Femtocell Activities in 3GPP2 TSG-C

TBD

31 March 2009

New Orleans, LA

March 2009 2

Status of Femto Work in TSG-C

• cdma2000 1x air interface signaling enhancement for Femto is part of cdma2000 1x air interface revision E specification

• Start: Q1 2008• Baseline: Q1 2009• Expected Publication: Q2 2009

• cdma2000 HRPD air interface signaling enhancement for Femto is on-going as part of cdma2000 HRPD air interface revision C specification

• May reuse some enhancements from 1x• Expected Publication in Q4 2009

• Enhanced system selection (ESS) to support femtocell selection• Based on enhancements to the Preferred User Zone List (PUZL) in the Over-the-

air Service Provisioning (OTASP) spec (C.S0016)

• Stage 2 of this work was completed in Jun 2008.

• C.S0016-D Publication with enhanced PUZL scheduled for May 2009.

March 2009 3

Challenges with the Current Practice (1/2)

• While femtocell deployment is possible without any enhancements to the air interface, the following challenges are addressed more efficiently with the enhancements in 1x Revision E– No prioritization of femtocell over macrocell

• Need to be able to distinguish femto pilot vs macro pilot

– Open / signaling association models increase number of idle handoffs and registrations

• Impact on MS standby time• Frequent registrations can lead to page loss and increase the signaling load

– MS may not select HRPD femtocell following the 1x femtocell selection• Select HRPD femtocell following 1x femtocell selection

– Manual search is slow and inconvenient• Support fast and user friendly manual search by providing human-readable ID

– Macro Femto handover encounters PN ambiguity problem• Support seamless connected handovers

March 2009 4

Challenges with the Current Practice (2/2)

• While femtocell deployment is possible without any enhancements to OTASP, the following challenges are addressed more efficiently– Acquisition of femtocells without the use of beacons

– Minimize access attempts on unauthorized femtocells

– Minimize repetitive system selection attempts (or loops)

– Minimize impact on the design and implementation of the PRL

– Maximize standby time

March 2009 5

Introduction to 1x Signaling Enhancements

• In order to more efficiently support Femto AP operations for cdma2000 1x, the following signaling messages are introduced– Access Point Pilot Information

• Allow the femto access point (FAP) and/or basestation to broadcast the band/channels/PN offsets of femto access points deployed in the geographical region

– Access Point Identification• Allow a FAP to advertise to the MS a unique identifier and other information

about the FAP that assist system selection and handoff

– Handoff Supplementary Information• During handoff to target FAP, allow the MS to report information that

disambiguates the target FAP

Note: Development of femtocell enhancements is on-going for HRPD revision C.

March 2009 6

Enhanced System Selection (ESS) – Summary

• ESS supports efficient discovery and scanning for femtocells– Based on enhancements to network-provisioned MS database PUZL

• New PUZL features include– ESS support for 1x, DO and dual 1x/DO femtocells

– Support for personal femtocells, hotspots, network of hotspots or communities

– Efficient off-frequency scans of a femto based on RF or Geo-based triggers• Only when MS is in the vicinity of a desired femtocell• To minimize battery power consumption and hit to stand-by time

– Manual femtocell acquisition with human-readable femto ID

– Blacklisting and white-listing of femtocells• Blacklisting helps prevent system selection loops• Network Provisioned

March 2009 7

Active Call Hand-in Example

• Under the same macro BS, it is likely that the same PN will be assigned to many Femto APs

• Macro BS needs to be able to resolve target MSC_ID and CELL_ID for the PN that has ambiguity

• One possible solution under consideration is that the Femto AP is configured with unique MSC_ID and CELL_ID. If agreed, this information would be advertised in the APID message. The MS includes this info with the PSMM. The remaining standard handoff process will route the call to the MFIF (based on MSC_ID) and correct femto AP (based on CELL_ID) with no modification to A1 and IS-41 interfaces

Macro BSPN = a

Femto AP1PN = b

Femto AP2PN = b

MSC

MFIF

2. PSMM+ HSIN<MSC_ID, CELL_ID>

3. A1-Handoff Required<MSC_ID, CELL_ID>

4. IS-41<CELL_ID>

1. APIDM (MSC_ID, CELL_ID)

5. MFIF contactsFemto AP2 for handoff

March 2009 8

Femto ESS – System Selection Sequence

Mobile is associated with a Macro system Identified to be in one or more User Zones

Mobile is associated with a Macro system Not in any User Zone

Mobile is not associated with a

system

Mobile finds a macro system

Mobile finds a femto system

Mobile finds a femto systemMobile loses femto

coverage and tries to acquire available macro/

femto system

Scan for Macro/Femto Channel based relative

priority

Mobile is associated with a Femto system

Mobile is on the most preferred system.

Identify one or more User Zones associated

with the macro-SID from the PUZL DB

Check to see if MS has entered the User Zones

based on the finer definitions of the scan regions (RF coverage based and GEO based

entries)

Execute efficient scans to find the femto(s) associated with the

User Zone(s).

Continually check to see if the trigger

conditions for the femto system scans remain

satisfied.

Mobile leaves the User Zone

Mobile enters a specific User Zone

March 2009 9

Working with the Broadband Forum?

