LTE Interoperability in Idle Mode(LTE-GU)

Slide 0Page*
Course Code
Confidential Information of Huawei. No Spreading Without Permission
LTE Interoperability in Idle Mode(LTE->G/U)
www.huawei.com
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
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Contents
IRAT PLMN Selection Procedure
IRAT Cell Selection Criteria
IRAT Cell Reselection Criteria
States of UE at Switch on
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Related to interoperability which will be discussed in this course
A UE that is powered on but does not have an RRC connection to the radio network is considered to be in idle mode. In the case of idle mode management, the eNodeB sends configurations by broadcasting system information, and accordingly, UEs select suitable cells to camp on. Idle mode management can increase the access success rate, improve the quality of service, and ensure that UEs camp on cells with good RX signal levels and qualities.
The idle mode management is related with the following aspects:
PLMN selection
A UE selects a Public Land Mobile Network (PLMN) and registers on the PLMN.
Cell selection
A UE selects a cell in the chosen PLMN and camps on the cell so that the UE can monitor system information and paging messages to obtain service.
Cell reselection
When camped on a cell, a UE reLTEarly searches for a better cell according to the cell reselection criteria, for the purpose of correctly receiving system information and successfully initiating services.
Tracking Area (TA) registration
A UE registers its location with the Evolved Packet Core (EPC) through a TA registration procedure so that the EPC can page the UE within the TA and request the UE to initiate services.
Cell reservation and access control
Cell reservation and access control are two mechanisms for operators to control their networks. In the cell reservation mechanism, specific cells can be reserved for operators' use only. In the access control mechanism, the UEs that can initiate calls in a cell are determined on the basis of the classes of the UEs.
System information broadcast and paging
In system information broadcast, the information such as parameters related to cell selection and reselection is broadcast to UEs through system information over the Broadcast Control Channel (BCCH). In paging, paging messages are used to inform all UEs in a cell of a change in the system information and to carry paging-related information.
The main activities of UEs in idle mode are PLMN selection, cell selection and reselection, and TA registration. The figure in the slide above shows the relationships between them.
Items with * will be focused on in this course in detail, for they are related with different RAT.
PLMN Selection
Idle Mode
States and Relationships in Idle Mode
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The main activities of UEs in idle mode are PLMN selection, cell selection and reselection, and TA registration. Figure in the slide above shows the relationships between them.
Camp-on Strategies in the Idle Mode
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UMTS
GSM
LTE
PLMN A
PLMN A
PLMN A
The dual-mode UE camps on the network with the highest priority (usually LTE by default) through cell reselection.
UMTS
GSM
LTE
PLMN A
PLMN B
PLMN C
The dual-mode UE camps on the network with the highest priority (usually LTE by default) through PLMN selection.
PLMN Selection
Cell Reselection
Cell selection
Power on
Idle-Mode Camp-On Within the Same PLMN
Assume that the GERAN/UTRAN and the LTE network share the same PLMN and both of them use system messages to broadcast information about the cells of other RATs and the cell priorities. By default, the LTE network is set with the highest priority. The dual-mode UE camps on the network with the highest priority through cell reselection. The camp-on principles are described in the following situations:
The UE in idle mode camps on the LTE network.
The eNodeB is configured with the cell reselection priorities and the thresholds for channel quality. These configurations are broadcast by the eNodeB in system messages to ensure that the UE does not reselect from the LTE network to the GERAN/UTRAN easily. When the strength of LTE signals is lower than the predefined threshold, the UE starts to measure GERAN/UTRAN cells and reselects the GERAN/UTRAN if the conditions are met.
The UE in idle mode camps on the UTRAN.
The system messages broadcast by the RNC include cell reselection parameters, LTE frequencies, and priority information. To enable the UE on the UTRAN to reselect to the LTE network, set the priority of the LTE network to be higher than that of the UTRAN. The UE periodically searches for and measures all RAT frequencies that have high priorities. The UE reselects the LTE network if the conditions are met. If the signal strength in multiple LTE cells is higher than the predefined threshold within a period, the UE camps on the LTE cell that has the highest priority.
Notes
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The UE in idle mode camps on the GERAN.
The system messages broadcast by the BSC include cell reselection parameters, LTE frequencies, and priority information. To enable the UE on the GERAN to reselect to the LTE network, set the priority of the LTE network to be higher than that of the GERAN. The UE periodically searches for and measures all RAT frequencies that have high priorities. The UE reselects the LTE network if the conditions are met. If the signal strength in multiple LTE cells is higher than the predefined threshold within a period, the UE camps on the LTE cell that has the highest priority.
Idle-Mode Camp-On Between Different PLMNs
When the GERAN/UTRAN and the LTE network use different PLMNs, operators can assign a lower priority PLMN to the GERAN/UTRAN, and a higher priority EPLMN to the LTE network. Over The Air (OTA) messages are sent to instruct the UE to update the EHPLMN data files in USIMs so that the LTE network is prior selected over the GERAN/UTRAN. If the UE is powered on to camp on a network or initiates idle-mode cell reselection, the UE prior camps on the LTE network. The camp-on principles are as follows:
If the UE in idle mode camps on the GERAN/UTRAN:
If the RAN of the GERAN/UTRAN is not upgraded, the UE in idle mode periodically searches for a PLMN with the highest priority. If the PLMN is found, the UE performs the cell reselection and camps on the serving cell on the PLMN with the highest priority. The searching period is specified by data files in a USIM. If the HPLMN and EHPLMN are equivalent, that is, the priorities are the same, the GERAN/UTRAN can only be used as the VPLMN and the LTE network as the HPLMN. The UE returns to the LET network by periodically searching for HPLMNs.
If the UE in idle mode camps on the LTE network:
The UE reselects the serving GERAN/UTRAN according to the camp-on principles for the UE in idle mode camping on LTE networks in the same PLMN.
