Proposed Improvement on PA Uplink Error Handling
Document Number:
Date Submitted:
Source:
Lu Zhaohua , Sun Bo
ZTE Corporation
IEEE C80216m-09/1261
2009-7-6
E-mail:
{ lu.zhaohua, sun.bo1}@zte.com.cn
*http://standards.ieee.org/faqs/affiliationFAQ.html
Venue:
RE:
IEEE 802.16m Session #62
Category: AWD comments / Area: Chapter 15.2.7 (Persistent scheduling)
“Comments on AWD 15.2.7 Persistent scheduling”
Base Contribution:
Purpose:
For discussion and adoption in the 802.16m AWD 802.16m-09/0010r2
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Error Handling in Current PA MAC Procedure
Problem
• Current error handling scheme is reasonable for DL persistent
resource allocation because:
– AMS shall feedback ACK/NACK or nothing on HARQ channel to the
first PA sub-packet. Thus
– ABS shall understand if AMS has successfully decoded the PA-AMAP
or not.
• For UL persistent resource allocation, it is another story:
– HFA is defined as a downlink HARQ feedback channel, so
– ABS cannot identify if AMS has failed to decode PA A-MAP thus
cannot transmit data using assigned LRU resources. Then
– ABS will trigger the HARQ process and until the HARQ process failed
it re-arrange PA resource for AMS. And
– This process will waste resources unnecessarily.
16e Solution
•
A MAP HARQ Feedback channel is allocated as well for AMS to feedback if the PA MAP
information is successfully decoded.
•
Problem
PA-MAP
MAP
HARQ
DL
UL
...
DL
UL
PA
PA(Wasted)
Frame k
Frame
(k+N*AP)
– In above case, the ABS sends PA MAP to assign UL persistent resource and MAP
HARQ feedback channel to an AMS, but the AMS fails to receive PA MAP, so
persistent resource in frame k assigned to the AMS is wasted.
•
Improvement
– In order to solve above problem, the AMS shall begin to transmit uplink data on UL
persistent resource after the frame which the AMS send ‘ACK’ through MAP HARQ
feedback channel to the ABS. In another words, the persistent resource in frame k can
be temporarily scheduled to other AMSs by the ABS.
Proposed Solution
• Proposed Solution:
– UL Persistent A-MAP IE should carry ‘MAP HARQ
Feedback channel Allocation’ field for AMS to feedback if
the UL PA MAP information is successfully decoded.
– When the ABS allocate a UL PA resource, it shall allocate a
corresponding MAP HARQ Feedback channel as well. And
the allocation of UL PA resource shall be delayed to the
corresponding MAP HARQ Feedback channel so that the
ABS can have chance to detect if the UL PA MAP
information is successfully decoded.
– If the ABS get nothing on the MAP HARQ Feedback
channel, neither ACK nor NACK, the ABS can transmit the
same UL Persistent A-MAP IE again.
Proposed AWD Text
•
===============Text Start========================
•
•
15.2.7.4 Error Handling Procedure
15.2.7.4.1 Error Handling Procedure for an Individual Connection
•
•
[Delete the red characters in following paragraph]
For transmissions with HARQ enabled, an ACK is transmitted to acknowledge the successful decoding of a
data burst, or a NACK is transmitted to notify failure in decoding a burst transmitted on the DL/UL. If an
ACK or a NACK for the initial data burst identified by the DL/UL Individual Persistent A-MAP IE is
detected in the assigned HARQ Feedback channel, the ABS shall assume that the DL/UL Individual Persistent A-MAP IE is correctly received.
In the absence (NULL detection) of an ACK or a NACK in the HARQ feedback channel assigned in the
DL/UL Individual Persistent A-MAP IE, the ABS shall assume that the AMS has not received the DL/UL
Individual Persistent A-MAP IE and the same DL/UL Persistent A-MAP IE can be transmitted again.
