Structure of the “Resource Allocation” field in the A-AMAP IEs – Proposal Summary
Document Number:
IEEE C80216m-09_1328
Date Submitted:
2009-07-06
Source:
Sudhir Ramakrishna,
Youngbo Cho,
Hyunkyu Yu,
Jeongho Park,
Heewon Kang,
Zhouyue Pi
Venue:
Re: 802.16m amendment working document
Category: AWD Comments
Area: Chapter 15.3.6 (DL Control)
E-mail: sudhir.r
@samsung.com
Base Contribution:
IEEE C80216m-09_1328
Purpose:
To be discussed and adopted by TGm for the 802.16m AWD
Notice:
This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups . It represents only the views of the participants listed in the
“Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein.
Release:
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE
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> and < http://standards.ieee.org/board/pat >.

• Contribution C80216m-09_1331 provides the AWD text defining the structure & interpretation of the “Resource Allocation” field, and the interpretation of the associated IEs, for the 5, 10 and 20
MHz cases
• This contribution provides a high-level summary of the detailed RA field text in Contribution C80216m-
09_13331, and provides some motivation, background & pointers to some supporting simulation results for the RA field design.
IEEE_C80216m-09_1328
Slide #2

•
• Should be possible to indicate a 1 LRU assignment
• No un-assigned LRUs due to assignment indication limitations
For VoIP support, need to indicate assignment of 1/2/3/4 & 6 LRUs
• RA field as small as possible, to keep signaling efficient
• Use “channel tree” approach

Nodes at bottom level of tree represent LRUs

Each node in tree, indexed by RA, indicates assignment of all nodes at bottom level branching from it
• Select channel tree such that

1 LRU granularity at lower assignment sizes  to support VoIP

Lower granularity at larger assignment sizes o
Leads to reduction in number of nodes in tree  reduction in size of RA field o
Granularity less important at larger assignment sizes, will not affect performance in “full buffer” type traffic o
In RL, large assignments unlikely due to transmit power limitations
IEEE_C80216m-09_1328
Slide #3

• From DL system-level simulation results in [2]

Allocation of smaller (<= 3) number of sub-bands is an important (dominant) use-case o
For this use case, using a common MCS for all assigned sub-bands leads to very small performance difference

Ability to indicate non-contiguous sub-band allocations important o
Can lead to performance gains (with PF scheduler) over purely contiguous allocations
• For allocation of sub-bands with contiguous indices, leverage channel tree indication method
• In all cases, all possible allocations of sub-bands with contiguous indices can be indicated
• RA field indexing designed so that
• Using 1 IE, can indicate most combinations of non-contiguous assignments of small (<= 3) number of sub-bands
• For allocation of larger # of non-contiguous sub-bands, use 2 IEs, and indicate using concatenated RA fields
• Do not need more than 2 IEs
IEEE_C80216m-09_1328
Slide #4

• For each of the BW cases (5 MHz, 10 MHz & 20 MHz)
• Use x + 1 bits for the RA Field
 x bits for RA itself (x depends on bandwidth and # of LRU combinations to be indicated)

1 distinguisher bit, called RA_Specifier, to distinguish between contiguous and non-contiguous LRU allocations o
Non-contiguous indicator used in sub-band allocations
IEEE_C80216m-09_1328
Slide #5

# of LRUs
# of sub-bands
# of all possible contiguous
LRU allocations
5 MHz
24
6
300
10 MHz
48
12
1176
20 MHz
96
24
4656
# of resource indication bits 7 Resource Allocation (RA) bits
+ 1 specifier bit = 8 bits total
8 RA + 1 specifier 10 RA + 1 specifier
252/1176
4
981/4656
4
# of possible contiguous LRU allocations indicable
Highest difference between consecutive contiguous LRU sizes
117/300
4
Non-contiguous sub-band allocations using 1 IE
Max. # of IEs needed for all possible non-contiguous subband indication
SS_RAField_IEEE_C80216m-09_1328
All combinations
1
All combinations of 2 SBs, almost all (210/220) combinations of 3 SBs
2
All combinations of 2 SBs, some combinations of 3 SBs
2
Slide #6

SS_RAField_IEEE_C80216m-09_1328
Slide #7

• 24 LRUs, 6 sub-bands
• RA Field = 8 bits
• Use 7-bits RA + 1 bit RA_Specifier
• RA_Specifier used to distinguish sub-band-CRU allocations vs DRU/miniband CRU allocations
• Design summary
• Full flexibility for sub-band allocation with 1 sub-band granularity
• For contiguous (DRU/mini-band CRU) allocations – can indicate 117 of the 300 possible combinations
• Never need more than 1 AAMAP IE for any allocation
SS_RAField_IEEE_C80216m-09_1328
Slide #8

117 nodes in tree, indexed by 7-bit RA
Each node allocates all the nodes at bottom level (Level 10) that it is connected to.
Allows indication of
117 of the 300 possible combinations of contiguous LRU indices (24 LRUs =
300 contiguous combinations)
SS_RAField_IEEE_C80216m-09_1328
Slide #9

SS_RAField_IEEE_C80216m-09_1328
Slide #10

• Table_RA_1 : This table maps value of 7-bit RA to a node in the channel tree, and then to a set of contiguous LRU indices.
Decimal Value of 7-bit R, n (= index of node in tree)
0 <= n <= 9
10 <= n <= 47
48 <= n <= 117
Level in tree, L
L
 floor






