙中最后一個符號，設定為1的bit位表示監測的第一個符號的位置，

其它引數：

nrofCandidates

Number of PDCCH candidates per aggregation level. Corresponds to L1 parameter 'Aggregation-level-1' to 'Aggregation-level-8'. The number of candidates and aggregation levels configured here applies to all formats unless a particular value is specified or a format-specific value is provided (see inside searchSpaceType). (see 38.213, section 10)

每種聚合等級的候選PDCCH數量，

searchSpaceType

Indicates whether this is a common search space (present) or a UE specific search space as well as DCI formats to monitor for.

指示該搜索空間是公共搜索空間還是UE專用的搜索空間，以及監測的DCI格式，

如下指示

有兩個searchSpace，搜索空間1和搜索空間8，都是使用CORESET0的資源，

搜索空間1的監測周期為1 slot，也就是每個slot進行監測，監測的符號為每個slot的符號0，搜索空間型別為公共搜索空間，監測DCI格式為formate0-0和format1-0，

搜索空間8的監測周期為40 slot，偏移為slot 21，連續監測兩個時隙，也就是21、22，監測的符號為每個slot的符號0，搜索空間型別為公共搜索空間，監測DCI格式為formate0-0和format1-0，

接收SIB1用搜索空間0，接收其它SIBs用搜索空間8，接收尋呼和RAR訊息都用搜索空間1，

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