3GPP2 Femto Cell Workshop: System Selection, Interference Management, Handoffs and Mobility

1. 3GPP2 Femto Cell Workshop:System Selection, Interference Management, Handoffs and Mobility Ed Tiedemann 15 October 2007

2. Presentations • John Burgess, Alcatel-Lucent • Femtocell System Selection • Minsh Den, Airvana • Femto Access Control Provisioning and Enhanced System Selection • Manoj Deshpande, Qualcomm • Femto Cells –Search and System Selection • Balaji Raghothaman, Airvana • Femto Air Interface Enhancements for Future Mobile Devices • Balaji Raghothaman, Airvana • Femto Air Interface Deployment Modeling, Simulation, and Performance • Mingxi Fan, Qualcomm • Interference Management in Femto-Cell Deployment

3. Femto Cell Association • Open access • All MS can use femto cell • Restricted access • Only specific MS can use femto cell • Family, friends, visitors • Signaling access • MS can receive signaling (may be limited) from femto • 911 issues • Restricted assocation • Position • Backhaul failures • Emergency broadcast issues

4. Some Basics • Femto Cell Identity • Use NID • Use BASE_ID • Use (SID, NID, REG_ZONE) • Same or Separate Carriers • Same carrier as macro cell • Separate carrier • Femto cells can be on a set of carriers • 1x and DO typically take two carriers

5. Femto Cell Selection for Legacy Mobiles • Two classes • Those that can update PRL • Those that cannot make PRL changes • Use PRL • Include femto cell in PRL • May cause MS to search frequently for femto cell • Mechanisms to construct PRLs need to be developed • Use GNLM • As long as neighbor is 3 dB stronger, the MS will choose • May limit the range of femto-cells • May require additional use of restricted assocation mechanisms • Use Beacon • May impact other mobiles; additional network interference • May needs to be on multiple frequencies • Adds complexity to femto cell • May require additional use of restricted assocation mechanisms • Registration, filter, redirect (SRDM) • Mobile will periodically check for femto; battery life issues • Global Service Redirection Message (GSRM)

6. Possible Modifications to Enhance System Selection • Two basic extreme approaches • Select first, reject • Select right • Use position location to indicate to MS when to search • Use user zones on Forward Link • Already in standards • User Zone Identification Message (UZIM) • Private Neighbor List Message (PNLM) • Limited number of user zones • Use PRL enhancements, such as PUZL in IS-683/C.S0016) • Allows PRL (PUZL) for femto cells to be separated from existing lists • Black lists • Add range/masks for NIDs and BASE_IDs • Would need to be done for DO • May want to reexamine whether another mechanism is preferable • Mechanisms to update lists

7. Interference Issues • Co-channel Macro-Femto deployment • MS using femto cell on same frequency as macro cell • Femtocell deployment on a carrier adjacent to a macro-cell carrier • Adjacent channel rejection • In dense femto cell deployments inter-femto outage scenarios must be addressed • More than just dense; any close coupling between femto cells • Modeling of interference between femto cells

8. RF Issues • Frequency interference and planning • Is a frequency reuse used over a set of frequencies • PN offset allocation • Is a small number used? Otherwise need to expand GNLM size significatly (there is a size limit) • Reuse pattern • Ambiguity at the macro cell level • Femto cell transmit power • Power classes • Femto cell emissions and other RF specifications • MS using femto cell can cause interference to macro cells or other femto cells • How to limit MS output power • Limit data rate when possible • Introduce limit for MS output power • Possibly have MS report output power to femto cell • Reduce minimum size of PN search window • Reverse Link silence periods • Synchronized or unsynchronized

9. Other • Smart femto cells • Learn environment

10. Handoff • For handoff into femto, ambiguity of PILOT_PN • Does MS need to report other information