参考ubuntu 16.04系统LimeSDR使用srsLTE搭建LTE实验环境构建实验环境,在实际运行时候，手机设备无法正常连接到基站，报告如下错误信息：
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Received Attach Request Attach Request -- IMSI-style attach request Attach Request -- UE is already attached.Attach request -- IMSI: 208920100001100 Attach request -- eNB-UE S1AP Id: 3, MME-UE S1AP Id: 3 Attach request -- Attach type: 2 Attach Request -- UE Network Capabilities EEA: 11110000 Attach Request -- UE Network Capabilities EIA: 11110000 Attach Request -- MS Network Capabilities Present: true PDN Connectivity Request -- EPS Bearer Identity requested: 0 PDN Connectivity Request -- Procedure Transaction Id: 1 PDN Connectivity Request -- ESM Information Transfer requested: false Downlink NAS: Sending Authentication Request Plain UL NAS: Authentication Failure Sequence number synch failure Downlink NAS: Sent Authentication Request DL NAS: Sent Downlink NAS Message. DL NAS Count=0, UL NAS count=1 DL NAS: MME UE S1AP id 3 Plain UL NAS: Authentication Failure Sequence number synch failure Downlink NAS: Sent Authentication Request DL NAS: Sent Downlink NAS Message. DL NAS Count=0, UL NAS count=2 DL NAS: MME UE S1AP id 3 Received UE Context Release Request. MME-UE S1AP Id 3 UE is not ECM connected. No need to release S1-U. MME UE S1AP Id 3 UE is ECM IDLE. |
初步分析BUG的原因是如下函数在重新生成同步序列号的时候出现错误：
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bool resync_sqn_milenage(uint64_t imsi, uint8_t *auts) |
目前还在分析，目前出现这个现象的时候，当EPC退出时候，应用一定向user_db.csv回写000000001b02，一旦出现这个数字，我们就没办法注册设备了。
目前的应对办法是把user_db.csv最后的SQN，要比设备最后一次通信记录的数据号大，如果SQN数字复位，可以让设备关机，应该就从0开始了。此问题还在持续跟进中。