1、载频间切换Interfrequency handoff 的流程进行切换的呼叫从一个CDMA 载频切换到另一个不同的CDMA 载频上,但仍 由同一个语音处理器处理。在这种情况下,从移动台的角度而言,为硬切换,因为它切换到不同的载频上;但从系统的角度而言,仍认为处于软切换状态,因为它仍然使用同一个语音处理器。所以称之为半软切换。半软切换与其它种类的切换不同,其实现的过程和方法中含有很多朗讯独特的做法,因此下面从切换方法,切换触发,允许执行半软切换的扇区(边界扇区)的特点,切换流程,参数设置,信令流程等几方面进行一些阐述。v 切换方法:CMPIFHO- 多目标小区的跨载频切换方法o 下切时,允许有最
2、多至6个的目标小区o 在切换的同时,在多个目标小区之间建立软切换o 大大提高了跨载频下切的可靠性o 朗讯特有v 切换触发机制: Direct Handoff(IFHOTI-Inter-frequency handoff trigger improvement)触发条件:条件一:BPIP(Border Pilot Versus Interior Pilot Threshold):当手机来到边界扇区,且边界扇区的Ec/Io比Active Set里其他所有的导频强BPIP门限。此条件确定载频间切换能否顺利触发条件二:Loss Matrix(Border Sector Loss Threshold f
3、or Inter-Frequency Handoff):手机距离边界扇区有一定的距离,信号发生了一定程度的衰减Loss Matrix门限。此条件确定载频间切换点离边界扇区的距离v 半软切换执行的扇区(边界扇区)的定义哪些扇区需发生跨载频下切,需根据站址分布情况事先进行设计并决定,一般为多载频系统内配置F(n)/F(i)的基站群中的最外一层的扇区。然后对相应的扇区在系统中加以设置,在CDHFL中定义的扇区即成为边界扇区。边界扇区的特性:o 配置为f(n)/f(i)的扇区o 只有边界扇区才会触发跨载频下切(拥塞情况下除外)o 每个边界扇区具有独立的下切关系数据库(CDHNL)o Channel_l
4、ist_message和Extend_channel_list中仅广播f(i),而不广播f(n)的信息-手机在边界扇区只能Idle在F(i)公共载频上o 边界扇区的RF Loading Weight Factor自动减半 o 切换触发门限各扇区可独立设定,优化。边界扇区的作用:o 手机在通话状态下穿越边界区域,引导手机跨载频下切o 在Idle状态下停留或跨出两载频区域时,引导手机Idle到公共载频上(特殊CLM,ECLM)o 切换主要参数及设置: 主要feature参数检查:CDMA MPIFHO (全网)cell2YCDMA IFHO TI (二载频边界站)cell2Y 边界扇区主要切换参数
5、Border Sector Loss Threshold for Inter-Frequency HandoffCeqface2Border Pilot Versus Interior Pilot ThresholdCeqface2Request for Pilot Measurement Interval (sec)Ceqface2 边界扇区切换邻区表CDHNL参数设置空中接口切换信令分析:载频间切换流程:rawdata见附件: inter-fre-drive-data.rar信令1:边界扇区按设置时间间隔发送导频测量请求给终端RecNo : 11646 : 06/08/2005 06:31
6、:13.140 : Order Message (ORDRM) State Variables: BAND_CLASS=0 MOB_P_REV=6 P_REV=6 P_REV_IN_USE=6 Record_Header RECORD_LENGTH 20 byte LOG_CODE 0x1008 MESSAGE_TIMESTAMP 06:31:13.140 EXPECTED_MESSAGE_LENGTH 8 byte Message CDMA CDMA Signalling Forward Channel Traffic Message MSG_LENGTH 8 byte MSG_TYPE 1
7、 SDU_AND_PDU_PADDING_LENGTH 32 bits Order Message FDSCH_LAYER2_BEG_FIELDS ACK_SEQ 1 MSG_SEQ 2 ACK_REQ 0 ENCRYPTION 0 USE_TIME 0 ACTION_TIME 0 second ORDER Pilot Measurement Request Order ADD_RECORD_LEN 0 IS2000_L2_PDU_PADDING PDU_PADDING 0 CRC 9593 信令2:终端发送导频测量给基站,计算得出Border Pilot Versus Interior Pi
8、lot Threshold=(-3.5)-(12.5)=9dB1.5dB符合条件一,但基站计算导频衰减条件二未达到,未进行切换。RecNo : 11658 : 06/08/2005 06:31:13.249 : Pilot Strength Measurement Message (PSMM) State Variables: BAND_CLASS=0 MOB_P_REV=6 P_REV=6 P_REV_IN_USE=6 Record_Header RECORD_LENGTH 25 byte LOG_CODE 0x1005 MESSAGE_TIMESTAMP 06:31:13.249 EXPE
