1. August 2012 C2 – Company Confidential SOURCE: Jialin Zou, Satish Kanugovi (Alcatel-Lucent) jialin.zou@, satish.k (@alcatel-lucent.com)satish.k (@alcatel-lucent.com ABSTRACT: A combined probability and priority grouping based idle traffic redistribution scheme is introduced in this proposal. The motivations and the merits of the scheme are described. 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. Idle AT Re-distribution and Load Balance between HRPD and LTE

2. 2 | | Motivations Proactive inter-RAT idle AT load balance will significantly reduce the chance of access overload and active traffic overload  Traffic model study indicated that the ratio of num. of active ATs vs. num. of idle ATs is a stable constant value The existing priority based reselection mechanism is basically adopted from LTE and it didn’t fully serve its original design purpose  It only conducts an on/off idle traffic redistribution – The value differences between the serving priority and the highest target priority do not change the behavior  As long as one carrier’s (LTE or HRPD) priority is set higher than others, most of the idle mobiles will reselect to the carrier with the highest priority  It is very hard for operator to conduct the load balance and very likely causing the jitter of the surging load between the LTE and HRPD carriers Support the typical LTE/HRPD coverage scenarios  HRPD has global coverage and LTE has spotty coverage overlaid with HRPD  Both HRPD and LTE have global coverage and is overlaid with each other

3. Example of Idle Traffic Re-distribution Requirement 3 | |

4. What is proposed? Support Network (NW) controlled HRPD to LTE partial re-selection and selective traffic re-direction based on load of HRPD/LTE carriers  It is desired to have a balanced load for overlaid HRPD and LTE carriers when traffic move from HRPD only coverage to LTE+HRPD overlaid coverage area ATs determining probability of reselection based on Randomization Consider the subscription priority based reselection to achieve better GoS and QoS Determining target LTE carrier for reselection with consideration to load on the target carrier 4 | |

5. All Rights Reserved © Alcatel-Lucent 2007 Combined probability and priority grouping based idle redistribution

6. What is needed? Define reselection classes for ATs For GoS/QoS ATs, based on subscription priority For normal ATs, randomly pick a normal reselection class (normally they are considered having same priority and not pre-assigned a class) Any soft-reselection-enabled normal classes are treated the same Allow operators some flexibility to assign ATs to different normal classes following certain prioritizing criteria – left to operator implementation Define signaling for network to configure reselection class for the AT, e.g.: attribute exchanged during session negotiation Define a bitmap to indicate the target carrier for reselection for QoS AT classes Define a bitmap per target carrier Size of bitmap => number of GoS/QoS AT classes Define mechanism for AT to choose reselection probability based on randomization 6 | |

7. Mechanism Network indicates via bitmap, which AT classes will reselect to target carrier Size of bitmap => number of QoS AT classes + Normal AT classes – one bit for each AT class For Normal AT classes ‘1’ indicates that AT does probability based reselection, ‘0’ indicates that AT does not do reselection For QoS AT classes ‘1’ indicates that AT does probability based reselection E.g.: If the group of ATs with this QoS AT class is large ‘0’ indicates that AT relies on bitmap of target carrier(s) to select reselection target If the AT moves into legacy system, where there is no bitmap broadcast by the network, the AT shall follow the rules of probability based soft reselection  Allows legacy system to conduct the soft UE redistribution with the new ATs 7 | |

8. Example of combined scheme operations 8 | | For UEs in normal groups (2~5), UEs randomly reselect to a LTE carrier based on the broadcast guidance from network on the serving and neighboring carriers, UEs in groups 0 and 1 stay with the serving carrier Priority group 12, 13 will be re-distributed to F1 Priority group 10, 11 will be re-distributed to F2 Priority group 9 is big in size, probability based reselection is enabled Priority group 6, 7, 8 stay with the serving carrier

