IEEE C802.16m-09/1125r2
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Harmonized proposed AWD text of Frame Structure for 5 MHz, 10 MHz and 20 MHz
bandwidth with 1/4 Tb CP Length
Date
Submitted
2009-05-01
Source(s)
Jia-Hao Wu, Yu-Tao Hsieh, Pang-An Ting
Voice : 886-3-5914854
E-mail: jefferywu@itri.org.tw
E-mail: guan.yanfeng@zte.com.cn
ITRI
Yanfeng Guan, Huiying Fang
ZTE
Re:
Re: Category: AWD comments /Area: Chapter 15.3.3 (Frame Structure)
“Comments on AWD 15.3.3 Frame Structure”
Abstract
The contribution proposes the text of frame structure section 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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Harmonized Proposed AWD text of Frame Structure for 5, 10 and 20
MHz bandwidth with 1/4 Tb CP length
Jia-Hao Wu, Yu-Tao Hsieh, Pang-An Ting
ITR
Yanfeng Guan, Huiying FangI
ZTE
1. Introduction
According to the current version of SDD [1] and IEEE 802.16m amendment working document (AWD) [2], the
OFDMA numerology with cyclic prefix (CP) length equal to 1/4 Tb has been defined. The OFDMA symbols
with this longer CP structure are expected to be used for long delay spread channel. For example, delay spread
of MBSFN channel model for 5 km cell inter-site distance is about 24.5 microseconds [3]. However, the frame
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IEEE C802.16m-09/1125r2
structures for CP equal to 1/4 Tb have not been defined yet. In this harmonized contribution based on the IEEE
802.16m-09_0884 [5] and IEEE 802.16m-09_0996 [6], amendment text including several illustrations is
proposed to provide the frame structures for the long CP scenario.
2. Proposed Frame Structure for 5, 10 and 20MHz with CP = 1/4 Tb
2.1 Design Criteria
Following we will discuss some design criteria when considering frame structures for CP = 1/4 Tb. This kind of
long CP frame structure is mainly used to mitigate inter-symbol interference (ISI) in long delay spread channel.
For example, it may be adopted for dedicated MBSFN carrier which contains only downlink broadcasting
subframes. Besides, when transmitting uplink control channel in large cells, long CP frame structures can be
used to accommodate diverse round-trip delay(RTD).
To follow the regulations of current SDD, we take following criteria into considerations:
 For 5, 10 and 20 MHz bandwidth, there shall be 8 subframes in a radio frame as cases of CP equal to 1/8
Tb and 1/16 Tb in order to reuse the same timing design for HARQ operation .
 A radio frame should be include 43 symbols for FDD and 42 symbols for TDD.
 A radio frame is composed of type-1, type-2 and type-3 subframes which are defined in both SDD and
AWD for 5, 10 and 20 MHz bandwidth, but including less subframe type in a radio frame will be better.
 The first subframe of a radio frame shall not be type-3 which only contains 5 OFDMA symbols since the
SCH would be allocated for synchronization purpose.
 For FDD subframes, the first, fifth and last subframe type should be the same type as cases of CP equal to
1/8 Tb and 1/16 Tb. This would ease hardware implementation for FDD frame structure.
2.2 Frame structure for 5, 10 and 20 MHz
In the current SDD, three types of subframes have been defined, i.e., type-1 with 6 symbols, type-2 with 7
symbols, and type-3 with 5 symbols. Moreover, there shall be 8 subframes in a radio frame with 5, 10 and 20
MHz bandwidth. In order not to violate the frame structure regulation in current SDD and to meet the
designated numerology in AWD, we propose following frame structures for TDD and FDD transmission
modes.
2.2.1 TDD frame structure
There are two possible frame structures for CP=1/4 Tb with TDD transmission modes. One contains two type-1
subframes and six type-3 subframes in a radio frame. The other contains one type-2 subframe and seven type-3
subframes in a radio frame. Figure 1 illustrates the TDD frame structure A for CP=1/4 Tb. The downlink and
uplink ratio (DL:UL) shown is 5:3 with TTG = 114.286 us and RTG = 85.7 us at the switching points.
Figure 2 illustrates TDD frame structure B for CP=1/4 Tb. The figure shows D:U = 5:3. Although there are two
possible frame structures that can meet the criteria stated before, we are more fond of the frame structure A.
It is because the last subframe is type-1 rather than type-3 and may be more feasible when uplink transmission
is allocated.