Comparation of Camp-on Strategies
LTE use the same or different PLMN IDs with GERAN/UTRAN
It is suggested EUTRAN uses the same PLMN ID with GERAN/UTRAN
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EUTRAN use different PLMN ID with GERAN/UTRAN
Remain in LTE network in Idle state
Set the cell reselect priority in eNodeB ENodeB broadcasts system information UE stay in LTE and not easy reselect to GERAN/UTRAN cell
Configure high priority PLMN ID for LTE and low priority PLMN ID for GERAN/UTRAN (notes UE update EHPLMN date in USIM card via SMS via OTA mode ) UE will select PLMN of LTE at first when attach or reselect in idle state
Remain in GERAN/UTRAN network in Idle State
RAN broadcasts cell reselection parameter in SIB3/4 RAN broadcasts inter-RAT cell reselection parameter in SIB3/4 and inter-RAT frequency priority of LTE UE searches all high priority of RAT frequency cell
Configure high priority PLMN ID for GERAN/UTRAN and low priority PLMN ID for LTE (notes UE update EHPLMN data in USIM card via SMS via OTA mode ) UE will select PLMN of GERAN/UTRAN at first when attach or reselect in idle state
Advantage
User smoothly upgrade (do not need update EHPLMN data in USIM card) The time of cell reselection is short UE Returns to LTE on time Reduce electric power
RAN does not need upgrade
Disadvantage
Need RAN upgrade
UE search and measure LTE cell for long time Consume electric power Can’t reselect to LTE on time
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Contents
PLMN Selection Principle
When a dual-mode UE is powered on in an area covered by both the LTE and the GERAN/UTRAN network, it needs to select a network to camp on. The principles of network selection are as follows:
After the dual-mode UE is powered on, it first tries the Registered Public Land Mobile Network (RPLMN) and the cell that it previously camps on.
If the RPLMN and cell do not meet the camp-on conditions, the UE selects a proper PLMN and RAT according to the configurations in the UMTS Subscriber Identity Module (USIM) and then a qualified cell.
To improve user experience and make full use of the newly deployed LTE network, the LTE network is usually set with the highest priority. The public priorities are broadcast through system messages.
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PLMN Selection Procedure Overview
(If present and not empty
RPLMN
PLMN,a PLMN identity consists of a Mobile Country Code (MCC) and a Mobile Network Code (MNC).
RPLMN
The Registered PLMN (RPLMN) is the PLMN on which the UE has performed a location registration successfully.
EPLMN List
The Equivalent PLMN (EPLMN) list is a list of PLMNs considered as equivalent to the local network by the UE in terms of service provisioning. During PLMN selection, the UE preferentially selects a PLMN from the list. The EPLMN list is sent from the EPC and stored in the UE.
EHPLMN
An Equivalent Home PLMN (EHPLMN) is an equivalent to the HPLMN, and takes precedence over the HPLMN.
The EHPLMN list is stored in the UMTS subscriber identity module (USIM) of the UE. During PLMN selection, the UE takes into account both the EHPLMNs and the HPLMN that is extracted from the international mobile subscriber identity (IMSI), and preferentially selects an EHPLMN.
HPLMN
The Home PLMN (HPLMN) is the PLMN in which the UE is defined. Each UE belongs to only one HPLMN.
VPLMN
The Visited PLMN (VPLMN) is the PLMN where the UE is located. A VPLMN can be the HPLMN.
notes
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PLMN Selection
Left figure shows the PLMN selection procedure. When a UE is powered on or recovers from lack of coverage, the UE first selects the last RPLMN and attempts to register on that PLMN. If the registration on the PLMN is successful, the UE shows the selected PLMN on the display, and now it can obtain service from an operator. If the last RPLMN is unavailable or the registration on the PLMN fails, another PLMN can be automatically or manually selected according to the priorities of PLMNs stored in the USIM.
PLMN Selection in Automatic Mode
When a UE fails to register on its last RPLMN, the UE attempts to select another PLMN. In automatic network selection mode, the UE selects a PLMN in the following order:
HPLMN or an EHPLMN.
Each PLMN in the "User Controlled PLMN Selector with Access Technology" data file in the USIM, in order of priority, according to the UE's support for Radio Access Technologies (RATs).
Each PLMN in the "Operator Controlled PLMN Selector with Access Technology" data file in the USIM, in order of priority, according to the UE's support for RATs.
Other PLMNs with signals of high received quality, in a random order. The high quality of signals is defined as the Reference Signal Received Power (RSRP) value of a cell in the PLMN being greater than or equal to -110 dBm.
Other PLMNs in order of decreasing RX signal quality.
When the UE finds a suitable cell in a PLMN during the preceding procedure, the UE attempts to register on the PLMN. If the registration is successful, the UE camps on the suitable cell; otherwise, the UE tries the next PLMN.
If the registration on none of the PLMNs is successful, the UE enters the limited service state. If no PLMN is available, the UE cannot obtain any service.
PLMN Selection in Manual Mode
When a UE fails to register on its last RPLMN, the UE attempts to select another PLMN. In manual network selection mode, the UE displays a list of PLMNs, in the same order as the PLMNs to be selected in automatic network selection mode.
In manual mode, the UE can also try forbidden PLMNs. If the UE succeeds in registering on the selected PLMN, the PLMN is no more a forbidden PLMN to the UE. The forbidden PLMNs are determined by the EPC.
Roaming
When in roaming state, a UE obtains service from a VPLMN that is different from its HPLMN. For example, the UE obtains service from a PLMN in another country (that is, from an international roaming area). When the UE with the roaming service moves out of the coverage area of its HPLMN, the UE can obtain service from another PLMN according to the PLMN information stored in the USIM. The operator determines whether roaming is allowed for a UE.
After the UE registers on a VPLMN by roaming, it periodically searches for its HPLMN and attempts to return to the HPLMN. The time interval between consecutive searches for the HPLMN is defined by the operator and stored in the USIM.
PLMN Selection Procedure in Detail
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Last RPLMN or equivalent PLMN
“HPLMN&EHPLMN Selector with Access Technology ” data file (in priority order)
“User Controlled PLMN Selector
“Operator Controlled PLMN Selector
The PLMN with Better Wireless Quality in random order
Other PLMN Base On Wireless Quality in order of decreasing signal quality
PLMN Select When UE Switch On
The Timer of HPLMN Reselection is Saved in USIM Card(6m~8h in 6m steps or no periodic attempts)
Stored in UE
Set in SIM
Set in SIM
Set in UE
PLMN + E-UTRAN
PLMN + UTRAN
PLMN + GSM
Customized PLMN/Frequency List in SIM card, UE Prefers to Camp on LTE Network
Camp-On After Power-on
When the dual-mode UE is powered on, it first selects a Public Land Mobile Network (PLMN) and then a proper cell. The selection of the PLMN and RAT is based on the following information stored in the USIM:
HPLMN (Home PLMN) Selector with Access Technology
Operator controlled PLMN Selector with Access Technology
User Controlled PLMN Selector with Access Technology
Forbidden PLMNs
Equivalent HPLMN
The first three data files control the selection of the PLMN and RAT. Each file includes multiple entries, such as a PLMN and the relevant RAT. The entries are arranged in a descending sequence based on priority.
For an entry that includes only a PLMN, the UE supports all RATs by default. Different entries may share the same PLMN but different specified RATs. These entries are also arranged in a descending sequence based on the priority of the RAT.
