August 2012 C2 – Company Confidential SOURCE: CT Telecom: Lupeng Li, Yuezhen Wang ， Alcatel-Lucent: Jialin Zou, Satish Kanugovi, Orlett Pearson; jialin.zou, satish.k, orlett.pearson Huawei: Jixing, Liu, Yingming, Wang; Qualcomm, Inc.: Jun Wang, Wentao Zhang, George Cherian, Jen Chen jwang, wentaoz ZTE: Yuanfang Yu, Ting Lu, ABSTRACT: UE class and randomization based scheme is proposed for idle traffic redistribution from eHRPD to LTE. TITLE: TSG-C RECOMMENDATION: Discuss and adopt for C.S0087. The source companies of this contribution grant a free, irrevocable license to 3GPP2 and its Organizational Partners to incorporate text or other copyrightable material contained in the contribution and any modifications thereof in the creation of 3GPP2 publications; to copyright and sell in Organizational Partner's name any Organizational Partner's standards publication even though it may include all or portions of this contribution; and at the Organizational Partner's sole discretion to permit others to reproduce in whole or in part such contribution or the resulting Organizational Partner's standards publication. The source companies of this contribution is also willing to grant licenses under such contributor copyrights to third parties on reasonable, non-discriminatory terms and conditions for purpose of practicing an Organizational Partner’s standard which incorporates this contribution. This document has been prepared by The source companies of this contribution to assist the development of specifications by 3GPP2. It is proposed to the Committee as a basis for discussion and is not to be construed as a binding proposal on The source companies of this contribution. The source companies of this contribution specifically reserves the right to amend or modify the material contained herein and to any intellectual property of The source companies of this contribution other than provided in the copyright statement above. UE Class and Randomization Based Idle Reselection

Load Balancing between eHRPD and E-UTRAN  Background  Requirement from China Telecom at Nanjing meeting, refer to [C CT-Requirement for loading balance between eHRPD and E-UTRAN]. 2

High Level Design  Load Balance Control Between eHRPD and LTE  Controlled by UEClass  The operator can control which UE class(es) should transition from eHRPD to LTE  Controlled by randomization procedures  When UE Class based load balance doesn’t fully solve load balance need  Interaction with existing idle-mode reselection mechanism defined in C.S0087  If serving priority and EARFCN priority is provided, then:  If the UE is set to go to LTE, the UE will ignore the serving frequency priority unless all LTE frequencies do not meet signal strength requirement  If the UE is set to stay in eHRPD, the UE will ignore LTE priorities unless eHRPD does not meet signal strength requirement  If serving priority and EARFCN priority is not provided, then:  If the UE is set to go to LTE, the UE will ignore eHRPD unless all LTE frequencies do not meet signal strength requirement.  If the UE is set to stay in eHRPD, the UE will ignore LTE unless eHRPD does not meet signal strength requirement  The rest follows the existing idle-mode reselection procedures 3

UEClass Definition and Provision  A new attribute UEClass is proposed  UEClass is created from subscription data or operator/vendor-based policy, could be specified by the network during initial call setup  When network detects its loading problem:  eAN broadcasts inter-RAT reselection rules to the UEs through UEClass based control signaling 4

UEClass Control Mechanism  UEs can be divided in 8 classes per operator policy  Two possible ways to control UEClass:UEClass threshold mode or UEClass bitmap mode  UEClass threshold Mode  3 bits UEClass number is broadcasted, UE Classes with numbers equal or higher than it go to LTE based on the specified randomization mode; UE classes with numbers less than it will stay in eHRPD  UEClass bitmap Mode  8 bits UEClass bitmap is broadcasted, 1 bit for each UEClass k; If UEClass_k=0 means eAN indicates UEs of class k stay in eHRPD; UEClass_k=1 means eAN indicates UEs of class k go to EUTRAN based on the specified randomization mode. 5 UEClass_8 indicator 1 Bit … UEClass_2 indicator UEClass_1 indicator 1 Bit UEClass Bitmap Mode UEClass Threshold 3 Bits UEClass Number Mode

