总体流程
一、初始化
找卡:
User Identity Module/High[ mmgsdi.c 9083] USIM app. present
读取搜网nv:
1) NV 00010:Digital/Analog Mode Preference,接入技术,通常采用Auto/2G/3G/4G四 个选项;
2) NV 00849:Network Selection Mode Preference,搜网模式,存在Auto和Manual两个 选项;
3) NV 00850:Service Domain Preference,服务域选取,可以是仅PS、仅CS或者PS+CS;
4) NV 00722:Acquisition Database,用来存放WCDMA的历史频点信息;
5) LTE的频段信息存放在nv/item_files/modem/mmode/lte_bandpref文件中,
二、PLMN选择
PLMN选择分为自动搜网和手动搜网两种模式:
1) 自动搜网:UE按照协议23.122 4.4.3.1.1 Automatic Network Selection Mode Procedure 规定的PLMN优先级进行搜网,即RPLMN->HPLMN->UPLMN->OPLMN。
2) 手动搜网:搜索RPLMN,协议23.122 4.4.3.1.2 Manual Network Selection Mode Procedure;UE会把所有的PLMN,包括不可用的PLMN列出来,供用户选择去注册;
3) 当没有找到可用的PLMN,单板会发起MMR_REG_REQ PLMN(0-0) RAT(LTE)的 请求,这样单板就可以获得限制服务,如紧急呼叫。
4)找到plmn则发起MMR_REG_REQ PLMN(460-0)
选择PLMN的时候会从SIM卡中读取,及配置文件中读取已有的PLMN信息,如RPLMN(上次驻留的PLMN),HPLMN(SIM卡中的HPLMN),EHPLMN(等价的HPLMN,可以在NV65602中配置)等,device_config配置。
Call Manager/High [ cmph.c 54148] =CM= cmph_read_ehplmn_list SUCCESS plmn_count=4
MCFG/Medium [ mcfg_sel.c 729] =MCFG= Comparing PLMN 460:7 against prefix 460:7
NAS REG/High [ reg_sim.c 2788] =REG= HPLMN(460- 07)
三、扫频
LTE扫频有两种方式:systerm scan和band scan。
1) System Scan会扫历史记录频点,LTE的历史频点存放在NV的acq_db文件中,其具体 保存路径为nv/reg_files/modem/lterrc/csp/acq_db (最多保存10个历史频点),可以通过 QPST查看
信息,左侧为低位字节,右侧为高位字节;绿色部分标记Band信息,标示1之后有 几个0);关于System Scan的相关log信息可以参考图1.7,其中关于LTE earfcn的定义可以参考协议3GPP TS 36.104 5.7.3 Carrier frequency and EARFCN;
LTE RRC/Low [ lte_rrc_csp.c 7680] CSP: Found 4 systems to scan
系统扫频扫到4个历史频点,并且都能SIB1找到对应plmnm,对这4个频点的信号进行排序,选取优先最高的
LTE RRC/Low [ lte_rrc_csp.c 7291] CSP: Candidate list not present
LTE RRC/Low [ lte_rrc_csp.c 2542] CSP: PLMN found
LTE RRC/Low [ lte_rrc_csp.c 7296] CSP: req PLMN in SIB1 list
LTE RRC/Low [ lte_rrc_csp.c 7291] CSP: Candidate list not present
LTE RRC/Low [ lte_rrc_csp.c 2542] CSP: PLMN found
LTE RRC/Low [ lte_rrc_csp.c 7296] CSP: req PLMN in SIB1 list
LTE RRC/Low [ lte_rrc_csp.c 7291] CSP: Candidate list not present
LTE RRC/Low [ lte_rrc_csp.c 2542] CSP: PLMN found
LTE RRC/Low [ lte_rrc_csp.c 7296] CSP: req PLMN in SIB1 list
LTE RRC/Low [ lte_rrc_csp.c 7291] CSP: Candidate list not present
LTE RRC/Low [ lte_rrc_csp.c 2542] CSP: PLMN found
LTE RRC/Low [ lte_rrc_csp.c 7296] CSP: req PLMN in SIB1 list
LTE RRC/Low [ lte_rrc_csp.c 12630] CSP: All frequencies prioritized for Req PLMN
LTE RRC/Low [ lte_rrc_csp.c 12685] CSP: Prioritization of system scan results complete
LTE RRC/High [ lte_rrc_csp.c 19327] CSP: Prioritize System scan results for priority bands
LTE RRC/Low [ lte_rrc_csp.c 12680] CSP: 0 frequencies prioritized after pass 1
LTE RRC/Low [ lte_rrc_csp.c 12680] CSP: 0 frequencies prioritized after pass 2
LTE RRC/Low [ lte_rrc_csp.c 12680] CSP: 0 frequencies prioritized after pass 3
LTE RRC/Low [ lte_rrc_csp.c 12680] CSP: 0 frequencies prioritized after pass 4
LTE RRC/Low [ lte_rrc_csp.c 12685] CSP: Prioritization of system scan results complete
LTE RRC/High [ lte_rrc_csp.c 19331] CSP: System scan results after prioritization
LTE RRC/High [ lte_rrc_csp.c 19338] CSP: band:40 earfcn:39148 energy: -72
LTE RRC/High [ lte_rrc_csp.c 19338] CSP: band:38 earfcn:38098 energy:-107
LTE RRC/High [ lte_rrc_csp.c 19338] CSP: band:39 earfcn:38496 energy:-109
LTE RRC/High [ lte_rrc_csp.c 19338] CSP: band:41 earfcn:40936 energy:-114
