各位，最近遇到一個(gè)問(wèn)題是：終端可以在SCELL上發(fā)隨機(jī)接入嗎？
最近在調(diào)測(cè)一個(gè)Case，發(fā)現(xiàn)協(xié)議規(guī)定，SS通過(guò)發(fā)送PDCCH Order要求終端在SCELL上發(fā)隨機(jī)接入（St5），在PCELL上回隨機(jī)接入響應(yīng)（St9）。這就讓我有以下幾點(diǎn)不懂
1）以前看的資料SCELL只是提供傳輸資源，不能進(jìn)行隨機(jī)接入。但是523協(xié)議上的步驟讓我不太理解，是不是Release變化，內(nèi)容也跟著變了？？？這是我自己唯一的解釋
answer：終端是不能在SECLL接入的，SCELL只能提供傳輸資源，這跟哪個(gè)Release無(wú)關(guān)。
2）步驟定義：SCELL上發(fā)隨機(jī)接入，PCELL回隨機(jī)接入響應(yīng)。為何不在SCELL上回隨機(jī)接入響應(yīng)？？？
answer：這個(gè)隨機(jī)接入不應(yīng)該叫隨機(jī)接入，應(yīng)該叫上行同步。終端若檢測(cè)到了跟SCELL上行失步了，要進(jìn)行上行同步，PCELL回同步響應(yīng)。
3）PCELL回隨機(jī)接入響應(yīng)后，站在終端角度來(lái)說(shuō)，那PCELL和SCELL對(duì)于終端是有何變化？？？
answer：PCELL還是PCELL，SCELL還是SCELL。
4）這個(gè)用例這么設(shè)計(jì)，在現(xiàn)網(wǎng)中有何應(yīng)用場(chǎng)景？？？
answer：終端檢測(cè)與SCELL上行失步了，通過(guò)隨機(jī)接入來(lái)重新獲得SCELL的同步。

我記得協(xié)議上有說(shuō)過(guò)，隨機(jī)接入目的有二：
一.申請(qǐng)上行同步
二.申請(qǐng)上行資源

因此這個(gè)解釋是合情合理的



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Cell 1 (PCell) and Cell 3(SCell)
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Cell 3 is an Active SCell according to [18] cl. 6.3.4
Table 7.1.2.10.1.3.2-1: Main behaviour

St	Procedure	Message Sequence		TP	Verdict
		U - S	Message
1	The SS transmits an RRCConnectionReconfiguration message with SCell (Cell 3) addition	<--	RRCConnectionReconfiguration	-	-
2	The UE transmits an RRCConnectionReconfigurationComplete message to confirm SCell (Cell 3) addition.	-->	RRCConnectionReconfiguration Complete	-	-
3	The SS transmits an Activation MAC control element to activate SCell (Cell 3).	<--	MAC PDU (Activation (C1=1))	-	-
4	The SS indicates a new transmission on PDCCH of CC1 (Cell 1) and transmits a MAC PDU (containing an RLC PDU )	<--	MAC PDU (CC1)	-	-
5	The SS transmits a PDCCH order providing Random Access Preamble on SCell (Cell 3)	<--	(PDCCH Order)	-	-
-	EXCEPTION: In parallel with step 6 to 8, parallel behaviour defined in table 7.1.2.10.1.3.2-2 is executed .	-	-	-	-
6	Check: Does the UE transmit a preamble on PRACH using the same preamble index as given in step 5 on SCell (Cell3)?	-->	(PRACH Preamble)	1	P
7	Check: Does the UE transmit a preamble on PRACH after ra-ResponseWindowSize using the same preamble index as given in step 5 on SCell (Cell3)?	-->	(PRACH Preamble)	3	P
8	Check: Does the UE transmit a preamble on PRACH after ra-ResponseWindowSize using the same preamble index as given in step 5 on SCell (Cell3)?	-->	(PRACH Preamble)	3	P
9	The SS transmits Random Access Response with RAPID corresponding to Preamble in step 5 on PCell (Cell 1).	<--	Random Access Response	-	-
10	The SS indicates a new transmission on PDCCH of CC2 (Cell 3) and transmits a MAC PDU (containing an RLC PDU )	<--	MAC PDU (CC2)	-	-
11	The SS sends an UL grant suitable for transmitting loop back PDU on Cell 3.	<--	(UL Grant)	-	-
12	Check: Does the UE transmit a MAC PDU containing the loop back PDU corresponding to step 10?	-->	MAC PDU(CC2)	4, 5	P
13	The SS transmits a MAC PDU containing RLC status PDU acknowledging reception of RLC PDU in step 12	<--	MAC PDU (CC2)	-	-

Table 7.1.2.10.1.3.2-2: Parallel behaviour

St	Procedure	Message Sequence		TP	Verdict
		U - S	Message
1	The UE transmits a Scheduling Request on PUCCH	-->	(SR)	2	P
2	The SS sends an UL grant suitable for transmitting loop back PDU on Cell 1.	<--	(UL Grant)	-	-
3	Check: Does the UE transmit a MAC PDU containing the loop back PDU corresponding to step 4?	-->	MAC PDU	2	P
4	The SS transmits a MAC PDU containing RLC status PDU acknowledging reception of RLC PDU in step 3	<--	MAC PDU (CC1)	-	-

[ 本帖最后由 銘哲 于 2016-6-28 09:45 編輯 ]