RE: stds-802-16-mobile: Handoff and Sleep Mode Ad-hoc: Start of discussion
Hello All,
This is about C802.16e/03-28 document. The tool suggested
for the solution of the problem seems appropriate: allocate for mobile users
a separated initial ranging channel. But it would be more convincing
with some statistical data. Is the problem really hard? The answer depends
on traffic/mobility characteristics.
For example, we know that for voice cellular networks busy hours arrival
rate may reach 3-4 users/sec per cell. If we assume that data terminals are
not more mobile than cellular
phones then we may expect same order of maximum arrival rate for 802.16e
cells.
If we take MAC frame duration = 5 ms then we have 50-60 frames per SS for
initial ranging. So we may allocate MAINT region with 1-2 slots once per 5
frames
and configure backoff window to 2 or 4 slots and still have 4-5 attempts for
power adjustment of each incoming SS.
Now, what is the role of "fixed" users in this picture? Probably, busy hours
are those when people power up their SSs in the evening. If 100 such events
are
distributed over one hour interval, then we have 36 sec for each user, 10
times more than for mobile one. Thus, under given assumptions, there is
just a small interference from fixed SSs. Do we need a separated MAINT
channel
in this case?
It would be interesting to hear from other participants of the discussion
on their view on traffic/mobility characteristics of future 802.16e users
Vladimir
-----Original Message-----
From: Itzik Kitroser [mailto:itzikk@runcom.co.il]
Sent: Monday, June 02, 2003 6:53 PM
To: stds-802-16-mobile@ieee.org
Subject: stds-802-16-mobile: Handoff and Sleep Mode Ad-hoc: Start of
discussion
Hello All,
Given enough time passed, I would like to start the discussion in the scope
of this group.
As indicated in working document the following topics should be discussed:
---->
1. Contributions to discuss:
a.C802.16e/03-28: Fast handoff service
b.C802.16e/03-30r1: Reporting of scanning results
c.C802.16e/03-31: Sleep mode enhancement
2. Clarification on the types of handoff that are supported; currently the
text implies that two kind of handoff are supported (break-before-make and
make-before-break) but descriptions are provided only for the
break-before-make type. I would like to request proposals on
make-before-break type (relevant to the current Tga/d technology of course)
3. Provide message flow diagrams for the Sleep mode and Handoff procedure,
such diagrams must provide a clear explanation of the actions performed by
the BS and by the MSS. The diagrams must be considered for different kind of
scenarios (i.e. handoff success, target BS rejection etc.)
<----
I would like to open the discussion with item 1.a. "C802.16e/03-28: Fast
handoff service " contribution:
This contribution presents the idea of improving the Initial Ranging of MSS
during handoff by using two backoff types of backoff parameters:
1. "Regular" backoff (min) value for initial ranging, called "MAX_BOFF"
2. HO MSS backoff (min) value for MSS during handoff time, called "HO_BOFF"
The backoff window of MSS doing HO will be: [0,2^HO_BOFF] and the backoff
window for MSS doing regular (i.e. not handoff) network entry will be:
[2^HO_BOFF+1,2^MAX_BOFF].
The advantage of this method, is that, when using a shared contention
resource, the MSS performing HO will not collide with MSS performing initial
network entry.
The drawback of this method is the inherited delay for the initial network
entry process for regular MSSs.
My view on this issue is:
a. One of the main targets of the 802.16 handoff procedures is to make the
handoff process efficient and fast. Coming for this orientation, we have the
ability to make the initial network synchronization for MSS performing
handoff, a contentionless process. This is achieved by using the
"Fast_UL_ranging_IE", which is sent unsolicited, by the target BS to the MSS
coming in. If the aspire that most of the MSS will be able to do so, than
the problem solved by C802.16e/03-28 dose not exists.
b. If there are subscribers, which still required to perform contention
entry to the target BS, then due to the fact that the number of MSS that
performing an initial ranging in a stabilized system is very low, it seems
more reasonable to make two contention windows, which are overlapping:
b1. "Regular" backoff (min) value for initial ranging, called "MAX_BOFF",
backoff window [0,2^MAX_BOFF]
b2. HO MSS backoff (min) value for MSS during handoff time, called
"HO_BOFF", [0,2^HO_BOFF]
When MAX_BOFF is large enough, then the probability of collision is still
low.
Please provide your views on this issue, deadline is 04/06/03.
Best Regards,
Itzik.
This mail passed through mail.alvarion.com
****************************************************************************
********
This footnote confirms that this email message has been scanned by
PineApp Mail-SeCure for the presence of malicious code, vandals & computer
viruses.
****************************************************************************
********
This mail was sent via mail.alvarion.com
************************************************************************************
This footnote confirms that this email message has been scanned by
PineApp Mail-SeCure for the presence of malicious code, vandals & computer viruses.
************************************************************************************