There are two PLMN selection modes for the dual-mode UE, namely, automatic selection and manual selection.
In automatic selection mode, the UE automatically selects the RPLMN or Equivalent PLMN (EPLMN) after it is powered on. If there is no RPLMN, the UE selects a PLMN according to the following priority list:
Notes
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The available Equivalent HPLMN (EHPLMN) with the highest priority, or the HPLMN when the EHPLMN list does not exist or is empty
Entries in the User Controlled PLMN Selector with Access Priority data file stored in the USIM (the entries are tried one by one based on priority)
Entries in the Operator Controller PLMN Selector with Access Technology data file stored in the USIM (the entries are tried one by one based on priority)
Other PLMNs and RATs with high channel quality
Other PLMNs and RATs (tried one by one based on channel quality)
In manual selection mode, the UE displays the available PLMNs and RATs (based on the preceding priority list) for the subscriber, and the subscriber selects a PLMN and RAT manually.
After the subscriber selects the PLMN and RAT, the dual-mode UE selects a proper cell. If the cell is not found, the UE automatically tries the next PLMN and RAT on the priority list.
Note: The subscriber may select only the PLMN and not specify the RAT. Data files stored in the USIM is not a must.
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Contents
Location of UE Search and Selection Procedure
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UE
idle
Behavior
phase
UE
access
phase
Decode system information
Power on
Invisible flow
Visible flow
PLMN Selection
Cell Search
UE Attach
Cell Search
ERFCN: E-UTRA absolute radio frequency channel number
A method of identifying the center carrier frequencies in E-UTRA. The carrier frequency in the uplink and downlink is designated by the EARFCN (E-UTRA Absolute Radio Frequency Channel Number) in the range 0 - 65535. The channel raster is 100KHz for all bands, which means that the carrier centre frequency must be an integer multiple of 100KHz. The relation between EARFCN and the carrier frequency in MHz for the downlink/uplink is given by an equation and associated table of frequency bands.
PSS: Primary Synchronize Signal
SSS: Secondary Synchronize Signal
Synchronized Signal
DL SS is used to realize DL synchronization between UE and eNodeB and also help UE to get PCI of cell
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The synchronization signals comprise of the PSS (Primary Synchronization Signal) and SSS (Secondary Synchronization Signal). Together they enable the UE to become downlink synchronized and identify the Physical Cell Identity. There are 504 unique physical cell identities, divided into 168 cell identity groups each containing three cell identities (sectors).
Downlink Synchronization Signals
System Message Receiving
Purpose: From the system message, UE get all necessary parameters for the further procedure, such as cell camping, random access, etc.
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AAL Est Ind(CCP)
System Message Overview
SI Block
Downlink bandwidth of a cell, Physical HARQ Indication Channel (PHICH) parameters, and System Frame Number (SFN)
SIB1
Parameters related to cell access and cell selection and scheduling information of SI messages
SIB2
Common radio parameters used by all the UEs in a cell
SIB3
Common cell reselection parameters for all the cells and intra-frequency cell reselection parameters
SIB4
SIB5
Inter-frequency EARFCN list and reselection parameters of each EARFCN used for cell reselection Inter-frequency cell list and reselection parameters of each neighboring cell used for cell reselection Inter-frequency cell reselection blacklist
SIB6
UMTS Terrestrial Radio Access (UTRA) Frequency Division Duplex (FDD) neighboring EARFCN list and reselection parameters of each EARFCN used for cell reselection UTRA Time Division Duplex (TDD) neighboring EARFCN list and reselection parameters of each EARFCN used for cell reselection
SIB7
GERAN neighboring EARFCN list and reselection parameters of each EARFCN used for cell reselection
System Information
Downlink bandwidth of a cell, Physical HARQ Indication Channel (PHICH) parameters, and System Frame Number (SFN)
Parameters related to cell access and cell selection and scheduling information of SI messages
Bears SIB2~SIB13
SIB2
SIB10
SIB11
SIB12
SIB13
SIB3
SIB4
SIB5
SIB6
SIB7
SIB8
SIB9
Common cell reselection parameters; intra-frequency cell reselection parameters
Intra-frequency Ncell related parameters
Intre-frequency Ncell related parameters
UTRAN Ncell related parameters
GERAN Ncell related parameters
CDMA2000 Ncell related parameters
NOTES
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SI Block
CDMA2000 pre-registration information CDMA2000 neighboring frequency band list and reselection parameters of each band used for cell reselection CDMA2000 neighboring cell list of neighboring frequency band
SIB9
SIB10
SIB11
RRC States
RRC Connection
LTE RRC State Interoperability with 2G/3G
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Cell Selection/Reselection Procedures
After selecting a PLMN, a UE selects a cell in the PLMN to camp on. When camped on the cell, the UE monitors system information, performs measurements on the serving cell and neighboring cells, and selects a better cell to camp on, according to measurement rules and cell reselection criteria.
UE performs this procedure according to the selection or reselection related parameters in the system information or in the RRC Connection Release message.
A UE can use one of the following two cell selection procedures: Stored Information Cell Selection and Initial Cell Selection. The Stored Information Cell Selection procedure takes precedence over the Initial Cell Selection procedure. The UE uses the latter procedure only when it fails to find a suitable cell by using the former procedure.
After receiving all necessary system message, UE start to measure RS (Reference Signal) for cell selection judgment
RSRP and RSRQ can be evaluated
Cell Selection
Squal = Qqualmeas – (Qqualmin + Qqualminoffset)
A UE considers an E-UTRAN cell as a suitable cell only when the measured RSRP and reference signal received quality (RSRQ) values of the cell are greater than the receive (RX) level threshold (Qrxlevmin) and the RX signal quality threshold (QQualMin) for the cell, respectively.
An E-UTRAN cell becomes a suitable cell when both the following conditions are met:
Srxlev > 0 Squal > 0
Squal = Qqualmeas - (QQualMin + QQualMinOffset)
Parameter
Description
Qrxlevmeas
Qrxlevminoffset
Offset to Srxlev, relative with PLMN priority ,.QrxlevminOffset is only applied when a cell is evaluated for cell selection as a result of a periodic search for a higher priority PLMN while camped normally in a VPLMN in SIB1
Pcompensation
max (PMaximum allowed power – PUE MAX Output Power, 0), where PMaximum allowed power is sent in SIB1
Qqualmeas
measured RX signal quality (RSRQ value) of the cell, expressed in units of dB.