Example: UE’s Behavior without Randomization 6 UE1 UE2 UE3 UE4 UE5 UE6 UE7 UE8 UE9 UEClass 1 UEClass 2 UEClass 3 indicates UEClass 1,2 stay in eHRPD, indicates UEClass 3 go to EUTRAN LTE eNodeB eHRPD AN UE1 UE2 UEClass 1 UEClass 2 LTE eNodeB eHRPD AN UE3 UE4 UE5 UE6 UE7 UE8 UE9 UEClass 3 time

 UEClass Mode indicator(GREEN), 1 bit  UEClass Mode indicator=0 means eAN uses UE class threshold mode  UEClass Mode indicator=1 means eAN uses UE class bitmap mode  UEClass_k indicator (YELLOW), 3 bits or 8 bits  For UE class threshold mode, 3 bits long  UE class=k means UE classes w/ numbers equal or larger than k shall go LTE; all the other UE classes stay in eHRPD  For UE Class bitmap mode, 8 bits long  UEClass_k=0 means eAN indicates UEs of class k stay in eHRPD  UEClass_k=1 means eAN indicates UEs of class k go to EUTRAN  Randomization_Mode Indicator (RED): 2 bit for all UE Classes  Randomization _mode=0 means UEs of all class shall not be randomized  Randomization _mode=1 means UEs of all class shall be randomized per LTE carrier probability  Randomization _mode=2 means UE shall be randomized per its own UEClass probability Message Format 7 UEClass Mode indicator 3 Bits 1 Bit UEClass mode value Randomizati on _mode 3 or 8 bits 2 Bit UE class mode value randomization _mode indicator LTE F1 probability LTE F2 probability … LTE FK probability LTE Multicarrier probabilities 3 Bits UE class mode indicator 2 Bits UEClass_8 probability UEClass_7 probability … UEClass_1 probability UEClass probabilities 2 Bits

 Randomization mode Indicator (RED): 2 bit for all UE Classes  LTE Multicarrier Randomization probability (BLUE): 3 bits for each LTE carrier  Notifies new UEs the probability of each LTE carrier for randomization and load balance and a UE reselects to the carrier at that probability  A UE will stay with CDMA at a probability = 1 – Sum of LTE carrier probabilities  Only present when Randomization _mode=1  UEClass Randomization Probability (Purple): 2 bits for each UEClass  Only present when Randomization _mode=2 Message Format-2 8

 If UEClass k UEs are redirected to EUTRAN, the UE performs the following procedures (assuming the LTE and eHRPD signal are good enough) :  UE derive the Serving Probability = 1 – sum of all the LTE carrier probabilities  The UE randomly generates a UEReselectionProbability (URP) over the range of (0~1) showing in the following diagram as an example  If URP value falls into interval T k of the following figure, then UE selects the carrier k with associated probability Prob k  If serving probability = 0, then all UEs select one of the available LTE carriers  If serving probability is NOT ZERO, then UEs in interval T 1 stay back in serving HRPD system Randomization Mode 1 Procedure Here Prob serving +Prob 1 +Prob+ …+Prob N =1 Probability value 0 Prob serving Prob serving +Prob 1 Prob serving +Prob 2 +Prob 1 … …. 1 Interval T 1 Interval T 2 Interval T 3 Interval T N 9

 If UEClass k UEs are redirected to EUTRAN, the UE performs the following procedures (assuming the LTE and eHRPD signal are good enough) :  The UE randomly generates a UERandomValue (URV) over the range of (0~1)  The UE gets the UEClassProbability for UEClass k (which broadcasts by AN through overhead message), mark it as UC_Prob k  If URV UC_Prob k, UE is still in eHRPD Randomization Mode 2 Procedure 10

 Upon entering a new cell, the UE executes the probability test.  UE executes the probability test upon receiving an indication by the AN to do the probability test. The Rules for Triggering Probability Test in Randomization 11

Recommendation  Adopt eHRPD-LTE load balance mechanism controlled by UEClass threshold or bitmap  UEs perform randomization per UEClass or per LTE carrier 12

Thanks 13