2) Band Scan:当System Scan中的历史记录频点Acq都失败时,会进行band scan;按照 单板支持的band,一般情况下会从Band1开始扫每个Band的频点,而在每个Band中 会将所有频点按照RSSI排序,将达到信号强度门限值的频点按信号强度从高到低列 出来,最多列出50个频点作为候选频点,然后在这50个频点中找一个合适的频点, 直到找到一个符合当前网络的频点。可以通过QXDM过滤LTE RRC/CSP的log来查 看扫频的过程时,如图1.8所示;Band Scan扫频时对每个频点Acq log信息参考图1.9
Log Analysis – System Scan
//Automatic service Request
11458 76:00:16:20.595reg_state.c1171HCM_SERVICE_REQ –AUTOMATIC
11491 89:00:16:20.600emm_reg_handler.c475HEMM: Received MMR_REG_REQ
//NAS sends service request to AS
11494 81:00:16:20.600emm_rrc_if.c310HEMM: Sent LTE_RRC_SERVICE_REQ
//RRC sends LTE_CPHY_START_REQ to ML1
11537 81:00:16:20.603lte_ml1_mgr_stm.c6923MLTE_CPHY_START_REQ
//LTE AS is initialized
11675 97:00:16:20.620lte_ml1_mgr_cphy_cnf_handlers.c976MLTE_CPHY_START_CNF
Status: 0
11680 89:00:16:20.620lte_ml1_mgr_stm.c12645LL1M: INACTIVE STATE ENTER
//ML1 initiates System Scan request
11704 153:00:16:20.620lte_ml1_sm_main.c1118HSM: Sys Scan Req module 1 num_sys 1
min_sys 0 early_abort 0 sys[0] band 13 earfcn 5230 bw 50
//RF tune request
11705 113:00:16:20.620lte_ml1_sm_main.c641HSM: RX cfg req freq 5230 BW 50 cell_id
65535
Log Analysis – Band Scan
//Acquisition database search (System Scan) is exhausted. No system found
11497 89:00:47:21.166lte_rrc_csp.c3603HCSP: All entries tried in acq list
11498 81:00:47:21.166lte_rrc_csp.c9373HCSP: Exhausted acquisition list
//Initiate Band Scan
11506 89:00:47:21.166lte_rrc_csp.c2191XCSP: Sending 1 bands in band scan
11507 81:00:47:21.166lte_rrc_csp.c2210XCSP: Sent Band Scan Request
11520 105:00:47:21.175rtr8600_lte.c866HRF LTE RX is tuned to band 13 and frequency 5230
所有频段都扫完,写到acq_db文件中,重新在做一次系统扫频
四、小区搜索
LTE小区搜索实际上就是PSS ( Primary Synchronization Signal ) / SSS ( Secondary Synchronization Signal)同步,实现UE对小区的识别和下行同步。这样单板就能收到小区广播的MIB消息和SIB消
五、解系统消息
系统消息解析主要是去读取MIB (Master Information Block)消息和SIB (System
Information Block)消息。系统消息的详细定义可以参考协议3GPP TS 36.331 5.2 System
information。系统消息的获取流程如图1.10。
MIB消息包含天线数、下行带宽、小区ID、注册的频点等消息,其格式定义如图1.11。
空口消息解析如图1.12
SIB消息会包含PLMN、小区ID、S准则中的q-RxLevMin(sib3中)等消息,当该PLMN、 和第二步得到的PLMN一致时才可以进行下一步;否则扫下一个频点,同时解系统消息会得 到S准则中参考信号功率的值和随机接入时PreamblesGroup以及功率攀升因子等消息。 查看MIB、SIB消息可以通过QCAT过滤空口(OTA)消息来获取,请参考图1.12。消息
解析可以参考图1.1
LTE RRC/High [ lte_rrc_csp.c 4650] CSP: Sent Get SIBs Request
LTE RRC/High [ lte_rrc_csp.c 7048] CSP: SIB-8 not scheduled in SIB-1
LTE RRC/Low [ lte_rrc_csp.c 11027] CSP: Cell is suitable
六、小区选择
小区选择过程就是S准则的判断,可以参考协议3GPP TS 36.304 5.2 Cell selection and
reselection和3GPP TS 36.304 5.2.4.6 Intra-frequency and equal priority inter-frequency Cell
Reselection criteria。LTE的S准则定义为:
LTE RRC/Low [ lte_rrc_csp.c 21301] CSP: Proceeding to cell select request
LTE RRC/High [ lte_rrc_csp.c 4554] CSP: Sent Cell Selection Request
LTE ML1/Medium [ lte_ml1_mgr_stm.c 14209] L1M: LTE_CPHY_CELL_SELECT_REQ
小区选择请求成功
LTE ML1/Medium [ lte_ml1_mgr_stm.c 14209] L1M: LTE_CPHY_CELL_SELECT_REQ
WCDMA L1/High [ l1mcmd.c 1419] Received CELL_SELECTION_REQ
WCDMA L1/High [ wsrch.c 24181] Cell Selection Succeed
七、小区驻留
扫到的一个频点满足S准则,小区选择成功后进行小区驻留。小区驻留log参考图1.14。
小区驻留成功
LTE RRC/Low [ lte_rrc_csp.c 18478] CSP: Camped on physical cell ID 223 on earfcn 3775
小区驻留成功后发起attach请求
BCCH_DL_SCH / SystemInformationRadio Bearer ID: 0, Freq: 39148, SFN: 128
八、attach流程
LTE NAS EMM Plain OTA Outgoing MessageAttach request Msg
LTE NAS EMM Plain OTA Incoming MessageAttach accept Msg
LTE NAS EMM Plain OTA Outgoing MessageAttach complete Msg