1 1 8
2 n





 s
 floor







15
  n

10 )
2






L s s
 floor







43
  n

48)
2






Index of node within level, j j n j j n 






 n
10 8 s
(

1)

2
48 8 s

(

1)
(
2
2

1)








Index of
1 st
LRU allocated
Index of last
LRU allocated
4j
2j j
4j + 23 – 4L
2j + 9 – 2s j + 2 - s
L s
SS_RAField_IEEE_C80216m-09_1328
Slide #11

SS_RAField_IEEE_C80216m-09_1328
Slide #12

• 48 LRUs, 12 sub-bands
• RA Field = 9 bits
• 8-bit RA + 1 bit RA_Specifier
• Design summary
• Contiguous allocations – use a channel tree, allowing indication of 252 of the 1176 possible LRU allocations
• Non-contiguous sub-band allocations
•
With 1 IE, can indicate all 2 and almost all (210/220) 3 non-contiguous sub-band allocations
•
With 2 IEs, concatenate 8 bit RA in each IE, interpret resultant as a 12 bit bitmap to allow arbitrary allocations of the 12 sub-bands
• Never use more than 2 IEs
SS_RAField_IEEE_C80216m-09_1328
Slide #13

# of LRUs assignable by node @ level
48
44
Node n1
Node n0
Node n2
Level(# of nodes @ level)
0 (1)
1 (2)
A power of two branch
40 n3 n5
252 nodes in tree, indexed by 8-bit RA 2 (3)
Triangular branch
36 3 (4)
32 4 (5)
5 (6) 28
24
20
16
12
8
6 n66 n55 n68
4
3 n88
2
LRU index
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
SS_RAField_IEEE_C80216m-09_1328
6 (7)
7 (8)
8 (9)
9 (10) n65
10 (11) n87
11 (22) n110
12 (23)
13 (46)
14 (47)
44 45 46 47
15 (48)
Slide #14

SS_RAField_IEEE_C80216m-09_1328
Slide #15

• Table_RA_2 : This table maps value of 8-bit RA to a node in the channel tree, and then to a set of contiguous LRU indices.
Decimal Value of 8-bit RA, n (= index of node in tree)
Level in tree, L
0 <= n <= 65 L
 floor






1 1 8 n
2






66 <= n <= 87 11
88 <= n <= 110 12
111 <= n <= 251 s
 floor







91
  n

111)
2






L

13
 s
Index of node within level, j j n j = n - 66 j = n - 88 j n


(
2


1) s

(

1)


2
Index of
1 st
2j
2j
LRU allocated
4j j
Index of last
LRU allocated
4j + 47 – 4L
2j + 5
2j + 3 j + 15 - L
• Table_RA_3 & Table_RA_4: Map 8-bit RA to indices of 2 & 3 non-contiguous sub-bands
• These tables are specified in the text proposal.
SS_RAField_IEEE_C80216m-09_1328
Slide #16

SS_RAField_IEEE_C80216m-09_1328
Slide #17

• 96 LRUs, 24 sub-bands
• RA field = 11 bits
• 10-bit RA + 1 bit RA_Specifier
• Design summary
• Contiguous allocations – use a channel tree, allowing indication of 981 of the 4656 possible LRU allocations
• Non-contiguous sub-band allocations
• Design very similar to the 10 MHz case
• With 1 IE, can indicate all 2 non-contiguous sub-band allocations, and some of the 3 sub-band possibilities
• With 2 IEs, concatenate 10 bit RA, interpret resultant as a 20 bit bitmap to allow arbitrary allocations of up-to 20 sub-bands
•
For allocations larger than 20 sub-bands, use contiguous sub-band indices
• Never use more than 2 IEs
SS_RAField_IEEE_C80216m-09_1328
Slide #18

SS_RAField_IEEE_C80216m-09_1328
Slide #19

SS_RAField_IEEE_C80216m-09_1328
Slide #20

• Table_RA_5 : This table maps value of 10-bit RA to a node in the channel tree, and then to a set of contiguous LRU indices.
Decimal
Value of 10bit RA Field, n (= index of node in tree)
Level in tree, L Index of node within level, j Index of
1 st
LRU allocated
Index of last LRU allocated
0 <= n <=
209
L
 floor







1 1 8 n
2






 j n
(

1)
2
4j 4j + 95 –
4L
210 <= n <=
510 s
 floor








L

20
 s

79
  n

210 )
2







 j n


210 8 s

(

1)


2
2j 2j + 17 –
2s
511 <= n <=
980 s
 floor








L

27
 s

183
  n

511)
2







 j n





511 8 s

(

1)
2 



 j j + 4 - s
• Table_RA_6 & Table_RA_7 : Maps 10-bit RA to indices of 2 or 3 non-contiguous sub-bands
 These tables are specified in the text proposal
SS_RAField_IEEE_C80216m-09_1328
Slide #21

• [1] C80216m-09_0918r2, “Proposed AWD text specifying the “Resource Allocation” field in the
Basic Assignment A-MAP IEs”, presented in IEEE 802.16m Session 61 (in Cairo).
• [2] C80216m-09_0917r2, “Design of the “Resource Allocation” field in the Basic Assignment A-
MAP IE: Simulation results, Insights & Methodology”, presented in IEEE 802.16m Session 61
(Cairo).
SS_RAField_IEEE_C80216m-09_1328
Slide #22