Extended MAC Header for System Information Update Notification (16.2.2.2)
Document Number: IEEE C80216m-10/0212r1
Date Submitted: 2010-03-16
Source:
Yih-Shen Chen, Kelvin Chou and Paul Cheng
MediaTek Inc.
E-mail: yihshen.chen@mediatek.com, kelvin.chou@mediatek.com
Re: Letter Ballot #31a on the Draft Amendment (IEEE P802.16m/D4)
Base Contribution: This is base contribution
Purpose: Propose to be discussed and adopted by TGm for the 802.16m Amendment
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Introduction (1/3)
• To sustain normal network operations, serving ABS broadcasts and
adjusts its configuration via system information updating
– The critical information is broadcasted via P-SFH/S-SFH IEs in 802.16m
• SFH update mechanism is defined in 16.2.23
– When P-SFH change count is updated, AMS shall decode the up-todate system information according to S-SFH bitmap information
– The minimal validity duration of each S-SFH IE SP is determined by
“Rate of change of S-SFH info” in SP3
• The timing of SFH broadcasting is superframe-based operation
• For sleep mode control, there are two time units:
– Frame-based operation is the default time unit
– Subframe-based operation is also supported if configured (16.2.16.2.1)
• E.g., VoIP
• Obviously, the timings of SFH transmission and and sleep mode
control are different
2
Introduction (2/3)
• In current specification, AMS may wake up a little bit
earlier to get the system information
– Micro-sleep-like mechanism can be applied
• With the knowledge of S-SFH update periodicity, AMS
can wake up some specific SFH time to decode SFH
information
• It is assumed that SFH update rate is very low
– Most of the time, AMS checks P-SFH change count and nothing
happens
• Moreover, S-SCH tracking is good enough to maintain
physical layer synchronization
• Therefore, it is motivated to reduce SFH decoding rate
for sleep-mode operation
3
Introduction (3/3)
• Another question is related to the information
update of broadcast messages:
– AAI_SCD
– AAI_NBR-ADV
• It’s better to have an indication to notify the
system information update for sleep mode AMS
4
Proposed Solution
• ABS transmits a unicasting message to sleep-mode AMS for
notifying the coming of system information update
– It can be a piggyback extended MAC header
• Once the AMS decodes the message, it figures out that system
information is going to be updated
– It can keep awake to decode SFH or broadcasting MAC management
messages
• Performance analysis:
– Pros:
• AMS does not require to decode SFH frequently
• AMS can figure out when broadcast MAC messages will be transmitted
– Cons:
• DL signaling overhead
• Since SFH update does not happen frequently, the overhead is
acceptable
5
Proposed Text (1/1)
• Add a new section 16.2.2.1.3.6
16.2.2.2.11 System Information Update Header (SUH)
ABS transmits SUH to notify that system information is going to be updated.
When detecting the message, AMS shall try to obtain the up-to-date system
information before entering sleep window.
Size (bits)
Notes
FID
4
Flow identifier. Set to 0001.
Type
4
MAC signaling header type =0b0101
SFH version
4
SFH version number
SFH update bitmap
3
Each bit represent the update of S-SFH
Syntax
System Information
Update Header (){
IEi, i=1~3, from LSB to MSB.
Broadcast MAC
messages
}
2
Bit #0: AAI_SCD
Bit #1: AAI_NBR-ADV
6