IEEE C802.16m-08/1447r1
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Proposed Text of uplink PHY physical structure section of the IEEE 802.16m Amendment
Date
Submitted
2008-11-03
Source(s)
Shaohua li, Xin Qi, Wei chao, Adiran
Boariu,
Voice:
E-mail:
+86-13501217803
shaohua.li@nsn.com
Nokia Siemens networks
Re:
802.16m amendment text
Target topic: “Uplink Physical Structure (data plane only)”.
Abstract
The contribution proposes the text of uplink physical structure section (11.6) to be included in the
802.16m amendment.
Purpose
To be discussed and adopted by TGm for the 802.16m amendment.
Notice
Release
Patent
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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.
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution,
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<http://standards.ieee.org/guides/bylaws/sect6-7.html#6> and
<http://standards.ieee.org/guides/opman/sect6.html#6.3>.
Further information is located at <http://standards.ieee.org/board/pat/pat-material.html> and
<http://standards.ieee.org/board/pat>.
Proposed Text of Uplink Physical Structure Section
for the IEEE 802.16m Amendment
Shaohua Li, Xin Qi, Wei chao,Adiran
Boariu,
Nokia Siemens Networks
1. Introduction
The contribution proposes the text of uplink physical structure section to be included in the 802.16m amendment. In SDD [1], the
procedure of subchannelization for UL distributed resource is defined. But the details are not given.
According to the text of SDD, LLRU shall be FDM with LDRU. In order to allocate PRUs for LDRUs, one way is firstly to allocate
PRUs for LLRUs according to the channel aware scheduling and then the left PRUs are used for LDRUs. With this method, it will
cause some problems. Firstly, when we allocate PRUs to LLRU before LDRUs allocation, it is possible that the resource for LDRUs
only consists of a few PRUs and therefore there is no enough frequency diversity for LDRUs and the performance is degraded.
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IEEE C802.16m-08/1447r1
Secondly, when the number of LLRUs is different from neighbouring cells, this method can not achieve interference averaging. In
other words, two LDRUs of neighbouring cells could have same physical resources and thus interfere with each other. Remember that
in 802.16e permutation is used for uplink PUSC subchannelization so that the collision probability of same physical resources in any
two subchannels of neighbouring cells are very small, e.g. interference are from multiple users instead of single user.
In order to solve the problems, we propose the permutation method which is shown in Figure 1. It can be seen that the second-level
permutation is based on PRUs instead of tiles as defined for uplink PUSC in 802.16e. Therefore after the permutation we get a number
of super- channels. Since a super-channel contains Nc non-continuous PRUs it can be configured to Nc LLRU subchannels, which
have the same size as PRUs. Meanwhile, a super-channel can also be configured to Nc LDRUs.
Outer permutation is applied to the PRUs, distributing the reordered
PRUs into frequency partitions
The PRUs in each frequency partition are divided into Nc groups of
continuous resource blocks
Allocation PRUs to form a super-channel by second-level
permutation, and a super-channel contains total Nc PRUs distributed
in the frequency partition
Divided resource into LLRU and LDRU group based on supperchannel. A super-channel can be configured to Nc LDRUs or Nc
LLRUs, where a LLRU is mapped directly from one PRU in the
supper-channel while a LDRU contains Nc non-continuous tiles
Figure 1 The proposed subchannelization procedure for 802.16m
In the proposed method, we propose that a super-channel is the basic unit for resource partition between LLRUs and LDRUs. A
LDRU/LLRU group consists of an integer number of super-channels. We suggest to firstly allocate a number of super-channels for
LDRU and then all the left super channels are used for LLRU.
In order to get LLRU/LDRU, the following steps shall be followed, which is shown in Figure 2.
1.
2.
3.
4.
NB PRU bands (each band of N1 continuous PRUs) should be reserved for band-based localized allocation. There
could be multiple predefined configurations of band reservation. Each configuration corresponds to a specific N B
value.
Renumber the remaining physical PRUs into logical PRU. LogicalPRU=RenumberingSequence(physical PRU), the
sequence is shown in Table 1, Table 2 and Table 3.
Distributing the reordered PRUs into frequency partition.
Perform Second-level permutation to get localized group and distributed group.
a.
The PRUs in the frequency partition are partitioned into N c=3 groups containing logical continuous PRUs
and further mapped to supper-channel. Each supper-channel consists of one PRU from each of these Nc
groups. The number of PRUs per supper-channel is equal to Nc, and the number of supper-channels,
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b.
