Call-back HO Procedure for Reentry Femtocell
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-09/1304
Date Submitted:
2009-07-06
Source:
Shiann-Tsong Sheu, Chih-Cheng Yang
National Central University
Kanchei (Ken) Loa,, Chun-Yen Hsu, Yung-Ting Lee,
Tsung-Yu Tsai, Chiu-Wen Chen
Institute for Information Industry
Yang-Han Lee, Yih Guang Jan
Tamkang University
*<http://standards.ieee.org/faqs/affiliationFAQ.html>
Re:
802.16m Amendment Working Document
Call for contributions on “Support for Femtocell BS”
Base Contribution:
IEEE 802.16m-09/0010r2
Purpose:
To be discussed and adopted by TGm for the 802.16m Amendment.
Notice:
jasonyyy@gmail.com
loa@iii.org.tw
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1
Problem Statement
• Since the Femtocell backhaul link may
disconnect from network and reconnect to
network sometimes, the method for
handling the associated MSs to leave and
return the Femtocell should be designed in
order to
– continue the services, and
– optimize the network performance.
2
Handover Trigger
• The WiMAX Forum document “Requirements for
WiMAX Femtocell Systems” states that
– A Femtocell BS SHALL disable its downlink air
interface transmitter until the connection with the
operator’s network is fully established.
• As the serving Femtocell loses the backhaul
connection, it shall command all the associated
MSs to perform handover procedure.
– The handover request signal shall include the reason
code, which is used to notify the MSs to record the
original Femtocell BS information and wait for any
callback signal.
3
Call-back handover procedure
• As the Femtocell BS reconnects to the network
again, the Femtocell BS or the network HO
controller initiates the call-back handover
procedure to generate the callback HO
message with the original Femtocell BS ID for
related BS in order to call back those MSs who
have recorded the information of original
Femtocell BS.
• Upon the MS receiving the call-back handover
signal from serving BS, it will try to handover to
the recorded Femtocell BS if the signal quality
is better than the current connection.
4
HO procedure when Serving
Femtocell BS lost backhual link
Serving
Femtocell BS
Target Macro
/Femtocell BS
AMS
Lost
backhaul link
AAI_MOB_BSHO-REQ
AAI_MOB_HO-IND
AMS Synchronization with Target BS
AAI_RNG-RSP
AAI_RNG-REQ
Reauthorization
AAI_REG-REQ
AAI_REG-RSP
Data path established
5
BS-initiated Call-back
handoverAMSprocedure
Target Macro
Serving
Femtocell BS
/Femtocell BS
Recover
backhaul link
AAI_MOB_CallBack_HO-REQ (via backhaul link)
AAI_MOB_CallBack_HO-RSP (via backhaul link)
AAI_MOB_CallBack_HO-REQ
AAI_MOB_CallBack_HO-IND
AMS Synchronization with Femto BS
AAI_RNG-REQ
AAI_RNG-RSP
Data path established
6
Proposed Text
[Add the following sections 15.x.y “Femtocell BS
Handover trigger condition” and 15.x.y “Call-back
Handover Support”]
15.x.y Femtocell BS Handover trigger condition
As the Femtocell BS loses the connectivity of
backhaul link, it shall send the handover command
message with reason code to all associated MSs. All
the notified MSs shall perform handover procedure to
re-associate with the designated BSs, if any.
15.x.y Call-back Handover Support
Upon the backhaul connectivity is recovered, the
Femtocell BS may issue call-back handover signals
with Femtocell BS ID to the related BSs for notifying
those MSs, who have stored the information of
Femtocell BS, to handover back.
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