IEEE C802.16n-11/0154r1
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Supplementary Channel for Talk-around Direct Communications
Date
Submitted
2011-09-20
Source(s)
Jihoon Choi, Young-Ho Jung
E-mail:
jihoon@kau.ac.kr, yhjung@kau.ac.kr
Korea Aerospace University
Sungcheol Chang, Seokki Kim, Eunkyung
Kim, Miyoung Yun, Won-Ik Kim,
Sungkyung Kim, Hyun Lee, Chulsik
Yoon, Kwangjae Lim
scchang@etri.re.kr
ETRI
Re:
Call for Comments on the 802.16n AWD
Abstract
This provides AWD text proposals for supplementary channel structure of talk-around direct
communications.
Purpose
To be discussed and adopted by 802.16 TGn
Notice
Release
Patent
Policy
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.
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 Standards publication; to copyright in the IEEE’s name
any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole
discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The
contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16.
The contributor is familiar with the IEEE-SA Patent Policy and Procedures:
<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>.
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Supplementary Channel for Talk-around Direct Communications
Jihoon Choi, Young-Ho Jung
Korea Aerospace University
Sungcheol Chang, Seokki Kim, Eunkyung Kim, Miyoung Yun, Won-Ik Kim, Sungkyung Kim, Hyun
Lee, Chulsik Yoon, Kwangjae Lim
ETRI
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1. Introduction
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In this contribution, we propose the details of Sup-CH structure for TDC in IEEE 802.16n. The Sup-CH is
composed of ranging channel, CQI (channel quality indicator) channel, and feedback channel. We define the
specific sequence for ranging channel and codeword set for CQI and feedback channels.
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2. Proposed Sup-CH structure
A part of communication resources for infra-structure communication link can be assigned for TDC (talkaround direct communications) in IEEE 802.16n [1]. Using the assigned resources, multiple pairs of TDC links
are provided based on OFDMA (orthogonal frequency division multiple access). The frame structure for TDC is
proposed in [2]. The TDC frame is composed of synchronization channel, Sup-CH (supplementary channel),
and dedicated channel.
time
OFDM symbol
frequency
subcarrier
mini-tile
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Figure 1. Proposed Sup-CH structure in the frequency domain
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Figure 1 describes the proposed Sup-CH structure for TDC in the frequency domain. Details of the Sub-CH
structure are defined in [2]. One Sup-CH is composed of four distributed mini-tiles, where a mini-tile denotes (2
subcarriers)(5 symbols) rectangular-shaped resources. A Sup-CH includes ranging channel, CQI channel, and
feedback channel, which are transmitted in TDM (time division multiplexing) manner. The specific sequence for
ranging channel and the codeword set for CQI and feedback channels are defined in the following sections.
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2.1 Ranging channel
time
frequency
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S0
S0
S0
S0
S0
S1
S1
S1
S1
S1
S2
S2
S2
S2
S2
S3
S3
S3
S3
S3
S4
S4
S4
S4
S4
S5
S5
S5
S5
S5
S6
S6
S6
S6
S6
S7
S7
S7
S7
S7
Figure 2. Ranging channel structure in the frequency domain
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When the Sup-CH is used to transmit the ranging channel, the ranging sequence is mapped to the Sup-CH
resources as shown in Figure 2. {Sk; 0k7} denotes a binary sequence with length 8, defined by
[S0 S1 S2 S3 S4 S5 S6 S7] = [1,-1, -1,1, -1,1, 1,-1]
(1)
The same binary sequence is repeatedly transmitted for 5 OFDM symbols. The ranging channel is periodically
transmitted, where the starting slot number and the transmission period are determined during the link
initialization for TDC. Using the ranging channel, the receiver can estimate time offset, frequency offset, link
SINR (signal to interference plus noise ratio), etc. Also, the estimation accuracy can be improved by
accumulating multiple ranging channels.
