一、BWP配置

1、BWP简介

1.1、BWP概念和意义 [参考38211]

BWP就是资源栅格内的一段连续的CRB，其目的和意义主要就是以下几点：

NR带宽很大，UE没必要强制性支持全部带宽，只需要支持部分带宽即可，这也是BWP这个名称的由来（bandwidth part）；
在不必要的时候节省功耗，因为带宽越大需要的功耗越高，所以没必要让UE时时刻刻都处在一个大带宽的状态；
实现灵活的调度，包括带宽大小和频带位置，用于适应不同的业务需求以及克服频率选择性衰落等。

1.2、BWP配置 [参考38213]

BWP的配置分为几种不同的情况：

1.初始BWP
初始上下行BWP，即Initial DL BWP和initial UL BWP会在SIB1中配置，如果initial BWP未配置，则默认为CORESET0。初始BWP主要用于初始接入过程，如SIB1的接收，随机接入过程当中RAR、Msg4的接收以及preamble和Msg4的发送等。

2.激活BWP
激活BWP即active BWP是用于初始接入完成以后，为UE配置的BWP。初始接入完成以后，UE会有各种业务需求，所以一般active BWP的带宽比初始BWP要大。

3.默认BWP
默认BWP即default BWP用于UE长时间没有业务需求的情况下，让UE从大带宽的active BWP切换到一个默认的一般带宽较小的BWP上，用于降低功耗。

一旦要配置BWP，则需要包含一些必要的参数，包括BWP的SCS和CP、BWP的频域位置和大小（指示方式为RIV）、ID以及该BWP内的PDCCH和PDSCH的generic parameters and dedicate parameters。在该BWP内的PDCCH、PDSCH等的SCS和CP都和该BWP相同。BWP的带宽可以是275RB以内的任意值，根据参数locationAndBandwidth指示一个RIV (Resource Indicator Value)，然后通过公式计算得到BWP的起始位置和RB数量，起始位置的参考点是Point A。
一个UE最多可以配置4个DL BWP和4个UL BWP。如果有SUL，则可以还有最多4个SUL上的BWP。在任意特定时刻，只能有一个激活上行BWP以及激活下行BWP。上下行数据信道、控制信道以及参考信号都不能在超出BWP的范围以外传输。在NR FDD系统中，NR TDD系统中，上下行BWP为一个pair，具有相同的ID以及中心频率，但是带宽和子载波间隔可以不同。

2、BWP频域资源

根据BWP计算公式：

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；

该范围与CORESET0的频域范围一致。

BWP1的频域资源为，表示整个小区带宽。

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

二、CORESET配置

controlResourceSetId	搜索空间关联的CORESET,决定了搜索空间的物理资源
frequencyDomainResources	频域占用的资源，每个bit对应BWP内一个6RB的组
duration	时域占用符号数
interleaved	专用于CCE-REG交织映射的参数
cce-REG-MappingType	CCE对应到具体的REG的映射关系
precoderGranularity	PDCCH预编码相关的配置

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中定义，或者在ServingCellConfigCommon的信元controlResourceSetZero中定义。

ControlResourceSetId定义了小区内唯一的控制资源集ID（跨BWP也不能重复）。每个BWP的CORESET最多为3个（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节定义，每bit表示6个RB，从该BWP的第一个RB group开始。

frequencyDomainResources提供了bitmap，bitmap中每个比特映射一个6 RB group。组与组之间PRB连续但不重叠，PRB按升序排列，总数为 $N_{RB}^{BWP}$ ，起始RB为 $N_{BWP}^{start}$ ，第一组中第一个PRB索引为 $6\left \lceil N_{BWP}^{start}/6 \right \rceil$ 。Bitmap中比特值为1标识对应的6个PRB属于该CORESET，值为0标识对应的6个PRB不属于该CORESET。

注意frequencyDomainResources第一个bit对应的RB并不一定从该BWP的第一个RB开始，比如 $N_{RB}^{BWP} = 3$ ，则第一个bit表示的PRB为PRB索引6，则PRB索引为3~5的RB不可能用于CORESET。

