LTE与GSM互操作指南

S_non-serving_XXX > THRESH_XXX_high during T_reselection
For 3G cells: CPICH RSCP – DEFAULT_UTRAN_QRXLEVMIN > DEFAULT_THRESH_UTRAN For LTE cells: RSRP – lteAdjCellMinRxLevel > lteAdjCellReselectUpperThr
GSM->LTE 小区重择-LTE低优先级
• Case 2: There is no measured non serving cell with higher priority inter-RAT frequency for which conditions related to Case 1 (see previous slide) are satisfied AND For serving and all measured neighbouring GSM cells during T_reselection (timeHysteresis):
• GERAN:
Cell is not barred and belongs to allowed LA and PLMN and RLA_C – RXLEV_ACCESS_MIN – Pcompensation > 0
GSM->LTE 小区重择-
GSM->LTE 小区重择-相关参数组
There is new object (ADJL) in the database for handling LTE neighbours similar to ADJW object for WCDMA neighbours. • 16 new parameters in ADJL and 6 new parameters in BTS object. One segment could have up to 8 ADJL objects – Activation State – LTE Adj Cell Index (INDEX) – Notification Origin – LTE Adj Cell Downlink Carrier Frequency (FREQ)
could take place with the help of this feature which it is possible from the GSM network point of view to: – Perform cell reselection to LTE – Perform IS-NACC from LTE to GSM • Better control over importance of given RAT in the reselection process by introduction of absolute priorities criteria NACC improvement • NACC is improved with the support for inter-BSC reselection support and intersystem cell change from UTRAN • Quality of Service as perceived by the user (throughput and delay values) is increased by means of reduction of service outage time during reselection process.
– Only minimum signal strength criteria of the neighbouring cells are considered for higher priority cells (and also minimum quality criteria in case of 3G cell)
LTE Interworking with GSM
LTE及W、G网的小区优先级设置
LTE->GSM小区重择相关参数
LTE->GSM小区重择相关参数
LTE->GSM小区重择相关参数
GSM->LTE 小区重择R算法• Self contained cell reselection to E-UTRAN cell if the MS is within the LTE coverage
YES
See previous slide
NO
ห้องสมุดไป่ตู้
UTRAN: DEFAULT_THRESH_UTRAN E-UTRAN: lteAdjCellReselectLowerThr
YES
Perform Cell Reselection Cells order: 1. Priority criteria 2. Decreasing order of S_non-serving_XXX (within the same priority)
– – – – – – – – – – – –
LTE Adj Cell Tracking Area Code(TAC) LTE Adj Cell Mobile Country Code(MCC) LTE Adj Cell Mobile Network Code(MNC) LTE Adj Cell Minimum Bandwidth(LTEMB) LTE Adj Cell Priority(LTECP) LTE Adj Cell Reselection Upper Threshold(LTERUT) LTE Adj Cell Reselection Lower Priority(LTERLT) LTE AdjCell Min Rx Level(LTERXM) Barred LTE Adj Cell List(LTEBCL) Barred LTE Adj Cell Group(LTEBCG) Barred LTE Adj Cell Pattern(LTEBCP) Barred LTE Adj Cell PatternSense(LTEPS)
Measured RSRP – Qrxlevmin – Qrxlevminoffset – Pcompensation > 0
• UTRAN:
Measured CPICH RSCP – Qrxlevmin – Qrxlevminoffset – Pcompensation > 0 and Measured CPICH Ec/No – Qqualmin > 0
LTE cell ltePriority = 3
2G cell gsmPriority = 0
UE reselects to the inter-RAT cell with the highest priority among the ones that satisfy threshold criteria (here: in case B and C signal strength is above the threshold but B has higher priority)
No dependency on the level of serving cell!
Assumptions: lteAdjCellMinRxLevel = -114 dBm, DEFAULT_UTRAN_QRXLEVMIN = -115 dBm lteAdjCellReselectUpperThr = DEFAULT_THRESH_UTRAN = 32 dB
• Direct comparison may lead to ping-pong effect especially if deployment of cells with different size on 2G/3G interworking (large UMTS cell and several small GSM cells) • Moreover, often value of ALWAYS was set for FDD_Qoffset leading to as soon as possible camping on 3G cell what effectively prioritizes 3G network over 2G (or vice versa)..
GSM->LTE 小区重择R算法– New concept is based on precise cell reselection priority order between different RATs without predefined offsets
– Direct comparison between signal levels of different RATs is no longer required
– Priority based cell reselection algorithm is used when LTE neighbors are present in the cell. The following segment level priority parameters are sent as part of the SI2q message to the MS when LTE neighbors are present in the cell:
prioritySearchThr
GSM->LTE 小区重择– The reselection does not take place if during last 5 seconds, there was inter-RAT reselection towards GERAN – Reselection to UTRAN cell could take place only if additionally quality related criterion is satisfied i.e.: • CPICH Ec/No ≥ FDD_Qmin – FDD_Qmin_Offset – Target cell should satisfy suitability criteria: • E-UTRAN: