LTE 中的Data Centric 和 Voice Centric含义

当终端在发起attach附着请求，或者TAU更新请求时，会携带ue_usage_setting参数，说明终端是DATA centric（以数据为中心）的，还是voice centric（语音为中心）

voice_domain_pref_incl = 1(0x1)

   voice_domain_pref

     length = 1 (0x1)

     UE_usage_setting = 1(0x1) (Data centric)

     voice_domain_pref_for_EUTRAN =2 (0x2) (CS Voice preferred, IMS PS Voice assecondary)

那么究竟什么是 DATA centric，什么是voice centric那？

3GPP 23.221中如下定义

To allow for appropriate domainselection for originating voice calls, a CSFB and/or IMS/CS-voicecapable UE is set to behave as "Voice centric" or "Data centric" inE-UTRAN:

-       A UE set to "Voice centric" shall always try to ensure that Voiceservice is possible. A CSFB and an IMS/CS-voice capable UE set to"Voice centric" unable to obtain voice service in E-UTRAN (e.g.CSFB and IMS voice are not supported or the configured preferenceson how to handle voice services prevent usage of any availablevoice services), shall disable the E-UTRAN capability, whichresults in re-selecting GERAN or UTRAN. The E-UTRAN capability isre-enabled by the UE under the conditions described in TS 24.301[34]. A voice centric CSFB capable UE that receives "CSFB NotPreferred" or "SMS-only" indication as a result of combinedEPS/IMSI attach or combined TA/LA Update procedures and unable toobtain voice services over IMS shall disable the E-UTRANcapability, which results in re-selecting GERAN orUTRAN.

-       A UE set to "Data centric" does not disable the E-UTRAN capabilityif voice services cannot be obtained. Upon receiving combinedEPS/IMSI attach accept or combined TA/LA Update accept with"SMS-only" indication, a data centric UE stays in the current RATand is not allowed to use CSFB. Upon receiving combined EPS/IMSIattach accept or combined TA/LA Update accept with "CSFB NotPreferred" indication, a data centric UE stays in the current RATand is allowed to use CSFB.

也就是说

voice centric的终端，必须要支持voice功能，如果注册到的LTE网络不支持CSFB，以及IMS等语音业务，那么终端应该关闭LTE的功能，重选回落3G/2G中来，这样用以保证语音业务使用。如果LTE网络支持CSFB/IMS语音业务，那么可以继续停留在LTE网络上。

Data centric的终端，如果注册到的LTE网络，既不支持CSFB，也不支持IMS等业务业务，那么可以继续停留在LTE网络上。

3gpp 24.008 关于voice domainpre以及use’susage setting的定义如下

9.4.1.11 Voice domain preference andUE's usage setting

This IE shall beincluded:

- if the MS supports CS fallback and SMSover SGs, or the MS is configured to support IMS voice, or both;and

- if the MS is E-UTRANcapable.

LTE 中的Data Centric 和 Voice Centric含义

Voicedomain preference and UE's usage setting value (octet 3, bit 1 to3)

UE's usage setting (1 bitfield)

Bit

3

0 Voice centric

1 Data centric

Voice domain preference for E-UTRAN(2 bit field)

Bit

2 1

0 0 CS Voice only

0 1 IMS PS Voice only

1 0 CSvoice preferred, IMS PS Voice as secondary

1 1 IMS PS voice preferred, CS Voice assecondary

MS not supporting IMS voice shallindicate "CS Voice only".

MS only supporting IMS voice shallindicate "IMS PS Voice only".

如果LTE网络既支持CSFB，又支持IMS多种语音解决方案，那么通话时，究竟使用哪个那？这个就要看voicedomain preference参数了

1 0 CS voice preferred, IMS PS Voice assecondary

1 1 IMS PS voice preferred, CS Voice assecondary

如何确定是支持CSFB以及是否支持IMS那，可以通过ATTACHACCEPT消息，或者TAU ACCEPT消息查看

eps_netwk_feature_support

     length = 1 (0x1)

     CS_LCS = 0 (0x0) (No info about support of loc service via cs isavailable)

     EPC_LCS = 0 (0x0) (Location Services via EPC notsupported)

     EMC_BS = 0 (0x0) (Emergency bearer services in S1 Mode notsupported)

     IMSVoPS = 0 (0x0)(IMS Vo PS Session in S1 Mode notsupported)

   add_update_result_incl =0 (0x0)

   t3412_ext_incl = 0 (0x0)

add_update_result_incl在3GPP中的定义如下

LTE 中的Data Centric 和 Voice Centric含义