MS Signaling for Femtocell Interference Mitigation
Document Number: IEEE C80216m-09/0480
Date Submitted: 2009-02-27
Source:
Baowei Ji, Farooq Khan, Zhouyue Pi,
Sudhir Ramakrishna, Kaushik Josiam,
Ying Li
Email: bji@sta.samsung.com
Phone: +1-972-761-7167
Samsung Electronics
Venue:
IEEE Session #60, Vancouver, Canada
Base Contributions:
Re:
CR for tgmsdd
Purpose:
Notice:
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Motivation
• Femtocell poses challenging IM issues
• Section 17.8 includes several good design
• But, none of them addresses the following scenario
–
–
–
–
–
MS-a belongs to Femto-a, but overwhelmed by Femto-b.
MS-a cannot access Femto-a, or
MS-a losses the connection with Femto-a.
MS-a cannot access Femto-b.
Bottom line: MS-a cannot access the network at all.
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Typical Femtocell Scenarios
Situation: MS is overwhelmed by a neighbor CSG Femtocell BS.
From: “Home Node-B’s for WCDMA/HSPA”,
Qualcomm, May, 2008
Solution: MS Signaling
• MS-a sends a signal to Femto-b
– The simplest way:
• MS-a sends a special ranging code to Femto-b using one of the
ranging TXOP.
• If possible, Femto-b reduces transmission power
– A finer way:
• MS-a sends a special ranging code to Femto-b using one of the
ranging TXOP.
• If possible, Femto-b requests MS-a to send the location info.
• If possible, Femto-b adjusts the transmission power
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Concern of Abuse?(1/2)
• If not designed carefully, a rogue MS could abuse this
feature and bother any CSG Femtocell BSs.
• To avoid abuse
– Limit MS signaling to layer-1 to avoid human abuse
– Define precise conditions that trigger MS signaling to avoid
unreasonable MS signaling
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7
Concern of Abuse?(2/2)
• If not designed carefully, a rogue MS could abuse this
feature and bother any CSG Femtocell BSs.
• After all, it is Femto controlled
– Femto-b schedules ranging TXOP
– Femto-b could ignore the signaling from neighbor MSs
– Femto-b decides how to adjust transmission power
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FBS-a
MS-a
FBS-b
CN
MS-a detects the overwhelming
interference from FBS-b
MS-a sends IM-Signal
Request for MS Identity
information
MS-a transmits MS
identity information
Optional: Validating MS-a’s requirement
Optional: Validating MS-a’s requirement
Requests for validating
MS-a’s requirement
Validate MS-a’s membership,
and legitimacy for sending the
IM_Signal
Validate MS-a cannot
access the FBS-a
Confirm MS-a’s requirement
Network entry
Normal Operation
MS-a’s requirement for
IM is validated
Adjust Radio Transmission
based on MS-a’s requirement
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Suggested Text
Insert the following paragraph into Section 17.8, at line 20, on page 136.
--------Start of Text--------Large interference from an inaccessible Femtocell may saturate or block
the MS radio receiver, such that it will not able to maintain the
communication with the serving BS. If a CSG MS being connected to
its own CSG Femtocell BS is seriously interfered by a neighbor CSG
Femtocell BS and cannot get any service from the network, the MS
may signal to the interfering Femtocell BS directly so that the latter
may mitigate the interference automatically, even though the MS is
not allowed to access the CSG Femtocell BS for regular data
communications.
--------End of Text---------
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