•
•
•
•
[Add the following text into the end of paragraph 15.2.7.4.1]
For UL PA transmission, a MAP feedback channel shall be assigned for AMS to feedback whether the UL
Persistent A-MAP information is decoded successfully or not. Any UL data transmission using the allocated
PA resource shall happen after the subframe carrying the corresponding MAP feedback channel. If an ACK
is detected in the assigned MAP feedback channel, the ABS shall assume that the UL individual Persistent
A-MAP IE is correctly decoded.
In the absence (NULL detection) of an ACK in the MAP feedback channel assigned in the UL Individual
Persistent A-MAP IE, the ABS shall assume that the AMS has failed to decode the UL Individual Persistent
A-MAP IE and the same UL Persistent A-MAP IE can be transmitted again.
Proposed AWD Text (Contd.)
•
15.2.7.4.2 Error Handling Procedure for an Multiple Connection
•
•
[Delete the red characters in following paragraph]
For transmissions with HARQ enabled, an ACK is transmitted to acknowledge the successful decoding of a
data burst, or a NACK is transmitted to notify failure in decoding a burst transmitted on the DL/UL. If an
ACK or a NACK for all the initial data bursts identified by the DL/UL Composite Persistent A-MAP IE is
detected in the assigned HARQ Feedback channel, the ABS shall assume that the DL/UL Composite
Persistent A-MAP IE is correctly received by all the connections.
In the absence (NULL detection) of an ACK or a NACK in the HARQ feedback channel assigned to one or
more connections in the DL/UL Composite Persistent A-MAP IE, the ABS shall assume that the
corresponding AMSs have not received the DL/UL Composite Persistent A-MAP IE and the DL/UL
Composite A-MAP IE can be transmitted again for these connections. If the persistent allocation needs to
be transmitted to only one connection the DL/UL Individual A-MAP IE can be transmitted again for this
connection.
•
•
•
•
•
[Add the following text into the end of paragraph 15.2.7.4.2]
For UL PA transmission, a MAP feedback channel shall be assigned for AMS to feedback whether the UL
Persistent A-MAP information is decoded successfully or not. Any UL data transmission using the allocated
PA resource shall happen after the subframe carrying the corresponding MAP feedback channel. If an ACK
is detected in the assigned MAP feedback channel, the ABS shall assume that the UL Composite Persistent
A-MAP IE is correctly decoded.
In the absence (NULL detection) of an ACK in the MAP feedback channel assigned in the UL Composite
Persistent A-MAP IE, the ABS shall assume that the AMS has not received the UL Composite Persistent AMAP IE and the same UL Persistent A-MAP IE can be transmitted again.
=========================End of Text======================
Proposed AWD Text (Contd.)
•
•
•
=============Text Start====================
15.3.6.4.2.7.1 UL Individual PA A-MAP IE
The UL individual persistent A-MAP IE is specified in Table 679.
•
Table 679: UL Individual Persistent A-MAP IE
Syntax
Size in bits
Description/Notes
UL Persistent A-MAP_IE() {
-
-
HFA
[4]
TBD
HARQ Feedback Allocation
MAP FA
[4]
MAP Feedback Allocation
3
HARQ channel identifier
2
Number of ACID for implicit cycling of HARQ channel identifier
0b00: 1
0b01: 2
0b10: 3
0b11: 4
-
-
...
ACID
N_ACID
}
…
}
Proposed AWD Text (Contd.)
•
•
15.3.6.4.2.7.1 UL Composite PA A-MAP IE
The UL Composite persistent A-MAP IE is specified in Table 680.
•
Table 680: UL Composite Persistent A-MAP IE
Syntax
Size in bits
Description/Notes
UL Composite Persistent A-MAP_IE() {
-
-
-
-
[4]
MAP Feedback Allocation
if (Allocation Period and ACID Indicator == 1) {
…
}
MAP FA
}
}
•
===================End of Text==========================