Qqualmin
QQualMinOffset
Offset to Qqualmin, relative with PLMN priority ,.QrxlevminOffset is only applied when a cell is evaluated for cell selection as a result of a periodic search for a higher priority PLMN while camped normally in a VPLMN in SIB1
Cell Selection Configuration
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The parameter “Minimum Required RX quality level offset(dB)” will appear only when the “Minimum required RX quality level offset configure indicator” is configured as “CFG(Configure)”.
Criteria for cell selection:
Squal = Qqualmeas – (Qqualmin + Qqualminoffset)
Following are the description of each parameters:
Parameter ID
Description
Qrxlevmin
Indicates the minimum required RX level. This parameter is used in the formula of the cell selection criterion S.
Qrxlevminoffset
Indicates the offset to the minimum required RX level. This value is included in criteria S and used in the evaluation of cell selection. This parameter is valid only when the cell selection is triggered by periodic searches for higher-priority PLMNs and the UE is served by a Visited Public Land Mobile Network (VPLMN).
Qqualmin
Indicates the minimum RX level of the cell. It is included in criteria S and used in the evaluation of cell selection.
QQualMinOffsetCfgInd
Indicates whether to set the offset to the minimum required RX qulity for the cell. If this parameter is set to CFG, the offset is required. If this parameter is set to NOT_CFG, the offset does not need to be set.
QQualMinOffset
Indicates the offset to the minimum required RX quality for the cell. It is included in criteria S and used in the evaluation of cell selection. This parameter is required only when the cell selection is triggered by periodic searches for higher-priority PLMNs and the UE is served by a Visited Public Land Mobile Network (VPLMN).
Cell Selection Configuration
Pcompensation = max (PMaximum allowed power – PUE MAX Output Power, 0)
PMaximum allowed power
Parameter ID
Description
PMaxCfgInd
Indicates whether to configure the the maximum TX power of the UE in the intra-frequency neighboring cell. Recommended value is NOT_CFG
PMax
Indicates the maximum TX power of the UE in the cell. If this parameter is not included in the SIB3, the UE uses the maximum TX power.
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Contents
Cell Reselection Overview
The signal strength of both the serving cell and neighboring cells varies with the movement of a UE, so the UE needs to select a better cell to camp on. This process is called cell reselection.
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Related to interoperability which will be discussed in this course
UE cell reselection include two steps:
Start the measurement for the neighboring cells
Rank the measured cells based on radio signal quality and priorities.
Cell Reselection Procedure
Neighboring Cell Measurement
Different-Priority Inter-Frequency or IRAT Cell Reselection
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Cell Reselection Evaluation Criteria
Confirm the target cell in cell reselection
Blacklisted Cell Identifying
During cell reselection, UEs are not allowed to measure or reselect blacklisted cells of the serving cell.
UEs identify blacklisted cells by PCIs(Physical Cell Identifiers).
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Inter-frequency blacklisted cells
Data Configuration of Blacklisted Cell
For intra-frequency blacklisted cells
For inter-frequency blacklisted cells
The Neighboring Cell Priority Overview
During implying measurements and the cell reselection, the UE needs to obtain the priorities of neighboring frequencies.
Note: Frequencies of different RATs must have different priorities. During the evaluation for reselection to an intra-frequency neighboring cell, the UE ignores the priority of the target frequency because cells that work on the same frequency have the same priority.
The priorities of inter frequency and IRAT are classified into two types:
Absolute priority
Dedicated priority
Assigned by RRC Conncection Release message and is valid for a specific UE
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The priorities of E-UTRAN frequencies and IRAT frequencies are classified into the following types:
Absolute priority: This priority is specified by the CellReselPriority parameter and is sent to UEs through broadcast of system information.
Dedicated priority: This priority is UE-specific. Dedicated priorities are generated by the internal dedicated prioritization algorithm or generated based on a Subscriber Profile ID (SPID) when a UE releases radio resources. They are sent to the UE through the RRC Connection Release message. The validity time of dedicated priorities is defined by the timer T320ForLoadBalance or T320ForOther, which is sent to the UE through the RRC Connection Release message.
During cell reselection, when a UE is camped on a suitable cell, the UE ignores all the absolute priorities provided in system information if dedicated priorities are assigned through dedicated signaling. If the UE acquires the priorities of other frequencies but no priority of the serving frequency, the UE regards the priority of the serving frequency as the lowest.
Types of the Neighboring Cell Priority
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The Serving Cell
Mapping to UE‘s SPID: RATFreqPriorityGroup. Priority
180min
Priority associated with the UE‘s SPID, has higher priority than that configured by CellReselPriority
The priority is delivered to the UE in an RRC Connection Release message when the UE attempts to release radio resources for "other” cause.
Valid within RRCCONNSTATETIMER.T320ForOther
The priority is delivered to the UE in an RRC Connection Release when the UE attempts to release radio resources for “load balancing TAU required” cause.
Valid within RRCCONNSTATETIMER.T320ForLoadBalance
Neighboring Cell Priority Handling
After having camped on a cell, a UE may decide to camp on another cell by performing cell reselection. Before cell reselection, the UE is required to measure the signal strength of certain neighboring cells and evaluate each of them by using the criteria that are suitable according to the priority of the neighboring cell, that is, the priority of the frequency on which the neighboring cell operates.
During the measurements and implementation of cell reselection, the UE needs to obtain the priorities of neighboring cells. Reselection to a neighboring cell is allowed if the cell works on an E-UTRAN or IRAT frequency that has a priority specified in system information, and reselection to a cell is prohibited if the cell is blacklisted by the serving cell as indicated in system information. Note that any two RATs must have non-overlapping priorities of frequencies. During the evaluation for reselection to an intra-frequency neighboring cell, the UE ignores the priority of the target frequency because cells that work on the same frequency have the same priority.
An E-UTRAN or IRAT frequency may have an absolute priority or a dedicated priority.
Absolute priority: The absolute priority of an E-UTRAN or IRAT frequency is specified by the CELLRESEL. CellReselPriority parameter and broadcast to UEs in system information.
– The absolute priority of the serving frequency is set by
CELLRESEL.CellReselPriority and broadcast in the SIB3.
– The absolute priority of the inter-frequency neighboring E-UTRAN frequency is set by
EUTRANINTERNFREQ.CellReselPriority and broadcast in the SIB5.
notes
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– The absolute priority of the neighboring UTRAN frequency is set by
UTRANNFREQ.CellReselPriority and broadcast in the SIB6.
– The absolute priority of the neighboring GERAN frequency is set by
GERANNFREQGROUP.CellReselPriority and broadcast in the SIB7.
– The absolute priority of the neighboring CDMA2000 frequency is set by
CDMA2000BANDCLASS.Cdma20001XrttCellReselPri and
CDMA2000BANDCLASS.Cdma2000HrpdCellReselPri and broadcast in the SIB8.
