August 2012C2 – Company Confidential

SOURCE: Jialin Zou, Satish Kanugovi, Orlett Pearson (Alcatel-Lucent)…jialin.zou@, 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.

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Idle UE Re-distribution and Load Balance between HRPD and LTE

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Motivations

Requirement from China Telecom at Nanjing meeting, refer to [C22-20120206-020 CT-Requirement for loading balance between eHRPD and E-UTRAN]

UE Priority Class Definition and Provision• New dedicated attribute UEReselectionPriority (URP) associated with a

UE reselection priority class is proposed• UE Reselection Priority Class is created from subscription data or

operator/vendor-based policy, could be specified by the network during initial call setup

• 8 UE reselection priority class can be pre-defined by an operator and each class associated with a dedicated URP from 0 to 7 respectively

• The dedicated URP are assigned to a UE of the class during the initialization

• Per priority class based randomization can be enabled• If randomization is enabled for a class, the UEs in the class will

randomly generate a URP

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URP Based Re-selection Procedures Upon the reception of the IWK overhead message broadcast by

the BTS, the UE shall perform the following new URP reselection procedures If the URP is lower than ServingPriority, the UE stays with HRPD

– Follow the existing reselection procedures as if ServingPriority is higher than all the EARFCNPriority(s)

If the URP is equal to or higher than Servingpriority, the UE shall pick the LTE carrier with the EARFCNPriority value higher than but closest to the URP as the reselection target

– Follow the existing reselection procedures as if the picked LTE carrier is ranked the highest priority

The highest value among servingPriority and EARFCNPriorities of all the carriers shall always be set to 7

If the URP is equal to 7, the UE shall pick the carrier with the priority 7 to stay or reselect to

– Follow the existing reselection procedures

Option 1. Redistribution by Dedicated URP & Randomized URP

• UEClass_Priorityk_RAND, 1 bit for each UEClass UEClass_Priorityk_RAND=0 means randomization is not performed in priority

class k. The UE shall use their dedicated URP to perform URP reselection procedures

UEClass_Priorityk_RAND=1 means randomization is performed in priority class k. The UE randomly generates a URP over the range of existing carrier priority values (0 to 7) and use it to perform URP reselection procedures. Now the pre-assigned dedicated URP is overwritten by randomly generated URP

• No matter whether the randomization bitmap is broadcasted or not, all legacy UEs will follow existing reselection procedure.

Example of combined per class re-distribution and intra class randomizations

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Priority UEclass 7, 6, 5, 4 will be re-distributed to EUTRAN F3Priority UEclass 3 will be re-distributed to EUTRAN F2Priority UEclass 1, 0 stay with the HRPD serving carrierPriority UEClass 2 is randomized across the carriers

Example of the Idle UE Redistribution and Load Balance Following the URP Randomization Procedures

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UEClass bitmap consists of UEClass reselection indicator and 1 bit randomization indicator

When UEClass bitmap(s) broadcasted, it indicates whether some UE classes go to EUTRAN or stay in eHRPD. If redirected to EUTRAN, URP based randomization may be enabled

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 using randomization procures:• If UE is indicated go to EUTRAN, the UE shall randomly generate a URP

and follow URP based LTE multi frequency reselection procedures • If UE is indicated to stay in eHRPD, it will ignore randomization bit

value, set eHRPD serving priority as highest and follow existing reselection procedures

No matter whether UEClass bitmap is broadcasted or not, all legacy UEs will follow existing reselection procedures

Option2: Redistribution by UEClass bitmap and URP Randomization

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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: 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

Message Format of Option 2

UEClass_8 indicator

1 Bit 1 Bit

… … UEClass_2 indicator

Randomization

_indicatorUEClass_1 indicator

1 Bit 1 Bit 1 Bit

UEClass reselection indicator randomization indicator

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