Interworking with LTE Source: Mike Dolan Tony Lee Consulting Member of Technical StaffPrincipal Engineer Alcatel-LucentVIA Telecom

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 2 Interworking with LTE At the CORE and RAN Level –LTE  eHPRD How eHRPD connects to the same Enhanced Packet Core (EPC) Handoff –LTE  cdma2000 ® 1x CSFB, eCSFB SMS At the RADIO Level –LTE  eHPRD –eHPRD  LTE –Circuit Switch Fall Back –Registration –SMS June 14, 2012 cdma2000 Technology Workshop 广州 Slide 2

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 3 Why Interwork between LTE and 1x/eHRPD? Simply: CDMA operators need a smooth transition path to take their subscribers to LTE technology. –Keep subscribers happy –Offer subscribers new features –Manage competition from other operators –Optimize the use of their spectrum –Take greatest advantage of their installed infrastructure while upgrading to LTE

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 4 LTE  eHPRD How eHRPD connects to the same Enhanced Packet Core (EPC) PDN Gateway Serving Gateway MME eNodeB HSS/AAA Home Agent Internet HSGW PDS N eAN/ ePCF AN/ PCF PCRF 3GPP2 AAA Signaling Data UE

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 5 Non-Optimized Handoff from LTE to eHRPD MME HSS/AAA Internet PCRF Signaling Data UE PDN Gateway Serving Gateway eNodeB HSGW eAN/ ePCF

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 6 HSS/AAA Internet PCRF Signaling Data UEUE S101 Optimized Handoff from LTE to eHRPD Step 1: Establish context on eHRPD via tunneled signaling PDN Gateway eNodeB Serving Gateway MMEHSGW eAN/ ePCF

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 7 Optimized Handoff from LTE to eHRPD Step 2: UE moves to eHRPD, bearers are moved HSS/AAA Internet PCRF Signaling Data UE S101 PDN Gateway Serving Gateway eNodeB HSGW eAN/ ePCF MME

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 8 Comparison of Optimized vs. Non-Optimized Optimized handoff takes less than 300 msec. Non-optimized handoff can take as much as 5-7 seconds. Optimized handoff requires in addition to what non-optimized needs: –S101 tunneling –Upgrades on the UE, MME, eAN/ePCF, HSGW

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 9 Circuit Switched Fall Back (CSFB) Core Network and RAN Uses tunneled signaling to the UE across the S102 interface between the IWS and MME. This supports: –CSFB, enhanced CSFB (eCSFB) –SMS

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 10 CSFB Page sent to IWS. IWS sends page to UE via MME and eNodeB using S102. UE moves to 1x. UE sends a normal page response on the 1x access channel. Call proceeds. IWS 1x BS Signaling Data UE MSC S102 eNodeB MME

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 11 eCSFB Page sent to IWS. IWS sends page to UE via MME and eNodeB using S102. UE sends a page response via the eNodeB and MME using S102. IWS sends a handoff command (UHDM) to the UE via S102, and sets up the traffic channel on 1x in preparation for the UE. UE does a handoff to the 1x traffic channel. 1x call proceeds. IWS 1x BS Signaling Data UE MSC S102 eNodeB MME

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 12 Comparison of CSFB to eCSFB CSFB requires extra time on 1x due to hashing and other procedures. For eCSFB, the traffic channel is prepared and waiting for the UE to arrive. Some issues at the radio level will be discussed later, when the radio level is covered.

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 13 SMS MT-SMS –SMS are sent via S102 to the UE –UE does not leave LTE. MO-SMS –SMS are sent via S102 from the UE –UE does not leave LTE. IWS 1x BS Signaling Data UE MSC S102 Both mobile-originated and mobile-terminated are supported. eNodeB MME

Radio Level June 14, 2012 cdma2000 Technology Workshop 广州 Slide 14

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 15 LTE-eHRPD Protocol Structure

June 14, 2012cdma2000 Technology Workshop 广州 Slide 16 Air Interface Protocol Enhancements New protocols to support LTE to eHRPD handover –Default Signaling Adaptation Protocol –Inter-RAT Initialization, Idle State, Route Update, Overhead Message, and Signaling Adaptation Protocols –Support for C.S0024-B Some existing protocols were also affected. Documented in C.S0087

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 17 Changes to the Application Layer Added alternate packet application subtype for: –MFPA -> Alternate MFPA –EMFPA -> Alternate EMFPA –MLMFPA -> Alternate MLMFPA The alternate packet application subtype is to identify the support of eHRPD

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 18 eHRPD to LTE Two methods available: OtherRATNeighborList Message –Broadcasted message –Contains E-UTRAN information for AT to search for E- UTRAN system –Threshold InterRATRedirect –Contains E-UTRAN redirection information

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 19 eHRPD  E-UTRAN inter-RAT redirection

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 20 LTE to 1x tunneling S102 Tunnel

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 21 1x to LTE OtherRATNeighborList Message –Broadcasted message –Contains E-UTRAN information for AT to search for E- UTRAN system –Threshold

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 22 Thank You! For more information, please visit INFORMATIONLINKS About 3GPP2http:// Partnershttp:// Membershttp:// Committeeshttp:// Specificationshttp:// Procedureshttp:// News/Eventshttp:// Contact ushttp:// How to joinhttp:// Related Linkshttp:// 22

cdma2000 ® is the trademark for the technical nomenclature for certain specifications and standards of the Organizational Partners (OPs) of 3GPP2. Geographically (and as of the date of publication), cdma2000 ® is a registered trademark of the Telecommunications Industry Association (TIA-USA) in the United States.

Backup

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 25 Signaling Adaptation Protocol Context

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 26 SAP functionalities Records the current air interface (HRPD or non-HRPD) Provides a virtual connection service between the access terminal and the access network over the S101 tunnel Provides encapsulation of HRPD packets over S101 Triggers idle and active handoffs from LTE to eHRPD It has a control plane as well as a user plane functionality

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 27 Changes to MAC and PHY Layer Initial output power calculation –X0 = - Mean RX Power (dBm) + OpenLoopAdjust + PilotInitialAdjust where: PilotInitialAdjust = InitialAdjust + min(PilotStrengthCorrectionMax, max(PilotStrengthNominal – PilotStrength, PilotStrengthCorrectionMin)), –This is necessary due to lack of access probe power correction.

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 28 Interworking with LTE Radio Level LTE  eHPRD non-optimized handoff –S-101 interface is not used. –Idle handoff from LTE to eHRPD –LTE SIB8 provides information on nearby eHRPD cells

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 29 Interworking with LTE Radio Level LTE  eHPRD non-optimized handoff –S-101 interface is not used.

June 14, 2012 cdma2000 Technology Workshop 广州 Slide 30 LTE  1x Tunneling on S102 Supports: –Circuit Switch Fall Back (CSFB) –Enhanced CSFB (eCSFB) –SMS, mobile-originated and mobile- terminated