Dedicated priority: The dedicated priority of an E-UTRAN or IRAT frequency is UE-specific. It can be determined in the following two ways:
It can be specified by the Priority parameter.
In this situation, the Priority values of frequencies for one RAT must all be higher than or less than those in another RAT. In Flexible User Steering Feature Parameter Description, subscriber profile IDs (SPIDs) (specified by the Spid parameter) are mapped to dedicated priorities.
The priority is valid for 180 minutes.
It can be generated by the internal algorithm.
In this situation, the priority is delivered to the UE in an RRC Connection Release message when the UE attempts to release radio resources.
The priority is valid only during the interval specified by the timer T320ForLoadBalance or T320ForOther. Either timer is sent in the RRC Connection Release message: T320ForLoadBalance is sent if the release cause is "load balancing TAU required", and T320ForOther is sent if the release cause is "other". If the timer expires or the UE enters the RRC_CONNECTED mode, the algorithm-generated dedicated priorities become invalid.
For details about the timers and SPID, see 3GPP TS 36.331 and Flexible User Steering Feature Parameter Description respectively.
In eRAN sharing scenarios, the dedicated priority of a UTRAN or GERAN frequency can be set for different operators. The priority is specified by the CellReselPriority parameter in a MO UtranRanShare or GeranRanShare. A UE preferentially uses the dedicated priority that is associated with the UE‘s SPID. If the UE is not assigned an SPID or the SPID is not configured on the eNodeB, the UE uses the dedicated priority set in the UtranRanShare or GeranRanShare MO for the corresponding operator.
A UE deletes priorities provided by dedicated signaling in any of the following situations:
The PLMN is manually selected for the UE.
The UE enters the connected mode.
The validity time (T320ForLoadBalance or T320ForOther) of the dedicated priorities expires.
The absolute priority of the serving frequency is set by CELLRESEL. CellReselPriority which is broadcasted in the SIB3.
The Absolute Priority Configuration- the Serving Cell Reselection Priority (1/4)
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Parameter ID
Description
CellReselPrio
Indicates the cell reselection priority of the serving frequency. 0 indicates the lowest priority. This parameter is the networking planning parameter and needs to be planned in all frequency layers.
The Absolute Priority Configuration- EUTRAN Target Cell (2/4)
MOD EUTRANINTERNFREQ
Note: if priority indicator is set Not CFG, then UE doesn’t implement cell reselection to the target frequency.
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This priority will be broadcast in SIB5
The absolute priority of the neighboring GERAN frequency is set by GERANNFREQGROUP. CellReselPriority which is broadcasted in the SIB7.
The absolute priority of the neighboring UTRAN frequency is set by UTRANNFREQ. CellReselPriority which is broadcasted in the SIB6.
The Absolute Priority Configuration- the IRAT Neighbor Cell Reselection Priority(3/4)
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GSM
UMTS
The Absolute Priority Configuration - the IRAT Neighbor Cell Reselection Priority(4/4)
The absolute priority of the neighboring CDMA2000 frequency is set by CDMA2000BANDCLASS. Cdma20001XrttCellReselPri which is broadcasted in the SIB8.
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Dedicated Cell Reselection Priority Configuration and Application Overview
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Dedicated cell reselection priority in RRC Release is received by UE when UE leave RRC-Connected state.
Dedicated cell reselection priority is configured in eNodeB based on Operator policy for every SPID.
Step1:Dedicated cell reselection priority configuration in eNodeB
Step2: setup the mapping between dedicated priority and SPID
Step3: eNodeB send dedicated cell reselection priority to UE
Step4: UE firstly applies dedicated priority before the optional validity time of dedicated priorities (T320) expires.
By dedicated Priority based on SPID, Operators can make its subscribers to camp in a suitable RAT (a cell of LTE/UMTS/GSM) or frequency (a cell of LTE) based on the service characteristics. For example, for a data centric subscriber, a LTE cell will be the more suitable selection than an UMTS cell or a GSM cell; for a voice centric subscriber, a GSM cell or an UMTS cell will be the more suitable selection than a LTE cell.
UE
The Dedicated Priority Configuration for the Flexible User Steering
If flexible user steering feature is activated, we can set the dedicated priority based on subscriber profile ID, and valid duration is 180 min.
It is delivered to the UE in an RRC Connection Release message when the UE's radio resources are released.
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mapping
Dedicated priority
The dedicated priority is set by RATFREQPRIORITYGROUP. Priority . The dedicated priority of frequencies for one RAT must all be different from those for another RAT. The flexible user steering feature maps a subscriber profile ID (SPID) onto dedicated priorities of a group of frequencies by configuring the SPIDCFG object.
A UE deletes priorities provided by dedicated signaling in any of the following situations:
The NAS signals the AS to perform PLMN selection.
The UE enters the connected mode.
The validity time (specified byT320) of the dedicated priority expires.
The value of T320 is fixed to 180 minutes for UE’s SPID. Otherwise, timers configured in the following figure will be used.
Timers Configuration of the Dedicate Priority
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T320 and the dedicated priority are sent to the UE in the RRC Connection Release message. The eNodeB determines the value of T320 in the following two ways:
If the dedicated priority is associated with the UE's SPID, the value of T320 is fixed to 180 minutes.
If the dedicated priority is not associated with the UE's SPID, T320 is set by RRCCONNSTATETIMER. T320ForLoadBalance when the RRC connection is released due to load imbalance and by RRCCONNSTATETIMER. T320ForOther when the RRC connection is released due to other reasons.
For details about T320, see section 7.3 "Timers (Informative)" in 3GPP TS 36.331 R10, which was released in March 2011.
Parameter ID
Description
T320ForLoadBalance
Indicates the length of timer T320 that is configured in the case of load balancing. It refers to the time period during which the dedicated priorities (used for cell reselection) retain valid. The time period is contained in the RRCConnectionRelease message that is received by the UE. After the timer specified in the RRCConnectionRelease message expires, the dedicated priorities become invalid.
T320ForOther
Indicates the length of timer T320 that is configured in the case of load imbalancing. It refers to the time period during which the dedicated priorities (used for cell reselection) retain valid. The time period is contained in the RRCConnectionRelease message that is received by the UE. After the timer specified in the RRCConnectionRelease message expires, the dedicated priorities become invalid.
Before the cell reselection, a UE performs measurements of neighboring cells based on the RX signal level and quality of the serving cell and frequency priorities of the neighboring cells.
The UE only measures the neighboring frequencies broadcasted in the system information and the neighboring frequencies whose priority information is carried in the RRC Connection Release message.