9、CTED_MESSAGE_LENGTH 13 byte Message CDMA CDMA Signalling Reverse Channel Traffic Message MSG_LENGTH 13 byte MSG_TYPE 5 SDU_AND_PDU_PADDING_LENGTH 72 bits Pilot Strength Measurement Message FDSCH_LAYER2_BEG_FIELDS ACK_SEQ 4 MSG_SEQ 2 ACK_REQ 1 ENCRYPTION 0 REF_PN 268 PILOT_STRENGTH -3.5 dB KEEP 1 PIL
10、OT_PN_PHASE_INFO PILOT_PN_PHASE 27904 chips PILOT_PN_OFFSET_DETERMINATION PILOT_PN 436 PILOT_DELAY 0 chips PILOT_DELAY_IN_TIME 0 second PILOT_STRENGTH -12.5 dB KEEP 1 PILOT_PN_PHASE_INFO PILOT_PN_PHASE 6400 chips PILOT_PN_OFFSET_DETERMINATION PILOT_PN 100 PILOT_DELAY 0 chips PILOT_DELAY_IN_TIME 0 se
11、cond PILOT_STRENGTH -13 dB KEEP 1 MSG_END_PADDING IS2000_L2_PDU_PADDING PDU_PADDING 0 CRC 20099 信令3:终端继续发送导频测量给基站,计算得出Border Pilot Versus Interior Pilot Threshold=(-4)-(16)=12dB1.5dB且基站计算导频衰减条件二达到。RecNo : 15329 : 06/08/2005 06:31:52.829 : Pilot Strength Measurement Message (PSMM) State Variables: BA
12、ND_CLASS=0 MOB_P_REV=6 P_REV=6 P_REV_IN_USE=6 Record_Header RECORD_LENGTH 22 byte LOG_CODE 0x1005 MESSAGE_TIMESTAMP 06:31:52.829 EXPECTED_MESSAGE_LENGTH 10 byte Message CDMA CDMA Signalling Reverse Channel Traffic Message MSG_LENGTH 10 byte MSG_TYPE 5 SDU_AND_PDU_PADDING_LENGTH 48 bits Pilot Strengt
13、h Measurement Message FDSCH_LAYER2_BEG_FIELDS ACK_SEQ 0 MSG_SEQ 1 ACK_REQ 1 ENCRYPTION 0 REF_PN 268 PILOT_STRENGTH -4.5 dB KEEP 1 PILOT_PN_PHASE_INFO PILOT_PN_PHASE 6400 chips PILOT_PN_OFFSET_DETERMINATION PILOT_PN 100 PILOT_DELAY 0 chips PILOT_DELAY_IN_TIME 0 second PILOT_STRENGTH -16 dB KEEP 0 MSG
14、_END_PADDING IS2000_L2_PDU_PADDING PDU_PADDING 0 CRC 53270 信令4:两个切换条件同时达到,基站发送载频间切换消息给终端RecNo : 15400 : 06/08/2005 06:31:53.661 : General Handoff Direction Message (GHDM) Record_Header RECORD_LENGTH 47 byte LOG_CODE 0x1008 MESSAGE_TIMESTAMP 06:31:53.661 EXPECTED_MESSAGE_LENGTH 35 byte Message CDMA CDMA Signalling Forward Channel Traffic Message MSG_LENGTH 35 byte MSG_TYPE 31 SDU_AND_PDU_PADDING_LENGTH 248 bits General Handoff Direction Message FDSCH_LAYER2_BEG_FIELDS ACK_SEQ 1 MSG_SEQ 1 ACK_REQ 1 ENCRYPTION 0 USE_TIME 0 HDM_SEQ 0 SEARCH_INCLUDED 1 SRCH_WIN_A 80 chips SR
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