9. Use the carrier reselection priorities in overhead message control the idle traffic random redistribution The existing carrier reselection priorities in the overhead message (OtherRATNeighborList) are used by the new reselection procedures  New ATs will follow the existing EARFCNPriority(s) and ServingPriority to perform the new priority based reselection procedures  The legacy ATs will follow the existing procedures with existing priorities  The percentage of the idle UE redistribution is controlled by setting the priority values constantly or dynamically 9 | Load Balance & Control

10. 10 | | Idle AT Reselection from HRPD to LTE with a Probability Controlled by NW Setting of Reselection Priorities Basic procedures when an AT received the IWK overhead message (OtherRATNeighborList) broadcast by the BTS  The AT will randomly generate a ATReselectionPriority (ARP) which is uniformly distributed between 0 to 7  If the randomly generated ARP of an AT is lower than the ServingPriority, the AT shall follow the existing reselection procedures as if ServingPriority is equal to or higher than all the EARFCNPriority(s)  If the ARP is equal to or higher than Servingpriority but lower than the EARFCNPriority of at least one of the LTE carrier listed in the overhead message, the AT shall pick the LTE carrier with the higher but closest EARFCNPriority value as the reselection target and follow the existing reselection procedures as if the picked LTE carrier is ranked the highest priority (great than 7)  The highest servingPriority and EARFCNPriority of all the carriers shall always be set to 7  If ARP is equal to the highest priority 7, the AT shall follow the existing reselection procedures

11. Example of the Idle UE Redistribution and Load Balance 11 | |

12. 12 | Load Balance & Control The Merits of the Idle AT Redistribution via Randomization Based on Existing Reselection Priorities  Efficiently redirect many idle ATs among carriers constantly and dynamically  Reuse of broadcast signaling (priority) provided by existing HRPD to LTE reselection procedures  Random selection of probability ensures fairness amongst AT groups  No need to have new network message to notify the UE for the HRPD to LTE reselection  When ATs moves into the cells with HRPD and LTE overlaid it will read overhead message broadcast by the network without need of page  The legacy system could also perform soft idle redistribution with the new ATs  In the legacy system also, the new ATs can use reselection probabilities based on randomization

13. BACKUP 13 | |

14. Overall combined scheme detailed example Define six normal UE groups (0~5)  Define six soft reselection enabling bits for each class, set to ‘1’: enabled  UEs in the normal groups shall always perform soft reselection with probability based approach as long as the soft reselection of the group is enabled –For soft redistribution large number of normal Ats  If the enabling bit is set to ‘0’ the the UEs shall follow the existing reselection procedures in 0087 as if the current serving (CDMA) carrier has the highest priority Define eight subscription-priority UE groups  For each LTE frequency channel in the OtherRATNeighborList an 8-bit bitmap is defined (bit map will be in freqency channel loop)  If a bit is set to ‘1’, the corresponding group of UEs shall choose the bitmap associated LTE carrier for reselection. Otherwise, the LTE carrier is not picked  For a priority group, at most only one target LTE frequency channel could be picked as the reselection target  If a frequency channel is picked, the UEs shall follow the existing reselection procedures in 0087 as if the picked frequency channel has the highest priority  If no frequency channel is picked, randomization bit should be further checked 14 | |

15. Overall combined scheme  Define eight soft (random) reselection enabling bits corresponding to the eight UE groups  If a bit is set to ‘1’, the ATs in the group corresponding to the bit shall perform the soft reselection based on randomly selected priority value –In case a priority group has very big size in certain area  If both the soft reselection bit and the UE-priority-group bit set to ‘0’, the UEs in the corresponding group shall follow the reselection procedures specified in 0087 as if the serving priority is the highest  For a UE group, either one frequency selection bit or the randomization bit could be set to ‘1’. At most, only one bit could be set to ‘1’ If the UE moves into legacy system, there is no any bitmap, the UE shall follow the rules of probability based soft reselection  Allow legacy system to conduct the soft UE redistribution with the new UEs The subscription priority of a UE could be specified by the network via the dedicated signaling during the initial call set-up 15 | |