The IRAT Neighboring Measurement Overview
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Inter-Frequency or Inter-RAT Measurement
To trigger inter-frequency or inter-RAT measurements, the following rules apply:
The UE always performs measurements on the inter-frequency or inter-RAT neighboring cells regardless of the RX signal level or quality of the serving cell if the priorities of the neighboring frequencies are higher than the priority of the serving frequency.
If the priorities of inter-frequency neighboring frequencies are less than or equal to the priority of the serving frequency, or if the priorities of inter-RAT neighboring frequencies are less than the priority of the serving frequency, the UE determines whether to start the corresponding measurements according to the following rules:
The UE does not perform inter-frequency or inter-RAT measurements if the RX signal level and quality of the serving cell are good, that is, if the Srxlev and Squal values of the serving cell are greater than SnonIntraSearchP and SnonIntraSearchQ, respectively. SnonIntraSearchP indicates the threshold for triggering inter-frequency or inter-RAT measurements, and is set by CELLRESEL. SNonIntraSearch . SnonIntraSearchQ indicates the threshold for triggering RSRQ-based inter-frequency or inter-RAT measurements, and is set by CELLRESEL. SNonIntraSearchQ . Both SnonIntraSearchP and SnonIntraSearchQ are broadcast in the SIB3.
The UE performs inter-frequency or inter-RAT measurements if the Srxlev or Squal value of the serving cell is less than or equal to SnonIntraSearchP or SnonIntraSearchQ, respectively.
The UE performs inter-frequency or inter-RAT measurements on neighboring cells regardless of the RX signal level or quality of the serving cell if CELLRESEL. SNonIntraSearchCfgInd is set to NOT_CFG. The value NOT_CFG indicates that the threshold for triggering inter-frequency or inter-RAT measurements does not need to be set. In this situation, SnonIntraSearchP and SnonIntraSearchQ are not broadcast in the SIB3; the UE uses the default settings of SnonIntraSearchP (default value: infinite) and SnonIntraSearchQ (default value: 0).
Neighboring Cell Measurement Procedure before Cell Reselection
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From SIB ,UE can get the serving cell and IRAT neighbors’ priorities.
For the high priority cells, UE measure them always, for the low priority cells, UE measure them in case of the serving cell signal is lower than the threshold.
The intra frequency cells have the same frequency priority, frequencies of different RATs must have different priorities.
Srxlev
Qqual
Before cell reselection, a UE performs measurements of neighboring cells based on the RX signal level and quality of the serving cell and frequency priorities of the neighboring cells.
The UE only measures the neighboring frequencies broadcast in the system information and the neighboring frequency whose priority information is carried in the RRC Connection Release message.
Inter-Frequency or Inter-RAT Measurement
To trigger inter-frequency or inter-RAT measurements, the following rules apply:
The UE always performs measurements on the inter-frequency or inter-RAT neighboring cells regardless of the RX signal level or quality of the serving cell if the priorities of the neighboring frequencies are higher than the priority of the serving frequency.
If the priorities of inter-frequency neighboring frequencies are less than or equal to the priority of the serving frequency, or if the priorities of inter-RAT neighboring frequencies are less than the priority of the serving frequency, the UE determines whether to start the corresponding measurements according to the following rules:
The UE does not perform inter-frequency or inter-RAT measurements if the RX signal level and quality of the serving cell are good, that is, if the Srxlev and Squal values of the serving cell are greater than SnonIntraSearchP and SnonIntraSearchQ, respectively. SnonIntraSearchP indicates the threshold for triggering inter-frequency or inter-RAT measurements, and is set by CELLRESEL. SNonIntraSearch . SnonIntraSearchQ indicates the threshold for triggering RSRQ-based inter-frequency or inter-RAT measurements, and is set by CELLRESEL. SNonIntraSearchQ . Both SnonIntraSearchP and SnonIntraSearchQ are broadcast in the SIB3.
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notes
The UE performs inter-frequency or inter-RAT measurements if the Srxlev or Squal value of the serving cell is less than or equal to SnonIntraSearchP or SnonIntraSearchQ, respectively.
The UE performs inter-frequency or inter-RAT measurements on neighboring cells regardless of the RX signal level or quality of the serving cell if CELLRESEL.SNonIntraSearchCfgInd is set to NOT_CFG. The value NOT_CFG indicates that the threshold for triggering inter-frequency or inter-RAT measurements does not need to be set. In this situation, SnonIntraSearchP and SnonIntraSearchQ are not broadcast in the SIB3; the UE uses the default settings of SnonIntraSearchP (default value: infinite) and SnonIntraSearchQ (default value: 0).
Data Configuration of Neighboring Cell Measurement Threshold
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SNonIntraSearchQ
SNonIntraSearchP
SNonIntraSearchCfgInd
For the neighbor with lower or equal priority
If the threshold is configured :
When Srxlev > SNonIntraSearchP and Squal > SNonIntraSearchQ, UE does not perform IRAT measurement
When Srxlev ≤ SnonIntraSearchP or Squal ≤ SNonIntraSearchQ UE perform inter frequency /RAT measurement
If the SNonIntraSearchCfgInd parameter is set to NOT_CFG, the UE always perform IRAT measurement
Low Prio.
S-eNB is worse than Thresh_serving.low & T-BTS is better than Thresh_x.low
T-eNB is better than Thresh_x.high
Cell Reselection
Cell Reselection Principal
High Prio. -> Low Prio.
UEs camp on Cell which providing best service
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Cell Reselection (High -> Low)
Cell Reselection (Low -> High)
Inter-RAT Cell Selection Criteria
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During reselection to an inter-RAT neighboring cell, the Srxlev and Squal values of inter-RAT neighboring cells need to be calculated as follows:
UTRAN Neighboring cell
Squal = Qqualmeas - (Qqualmin + Qqualminoffset)
Srxlev = -FLOOR(-2 x 10 x log10 Ec/Io)
Reselection to an inter-RAT cell can be classified into reselection to a higher-priority cell and reselection to a lower-priority cell.
Inter-RAT Cell Selection Criteria
During reselection to an inter-RAT neighboring cell, the Srxlev and Squal values of inter-RAT neighboring cells need to be calculated as follows:
UTRAN Neighboring cell
Squal = Qqualmeas - (Qqualmin + Qqualminoffset)
Pcompensation = max(UE_TXPWR_MAX_RACH - P_MAX, 0)
The variables in the preceding formulas are described as follows:
Qrxlevmeas is the measured RX signal level of the neighboring UTRAN cell.
Qqualmeas is the measured RX signal quality of the neighboring UTRAN cell.
The values of the preceding parameters are broadcast in the SIB6 from the E-UTRAN when the UE implements reselection estimation on a neighboring UTRAN cell.
