VOLTE关键性能指标优化.pptVIP

RRC重建-触发条件 RRC重建只能由UE触发，可能的触发条件有以下几种： UE发现上行无线链路失败 T310 expiry as result of out-of-sync problems controlled by n310(LNCEL), n311(LNCEL), t310(LNCEL) upon random access problem indication from MAC upon indication from RLC that the maximum number of retransmissions has been reached 切换失败 handover failure due to t304 expiry for intra LTE HO controlled by t304IntraLte (LNCEL)) mobility from E-UTRA failure due to t304 expiry applicable for inter-RAT handover types; controlled by t304InterRAT(LNCEL) for PSHO and SRVCC to WCDMA, t304InterRatTd(LNCEL) for PSHO to TD-SCDMA; t304InterRATGsm(LNCEL) for SRVCC to GSM, t304eNaccGsm(LNCEL) for eNACC to GSM) 其他原因 integrity check failure RRC connection reconfiguration failure 关掉Nokia一些私有下行无线链路失败检测的方法，并不能减少RRC重建的触发 RRC重建-请求的原因分类 Change information classification in footer 3GPP TS 36.331 规定RRC重建请求消息reestablishmentCause 字段有以下分类： if the re-establishment procedure was initiated due to RRC reconfiguration failure (i.e., the UE is unable to comply with the reconfiguration), UE sets the reestablishmentCause to the value reconfigurationFailure‘ if the re-establishment procedure was initiated due to intra-LTE handover failure or inter-RAT mobility from EUTRA failure, UE sets the reestablishmentCause to the value handoverFailure Otherwise UE sets the reestablishmentCause to the value otherFailure‘. NOTE: This includes T310 RLF failure. Nokia定义了以下几种RRC重建请求的类型： M8008C4 RRC_CON_RE_ESTAB_ATT 所有重建请求 M8008C6 RRC_CON_RE_ESTAB_ATT_HO_FAIL 对应规范handoverFailure M8008C8 RRC_CON_RE_ESTAB_ATT_OTHER 对应规范otherFailure 暂定reconfigurationFailure= M8008C4 - M8008C6 - M8008C8，以厦门网络为例： otherFailure占大部分， handoverFailure有一定比例， reconfigurationFailure非常少，几乎可以忽略不计。 Change information classification in footer RRC重建-比例优化 重建比例定义为：RRC重建请求次数/RRC建立请求次数 重建比例劣化小区：重建比例高于5% RRC重建本质上是由无线质量差引起的，无线环境优化是关键，任何参数优化都不可能使无线环境变好 RRC重建比例相关参数优化，具体见后面4页胶片： 随机接入过程优化，可以改善切换失败以及其他随机接入失败导致的RRC重建； 上行无线链路失步相关参数优化； 切换定时器t304优化； 上行RLC最大重传次数优化； Presentation / Author / Date 1. RLF due to T310 exp