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2.2 CQI channel
time
C0,0 C0,2 C0,4 C0,6 C0,8
frequency
C0,1 C0,3 C0,5 C0,7 C0,9
C1,0 C1,2 C1,4 C1,6 C1,8
C1,1 C1,3 C1,5 C1,7 C1,9
C2,0 C2,2 C2,4 C2,6 C2,8
C2,1 C2,3 C2,5 C2,7 C2,9
C3,0 C3,2 C3,4 C3,6 C3,8
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4
C3,1 C3,3 C3,5 C3,7 C3,9
Figure 3. CQI channel structure in the frequency domain
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CQI
payload
Sequence
generation
Modulation
(& repetition)
Symbol sequence to
subcarrier mapping
CQI
channel
symbol
Figure 4. Mapping of information in the CQI channel
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The process of composing the CQI channel is illustrated in Figure 4. The CQI channel payload bits are used to
generate the CQI sequence according to Table 1. The resulting bit sequence is modulated, repeated and mapped
to the CQI channel symbols s[k] (0 mapped to +1 and 1 mapped to -1). The mapping of s[k] to the Sup-CH
resources is defined as follows.
Ci , j  s[ K i [ j ]], for i  0,1, 2,3, 0  j  9
(2)
where Ki[j] denotes the j-th element of Ki , defined by
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K0  {0,1, 2,3, 4,5,6,7,8,9}
(3)
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K1  {2,3, 4, 6, 7,8,9, 0,1,5}
(4)
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K2  {8,9, 2,3, 4,5,6,7,0,1}
(5)
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K3  {5, 6, 7,8,9, 0,1, 2,3, 4}
(6)
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Table 1. Sequences for CQI channel
Index
Sequence
Usage
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1111111111
0010110001
0100100110
1001101000
1011000100
0110001010
0000011101
1101010011
1100011000
0001010110
0111000001
1010001111
1000100011
0101101101
0011111010
1110110100
level 0
level 1
level 2
level 3
level 4
level 5
level 6
level 7
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
3
4
5
6
The codeword set defined in Table 1 can carry up to 4 information bits. The codeword set is mapped to the
SINR level, determined by the AMS transmitting the CQI channel using the Ded-CH preamble and the pilot
symbols included in the Ded-CH.
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The CQI channel is periodically transmitted, where the starting slot number and the transmission period are
determined during the link initialization for TDC. Since the ranging channel and the CQI channel are
transmitted in TDM manner, the ranging channel and the CQI channel should be assigned to separate time slots,
by properly adjusting the starting slot number and the transmission period.
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2.3 Feedback channel
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The Sup-CH can be assigned for feedback channel, that includes ACK (acknowledgement) channel, NAK (no
ACK) channel, MCS (modulation and coding scheme) Change Confirm, RCHG (resource change) indication,
etc. The feedback channel is transmitted using the slots which are not used by the ranging channel and the CQI
channel. The feedback channel uses the same codeword set and symbol sequence to subcarrier mapping as the
CQI channel.
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The codeword sequences and mapping of feedback channel are defined in Table 2. When the data packet
received at the Ded-CH is successfully decoded, ACK information is transmitted. When HARQ is used, the
failure of data packet decoding is denoted as 4 kinds of NAK information corresponding to the HARQ frame
number. The AMS transmitting data packets can transmit the MCS Change Command message considering the
CQI level received from the Sup-CH. As a response to the MCS Change Command message, the MCS Change
Confirm is transmitted. The AMS receiving data packets sends RCHG Indication to request the change of the
Ded-CH in use.
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Table 2. Sequences and mapping of feedback channel
Index
Sequence
Usage
0
1
2
3
4
5
6
7
8
9
10
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12
13
14
15
1111111111
0010110001
0100100110
1001101000
1011000100
0110001010
0000011101
1101010011
1100011000
0001010110
0111000001
1010001111
1000100011
0101101101
0011111010
1110110100
ACK
NAK for frame 0
NAK for frame 1
NAK for frame 2
NAK for frame 3
MCS Change Confirm
RCHG Indication
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
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5
6
7
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3. Simulation results for CQI and feedback channels
We perform numerical simulations in TDC environments to evaluate the CQI and feedback channels for
various codeword sets. For fading channel generation, we developed a M2M (mobile-to-mobile) channel model
by modifying the 802.16m EMD MIMO SCM (spatial channel model) described in [4] considering the M2M
channel models proposed in [5] and [6]. The M2M channel model used in the simulation exploits the time
domain power profile of the 802.16m EMD, and considers the mobility of the transmitter. Also, the spatial
parameters for the transmitter have similar statistical characteristics with those for the receiver. Among the
channel generation scenarios of the 802.16m EMD, we used the Bad Urban Macro NLOS channel.