Qrxlevmin is set by the UTRANNFREQ. QRxLevMin parameter.
Qqualmin is set by the UTRANNFREQ. Qqualmin parameter.
UE_TXPWR_MAX_RACH is set by the UTRANNFREQ. PmaxUtran parameter.
P_MAX is the maximum output power that the UE can physically provide. It is unconfigurable on the network side.
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notes
Values of Qrxlevminoffset and Qqualminoffset are obtained from UTRAN system information. For details, see section 5.2.3.1 "UTRA case" in 3GPP TS 25.304 R10, which was released in March 2011.
GERAN Neighboring cell
Srxlev = Qrxlevmeas - Qrxlevmin - Pcompensation
Qrxlevmeas is the measured RX signal level of the neighboring GERAN cell.
Pcompensation = max(MS_TXPWR_MAX_CCH - P, 0)
The values of the preceding parameters are broadcast in the SIB7 from the E-UTRAN when the UE implements reselection estimation on a neighboring GERAN cell.
Qrxlevmin is set by the GERANNFREQGROUP.QRxLevMin parameter.
MS_TXPWR_MAX_CCH is set by the GERANNFREQGROUP.PmaxGeran parameter.
P is the maximum output power that the UE can physically provide. It is unconfigurable on the network side.
For details, see section 3.6 "Radio constraints" in 3GPP TS 43.022 R10, which was released in March 2011.
CDMA2000 Neighboring cell
Srxlev = -FLOOR(-2 x 10 x log10 Ec/Io)
Ec/Io is the measured RX signal quality of the neighboring CDMA2000 cell.
For details, see 3GPP2 C.S0005-A.
The General Procedure of Reselection to a Higher-priority Cell
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When ThrshServLowQCfgInd CFG that is to say, SIB3 contains threshServingLowQ, only for EUTRAN and UTRAN neighbour cells, using :
Squal>Threshx.highQ.
While for GERAN and CDMA neighbour cells , no matter whether ThrshServLowQCfgInd CFG, always using:
Srxlev> Threshx.high
Cell Reselection( Low -> High)
Parameter threshServingLowQ is available only when “ThrshServLowQCfgInd” is configured as CFG(Configure).
The Data Configuration of Reselection to a Higher-priority Cell(1/2)
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TReselUtran
TReselGeran
ThreshXHigh
ThreshXHighQ
ThreshXHigh
GERAN
UTRAN
The Data Configuration of Reselection to a Higher-priority Cell(2/2)
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CDMA2000
TreselectionHrpd
Cdma1XrttTreselection
Cdma2000HrpdThreshXHigh
Cdma20001XrttThreshXHigh
The General Procedure of Reselection to a Lower-priority Cell
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When ThrshServLowQCfgInd CFG that is to say, SIB3 contains threshServingLowQ,
For serving cell, Squal<threshServingLowQ
For EUTRAN and UTRAN neighbour cells, Squal>threshXLowQ
When ThrshServLowQCfgInd NOT CFG,
For EUTRAN and UTRAN neighbour cells, Srxlev>threshXLow
While for GERAN and CDMA neighbour cells , no matter whether ThrshServLowQCfgInd CFG,
Srxlev> threshXLow
Cell Reselection (High -> Low)
The Data Configuration of Reselection to a Lower-priority Cell(1/2)
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UTRAN
GERAN
TReselUtran
TReselGeran
ThreshXLow
ThreshXLowQ
ThreshXLow
The Data Configuration of Reselection to a Lower-priority Cell(2/2)
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CDMA2000
Cdma20001XrttThreshXLow
TreselectionHrpd
Cdma1XrttTreselection
Cdma2000HrpdThreshXLow
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Contents
LTE->GU Cell Reselection – GnGp SGSN
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Locate UE identity
MME check P-TMSI signature
MME mapping MM context
MME performs EPS and PDP context mapping include pre-R8 and R8 QoS mapping
Create PDP context and delete bearer
Other step is just as intra RAU
When the UE in idle mode leaves the area covered by both the LTE network and GERAN/UTRAN and enters an area covered solely by the GERAN/UTRAN, cell reselection occurs. The UE initiates the RAU procedure to camp on the GERAN/UTRAN cell. Figure in the slide above shows the signaling procedure of the cell reselection from the LTE network to the GERAN/UTRAN.
For details on the signaling procedure, see Appendix D.3.5 of TS23.401. This course focuses on only major parameters and steps.
0. The UE selects a GERAN/UTRAN cell. The routing area of the cell is not registered with the network.
The UE sends an RAU request to the new SGSN. This request includes parameters such as old-TMSI (TMSI stands for temporary mobile subscriber identifier), old RAI (RAI stands for routing area identifier), old P-TMSI signature (P-TMSI stands for packet-temporary mobile subscriber identity), and Update Type.
The new SGSN obtains SGSN contexts from the MME.
The new SGSN sends an SGSN context request to the MME to obtain Mobility Management (MM) contexts and PDP contexts.
The MME completes the mapping between EPS bearers and PDP contexts and the mapping of EPS bearer QoS parameters to pre-Rel-8 QoS parameters. After the mapping is complete, the MME sends an acknowledgement to the new SGSN. The response includes MM contexts and PDP contexts. At the same time, the MME starts a timer, which controls the subsequent deletion of bearers.
If the PDP contexts sent by the MME do not include any security parameters, the security procedure is required.
0. UE changes to UTRAN or GERAN
S-GW
13. Delete Session Response
13. Delete Session Request
8. Cancel Location Ack
10. Update Location Ack
2. SGSN Context Request
3. Security Functions
LTE->GU Cell Reselection, GnGp SGSN
Notes
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The new SGSN receives SGSN contexts from the MME and returns a confirmation message to the MME. Then, the MME invalidates the contexts of the P-GW/S-GW and HSS.
The P-GW updates the PDP contexts as follows
The new SGSN sends a PDP context update request to the P-GW.
The P-GW updates the PDP contexts and sends an acknowledgement to the new SGSN.
The new SGSN instructs the HSS to update location information.
Before updating location information, the HSS cancels the location information in the old SGSN.
The HSS instructs the old SGSN to cancel location information.
After canceling location information, the old SGSN sends an acknowledgement to the HSS.
Before updating location information, the HSS inserts subscriber data into the new SGSN.
The HSS inserts subscriber data to the new SGSN.
The new SGSN accepts the subscriber data inserted by the HSS and sends an acknowledgement to the HSS.
After updating the location information, the HSS sends an acknowledgement to the new SGSN.
The new SGSN obtains SGSN contexts and subscriber data. After updating the location information, the new SGSN sends an RAU accept message to the UE.
