Proposal of Different CRC Masks for Concatenated Subband Assignment AMAP IEs (16.3.6.5.2.4)
Document Number: IEEE C802.16m-10/0041
Date Submitted: 2010-3-5
Source:
Yan-Xiu Zheng, Chang-Lan Tsai
Yu-Chuan Fang, Chung-Lien Ho
ITRI
E-mail: zhengyanxiu@itri.org.tw
tsaichangl@itri.org.tw
Venue:
IEEE 802.16 Session#66 at Orlando, USA.
Base Contribution:
Purpose:
Propose to be discussed and adopted by TGm for the use in Project 802.16m/D4
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Motivation
• When the subband allocation is made using two
concatenated IEs, there shall exist a bit in subband A-AMAP for indicating the IE to be concatenated with the
previous or next IE for subband allocation.
• The same CRC mask is used for the two concatenated
subband A-A-MAP IEs.
• There would be hesitation in searching concatenated
subband A-A-MAP IEs.
Example 1
• IE1 and IE4 are single IEs with STID1 and STID4,
respectively. The CRC masks are (0000|STID1) and
(0000|STID4), respectively. The one bit indicator NumIEs
is set to 0 representing a single IE.
• IE2 and IE3 are concatenated for subband allocation.
They have the same STID and CRC mask which are
STID2 and (0000|STID2), respectively. The one bit
indicator NumIEs is set to 1 representing that the IE is
concatenated with another IE with NumIEs equaling 1.
IE1
IE2
IE3
IE4
NumIEs = 0
NumIEs = 1
NumIEs = 1
NumIEs = 0
(0000|STID1)
(0000|STID2)
(0000|STID2)
(0000|STID3)
Example 1
• In the case that the two subband A-A-MAP IE2 and IE3
are decoded correctly and CRC check is success, since
the indicator NumIEs == 1 in subband IE2, AMS check
the next subband IE content to find the IE with NumIEs
== 1 and combine these two IEs for subband allocation.
• In the case that the CRC check for IE2 is failure, IE2 is
discarded. And if CRC check for IE2 is success, since the
indicator NumIEs == 1, AMS has to seek another
subband IE with NumIEs == 1. This wastes logic
processing time.
Distinct CRC Masks on Concatenated IEs
• We propose to use distinct CRC mask for the second IE
of the two concatenated subband A-A-MAP IEs.
– CRC mask = (0010|STID)
• Using the previous example for explanation. Now CRC
mask of the second subband IE is (0010|STID2).
IE1
IE2
IE3
IE4
NumIEs = 0
NumIEs = 1
NumIEs = 1
NumIEs = 0
(0000|STID1)
(0000|STID2)
(0010|STID2)
(0000|STID3)
CRC Check
• In the case that CRC check of subband IE2 is success
using CRC mask (0000|STID2) and the indicator NumIEs
== 1, the next subband IE is check by CRC mask
(0010|STID2). If the CRC check of subband IE2 is
success, then IE2 and IE3 are combined for subband
allocation
• In the case that the CRC check for IE2 is failure using
CRC mask (0000|STID2), IE2 is discarded. AMS
continues using CRC mask (0000|STID2) to check IE3.
Of course the check would be failure.
Flow Chart
IEk
CRC mask
(0000|STID)
k=k+1
Yes
Yes
Subband A-A-MAP
and NumIEs == 1
k=k+1
CRC mask
(0010|STID)
Concatenate
IEk-1 and IEk
Success
No
Single IE
IEk
Yes
Success
No
Discard IEk-1
and IEk
No
Discard
IEk
Text Modification
[Modify Table 819 on page 461]
Masking
Prefix
Description
0b0
CRC is masked by 1 bit masking prefix, 3 bit message type
indicator, and 12 bit Masking Code
The 3-bit type indicator shall be set/interpreted as follows.
000: 12 bit Masking Code refers to an STID (i.e. CRC mask =
0000| Masking Code)
010: 12 bit Masking Code refers to an STID used to mask the
second IE if two assignment A-MAP IEs are concatenated for
resource allocation (i.e. CRC mask = 0010| Masking Code)
001: 12 bit Masking Code used to mask Broadcast Assignment
A-MAP IE, BR-ACK A-MAP IE, and Group Resource
Allocation A-MAP IE, which is described in Table 820 (i.e.
CRC mask = 0001| Masking Code).
0b1
CRC is masked by 1 bit masking prefix, and 15 bit RAID (i.e.
CRC mask = 1|RAID)