Proposal on Update of S-SFH (16.2.23)
Document Number: C80216m-10_0132r4
Date Submitted: 2009-03-16
Source:
Xianming Chen, Yanfeng Guan, Lei Zhang, Feng Xie, Yang Liu
ZTE Corporation
E-mail: guan.yanfeng@zte.com.cn
Chun-Yuan Chiu, Yan-Xiu Zheng, Frank Ren
ITRI
Venue:
IEEE Session #66, Orlando, Florida, USA.
Category: P802.16m_D4 comments/Area: Chapter 16.2.23 Update of S-SFH IEs
Base Contribution: This is base contribution
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For TGm discussion and adoption of P802.16m_D4 text.
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Issue Introduction
• When the system information is changed, it is generally desirable for the
active AMSs to acquire and apply updated system parameters as soon as
possible, for the purpose of the improvement of current system
bandwidth utilization or network coverage.
• However, the time interval for update may be long, if S-SFH SPx
scheduling periodicity is set based on a longer interval, i.e. 160ms or
320ms, and if transmission times (i.e. 4) of each changed S-SFH SP
before taking effect is guaranteed.
• Besides, within the equivalent time interval beginning from SP change
superframe, the probability of decoding correctly of the S-SFH SP with
long scheduling period is much smaller than that of the S-SFH SP with
short scheduling period.
• This can cause that the active AMSs can not receive and apply updated
system information in a timely fashion.
Proposed Solution
• During the update process, the update method is the same for each SP.
– ABS may adjust the scheduling period for each SP, and it can equal
the minimal SP scheduling period supported by ABS, such as current
SP1 scheduling period.
– After the updated SP has taken effect, ABS can restore the adjusted
SP scheduling period to the original value before the update process.
• For example: Assuming that SP1 scheduling periodicity is 40ms (2
superframes), SP2 scheduling periodicity is 80ms (4 superframes), SP3
scheduling periodicity is 160ms (8 superframes), and the changed SP is
transmitted four times before it taking effect. Then, SP1, SP2 and SP3
need 160ms (8 superframes), 320ms (16 superframes) and 640ms (32
superframes) before the changing taken effect respectively. By decreasing
SP2 or SP3 scheduling periodicity, SP2 needs much less than 320ms (16
superframes) before the changing taken effect, and SP3 needs much less
than 640ms (32 superframes) before the changing taken effect.
Advantage
• This method ensures that an active AMS can acquire and apply
the up-to-date system information as soon as possible, and the
SPs with different period may have a little difference of
decoding probability for an AMS.
Figure for Solution
Current SP Scheduling and Update Method in D3
Superframe n+1 ~ n+8
SP1(40ms)
SP2(80ms)
SP3(160ms)
Proposed SP Update Method
Superframe n+1 ~ n+8
Superframe n+9 ~ n+16
SP3 Update Duration
Superframe n+17 ~ n+24
Superframe n+25 ~ n+32
SP1(40ms)
SP2(80ms)
SP3(160ms, but 80ms in update process)
This figure above gives one case that ABS decreases SP3 scheduling periodicity
during SP3 update.
Proposed Text
•
Add the new text and figure in page 336, line 56 in section 16.2.23
When S-SFH SPx IE is changed, ABS may additionally transmit the changed S-SFH SPx IE in
superframes only carrying P-SFH. This additional transmission doesn’t affect the
transmissions of changed S-SFH SPx IE determined by the scheduling periodicity and the SSFH applying offset.
ABS additionally transmitted an SP2 whose original
scheduling periodicity is 80ms.
20 ms
80 ms
160 ms
20 ms
S-SFH SP1
S-SFH SP2
S-SFH SP3
Figure XXX: Illustration of S-SFH SP2 content update