In the simulation, we consider codeword sets with 3-bit, 4-bit, 5-bit, and 6-bit information. For comparison,
IEEE 802.16m PFBCH (primary fast feedback channel) with 6-bit information is considered as well. The
codeword set with 4-bit information is defined in Table 1, and codeword sets with 3-bit, 5-bit, 6-bit information
are defined in Tables 3-5.
Table 3. Sequences for CQI and feedback channels (6-bit information)
Index
Sequence
Index
Sequence
0
1111111111
32
1111111100
1
1010101111
33
1010101100
2
1100111110
34
1100111101
3
1001101110
35
1001101101
4
1111001111
36
1111001100
5
1010011111
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1010011100
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31
1
2
1100001110
1001011110
1111110110
1010100110
1100110111
1001100111
1111000110
1010010110
1100000111
1001010111
1111111010
1010101010
1100111011
1001101011
1111001010
1010011010
1100001011
1001011011
1111110011
1010100011
1100110010
1001100010
1111000011
1010010011
1100000010
1001010010
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44
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46
47
48
49
50
51
52
53
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56
57
58
59
60
61
62
63
1100001101
1001011101
1111110101
1010100101
1100110100
1001100100
1111000101
1010010101
1100000100
1001010100
1111111001
1010101001
1100111000
1001101000
1111001001
1010011001
1100001000
1001011000
1111110000
1010100000
1100110001
1001100001
1111000000
1010010000
1100000001
1001010001
Table 4. Sequences for CQI and feedback channels (5-bit information)
Index
Sequence
Index
Sequence
0
1111111111
16
1111111000
1
1010111101
17
1010111010
2
1100111110
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1100111001
3
1001111100
19
1001111011
4
1111010101
20
1111010010
5
1010010111
21
1010010000
6
1100010100
22
1100010011
7
1001010110
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1001010001
8
1111100110
24
1111100001
9
1010100100
25
1010100011
10
1100100111
26
1100100000
11
1001100101
27
1001100010
12
1111001100
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1111001011
13
1010001110
29
1010001001
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1100001101
30
1100001010
15
1001001111
31
1001001000
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Table 5. Sequences for CQI and feedback channels (3-bit information)
Index
Sequence
Index
Sequence
0
1111111111
4
1111000011
1
1010101010
5
1010010110
2
1100110001
6
1100001101
3
1001100100
7
1001011000
In the simulation, the SNR (signal-to-noise ratio) is defined by
P
SNR  S
(5)
NS
where PS is the per-subcarrier average power of TDC link and NS is the per-subcarrier noise power. Simulation
parameters for signal generation and OFDMA operations are summarized in Table 6. Non-coherent detection is
used for codeword decoding.
Table 6. Simulation parameters
Parameter
Carrier frequency
Bandwidth
FFT size
CP size
Sampling rate
Number of transmit antennas
Number of receive antennas
Velocity of transmitter
Velocity of receiver
Moving direction of transmitter
Moving direction of receiver
Timing offset
Normalized frequency offset
Value
2.3 GHz
10 MHz
1024
128
11.2 MHz
1
1
30 km/h
30 km/h
/6
-/4
16 samples
0.02
Figures 3 and 4 show the BLER (block error rate) of CQI and feedback channels for various codeword sets in
AWGN and fading channel, respectively. The Sup-CH for TDC uses 8 subcarriers for one codeword
transmission, while IEEE 802.16m PFBCH uses 6 subcarriers per codeword. Therefore, the Sup-CH for TDC
requires 1.25 dB SNR gain to achieve the same coverage as IEEE 802.16m PFBCH. The codeword set with 4bit information exhibits 1.5 dB gain in AWGN and 1.7 dB gain in fading channel, compared to PFBCH with 6
bits. Therefore, using the codeword set with 4-bit information, the CQI and feedback channels for TDC have
comparable or slightly better coverage than IEEE 802.16m PFBCH.