After the RAU procedure is complete, the UE sends an acknowledgement to the new SGSN.
When the timer started in step 2b expires, the MME initiates the deletion of the original bearers.
The MME sends a bearer deletion request to the S-GW.
The S-GW deletes the original bearers and sends an acknowledgement to the MME.
If an S1 connection is established on the user plane before the RAU procedure is initiated, the MME must instruct the eNodeB to release the S1 connection. After released, the eNodeB sends an acknowledgement to the MME.
GU->LTE
Locate UE identity
MME check PTMSI signature
MME performs EPS and PDP context mapping include pre-R8 and R8 QoS mapping
Crete PDP context and delete PDP context
Other is just as the same as intra E-UTRAN TAU
When the UE in idle mode moves into an area covered by both the LTE network and GERAN/UTRAN, the UE reselects an LTE cell with a high priority. The UE initiates the TAU procedure to camp on an LTE cell. Figure 3-9 shows the signaling procedure of the cell reselection from the GERAN/UTRAN to the LTE network.
For details on the signaling procedure, see Appendix D.3.6 of TS23.401.
When the UE moves into an area covered by both the LTE network and GERAN/UTRAN, the UE selects an LTE cell to camp on. The TAU procedure is triggered.
The UE sends a TAU request to the eNodeB. The TAU request includes parameters such as last visited TAI (TAI stands for tracking area identity), P-TMSI Signature, and old GUTI (GUTI stands for globally unique temporary identity).
The eNodeB selects a proper MME and forwards the TAU request to the MME.
The MME obtains contexts from the old SGSN. The MME sends an SGSN Context Request message to the old SGSN to obtain MM contexts and PDP contexts.
The old SGSN sends a response to the MME. The response includes MM contexts and PDP contexts. At the same time, the old SGSN starts a timer, which controls the subsequent deletion of bearers.
If the PDP contexts sent from the old SGSN do not include any security parameters, the security procedure is required.
The MME receives the SGSN contexts and returns a confirmation message to the old SGSN. Then, the old SGSN invalidates the contexts of the SGSN and HLR.
TAU procedure
HSS
GW
PDN
SGSN
Gn/Gp
MME
eNodeB
UE
19. Iu Release Complete
18. Iu Release Command
6. Security procedures
NOTES
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The MME maps the PDP contexts one by one to EPS bearers and maps the pre-Rel-8 QoS parameters to the QoS parameters of the EPS bearers. The MME sends a session setup request to the S-GW. The parameters in the request include IMSI (IMSI stands for international mobile subscriber identity), MME Address and TEID (TEID stands for tunnel end point identifier), P-GW Address and TEID, and EPS Bearer QoS.
The S-GW creates contexts and sends a bearer update request to the P-GW. The bearer update request is used to inform the P-GW that the RAT of the UE is changed and the bearer update is required.
If a PCRF is deployed on the network, the P-GW forwards RAT information to the PCRF. The PCRF then performs IP-CAN session establishment.
The P-GW can proceed with the following operations before the PCRF completes IP-CAN session establishment. If the execution result of the PCRF requires bearer update, the P-GW initiates the bearer update procedure.
The P-GW updates contexts and sends a bearer update response to the S-GW.
The S-GW updates contexts and sends a session creation response to the MME.
The MME instructs the HSS to update location information.
Before the HSS updates location information, it sends a cancel location message to the old SGSN. After receiving the message, the old SGSN cancels the location information about the UE.
If Iu connections are established before the TAU request is initiated, the old SGSN initiates the release of Iu connections on receiving the cancel location message.
When the data transfer timer expires, the RNC informs the old SGSN that the Iu connections are released.
The old SGSN sends an acknowledgement to the HSS.
After updating the location information, the HSS sends an acknowledgement to the MME.
The UE completes the TAU procedure. The MME accepts the TAU request and sends E-UTRAN's roaming restrictions and access restrictions for the UE to the eNodeB.
The UE returns a response to the MME after completing the TAU procedure.
LTE->GU
Cell Seselection–
S3/S4 SGSN
(S-GW Unchanged)
Locate UE identity
MME check PTMSI signature
S4 SGSN performs EPS and PDP context mapping include pre-R8 and R8 QoS mapping
Modify EPS bearer
For details on the signaling procedure, see section 5.3.3.3 of TS23.401.
9. PCEF Initiated IP-CAN Session Modification
22b. Modify Bearer Response
22. Modify Bearer Request
connection
10. Modify Bearer Response
3. Context Request
6. Context Acknowledge
5. Authentication
(A)
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Locate UE identity
MME Check PTMSI signature
MME Mapping MM context
S4 SGSN performs EPS and PDP context mapping include pre-R8 and R8 QoS mapping
Modify EPS bearer
When the UE in idle mode moves into an area covered by both the LTE network and GERAN/UTRAN, the UE reselects an LTE cell with a high priority. The UE initiates the TAU procedure to camp on an LTE cell, and the S-GW remains unchanged. Figure 3-10 show the signaling procedure of the cell reselection from the GERAN/UTRAN to the LTE network.
11. PCEF Initiated IP-CAN
MME
eNodeB
UE
ServingGW
HSS
PDN
eNodeB
UE
18. Iu Release Complete
17. Iu Release Command
6. Authentication / Security
5. Context Response
Thank you
Idle Mode
Cell Selection
(PHICH) parameters, and System Frame Number (SFN)
Parameters related to cell access and cell selection and scheduling
information of SI messages
SIB2
SIB10
SIB11
SIB12
SIB13
SIB3
SIB4
SIB5
SIB6
SIB7
SIB8
SIB9
Common cell reselection parameters;
intra-frequency cell reselection parameters
Intra-frequency Ncell related parameters
Intre-frequency Ncell related parameters
UTRAN Ncell related parameters
GERAN Ncell related parameters
CDMA2000 Ncell related parameters
2. SGSN Co
7. Update Location
8. Cancel Location
9. Ins
S
13. S1
14. Update Location Request
15. Cancel Location
UE eNodeB MME
21. Update
Location Ack
13. Cancel Location
UE
RNC/
BSS
eNodeB
SGSN
MME
Serving
GW
PDN
GW
HSS
Release E-UTRAN
PCRF
14. Update Location Request
15. Cancel Location
7. Context Acknowledge
4. Context Request
UE eNodeB
19. Update Location Ack
16. Cancel Location Ack
procedure
RRC Connection (SRB)
Send and/or Receive Data to/from UE
Network Controlled Mobility
UE Reports Channel Quality
DRX can be Configured

Documents

LTE Interoperability in Idle Mode(LTE-GU)