Nsupper-channel, varies with FFT sizes and NB. The number of PRUs in this frequency partition is thus equal to
Nsupper-channel*Nc.
The exact partitioning into supper-channel is according to equation x:
PRU(s,n) = Nsupper-channel*n+(Ps[(s+n) mod Nsupper-channel]+UL_Permbase) mod Nsupper-channel (x)
Where
PRU(s,n)
n
Pt
s
UL_PermBase
c.
is the logical PRU index
is the PRU index 0 … 2 in a super-channel
is the PRU permutation sequence which is given in Table 4.
is the supper-channel in the range 0 … Nsupper-channel-1
is an integer value which is assigned by a management entity
Divided resource into LLRU and LDRU group based on supper-channel.
In LLRU group, the PRUs in each supper-channel are mapped into LRU directly. Each supper-channel is mapped into Nc=3 LRUs. In
LDRU group, the inner permutation is performed using the following procedures:
I. Renumber physical tiles into logical tiles in the LDRU group. The PRUs in each supper-channel shall be divided into
Nc*3 physical tiles as defined in Section 11.6.3. The logical index of the v-th (v=0,…,2) physical tile in the n-th PRU
of the s-th supper-channel is given as
u = s* Nc*3 + n * Nc + v.
II. Mapping logical tiles into LDRUs. The exact partitioning into LDRUs is according to equation xx,
Tiles(k,m) = 3*Nc*floor(k/Nc)+3*m (xx)
Tiles(k,m)
is the logical Tiles index
k
is the LRU index 0, …, NLRU-1.
m
is the Tile index 0, …, Nc-1 in each LRU.
III. LDRUs are mapped into LRUs.
To illustrate the subchannelization procedure for DRU, an example is provided to clarify the operation of the permutation procedure.
The relevant parameters characterizing the UL are, therefore, given as

Band reserved for band allocation: NB = 0

Number of PRUs: 48

Number of supper-channel: Nsupper-channel = 16
The permutation and subchannelization are illustrated in Figure 2.
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IEEE C802.16m-08/1447r1
T0
Step 3:
Lgical PRUs
T1
1
T2
2
...
3
PRU Group 1
Step 4.a:
PRUs groups
1
...
2
48
PRU Group 2
16
17
...
18
PRU Group 3
32
33
34
...
48
9
17
34
Nsupper-channel=16
Step 4.b:
Supper-channel
partition
1
18
1
7
36
7
31
48
48
Supper-channel 11
Supper-channel 0
Step 4.c
LLRU and LDRU
partition
31
Supper-channel 15
...
...
Supper-channel 11
LDRUs
T0
T1
T2 T0
PRU 7
Logical Tile
index u
Step I:
Renumbering
tiles
0
1
2
T0
T1
T2 T0
3
4
T1
5
3
6
1
T0
T0
T0 T1
4
6
T2 T0
T1
7
T2
7
8
T1
T2
PRU 48
2
T1 T2
LDRU 1
T1
PRU 48
PRU 31
0
LDRU 0
T2 T0
PRU 31
PRU 7
Step II
LDRU
T1
LLRUs
5
8
T2
T2
LDRU 2
Figure 2 Example subchannelization for LDRU with 10MHz BW
Text proposal for inclusion in the 802.16m amendment
-------------------------------
Text Start
---------------------------------------------------
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IEEE C802.16m-08/1447r1
1.1
Uplink Physical Structure
Each UL subframe is divided into a number of frequency partitions, where each partition consists of a set of physical resource units
across the total number of OFDMA symbols available in the subframe. Each frequency partition can include contiguous (localized)
and/or non-contiguous (distributed) physical resource units. Figure 3 illustrates the uplink physical structure in the example of two
FFR groups with FFR group 2 including both localized and distributed resource allocations.
Figure 3 Example of uplink physical structure
1.1.1
Physical and Logical Resource Unit
A physical resource unit (PRU) is the basic physical unit for resource allocation that comprises Psc consecutive subcarriers by Nsym
consecutive OFDMA symbols. Psc is 18 subcarriers and Nsym is the number of OFDMA symbols depending on the subframe type. A
logical resource unit (LRU) is the basic logical unit for distributed and localized resource allocations and its size is Psc*Nsym
subcarriers for data transmission. For control channel/message transmission, the size of LRU should be the same as that of data
transmission and multiple users are allowed to share one control LRU. The LRU includes in its numerology the number of pilots that
are used in a PRU, and may include control information. So, the effective number of data subcarriers in an LRU depends on the
number of allocated pilots and control channel presence.
