1. IEEE 802.16m Supporting Femtocell Low Duty Cycle Mode
Document Number: IEEE C80216m-09_0459
Date Submitted:
Source:
Ying Li, Zhouyue Pi, Baowei Ji, Phone:
Jung Je Son, Anshuman Nigam
Samsung Electronics
Venue: IEEE Session #60
Base Contributions:
Re: Change Request for IEEE m SDD, Section 17
Purpose: Discussion and Approval
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2. Low duty cycle mode for open femtocells
In current SDD, LDC mode is only for CSG femtocells
“Besides the normal operation mode, CSG Femtocell BSs may support Low-duty Operation Mode, in order to reduce interference to neighbor cells.”
Propose: LDC mode should be also available for open femtocells
For an open femto BS, it also has chances to have no active user in its coverage, due to smaller coverage of femtocell
If open femtocells have LDC mode, it can help reduce interference to neighbor cells as well.
LDC for open femtocell can save energy as well.

3. FA information to help MS scan femtocells in LDC mode (1/4)
Frequency allocation (FA) of femtocells is the key information an MS needs to shorten the time of searching for femtocells
MS knowing the active timings of LDC of femtocells can help MS search for femtocells
Combine them
Femtocells with the same FA use the same active timing and MS scans correspondingly
Femtocells with different FA use different active timing and MS scans correspondingly
A mapping of FA to LDC pattern in broadcast channel

4. FA information to help MS scan femtocells in LDC mode (2/4)
Femtocells with the same FA use the same active timing and MS scans correspondingly AI
UAI
time
FA1
Regular mode
FA2
LDC mode
FA2
Scan others MS
FA2
Preamble
AI: available interval
UAI: Unavailable interval

5. FA information to help MS scan femtocells in LDC mode (3/4)
Femtocells with different FA use different active timing and MS scans correspondingly AI
UAI
time
FA1
Regular mode
FA2
LDC mode
FA3
FA3
Scan others MS
FA2
Preamble
others
AI: available interval
UAI: Unavailable interval

6. FA information to help MS scan femtocells in LDC mode (4/4)
Macrocell may broadcast a mapping of femtocell FA to LDC pattern
If a mapping is predefined by the system, macrocell may only need to broadcast femtocell FAs, and MS can generate femto LDC patterns using the predefined mapping once knowing FAs.
Femtocell FAs and LDC patterns may be written in MS white list.
Femtocell FA1
LDC Pattern 1
Femtocell FA2
LDC Pattern 2
Femtocell FA3
LDC Pattern 3

7. Proposed text 17.7 Low duty cycle operation mode
To reduce the interferences to others, femtocells (OSG, CSG) may support low duty cycle operation mode.
To help MS scan femtocells in low duty cycle mode, femtocell frequency allocations (FAs) may be mapped to patterns of low duty cycle, and femtocell FAs and patterns of low duty cycle may be broadcast over the air.