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IEEE C802.16m-09/1125r2
Superframe: 20ms (4 frames, 32 subframes)
UL/DL PHY Frame 5ms (8 subframes )
F0
F1
F2
F3
DL:UL = 5:3
DL
SF0(6)
DL
SF1(5)
DL
SF2(5)
DL
SF3(5)
DL
SF4(5)
UL
SF5(6)
UL
SF6(5)
UL
SF7(5)
RTG = 85.7 us
TTG = 114.286 us
Subframe length = 5 full OFDMA symbols = 0.5714 ms
S0
S1
S2
S3
S4
Subframe length = 6 full OFDMA symbols = 0.6857 ms
Type-3 subframe
114.286 us
S0
S1
S2
S3
S4
S5
Type-1 subframe
CP = ¼ Tb
Figure. 1 TDD frame structure A for 5, 10 and 20 MHz TDD with CP = 1/4 Tb
Superframe: 20ms (4 frames, 32 subframes)
UL/DL PHY Frame 5ms (8 subframes )
F0
F1
F2
F3
DL:UL=5:3
DL
SF0(7)
DL
SF1(5)
DL
SF2(5)
DL
SF3(5)
DL
SF4(5)
DL
SF5(5)
DL
SF6(5)
DL
SF7(5)
Idle time = 200 us
Subframe length = 5 full OFDMA symbols = 0.5714 ms
S0
Subframe length = 7 full OFDMA symbols = 0.8 ms
S0
S1
S2
S3
S4
S5
S1
S2
S3
S4
Type-3 subframe
S6
Type-2 subframe
CP = ¼ Tb
Figure. 2 TDD frame structure B for 5, 10 and 20 MHz TDD with CP = 1/4 Tb
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IEEE C802.16m-09/1125r2
2.2.2 FDD frame structure
In the FDD transmission mode, there are also two possible frame structures when taking aforementioned design
criteria into considerations. One contains three type-1 subframes and five type-3 subframes. The other contains
one type-1 subframe, one type-2 subframe and six type-3 subframes. Figure 3 and 4 show the two kinds of FDD
frame structures. In order to make frame structure as simple as possible, the frame structure C is preferable
since it is only composed of two subframe types.
Superframe: 20ms (4 frames, 32 subframes)
UL/DL PHY Frame 5ms (8 subframes )
F0
F1
F2
F3
Idle time = 85.7 us
DL/UL
SF0(6)
DL/UL
SF1(5)
DL/UL
SF2(5)
DL/UL
SF3(5)
DL/UL
SF6(6)
DL/UL
SF5(6)
DL/UL
SF4(5)
DL/UL
SF7(5)
Subframe length = 5 full OFDMA symbols = 0.5714 ms
S0
S1
S2
S3
S4
Subframe length = 6 full OFDMA symbols = 0.6857 ms
Type-3 subframe
S0
S1
S2
S3
S4
S5
Type-1 subframe
114.286 us
Figure. 3 Frame structure C for 5, 10 and 20 MHz FDD with CP = 1/4 Tb
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IEEE C802.16m-09/1125r2
Superframe: 20ms (4 frames, 32 subframes)
UL/DL PHY Frame 5ms (8 subframes )
F3
F2
F1
F0
Idle time = 85.7 us
DL/UL
SF0(7)
DL/UL
SF2(5)
DL/UL
SF1(5)
DL/UL
SF3(5)
DL/UL
SF4(5)
DL/UL
SF7(6)
DL/UL
SF6(5)
DL/UL
SF5(5)
Subframe length = 7 full OFDMA symbols = 0.8 ms
S0
S1
S2
S3
S4
S6
S5
Subframe length = 6 full OFDMA symbols = 0.6857 ms
Type-2 subframe
S0
S2
S1
S3
S4
S5
Type-1 subframe
Subframe length = 5 full OFDMA symbols = 0.5714 ms
CP = ¼ Tb
S0
S1
S2
S3
S4
Type-3 subframe
Figure 4. Frame structure D for 5, 10 and 20 MHz FDD with CP = 1/4 Tb
3. References
[1] IEEE 802.16m-08/003r8, “The Draft IEEE 802.16m System Description Document.”
[2] IEEE 802.16m-08/0010r1a, “IEEE 802.16m Amendment Working Document.”
[3] IEEE 802.16m-07/004r5, “IEEE 802.16m Evaluation Methodology Document.”
[4] IEEE 802.16m-08/043, “Style guide for writing the IEEE 802.16m amendment.”
[5] IEEE 802.16m-08_0884, “Proposed AWD text of Frame Structure for 5 MHz, 10 MHz and 20 MHz
bandwidth with 1/4 Tb CP Length.”
[6] IEEE 802.16m-08_0996, “Frame Structure for 1/4 Tb in IEEE 802.16m Amendment Working Document
4. Text proposal for the 802.16m amendment
============================== Start of Proposed Text ================================
[Insert the following text and illustration after Figure 402 on page 26 and modify the involved clause indices:]
15.3.3.4 Frame structure for CP = 1/4 Tb
The frame structure for CP = 1/4 Tb shall consist of type-1 and type-3 subframes.