1.1.1.1
Distributed Resource unit
The logical distributed resource unit (LDRU) can be used to achieve frequency diversity gain. The LDRU contains a group of
subcarriers which are spread across several PRUs which are part of a distributed group. The size of the LDRU equals the size of the
LRU for distributed allocations. The minimum unit for forming the LDRU is a tile. T different types of tiles are defined, where T is 1.
The UL tile sizes are 6xNsym, where Nsym depends on the subframe type defined in section 11.4.1. 18x2 tile size for UL transmit power
optimized distributed allocation and other tile sizes are FFS.
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1.1.1.2
Localized Resource unit
The logical localized resource unit (LLRU) can be used to achieve frequency-selective scheduling gain. The LLRU contains a group
of subcarriers which are contiguous across several PRUs which are part of a localized group. The size of the LLRU equals the size of
the LRU for localized allocations, i.e., Psc subcarriers by Nsym OFDMA symbols.
1.1.2
Subchannelization and Resource mapping
The subcarriers of an OFDMA symbol are partitioned into N g,left left guard subcarriers, Ng,right right guard subcarriers, and Nused used
subcarriers. The DC subcarrier is not loaded. The Nused subcarriers are divided into PRUs. Each PRU contains pilot and data
subcarriers defined in 11.6.3. The number of used pilot and data subcarriers depends on MIMO mode, rank and number of multiplexed
MSs and the type of resource allocation, i.e., distributed or localized resource allocations as well as the type of the subframe, i.e.,
type-1 or type-2. The values of the parameters depend on system bandwidth, which are given in Table 1 to Table 3.
Table 1: OFDMA UL subcarrier allocations 2048 FFT
Parmater
Number of DC subcarriers
Number of Guard subcarriers, left
Number of Guard subcarriers,
right
Number of used subcarriers
Number of PRUs
Renumbering sequence
value
1
160
Comments
index 2048 (counting from 0)
159
1729
96
1
used to renumber sets before allocation to
frequency partition (TBD)
Table 2: OFDMA UL subcarrier allocations 1024 FFT
Parmater
Number of DC subcarriers
Number of Guard subcarriers, left
Number of Guard subcarriers, right
Number of used subcarriers
Number of sets
Renumbering sequence
value
1
80
79
865
12
1
Comments
index 1024 (counting from 0)
used to renumber sets before allocation to
frequency partition (TBD)
Table 3: OFDMA UL subcarrier allocations 512 FFT
Parmater
Number of DC subcarriers
Number of Guard subcarriers, left
Number of Guard subcarriers, right
Number of used subcarriers
Number of PRUs
Renumbering sequence
value
1
40
39
433
24
1
Comments
index 512 (counting from 0)
used to renumber sets before allocation to
frequency partition
(TBD)
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1.1.2.1
Uplink Subcarrier to Resource Unit Mapping
The main features of resource mapping include:
1. Support of localized resource unit (LLRU) and distributed resource unit (LDRU) in an FDM manner.
2. DRUs comprise multiple tiles which are spread across the distributed group to achieve diversity gain.
3. FFR can be applied in UL.
The UL subcarriers to resource unit mapping process is defined as follows and illustrated in Figure 4:
1. First-level or outer permutation is applied to the PRUs in the units of N1 and N2 PRUs, where N1=4 (TBD) and
N2=1 (TBD). Direct mapping of outer permutation can be supported.
2. Distributing the reordered PRUs into frequency partitions.
3. The frequency partition is divided into localized (LLRU) and/or distributed (LDRU) resource groups. Using sector
specific permutation can be supported; directly mapping of the resources can be supported for localized resource.
The sizes of the distributed/localized resources are flexibly configured per sector. Adjacent sectors do not need to
have same configuration of localized and diversity groups.
4. The localized and distributed groups are further mapped into LRUs. For the LLRU groups, the mapping is direct.
For the LDRU groups, the mapping is carried out via a tile permutation/hopping
Figure 4 Illustration of the uplink subcarrier to resource unit mapping
The Uplink LLRU and LDRU distribution is performed using the following procedures:
1. NB PRU bands (each band of N1 continuous PRUs) should be reserved for band-based localized allocation. There
could be multiple predefined configurations of band reservation. Each configuration corresponds to a specific NB
value.
