Proposals on Update of S-SFH
Document Number: C80216m-09_2893r2
Date Submitted: 2009-12-31
Source:
Xianming Chen, Yanfeng Guan, Lei Zhang, Feng Xie, Yang Liu
E-mail: [email protected]
ZTE Corporation
Venue:
IEEE Session #65, La Jolla, San Diego, CA, USA.
Category: P802.16m_D3 comments/Area: Chapter 16.2.23 Update of S-SFH IEs & 16.3.6.5.1.2 S-SFH IE
Base Contribution: This is base contribution
Purpose:
For TGm discussion and adoption of P802.16m_D3 text.
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Introduction
• To maintain normal network operations, ABS broadcasts and
adjusts its configuration via system information updating.
– The critical information is broadcasted via P-SFH/S-SFH IEs in
802.16m.
– The critical information includes a minimal set of time critical system
configuration information and parameters needed for the AMSs to
complete cell selection and system access in a power efficient manner.
• But, there is no harmonized update method for the system
information. This contribution lists some problems to be
considered for the system information update and the
solutions.
Problem (1/2)
• Problem 1:
– When the system information is changed, it is generally required that AMSs
can apply the changed system information as soon as possible, and make the
time interval between the system information changing and taking effect short
as possible. But, the time interval may be also longer if S-SFH SPx scheduling
periodicity is much longer, such as 160ms; furthermore, the correct decoding
probability of the long period S-SFH SP will be smaller than that of the short
period S-SFH SP.
• Problem 2:
– For making each SP update process simple and independent, the system
information in the different SP should have no strong association. But, the
resource mapping indication information in SP1 and SP2 has too much
association. For example, assuming that initial “DFPSC” value in SP2 is 2, and
initial “DCASi” value in SP1 also is 2, and if “DFPSC” value is changed into 1
subsequently, then it’s impossible that “DCASi” value remains unchanged.
That means, in this case, the information fields related to resource mapping in
SP1 and SP2 need to take effect simultaneously.
Problem (2/2)
• Problem 3:
– In sleep mode, P802.16m/D3 has description as follows:
• During Listening Window, the AMS is expected to receive all DL
transmissions same way as in the state of normal operations. AMS shall
ensure that it has up-to-date system information for proper operation.
• If the AMS detects that the information it has is not up-to-date, then it shall
not transmit in the Listening Window until it receives the up-to-date system
information.
– For an AMS in sleep mode, if it doesn't receive the updated system
information when it wakes up, the normal operation will be affected.
Therefore, a mechanism shall be needed to ensure that an AMS can get
up-to-date system information as soon as possible after it wakes up.
• Problem 4:
– If an AMS can’t decode the SFH correctly, there’s no special text to
specify the possible operation.
Solution (1/2)
• Solution to Problem 1:
– During the update process, the update method is same for each SP.
• ABS may adjust the SP scheduling periodicity, and it can equal the minimal
SP scheduling periodicity supported by ABS.
• After the updated SP has taken effect, ABS can restore the adjusted SP
scheduling periodicity to the original periodicity before the update process.
[Refer to Figure 1 and 2]
– Advantage:
• This method ensures that an AMS can acquire and apply the up-to-date
system information as soon as possible, and the SP with different
periodicities may have the same decoding probability for an AMS.
• Solution to Problem 2:
– All indication information for the resource mapping is packed into one
SP1 or SP2 (Refer to the C802.16m-09/2894).
– Advantage:
• Make each SP’s transmission period and update process independent.
Solution (2/2)
• Solution to Problem 3:
– In sleep mode, if the S-SFH SP has changed and taken effect during the
sleep window, the changed S-SFH SP should be immediately sent in the
first or second SFH subframe, or the first SFH subframe without any SSFH SP after the AMS wakes up. [Refer to Figure 3 and 4]
– Advantage:
• Guarantee the normal operation after a sleep AMS wakes up.
• Solution to Problem 4:
– If the failure times of decoding the P-SFH or S-SFH are more than
Maximum_Retry_Time, the AMS will perform reentry process.
– Advantage:
• Faster the reentry process if an AMS can’t decode SFH correctly.
Figure 1 for Solution 1
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 40ms in update process)
This figure above gives a case that ABS decreases SP3 scheduling periodicity
during SP3 update, when each SFH subframe can allow two S-SFH SPs to be
transmitted simultaneously.
Figure 2 for Solution 1
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 another case that ABS decreases SP3 scheduling
periodicity during SP3 update, when each SFH subframe can only allow one SSFH SP to be transmitted due to the lack of resource.
Figure 3 for Solution 3
Current SP Scheduling Position:
Superframe n+1 ~ n+8
SP1(40ms)
Proposed SP Scheduling Position:
Superframe n+1 ~ n+8
SP1(40ms)
AMS wakes
up earlier
SW
SP2(80ms)
SW
SP2(80ms)
The changed SP3 has taken
effect before the moment
LW
SW
SP3(160ms)
The changed SP3 has taken
effect before the moment
AMS wakes
up earlier
LW
SW
SP3(160ms, but additionally increase one SP3 transmission)
This figure above gives a case that ABS transmits the changed SP3 IE in
superframe n+5 additionally, when each SFH subframe can allow two SSFH SPs to be transmitted simultaneously.
Figure 4 for Solution 3
Current SP Scheduling Position:
Superframe n+1 ~ n+8
SP1(40ms)
Proposed SP Scheduling Position:
Superframe n+1 ~ n+8
SP1(40ms)
AMS wakes
up earlier
SW
SP2(80ms)
SW
SP2(80ms)
The changed SP3 has taken
effect before the moment
LW
SW
SP3(160ms)
The changed SP3 has taken
effect before the moment
AMS wakes
up earlier
LW
SW
SP3(160ms, but additionally increase one SP3 transmission)
This figure above gives a case that ABS transmits the changed SP3 IE in
superframe n+8 additionally, when each SFH subframe can only allow one
S-SFH SP to be transmitted due to the lack of resource.
Proposed Text
• Add the new text in page 285, line 62 in section 16.2.23
When multiple sub-packets have changed before taking effect, ABS should adjust
the SP2/3 scheduling periodicity to the smaller value supported by ABS depending
on the system configuration. After the changed SPs have taken effect, ABS can
restore the adjusted SP scheduling periodicity to the original periodicity.
In sleep mode, if the S-SFH SP has changed and taken effect during the sleep
window, the changed S-SFH SP should be immediately sent after the AMS wakes
up.
If the failure times of decoding the P-SFH or S-SFH are more than
Maximum_Retry_Time, AMS will perform reentry process.