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UE在CELL_FACH状态一定有C-RNTI吗?
2006-12-11 22:12:13
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155069596
发布于2007-02-12 10:33:21
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vvv
本人认为C-RNTI是可选的,投B一票。
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horsey发布于2007-02-12 10:23:52
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对于U-RNTI和C-RNTI的作用还是不是很清晰,个人理解:
当有RRC连接的时候,一定有U-RNTI的分配,C-RNTI可选
C-RNTI主要用于CELL-FACH状态下DCCH和DTCH映射到
FACH或RACH时,用作UE-ID,可是为什么不能用户U-RNTI作为UE-ID呢?
难道是从空口资源利用率的考虑,U-RNTI是32bit,而C-RNTI只是16bit?
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luckstar发布于2007-01-09 14:04:11
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-RNTI is allocated to an UE having a RRC connection. It identifies the UE within UTRAN and is used as a UE identifier in cell update, URA update, RRC connection reestablishment and (UTRAN originated) paging messages and associated responses on the radio interface. The SRNC identifier within the U-RNTI is used by the Controlling RNC to route the received uplink messages towards the Serving RNC.
C-RNTI is used as a UE identifier in all other DCCH/DTCH common channel messages on the radio interface.
DSCH-RNTI is used as a UE identifier for DTCH and DCCH in downlink when mapped onto DSCH transport channel.
NAS identifiers are used as the UE identifier in the initial access CCCH message on the radio interface.
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luckstar发布于2007-01-09 13:56:37
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//GOT A CLEAR DESCRIPTION OF RNTI... share with you
A Radio Network Temporary Identity (RNTI) is used as an UE identifier on RACH/FACH, RACH+CPCH/FACH or, for FDD mode, also on DSCH by the MAC protocol, or on PCH by the RRC, when a RRC connection exists.
Definition of UE identifiers
Several types of RNTIs exist. One is used within the Serving RNC and it is denoted by Serving RNC RNTI (S-RNTI). A second type is used within a cell controlled by a CRNC, when applicable, and it is denoted by Cell RNTI (C-RNTI). A third type is used within a cell controlled by a CRNC when a DSCH is allocated and it is denoted by DSCH-RNTI.
S-RNTI is allocated for all UEs having a RRC connection. It is allocated by the Serving RNC and it is unique within the Serving RNC. S-RNTI is reallocated always when the Serving RNC for the RRC connection is changed and deallocated when the RRC connection is released.
In addition for each UE having an RRC connection, there is an identifier of its current serving RNC, which is denoted as SRNC identifier. The SRNC identifier together with S-RNTI is a unique identifier of the RRC connection within PLMN. The combination of SRNC identifier and S-RNTI is referred to as U-RNTI (UTRAN Radio Network Temporary Identity), which is used on the radio interface.
C-RNTI for a UE is allocated by a controlling RNC and it is unique within one cell controlled by the allocating CRNC. C-RNTI can be reallocated when a UE accesses a new cell with the cell update procedure.
DSCH-RNTI for a UE is allocated by controlling RNC when a DSCH channel is configured. DSCH-RNTI is unique within the cell carrying the DSCH.
Usage of UE identifiers
U-RNTI is allocated to an UE having a RRC connection. It identifies the UE within UTRAN and is used as a UE identifier in cell update, URA update, RRC connection reestablishment and (UTRAN originated) paging messages and associated responses on the radio interface. The SRNC identifier within the U-RNTI is used by the Controlling RNC to route the received uplink messages towards the Serving RNC.
C-RNTI is used as a UE identifier in all other DCCH/DTCH common channel messages on the radio interface.
DSCH-RNTI is used as a UE identifier for DTCH and DCCH in downlink when mapped onto DSCH transport channel.
NAS identifiers are used as the UE identifier in the initial access CCCH message on the radio interface.
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luckstar发布于2007-01-09 00:59:38
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还有一点不太明白. U_RNTI的用处到底是干吗的? 它与C_RNTI的本质区别又是什么? expect experts' comments
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epaheng发布于2007-01-04 17:03:49
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在25.321 section 9.2.1.1中说到
For FACH, the UE-Id type field used is the C-RNTI or U-RNTI. For RACH, the UE-Id type field used is the C-RNTI.
所以看来UE在CELL_FACH状态不一定有C-RNTI. 不知道这样理解是否有问题?