2. Renumber the remaining physical PRUs into logical PRU. LogicalPRU=RenumberingSequence(physical PRU), the
sequence is shown in Table 1, Table 2 and Table 3.
3. Distributing the reordered PRUs into frequency partition.
4. Perform Second-level permutation to get localized group and distributed group.
a. The PRUs in the frequency partition are partitioned into N c=3 groups containing logical continuous PRUs
and further mapped to supper-channel. Each supper-channel consists of one PRU from each of these Nc
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IEEE C802.16m-08/1447r1
b.
groups. The number of PRUs per supper-channel is equal to Nc, and the number of supper-channels,
Nsupper-channel, varies with FFT sizes and NB. The number of PRUs in this frequency partition is thus equal to
Nsupper-channel*Nc.
The exact partitioning into supper-channel is according to equation x:
PRU(s,n) = Nsupper-channel*n+(Ps[(s+n) mod Nsupper-channel]+UL_Permbase) mod Nsupper-channel (x)
Where
PRU(s,n)
n
Pt
s
UL_PermBase
c.
1.1.2.2
is the logical PRU index
is the PRU index 0 … 2 in a super-channel
is the PRU permutation sequence which is given in Table 4.
is the supper-channel in the range 0 … Nsupper-channel-1
is an integer value which is assigned by a management entity
Divided resource into LLRU and LDRU group based on supper-channel.
Subchannelization for UL Distributed Resource
The tiles for an uplink distributed group are permuted using an inner permutation.
Two kinds of distributed resource allocation are used for UL distributed subchannelization, (1) regular distributed allocation (2) UL
transmit power optimized distributed allocation. The UL transmit power optimized distributed resource is allocated first. The rest of
the frequency resource is then allocated for regular distributed allocation. A hopping/permutation sequence (TBD) is defined for the
power optimized allocation that spreads the hopping units across frequency. The second-level or inner permutation defined for the UL
regular distributed resource allocations spreads the tiles of the LDRU across the frequency band. The granularity of the inner
permutation is equal to the tile size for forming a LDRU according to section 1.1.1.1.
The inner permutation is performed using the following procedure:
1.
Renumber physical tiles into logical tiles in the LDRU group. The PRUs in each supper-channel shall be divided
into Nc*3 physical tiles as defined in Section 11.6.3. The logical index of the v-th (v=0,…,2) physical tile in the n-th
PRU of the s-th supper-channel is given as
u = s* Nc*3 + n * Nc + v.
2.
Mapping logical tiles into LDRUs. The exact partitioning into LDRUs is according to equation xx,
Tiles(k,m) = 3*Nc*floor(k/Nc)+3*m (xx)
Tiles(k,m)
is the logical Tiles index
k
is the LRU index 0, …, NLRU-1.
m
is the Tile index 0, …, Nc-1 in each LRU.
3.
LDRUs are mapped into LRUs.
Table 4: Basic permutation sequence
Sequence length
8
16
Basic permutation sequences
1, 2, 4, 3, 6, 7, 5
1, 2, 4, 8, 3, 6, 12, 11, 5, 10, 7, 14, 15, 13, 9
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IEEE C802.16m-08/1447r1
32
12
6
1.1.2.3
1, 2, 4, 8, 16, 5, 10, 20, 13, 26, 17, 7, 14, 28, 29, 31, 27, 19
36, 12, 24, 21, 15, 30, 25, 23, 11, 22, 9, 18
6, 9, 4, 8, 10,11, 5, 2, 7, 3,1,0
3, 2, 0, 4, 5,1
Subchannelization for UL Localized Resource
Localized subchannels contain subcarriers which are contiguous in frequency. There is no inner permutation defined for the UL
localized resource allocations. The LLRU is directly mapped to localized LRU within each frequency partition. Precoding and/or
boosting applied to the data subcarriers will also be applied to the pilot subcarriers.
In LLRU group, the PRUs in each supper-channel are mapped into LRU directly. Each supper-channel is mapped into Nc=3 LRUs.
[1] IEEE 802.16m-08/003r5, Draft IEEE 802.16m System Description Document, 2008-Oct
9