Transcript No Slide Title

Clarification on ACK of Bandwidth Request
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-09/0180r4
Date Submitted:
2009-1-15
Source:
Gang Shen, Kaibin Zhang, Jimin Liu, Xiaobing Leng
Alcatel Shanghai Bell
E-mail:
[email protected]
Kelvin Chou, Yih-Shen Chen, I-Kang Fu, Paul Cheng
MediaTek
Email:
[email protected]
Heejeong Cho, Jinyoung Chun, Sukwoo Lee, Kiseon Ryu
LG Electronics
E-mail:
[email protected]
Venue:
Re: Call for Comments on Project 802.16m System Description Document (SDD)
Base Contribution:
N/A
Purpose:
To be discussed and adopted by TGm for the 802.16m SDD
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Acknowledgement of bandwidth request in 16m SDD
• 16m SDD allows acknowledgement
of the reception of bandwidth request
1
Acknowledgement for BR indicators
2
BS
BW REQ message
3
Acknowledgement for BW REQ
4
– Acknowledge of BR enables MS to
restart BR to recover quickly from a
BR failure
•
UL grant for BW REQ message
UL grant
UL scheduled transmission with optional
piggybacked bandwidth request
However, it is not necessary for ABS to response every BR with ACK
considering the extra overhead
5
MS
– In SDD it states “In step 2 and step 4,
ABS may send message to
acknowledge the reception Status”
(line 20 of page 110)
Bandwidth Request indicator
ACK of Bandwidth Request
• It is also not necessary for extra ACK together with UL grant in Step 2 and
Step 4
– If AMS receives the UL grant, thus it knows ABS has correctly received the
BR. So extra ACK together with UL grant is not necessary
– ACK should follow the procedure step 1 or step 3 to let AMS be informed
early
• If ABS allocates UL grant immediately, it is not necessary to send ACK of
BR
– The ABS should respond by the acknowledgement only when needed
– ACK is useful
• when BS receives BR indicator (step 1) but can not respond by UL grant for BW
REQ message immediately
• when BS receives BW REQ (step 3) but can not allocate the bandwidth request
immediately
AMS Activities
• SDD has not mentioned AMS activities to restart BR
• AMS should restart the BR retransmission quickly
– If AMS does not receive UL grant or ACK within a pre-defined period
(e.g. next frame), it then restarts the bandwidth request
Suggested Remedy
[Change the following texts in line 20 of page 110 as indicated]
In step 2 and step 4, ABS may send message to acknowledge the reception status. Following Step
1 and Step 3, ABS may acknowledge the reception of bandwidth request. If AMS does not receive
any acknowledgement or UL grant, it waits until the expiration of a pre-defined period and
restarts the bandwidth request. The pre-defined period may be differentiated by factors such as
QoS parameters (e.g. scheduling type, priority, etc). In case BW is granted immediately, there is
no need for ABS to send explicit Ack