在NR中Timing Advance定義和功能與LTE相同，其具體定義見附件。

5G(NR)中的Timing Advance

The concept and functionality of NR Timing Advance is same as the LTE Timing Advance. So I suggest you to read LTE Timing Advance as well if you are not familiar with the concept.

Timing Advance定義和功能在NR中與LTE相同；可參考LTE相關(guān)內(nèi)容；

Simply put, Timing Advance is a special command (notification) from eNB to UE that enable UE to adjust its uplink transmission as shown below. This kind of UL adjustment applies to PUSCH, PUCCH and SRS

Timing Advance是eNB給UE的一條特殊命令，通知UE調(diào)整上行發(fā)送時(shí)機(jī)；

這種上行調(diào)整應(yīng)用在PUSCH,PUCCH和SRS上。

  < 38.211 - Figure 4.3.1-1: Uplink-downlink timing relation

                                 圖表1.上(下)行幀時(shí)間關(guān)系圖

How TimingAdvance information is delivered to UE ?

Timing Advance是怎么傳遞給UE的？

Case 1 : Through RAR

Case 1：通過RAR消息

UE figures out the timing advance value from two different MAC layer command depending on situation. For the first Uplink message after PRACH, UE applies the Timing Advance value that it extracts from RAR (RACH Response). After the initial RACH process, UE would apply the timing Advance value that it extract from Timing Advance MAC CE if it received it. 

根據(jù)場景不同，UE通過兩種不同的MAC層命令獲取TA值；

在PRACH上發(fā)送接入請求消息后，UE通過解析接收的RAR(接入響應(yīng))消息，得到TA值；

                                  圖表2. TA的位圖

Case 2 : Through MAC CE

Case 2：通過MAC CE

As mentioned above, UE adjust UL transmission timing based on RAR during the initial attach. Once the initial attach is complete, UE adjust UL transmission based on the MAC CE-Timing Advance.

在完成接入流程后，UE將啟用從MAC CE消息中解析獲取TA值。 

The structure of MAC CE Timing Advance is as shown below.

MAC CE中的TA結(jié)構(gòu)如下：

< 38.321 - Figure 6.1.3.4-1: Timing Advance Command MAC CE >

圖表3.TA命令結(jié)構(gòu)圖

You see here the Timing Advance Command Field is 6 bits which mean 64 steps in total ranging from -32 to 32 Tc in real timing. Since Tc is 0.509, the range of the physical timing is -16.3 us to 16.3 us.

Timing Advance命令由6 bit構(gòu)成，總共有64個(gè)，范圍從-32到32 Tc;

1個(gè)Tc為0.509，取值范圍：-16.3到16.3 us. 

At which slot the received Timing Advance value is applied ?

 TA是在那個(gè)slot上收到和應(yīng)用的？

Once the Timing Advance(TA) value is received by UE, the UE should apply the value for UL transmission 6 slot after the reception. That is, if TA is received at slot n, the value is applied from slot n+6 as stated in 38.213-4.2.

當(dāng)UE收到TA值后，將在其收到后的第6個(gè)上行slot上應(yīng)用；

根據(jù)38.213-4.2說明，UE在slot n上收到TA值后，該值將在slot n+6上啟用；

5G(NR)中的TA.docx