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0
10
-1
10
-2
10
-3
10
-4
-7
Sup-CH 6bits
Sup-CH 5bits
Sup-CH 4bits
Sup-CH 3bits
16m CQI 6bits
-6
-5
-4
-3
-2
SNR (dB)
-1
0
1
Figure 4. Performance comparison in AWGN
0
10
-1
BLER
10
-2
10
-3
10
Sup-CH 6bits
Sup-CH 5bits
Sup-CH 4bits
Sup-CH 3bits
16m CQI 6bits
-4
10
4
5
6
7
8
9
10
11
12
-7
-6
-5
-4
-3
-2
-1
SNR (dB)
0
1
2
3
Figure 5. Performance comparison in fading channel
4. References
[1] IEEE C802.16n-11/0051r2, “Dedicated resources allocation for direct communications in IEEE 802.16n,”
March 2011.
[2] IEEE C802.16n-11/0152, “Frame structure for talk-around direct communications,” Sept. 2011.
[3] IEEE Std. 802.16-2009, “IEEE Standard for Local and metropolitan area networks; Part 16: Air Interface
for Broadband Wireless Access Systems,” May 2009.
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[4] IEEE 802.16m-08/004r5, “IEEE 802.16m evaluation methodology document (EMD),” Jan. 2009.
[5] C. S. Patel, G. L. Stuber, and T. G. Pratt, “Simulation of Rayleigh-faded mobile-to-mobile communication
channels,” IEEE Trans. Commun., Nov. 2005.
[6] M. Patzold, B. O. Hogstad, and N. Youssef, “Modeling, analysis, and simulation of MIMO mobile-to mobile fading channels,” IEEE Trans. Wireless Commun., Feb. 2008.
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5. Proposed Text for the 802.16n Amendment Working Document (AWD)
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The text in BLACK color: the existing text in the 802.16n Amendment Draft Standard
Note:
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The text in RED color: the removal of existing 802.16n Amendment Draft Standard Text
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The text in BLUE color: the new text added to the 802.16n Amendment Draft Standard Text
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[-------------------------------------------------Start of Text Proposal---------------------------------------------------]
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[Remedy1: Adapt the following change in Section 17.3.2.6 in the 802.16n AWD]
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17.3.2.6 Talk-around Direct Communication
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[note: This contribution provides text proposals for the following sections:
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17.3.2.6.2.1 Frame structure
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17.3.2.6.2.2 Synchronization channel
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17.3.2.6.2.3 Dedicated channel
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17.3.2.6.2.4 Supplementary channel]
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17.3.2.6.2.4 Supplementary channel
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time
OFDM symbol
frequency
subcarrier
mini-tile
1
2
Figure xx1. Supplementary channel structure
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Figure xx1 describes the proposed Sup-CH structure for TDC. Details of the Sub-CH structure are defined in
17.3.2.6.2.1. One Sup-CH is composed of four distributed mini-tiles, where a mini-tile has (2 subcarriers)(5
symbols) rectangular-shaped resource elements. A Sup-CH includes ranging channel, CQI channel, and
feedback channel, which are transmitted in TDM (time division multiplexing) manner.