For channel bandwidths of 5, 10, and 20 MHz, a TDD frame shall have six type-3 subframes and two type-1
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IEEE C802.16m-09/1125r2
subframes, and an FDD subframe shall have five type-3 subframes and three type-1 subframes.
In the TDD frame, the first and last subframes within each frame shall be type-1 subframes.
In the FDD frame, the first, fifth, and last subframes within each frame shall be type-1 subframes.
Figure X-1 illustrates an example of TDD and FDD frame structure for 5, 10 and 20 MHz channel bandwidth
with CP = 1/4Tb. Assuming OFDMA symbol duration of 114.286 us, the type-1 and type-3 subframe durations
are 0.6857 ms and 0.5714 ms, respectively. For TDD frame, the figure shows DL:UL = 5:3 with TTG = 114.286
us and RTG = 85.7 us.
Superframe: 20ms (4 frames, 32 subframes)
UL/DL PHY Frame 5ms (8 subframes )
F0
F1
F2
F3
DL:UL = 5:3
5ms TDD frame
DL
SF0(6)
DL
SF1(5)
DL
SF2(5)
DL
SF3(5)
DL
SF4(5)
UL
SF5(6)
UL
SF6(5)
UL
SF7(5)
TTG = 114.286 us
RTG = 85.7 us
Subframe length = 5 full OFDMA symbols = 0.5714 ms
S0
S1
S2
S3
S4
Subframe length = 6 full OFDMA symbols = 0.6857 ms
Type-3 subframe
114.286 us
S0
S1
S2
S3
S4
S5
Type-1 subframe
CP = ¼ Tb
DL/UL
SF0(6)
DL/UL
SF1(5)
DL/UL
SF2(5)
DL/UL
SF3(5)
DL/UL
SF6(6)
DL/UL
SF5(6)
DL/UL
SF4(5)
DL/UL
SF7(5)
5ms FDD frame
Idle time = 200 us
Figure. X-1—TDD and FDD frame structure for 5, 10 and 20 MHz with CP = 1/4Tb
For a channel bandwidth of 7MHz, a FDD frame shall have four type-1 subframes and one type-2 subframes.
And a TDD frame shall have five type-1 subframes.
Figure x-2 illustrates an example of TDD and FDD frame structure with DL/UL ratio = 3:2 for the 7MHz
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IEEE C802.16m-09/1125r2
channel bandwidth with a CP of 1/4 Tb. Assuming OFDMA symbol duration of 160μs and a CP length of 1/4Tb
the length of type-1 and type-2 subframes are 0.960 ms and 1.120 ms, respectively. TTG and RTG are 140 µs and
60 µs, respectively.
TDD Frame: 5ms
DL
SF0(6)
DL
SF1(6)
DL
SF2(6)
UL
SF3(6)
UL
SF4(6)
TTG
160us
160us
S6
S5
S4
S3
S2
S1
S0
S5
S4
S3
S2
S1
S0
Type-1 Subframe
Type-2 Subframe
7 OFDM Symbols = 1.120ms
6 OFDM Symbols = 0.960ms
Idle
DL/UL
SF0(6)
DL/UL
SF1(6)
DL/UL
SF2(7)
DL/UL
SF3(6)
DL/UL
SF4(6)
FDD Frame : 5ms
Figure x-2 Frame structures for 7MHz TDD and FDD modes (G=1/4)
For a channel bandwidth of 8.75MHz, a FDD frame shall have four type-1 subframes and two type-2
subframes. And a TDD frame shall have one type-3 subframe, three type-1 subframes and two type-2
subframes. In TDD, the subframe preceding a DL to UL switching point shall be type-1 subframes.
Figure x-3 illustrates an example of TDD and FDD frame structure with DL/UL ratio = 4:2 for the 8.75MHz
channel bandwidth with a CP of 1/4 Tb. Assuming OFDMA symbol duration of 128μs and a CP length of 1/4Tb
the length of type-1 and type-2 subframes are 0.768 ms and 0.896 ms, respectively.
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IEEE C802.16m-09/1125r2
TDD Frame: 5ms
DL
SF0(6)
DL
SF1(6)
DL
SF2(6)
DL
SF3(5)
UL
SF4(7)
UL
SF5(7)
TTG
128us
128us
S6
S5
S4
S3
S2
S1
S0
S5
S4
S3
S2
S1
S0
Type-1 Subframe
Type-2 Subframe
7 OFDM Symbols = 0.896ms
6 OFDM Symbols = 0.768ms
Idle
DL/UL
SF0(6)
DL/UL
SF1(6)
DL/UL
SF2(6)
DL/UL
SF3(6)
DL/UL
SF4(7)
DL/UL
SF5(7)
FDD Frame : 5ms
Figure x-3 Frame structures for 8.75MHz TDD and FDD modes (G=1/4)
============================== End of Proposed Text =================================
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