Interference mitigation to support overlaid CSG-closed femto ABS
Document Number: IEEE C80216m-09_2596r1
Date Submitted: 2009-11-15
Source:
Ying Li, Baowei Ji, Zhouyue Pi,
Youngkyu Baek, Jung Je Son,
Anshuman Nigam
Email: yli2@sta.samsung.com
Phone: +1-972-761-7903
Samsung Electronics
Venue:
IEEE Session #64
Base Contributions:
Re:
Contribution in support of a comment on LB30a
Purpose:
Notice:
Discussion and Approval
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Problem definition
• 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.
• When a non-member AMS is seriously interfered
by a neighbor CSG-closed Femtocell ABS and
cannot get any service from the network, what
should be done for such MS?
Solution (1/2)
•
This case is for that an AMS has no valid AK
Non-member AMS
CSG-Closed FBS context.
Receiving SFH,
• If an AMS is seriously interfered by a
A-preamble
MS can judge
neighbor CSG-closed femto ABS and cannot
SFH
whether it is a
get any service from the network, the MS
Initial ranging code
member/nonmay request the femto ABS to mitigate the
RNG-RSP
member of FBS
interference .
RNG-REQ, with a purpose bit
based on
• MS can send an AAI_RNG-REQ message with
indicating IM
CSGID/BSID
Ranging Purpose Indication Bit#5 set as ‘1’.
SBC-REQ/RSP
• Having received this IM indication, the CSGclosed Femto ABS may further allow MS to
PKM-REQ
enter the EAP stage for authentication.
• If the FBS recognize the AMS is illegal, it
Authentication
rejects any request from MS. If the FBS
PKM-RSP
recognize that the AMS is a legal user but a
non-member, the FBS may either accept the
Interference
IM request, or reject.
mitigation
• Whether to accept the request of IM or
reject, depends on the FBS service provider
or operator rule.
• Advantage:
– Prevent the CSG femto generating coverage hole
to non-member MS
Solution (2/2)
•
This case is for that an the case that an AMS
Non-member AMS
CSG-Closed FBS has a valid AK context
• This can happen, for example, AMS was in
Receiving SFH,
A-preamble
idle state served by a macro BS, but now it
MS can judge
SFH
whether it is a
cannot hear macro, but only a strong
ranging code
member/noninterference from inaccessible CSG-closed
RNG-RSP
member of FBS
FBS.
based on
• If an AMS is seriously interfered by a
RNG-REQ, with a purpose bit
CSGID/BSID
neighbor CSG-closed Femtocell ABS and
indicating IM. RNG-REQ
contains CMAC
cannot get any service from the network, the
MS may request the femto ABS to mitigate
the interference.
Authenticati
on
• MS can send an AAI_RNG-REQ message with
Ranging Purpose Indication Bit#5 set as ‘1’,
and the CMAC is contained.
RNG-RSP
• The Femto ABS may authenticate the
request.
Interference•
If the FBS recognize the AMS is illegal, it
mitigation
rejects any request from MS. If the FBS
recognize that the AMS is a legal user but a
non-member, the FBS may either accept the
IM request, or reject.
• Whether to accept the request of IM or
reject, depends on the FBS service provider
or operator rule.
Proposed text (1/2)
Insert the following text to page 551, line 22
If an AMS who is a non-member of a CSG-closed femto measures that the
CSG-closed femto ABS is the only ABS with a RSSI or CINR higher than the
minimum acceptable RSSI or CINR for MS to access a BS, for a period of
time T greater than a threshold TH1, the AMS may request the femto ABS
to mitigate the interference by sending an AAI_RNG-REQ message with
Ranging Purpose Indication Bit#7 set as ‘1’, to indicate the IM request. If
the AMS has a valid AK context, the AAI_RNG-REQ message shall contain
CMAC tuple.
Having received this message, and decoded the ranging purpose
indication bit #7 as ‘1’, if the operator policy does not allow such IM, the
femto ABS responds with an AAI_RNG-RSP message with IM Indication
‘00’, which means IM not allowed and not to try again. If the policy allows
such IM, the CSG-closed femto ABS may further authenticate the AMS. If
the authentication result is that the AMS is illegal, it rejects any request
from MS. If the authentication result is that the AMS is a legal user but a
non-member, then the CSG-closed femto ABS checks the IM policy.
Proposed text (2/2)
On page 36, 15.2.3.1 AAI_RNG-RSP
In Table 674, revise
Name
Value
Usage
Ranging Purpose
Indication
If bit #7 is set to ‘1’, it indicates that an
non-member AMS requests
interference mitigation to a CSG-closed
femto ABS.
To avoid the
coverage hole
generated by the
CSG-closed femto
On page 38, 15.2.3.2 AAI_RNG-RSP
In Table 675, add
Name
Value
Usage
IM request
response
‘00’= IM not allowed and not to try
again
‘01’= IM performed and AMS to find
other BS to access
‘10’ =IM allowed but failed
‘11’ = AMS allowed to access CSGclosed femto ABS with lower priority
For CSG-femto to
respond
AAI_RNG-REQ
with Ranging
Purpose
Indication Bit#7
set as ‘1’
6