1. August 2012 C2 – Company Confidential SOURCE: Alcatel-Lucent: Jialin Zou, Satish Kanugovi, Orlett Pearson jialin.zou@, satish.k (@alcatel-lucent.com) Qualcomm, Inc.: Jun Wang, Wentao Zhang, George Cherian, Jen Chen jwang, wentaoz (@qti.qualcomm.com) ABSTRACT: UE class and randomization based scheme is proposed for idle traffic redistribution from eHRPD to LTE. TITLE: TSG-C RECOMMENDATION: Discuss and adopt. 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

2. Load Balancing between eHRPD and E-UTRAN  Background  Requirement from China Telecom at Nanjing meeting, refer to [C22- 20120206-020 CT-Requirement for loading balance between eHRPD and E-UTRAN]. 2

3. 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 the UE is set to go to LTE, the UE will set the serving frequency priority to be the lowest  If the UE is set to stay in eHRPD, the UE will set the serving frequency priority to be the highest  The rest follows the existing idle-mode reselection procedures 3

4. 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 using UEClass bitmap to the UEs through overhead signaling 4

5. UEClass Bitmap Concept  UEs can be divided in 8 classes per operator policy  UEClass_k indicator (k=1, 2,..,8), 1 bit for each UE class  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 5 UEClass_8 indicator 1 Bit … UEClass_2 indicator UEClass_1 indicator 1 Bit UEClass reselection indicator

6. 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

7.  In addition to UEClass reselection indicator, 1 bit randomization indicator is introduced to control if multi-carriers randomization is enabled  UEClass bitmap(s) indicate(s) whether some UE classes go to EUTRAN or stay in eHRPD. If redirected to EUTRAN, multi-carriers randomization may be enabled.  It is desirable to consider multi-carrier randomization with the impacts of legacy UEs  Therefore, a new set of LTE frequency probability parameter is introduced (with the probability of stay with serving derived) for new UEs to allow the operator to better control load balance  If UE is indicated not using randomization procedures:  If UE is indicated go to EUTRAN, the UE shall set eHRPD serving priority to lowest and follow existing reselection procedure.  If UE is indicated to stay in eHRPD, it will ignore randomization bit value, set eHRPD serving priority as highest and follow existing reselection procedure.  If UE is indicated using randomization procedures:  If UE is indicated go to EUTRAN and randomization bit is set to 1, the UE shall follow multi frequency reselection procedure.  If UE is indicated to stay in eHRPD, it will ignore randomization bit value, set eHRPD serving priority as highest and follow existing reselection procedure.  No matter whether UEClass bitmap is broadcasted or not, all legacy UEs will follow existing reselection procedure. Randomization Procedures 7

8.  UEClass_k indicator (YELLOW), 1 bit for each UE class  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 Indicator (RED): 1 bit for all UE Classes  Randomization _indicator=0 means UEs of all class shall not be randomized  Randomization _indicator=1 means UEs of all class shall be randomized  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 _indicator=1 Message Format 8 UEClass_8 indicator 3 Bits 1 Bit … UEClass_2 indicator Randomizati on _indicator UEClass_1 indicator 1 Bit UEClass reselection indicator randomization indicator LTE F1 probability LTE F2 probability … LTE FK probability LTE Multicarrier probabilities 3 Bits

9.  If UEClass k UEs are redirected to EUTRAN(UEClass_k=1) randomization indicator set to 1, the UE performs the following procedures:  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  If the selected carrier signal is weak, then UE sets the selected carrier priority to lowest and follows existing idles reselection procedure Probability Based Multi-Carrier Randomization 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

10.  Assume eAN broadcasts three LTE carriers with probabilities 0.2(F1), 0.3(F2) and 0.5(F3), eHRPD probability=0.  Assume eAN broadcast three LTE carriers with priorities 3 (F1), 6 (F2) and 4 (F3) in OtherRATNeighbor message.  Example 1: Assume UE generated URP value is 0.1, then  If F1 signal is good, UE goes to F1  If F1 signal is weak, UE performs existing idle reselection procedure w/ F2(priority=6) first, then F3(priority=4)  Example 2: Assume UE generated URP value is 0.4, then  If F2 signal is good, UE goes to F2  If F2 signal is weak, UE performs existing idle reselection procedure w/ F3(priority=4) first, then F1(priority=3) Examples 10 Probability value 0 0.2 0.2+0.3 1 F1 Interval T 1 F2 Interval T 2 F3 Interval T 3

11. Recommendation  Adopt eHRPD-LTE load balance mechanism controlled by UEClass as specified in this document  Consider multiple LTE carrier randomization with impacts of legacy UEs proposed in this document 11

12. Thanks 12