根据前面一节的计算，下图中BWP频域资源为L = 273，RBstart = 0。

ControlResourceSetId = 1的frequencyDomainResources前面有9个0，表示前面54个（0~53）PRB都不是该CORESET的频域资源。

CORESET1频域上为54~149PRB，总共96个RB，时域为1个符号。

CORESET2频域上为54~77PRB，总共24个RB，时域上为1个符号。

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信元用于配置小区级别的PDCCH参数，在小区SIB消息和切换消息，以及PSCell/SCell添加时使用。主要包含CORESET0定义，以及指示该BWP接收寻呼、SIB1、SIBs、RAR的搜索空间。

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。如果网络配置了该域，则使用该附加的CORESET。

commonSearchSpaceList

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

附加的公共搜索空间。如果网络配置了该域，则使用该附加的公共搜索空间，否则使用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配置参数，该参数与MIB pdcch-ConfigSIB1的含义一致。尽管该参数只在初始BWP配置，该参数也可以用于其他BWP的其它搜索空间。

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).

寻呼消息所用搜索空间，如果不配置该域，表示UE在该BWP不接收寻呼消息。

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.

随机接入所用搜索空间，如果不配置该域，表示UE在该BWP不接收RAR消息。

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）消息所用搜索空间，如果不配置该域，表示UE在该BWP不接收其它SIB消息。

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所用搜索空间，如果不配置该域，表示UE在该BWP不接收SIB1消息。

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的参数，该参数与MIB pdcch-ConfigSIB1的含义一致。尽管该参数只在初始BWP配置，该参数也可以用于其他BWP的其它搜索空间。

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专用PDCCH参数，例如CORESET、搜素空间，以及获取PDCCH的其它参数。

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专用的CORESET，对于每个小区的每个BWP，网络最多配置3个CORESET（包括UE专用和公用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专用搜索空间，对于每小区的每个BWP，网络最多配置10个搜索空间。（包括UE专用和公共搜索空间）

四、搜索空间

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.

搜索空间ID，PBCH(MIB)或者ServingCellConfigCommon配置的搜索空间ID为0。searchSpaceId在一个小区的所有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.

该搜索空间所用的CORESET，0指示为PBCH(MIB)或者ServingCellConfigCommon配置的CORESET#0，其他数值指示为SIB或者专用信令配置的CORESET。非0的CORESET与该搜索空间在同一个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)

搜索空间有common和ue-Specific两种，common表示公共搜索空间。ue-Specific表示UE专用搜索空间，此时DCI用C-RNTI，CS-RNTI、或SP-CSI-RNTI进行CRC加扰。

monitoringSlotPeriodicityAndOffset、duration、monitoringSymbolsWithinSlot参数确定了该搜索空间在CORESET中的周期和持续时间。

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).

搜索空间持续的时隙数量，如果没有该参数，表示持续1个时隙。最大持续时隙数量比周期少1个时隙。

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)

以时隙为单位的PDCCH监测周期和偏移，如果UE监测DCI format 2_1 ，则只有'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监测时隙中监测的第一个符号。最左边（最大一位）的bit表示时隙中第一个符号，最右边（最小一位）的bit表示时隙中最后一个符号。设置为1的bit位表示监测的第一个符号的位置。

其它参数：

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)

每种聚合等级的候选PDCCH数量。

searchSpaceType

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

指示该搜索空间是公共搜索空间还是UE专用的搜索空间，以及监测的DCI格式。

如下指示

有两个searchSpace，搜索空间1和搜索空间8，都是使用CORESET0的资源。

搜索空间1的监测周期为1 slot，也就是每个slot进行监测。监测的符号为每个slot的符号0，搜索空间类型为公共搜索空间，监测DCI格式为formate0-0和format1-0。

搜索空间8的监测周期为40 slot，偏移为slot 21，连续监测两个时隙，也就是21、22。监测的符号为每个slot的符号0，搜索空间类型为公共搜索空间，监测DCI格式为formate0-0和format1-0。

接收SIB1用搜索空间0，接收其它SIBs用搜索空间8，接收寻呼和RAR消息都用搜索空间1。

移动公网5G配置（二）