• How will 3GPP2 submit items to the Broadband Forum?• Should 3GPP2 develop a consolidated document?

– Or should each TSG (i.e., TSG-A, TSG-C, TSG-S and TSG-X) develop individual documents for the Broadband Forum?

• What is the process for developing the Femto Auto-Config Parameters?

March 2009 10

Details

1x Signaling

March 2009 11

1. Access Point Pilot Information Message (APPIM)

• APPIM is broadcasted by FAPs and/or macro network– Broadcast from FAPs allows the macro network to remain unchanged

• APPIM includes femtocell deployment information– Band, frequencies, and PN offsets allocated for the femtocell deployment– Scope of allocation in the macro network, e.g., SID/NID that information would be

valid– MS can cache the information up to LIFETIME limit specified– To optimize overhead when this message is advertised on macro paging channel, the

message can be sent with low duty cycle and MS can go to sleep mode before receiving this message

• Benefits– Helps MS distinguish between macrocells and femtocells, e.g., MS may want to only

idle handoff to FAP in the home area– MS would not need to be pre-provisioned with such scan information especially when

in roaming conditions– Offers flexibility in allocation of frequencies and PN offsets for femtocell deployment– Speeds up manual / exploratory scans to discover nearby femtocells

March 2009 12

2.1 Access Point Identification Message (APIDM)

• Contents– SID, NID, and unique access point identifier– Supported association model (i.e., open/restricted/signaling-only)– MSC_ID, CELL_ID (for assisting hand-in to FAP)– Associated HRPD band class and channel– Location Information LAT, LONG, ALT, and horizontal and vertical uncertainty

• Broadcasted by FAP at high frequency schedule

• Benefits– Quick identification of FAP with synergy to Enhanced System Selection (ESS)– Association model information helps MS avoid registration on unknown femtocells

with signaling/restricted association– Reporting MSC ID and Cell ID information identifies target FAP in macro femto

handoff– HRPD information enables selection of FAP for HRPD following 1X selection

March 2009 13

2.2 Access Point Identification Text Message (APIDTM)

• Contents– Variable length text identification of the FAP (similar to WIFI SSID)

– International encoding supported

• Broadcasted by femtocell on only normal channel at low frequency schedule

• Benefits– Enable user friendly manual scans to discover and identify nearby

femtocells

March 2009 14

3. Handoff Supplementary Information Notification / Solicit

• The notification message includes mapping between PN Offset and <CELL_ID, MSC_ID> of APs that the MS considers to handoff to– Purpose is to disambiguate target FAP during handoff

• Same PN may be used by several FAPs under the same macro network• CELL_ID and MSC_ID are used in Handoff Required message from macro

basestation to MSC identically to handoff in macro network

– The MS retrieves the <CELL_ID, MSC_ID> information from Access Point Identification message

– This message can be sent along with Pilot Measurement report

• The BS may request the information using the Handoff Supplementary Information Solicit message

March 2009 15

Details

Enhanced System Selection

March 2009 16

ESS – Preferred User Zone List (PUZL)

• User Zone (UZ) refers to a region in which femto-cell scans are performed based on– Geo-spatial (e.g. GPS) or RF coverage (e.g. SID/NID/AP_ID)

• PUZL consists of two parts:– A global set of general parameters (e.g. Manual Acq Allowed)

– A list of individual User Zones (UZs).

• Each UZ has several main functions:– Defines geo-spatial or RF regions in which a MS can execute RF Scans for

a femtocell – to use minimal battery power

– Defines the RF Scan parameters to find the femto-cell.

– Defines a set of parameters to uniquely identify a desired or undesired femtocell.

March 2009 17

ESS – New PUZL Features

• ESS support for 1x, DO and dual 1x/DO femtocells• Efficient off-frequency scans of a femto based on RF or Geo-based triggers

• Only when MS is in the vicinity of a desired femtocell• To minimize battery power consumption and hit to stand-by time

• Manual femto-cell acquisition with human-readable femto ID• White-listing and blacklisting of femtocells

• Network Provisioned• Blacklisting helps prevent system selection loops

• Handset Display Control to indicate Femto selection / connection• Prioritization of UZs in case of overlapping UZs • PUZL vs. PRL priority indication• Generalization of user zone spatial definitions:

• From current 2-D surfaces and latitude/longitude centers to include 3-D volumes and altitude center

• Identification of a femtocell based on the • New broadcast message AP_ID (1x Rev. E) and• Existing Registration Zone and/or LAT/LONG in System Parameters Message (SPM)

– A Registration Zone value is unique within a system defining a paging region (collection of sectors)

March 2009 18

ESS – Femto Usage Models

• Personal hotspot model– Femto cells deployed in private homes and small home offices

– Each femto cell allowing access only to a small number of specific users

• Community hotspot model– Pico or femto cells deployed in enterprises, campuses, apartment buildings,

etc.

– A network of small number of pico or femto cells all concentrated in a fairly small geographic area allowing access only to specific group users in that area that change infrequently.

• Distributed “network of hotspots” model– Geographically distributed networks of pico or femto cells deployed across

hotel chains, airports, Starbucks, etc.

– Networks of pico or femto cells