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17.3.2.6.2.4.1 Ranging channel
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time
frequency
1
2
S0
S0
S0
S0
S0
S1
S1
S1
S1
S1
S2
S2
S2
S2
S2
S3
S3
S3
S3
S3
S4
S4
S4
S4
S4
S5
S5
S5
S5
S5
S6
S6
S6
S6
S6
S7
S7
S7
S7
S7
Figure xx2. Ranging channel structure
3
4
5
6
7
8
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The ranging sequence is mapped to the Sup-CH resource elements as shown in Figure xx2. {Sk; 0k7} denotes
a binary sequence with length 8, defined by
[S0 S1 S2 S3 S4 S5 S6 S7] = [1,-1, -1,1, -1,1, 1,-1]
The same binary sequence is repeatedly transmitted for 5 OFDM symbols. The ranging channel is periodically
transmitted, where the starting slot number and the transmission period are determined during the link
initialization.
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17.3.2.6.2.4.2 CQI channel
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time
C0,0 C0,2 C0,4 C0,6 C0,8
frequency
C0,1 C0,3 C0,5 C0,7 C0,9
C1,0 C1,2 C1,4 C1,6 C1,8
C1,1 C1,3 C1,5 C1,7 C1,9
C2,0 C2,2 C2,4 C2,6 C2,8
C2,1 C2,3 C2,5 C2,7 C2,9
C3,0 C3,2 C3,4 C3,6 C3,8
C3,1 C3,3 C3,5 C3,7 C3,9
1
2
Figure xx3. CQI channel structure
3
4
5
CQI
payload
Sequence
generation
Modulation
(& repetition)
Symbol sequence to
subcarrier mapping
CQI
channel
symbol
Figure xx4. Mapping of information in the CQI channel
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The process of composing the CQI channel is illustrated in Figure xx4. The CQI channel payload bits are used
to generate the CQI sequence according to Table yy1. The resulting bit sequence is modulated, repeated and
mapped to the CQI channel symbols s[k] (0 mapped to +1 and 1 mapped to -1). The mapping of s[k] to the SupCH resource elements is defined as follows.
Ci , j  s[ K i [ j ]], for i  0,1, 2,3, 0  j  9
where Ki[j] denotes the j-th element of Ki , defined by
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K0  {0,1, 2,3, 4,5,6,7,8,9}
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K1  {2,3, 4, 6, 7,8,9, 0,1,5}
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K2  {8,9, 2,3, 4,5,6,7,0,1}
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K3  {5, 6, 7,8,9, 0,1, 2,3, 4}
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Table yy1. Sequences for CQI channel
Index
Sequence
Usage
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
1111111111
0010110001
0100100110
1001101000
1011000100
0110001010
0000011101
1101010011
1100011000
0001010110
0111000001
1010001111
1000100011
0101101101
0011111010
1110110100
level 0
level 1
level 2
level 3
level 4
level 5
level 6
level 7
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
2
3
4
5
6
7
8
The codeword set defined in Table yy1 can carry up to 4 information bits. The codeword set is mapped to the
SINR level, measured by the AMS transmitting the CQI channel using the Ded-CH preamble and the pilot
symbols included in the Ded-CH. The CQI channel is periodically transmitted, where the starting slot number
and the transmission period are determined during the link initialization. The ranging channel and the CQI
channel shall be assigned to separate time slots, by properly adjusting the starting slot number and the
transmission period.
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17.3.2.6.2.4.3 Feedback channel
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14
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The Sup-CH can be used to transmit the feedback channel, that includes ACK channel, NAK channel, MCS
Change Confirm, RCHG Indication, etc. The feedback channel is transmitted using the slots which are not used
by the ranging channel and the CQI channel. The feedback channel uses the same codeword set and symbol
sequence to subcarrier mapping as the CQI channel. The codeword sequences and mapping of feedback channel
are defined in Table yy2.
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Table yy2. Sequences and mapping of feedback channel
Index
Sequence
Usage
0
1
2
3
4
5
1111111111
0010110001
0100100110
1001101000
1011000100
0110001010
ACK
NAK for frame 0
NAK for frame 1
NAK for frame 2
NAK for frame 3
MCS Change Confirm
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8
9
10
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12
13
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15
0000011101
1101010011
1100011000
0001010110
0111000001
1010001111
1000100011
0101101101
0011111010
1110110100
RCHG Indication
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
1
2
[-------------------------------------------------End of Text Proposal----------------------------------------------------]
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