Here is my view on the Network Assisted
HO Flag going through the specification.
The Network Assisted Flag in MOB_BSHO-REQ
and MOB_BSHO-RSP
messages indicates to MS
of serving BS support in specifying
the candidate BSs for Handoff .
In this scenario there are 3 cases.
Case 1: When MS decides to handoff with
recommended BSs of MOB_BSHO-REQ
or MOB_BSHO-RSP,
as per section 6.3.2.3.55 of IEEE 802.16e-2005 MS may
choose to send MOB_HO-IND as a n acknowledgment
with Target BS set to 0x00000000 which indicates the serving
BS of MS deciding to handoff.
In which case BS may release its resources allocated for
that particular MS without waiting for resource retain timer to expire.
Case 2: When MS decides to handoff but does not send MOB_HO-IND,
it is like uncontrolled HO specified in NWG stage 2,
and BS shall retain its resources till the resource retain
timer expiry.
Case 3. When MS does not want to handoff, it may choose
to send MOB_HO-IND with reject/cancel.
Hence i think the network assisted flag is necessary to
be included in the message and signifies a specific behavior in HO.
Let me know if there is any difference in opinion.
Thanks,
Malini Raghavendra
Project Lead
Communication and Embedded Systems,
Larsen &Toubro Infotech,
Bangalore,INDIA
Chi-Chen Lee <jjlee@ITRI.ORG.TW>
06/27/2006 11:28 AM
Please respond to
Chi-Chen Lee <jjlee@ITRI.ORG.TW>
To
STDS-802-16@listserv.ieee.org
cc
Subject
[STDS-802-16] [HO] Usage of "network
assisted HO supported flag"
Hi,
I have one question about the usage of Network Assisted HO supported flag
in MOB_BSHO-REQ message and MOB_BSHO-RSP message. In my understanding,
if Network Assisted HO supported flag is set to "1" in MOB_BSHO-REQ
or MOB_BSHO-RSP message, MS may perform a handover to any BS among the
recommended BSs without MOB_HO-IND. However, according to section 6.3.2.3.55
of IEEE 802.16e-2005, an MS "shall" transmit a MOB_HO-IND message
for final indication that it is about to perform a HO. It seems that there
is conflict between the usage of MOB_HO-IND and the usage of Network Assisted
HO supported flag.
There are two possibilities of the above issue:
(1) An MS shall transmit a MOB_HO-IND message for final indication even
though the Network Assisted HO supported flag is set to "1",
i.e. MS behavior has no difference between Network Assisted HO supported
flag is set to 0 and 1. In this case, why we still need Network Assisted
HO supported flag? What does it mean to MS?
(2) An MS may perform a handover to any BS among the recommended BSs without
MOB_HO-IND. Note that in this case, the MS MAY send MOB_HO-IND with target
BS ID = "0x00000000" as an acknowledgement to the MOB_BSHO-REQ
message but may not send MOB_HO-IND during actual HO. However, this case
incurs another issue: if there is no MOB_HO-IND before MS starts HO, how
does the Resource retain timer work in this case? Without Resource retain
timer, how can the MS decide that it can cancel HO except in the drop case?
I appreciate any comments and discussion on this issue.
thanks,
==========================================
Chi-Chen Lee
Design Engineer
Wireless System Technology Div.,
SoC Technology Center(STC),
Industrial Technology Research Institute
Tel: +886-3-5914579
Fax: +886-3-5829733
E-mail: jjlee@itri.org.tw http://www.stc.itri.org.tw/
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