CSI-RS

2021-08-19 本文已影响0人 zxlele_c763

CSI-RS

Channel state information Reference Signal

CSI-RS protocol

CSI-RS protocol reference : 38.211: 7.4.1.5 CSI reference signals

38.211 | NR; Physical channels and modulation

other reference

math format : math format

Common Concept

Frame struct(LTE(TDD) and NR)

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One Slot resource

one slot resouce include time and frequency two parts.

time: OFDM symbols $N_{symbol}^{slot}$ = 14
frequency : $N_{RB\;\;\;}^{UL}\times\;N\;_{SC}^{RB}\;$ subcarries

one slot

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RE define

Resource element with frequency-domain index and time-domain index , antenna port p and
subcarrier spacing configuration μ in one RB.
$(k,l)_{p,u}^{}$
The reference point for k=0 is subcarrier 0 in common resource block 0.
k range is : 0.. ( $N_{RB\;\;\;}^{UL}\times\;N\;_{SC}^{RB}\;$ -1) ( consecutive subcarriers in the frequency domain:12)
l range is : 0..13 (OFDM symbol number:14)

RB define

A resource block is defined as
$N_{sc\;}^{RB}\;=\;12\;$
consecutive subcarriers in the frequency domain.

RB numbers

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CSI-RS作用

3GPP定义了CQI（Channel Quality Indication，信道质量指示）这个概念，CQI用于UE 想网络侧指示，通过下行测量，UE所感知到的下行链路的信干扰噪声比 (SINR)
通过UE所报告的SINR,网络决定UE在下行的频谱效率,这频谱效率可以通过通过香农定理得到。
当频谱效率被决定了以后，那么下行的码率就决定了，因为频谱效率的本意就是成功发送每个bit所需要的赫兹。
如果码率决定了，那么MCS（Modulation and Coding Scheme，调试与编码策略：调制方式和码率）也就确定了。
此外还有波束管理（主要包括发端波束测量、收端波束测量以及收发端同时波束测量），时频跟踪（精确测量时偏和频偏，通过TRS信号实现），移动性管理（通过对本区以及邻区的CSI-RS跟踪测量），速率匹配（主要ZP CSI-RS实现对PDSCH的RE级速率匹配）等。

UE需要一个参考信号，来测得下行的SINR，并且进行上报，那么CSI-RS的基本功能就是提供这个参考信号。

CSI-RS type :为非零功率NZP CSI-RS和零功率ZP CSI-RS两种

Zero power CSI-RS（不需要产生并映射到RE上，用于PDSCH的速率匹配，不发东西）
Non zero power CSI-RS（需要实际产生并映射到RE上）
（1）主要的CSI report（2）TRS（3）LI-RSRP computation:参考信号接收功率（参数Repetition=on/off）（4）Mobility Management

CSI-RS中的CDM

CSI-RS resource的port数量可以是单个port，也可以是multi-port，最多到32个port。在multi-port映射的时候会用到CDM的这个概念，即多个CSI-RS port可以在相同时频资源上通过CDM的方式加以区分和映射

cdm-Type

cdm-Type: include 4 types : {noCDM, fd-CDM2, cdm4-FD2-TD2, cdm8-FD2-TD4}

noCDM就是将CSI-RS只映射在一个RE上
FD-CDM2：在频域2载波，时域1符号的2个RE上实现2个port的复用, one port two REs
CDM4-FD2-TD2：在频域2载波，时域2符号的4个RE上实现4个port的复用 , one port four REs
CDM8-FD2-TD4：在频域2载波，时域4符号的8个RE上实现8个port的复用

CDM types table

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FOR example : fd- CDM2 port

frequency domain : two subcarries
time domain: one symbol
code domain: [W0, W1]

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CSI-RS(used REs) location within a slot

HOW decide CSI-RS time and frequency domains in one slot

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n : the number of RB whitin one slot
$\overset-K$ : 取值可能为k0,k1,k2,k3，..k6 这些值会通过RRC参数frequencyDomainAllocation计算得出

$\overset-K$ [k0, k1,...,k6] compute table.

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$\overset-L$ value include [ $l_0$ , $l_1$ ]

$\overset-L$ 有两个取值， $l_0$ 和 $l_1$ ，值会通过 RRC参数 firstOFDMSymbolInTimeDomain和firstOFDMSymbolInTimeDomain2得到，l0和l1的区别在于不同的场景中使用，表示CSI-RS的时域起始符号。

$l^`$ and $k^`$ can get from the table 7.4.1.5.3-1: CSI-RS locations within a slot.

PORT compute

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ports range:

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accordifng to : Table 7.4.1.5.3-1: CSI-RS locations within a slot compute the CSI-RS resources(REs and port information ).

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For Example

1. $\overset-K$ [k0, k1,...,k5] compute(other).