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swjtujliu发布于2006-12-12 13:29:42
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QUOTE:
原帖由 antoniuslv 于 2006-12-12 13:25 发表
没错,是这样的。可惜今天没有币可加了。呵呵~~
这里的不能发送的数据是特指data of Dedicated Logical Channel。而对于CCCH数据是没有关系的。
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antoniuslv
发布于2006-12-12 13:25:18
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QUOTE:
原帖由 swjtujliu 于 2006-12-12 13:05 发表
UE要想发数据,必须等C-RNTI不为空
这里的不能发送的数据是特指data of Dedicated Logical Channel。而对于CCCH数据是没有关系的。
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swjtujliu发布于2006-12-12 13:12:03
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对了,上面的截图在25.331的8.3.1.2中
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swjtujliu发布于2006-12-12 13:05:36
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还有一种情况:处于CELL_FACH或者CELL_PCH状态的UE进行了CELL RESELECTION之后,在发起CELL UPDATE之前,会将本地的C-RNTI清除,在收到CELL UPDATE CONFIRM之前的这段时间,UE的C-RNTI是空的。在这段时间里,UE和RNC之间由于还没有同步到CELL_FACH状态,也就是必要的资源还没有准备好,所以不能发送数据,这和C-RNTI为空也是一致的,UE要想发数据,必须等C-RNTI不为空,而C-RNTI不为空,就意味着小区更新已经完成,资源已经准备好了。
[ 本帖最后由 swjtujliu 于 2006-12-12 13:06 编辑 ]
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James-Ran
发布于2006-12-12 12:35:48
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and for this case:
when UE met the RL failure, then UE will transfer to CELL_FACH and start configure RACH and FACH etc..
But at this time, NO C-RNTI is kept in UE before the "CELL Update" procedure.
Thus, I think UE have no C-RNTI in this unstable CELL_FACH state.
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James-Ran
发布于2006-12-12 11:34:55
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But another one to reverse this result
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James-Ran
发布于2006-12-12 11:10:00
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Pls check the attached figures,
and welcome more comments.
James
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antoniuslv
发布于2006-12-12 10:35:59
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如果DCCH存在,那么C_RNTI必须要使用。虽然CRNC和SRNC合在一起是一种特列,但是,协议设计必须要保证其严密性。
所以,该问题等价于CELL_FACH下的DCCH是否一定存在。
按照RRC协议,CELL_FACH下的描述是:
NOTE: DCCH and, if configured, DTCH are available in this state
这里没有只说available,对这个单词理解,我目前认为表明可以存在,但不明确是否一定存在。
问题1:
在CELL_FACH的稳定状态下(不是过渡状态,比如CELL_PCH下进行CellUpdate过程),是否必须存在DCCH?
问题2:
在CELL_FACH的稳定状态为什么而设计?
--我目前只认为是用于小数据量的PS业务。其他是否在没有业务进行(没有RB)的情况下,让该UE稳定存在在这个状态下吗?
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lixiang0599
发布于2006-12-12 10:07:27
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我选B
因为CRNC是UE在CRNC内的标识,因此如果SRNC和CRNC是同一个RNC的话,就没有必要用两套标识,这也是为什么C-RNTI是可选的原因吧!
个人意见!
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swjtujliu发布于2006-12-12 09:07:32
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我选A。我认为如果想把这个问题搞清楚,就要知道C-RNTI和U-RNTI的区别和联系(虽然我现在也拿不准,呵呵)。U-RNTI是在RRC连接建立的时候由SRNC分配给UE的,它在SRNC内部是唯一的。既然U-RNTI可以唯一的标识UE,为什么还要C-RNTI呢?在FACH上发送信息的时候,由于是公共信道,所以每个消息需要给出UE的标识,我还没有发现这种标识采用U-RNTI的,可能是这里使用U-RNTI不合适?所以不得不给出一个C-RNTI?乱说的,自己的猜测而已,请大家指正。:)
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message
发布于2006-12-12 08:56:18
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我选B, 正如tearlessman所说,rrc连接建立以后需要用RNTI来标识UE,所以在rrc connection setup消息里肯定有U-RNTI, C-RNTI是一个optional的,是否需要需要看UE所处的级别,我认为CRNC如果和SRNC是同一个RNC,则有U-RNTI即可,如果不同,那么应该都需要,这样才能清楚地知道UE所在的位置。 说的也不一定对,欢迎指正。
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James-Ran
发布于2006-12-11 23:17:38
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希望大家继续参与
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tearlessman发布于2006-12-11 22:54:36
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UE在cell_FACH的时候,是否有C-RNTI是要看情况,因为在RRC CONNECTION建立的时候,RNC是一定要向UE分配U-RNTI的,但是是否分配C-RNTI是optional的
当UE in CELL_FACH的时候,只是进行cell update等这种单纯的signalling 的交互的时候,可以用U-RNTI来区分UE,因为消息中有RRC的三层地址。
但是当UE in CELL_FACH的时候,如果DCCH和DTCH的映射到common channel的时候,这时用户数据不包括RRC层的地址,只能用C-RNTI来address UE。
一点自己的看法,很有可能不对:),请指正。