IE information in RRC

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[ $b_5$ , $b_4$ , $b_3$ , $b_2$ , $b_1$ , $b_0$ ] , $K_{i-1}$ = 2 * $f(i)$
[ $b_5$ ... $b_0$ ] : 100011
$i_{th}$ not 0 bit location in bitmap:
=> i = 1 , $f(1)$ = 0 , $K_{0}$ = 2 * 0 = 0
=> i = 2 , $f(2)$ = 1, $K_{1}$ = 2 * 1 = 2
=> i = 3 , $f(3)$ = 5, $K_{2}$ = 2 * 5 = 10

port compute

for example

Table 7.4.1.5.3-1: CSI-RS locations within a slot : row 14
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$p = 3000 + s + jL$
$j = 0, 1, ... ,(N/L - 1)$ $L\in\{1,2,4,8\}$
$s = 0, 1, ..., (L -1)$
==> Row 14: Ports X(24) ==> N = 24
==> cdm-type is cdm4-FD2-TD2 : ==> L = 4 (4 cdm types )
==> s = 0,1,2,3
==> N/L -1 = 24/4 -1 = 5
==> j = 0,1,2,3, 4, 5
24 Ports divided 6 arrays, every array 4 ports:
P[6][4] : ( $P_0$ , ( $K_{0\;\;},\;l_0$ ) ); ( $P_1$ , ( $K_{1\;\;},\;l_0$ ) ); .... ;( $P_5$ , ( $K_{2\;\;},\;l_1$ ) )
$P_0$ = 3000 + 0 + 0 * 4 , 3000 + 1 + 0 * 4 , 3000 + 2 + 0 * 4, 3000 + 3 + 0 * 4
P[0][0] = 3000, P[0][1] = 3001, P[0][2] = 3002, P[0][3] = 3003
...
$P_5$ = 3000 + 0 + 5 * 4 , 3000 + 1 + 5 * 4 , 3000 + 2 + 5 * 4, 3000 + 3 + 5 * 4
P[5][0] = 3020, P[5][1] = 3021, P[5][2] = 3022, P[5][3] = 3023
ports range: [3000, 3023]

every port used RE number: 4 REs

in one RB : for example ( $P_0$ , ( $K_{0\;\;},\;l_0$ ) ) in Table 7.4.1.5.3-1
$K\;=\;\overset-K\;+\;\;K^`$
$l\;=\;\overset-l\;+\;\;l^`$
$K^`\;\in\lbrack0,1\rbrack$ $l^`\;\in\lbrack0,1\rbrack$
==> $K_1=\;K_0\;+\;0$ , $K_2=\;K_0\;+\;1$
==> $l_1=\;l_0\;+\;0$ , $l_2=\;l_0\;+\;1$

two examples

No.1

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No. 2

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RRC IEs

confirm which row in Table 7.4.1.5.3-1: CSI-RS locations within a slot
csi information

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CSI-RS

CSI-RS

CSI-RS protocol

other reference

Common Concept

Frame struct(LTE(TDD) and NR)

One Slot resource

one slot

RE define

RB define

CSI-RS作用

CSI-RS type :为非零功率NZP CSI-RS和零功率ZP CSI-RS两种

CSI-RS中的CDM

cdm-Type

CDM types table

FOR example : fd- CDM2 port

CSI-RS(used REs) location within a slot

HOW decide CSI-RS time and frequency domains in one slot

$\overset-K$ [k0, k1,...,k6] compute table.

$\overset-L$ value include [ $l_0$ , $l_1$ ]

$l^`$ and $k^`$ can get from the table 7.4.1.5.3-1: CSI-RS locations within a slot.

PORT compute

ports range:

accordifng to : Table 7.4.1.5.3-1: CSI-RS locations within a slot compute the CSI-RS resources(REs and port information ).

For Example

1. $\overset-K$ [k0, k1,...,k5] compute(other).

for example

two examples

RRC IEs

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热点阅读

CSI-RS

CSI-RS

CSI-RS protocol

other reference

Common Concept

Frame struct(LTE(TDD) and NR)

One Slot resource

one slot

RE define

RB define

CSI-RS作用

CSI-RS type :为非零功率NZP CSI-RS和零功率ZP CSI-RS两种

CSI-RS中的CDM

cdm-Type

CDM types table

FOR example : fd- CDM2 port

CSI-RS(used REs) location within a slot

HOW decide CSI-RS time and frequency domains in one slot

[k0, k1,...,k6] compute table.

value include [ , ]

and can get from the table 7.4.1.5.3-1: CSI-RS locations within a slot.

PORT compute

ports range:

accordifng to : Table 7.4.1.5.3-1: CSI-RS locations within a slot compute the CSI-RS resources(REs and port information ).

For Example

1. [k0, k1,...,k5] compute(other).

for example

two examples

RRC IEs

猜你喜欢

热点阅读

$\overset-K$ [k0, k1,...,k6] compute table.

$\overset-L$ value include [ $l_0$ , $l_1$ ]

$l^`$ and $k^`$ can get from the table 7.4.1.5.3-1: CSI-RS locations within a slot.

1. $\overset-K$ [k0, k1,...,k5] compute(other).