Transcript IEEE C802.16m-08/927

UL Control Structure and Fast Feedback channel Structure
IEEE 802.16 Presentation Submission Template (Rev. 9)
Document Number:
IEEE C802.16m-08/927
Date Submitted:
2008-09-05
Source:
Jinyoung Chun ([email protected])
Bin-chul Ihm ([email protected])
LG Electronics
*<http://standards.ieee.org/faqs/affiliationFAQ.html>
Venue:
PHY: Text; in response to the TGm Call for Contributions 802.16m-08/033 for Session 57
Base Contribution:
This is the base contribution.
Purpose:
Discussion and adoption for 802.16m SDD
Notice:
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Contents
• UL Control Structure in UL PHY Structure
• Fast Feedback Channel Structure
– Fast Feedback Physical structure
– Fast Feedback Information
– Simulation results
• Conclusion
• The proposed text
 The detail about Fast Feedback Channel Coding refers to C80216m08_928.
2/13
UL Control Structure in UL PHY Structure
Figure 33
in SDD text
•
UL control subcarriers to UL control resource unit mapping
–
–
–
One of freq parts is used as UL control part in figure 33.
Control part is divided into UL Control LLRUs and UL Control LDRUs.
UL Control LDRUs are mapped by tile permutation and index permutation for
CDM or FDM into LRUs.
3/13
UL Control Structure
• UL Control LDRU
– UL Control LDRU consists of three distributed tiles, each of which
comprises Nsc(=6) consecutive subcarriers by Nsym(=6) consecutive
OFDMA symbols.
– UL Control LDRU is used for the transmission of UL Fast Feedback
Channel, UL HARQ Feedback Channel, or Contention-based Bandwidth
Request Channel.
• UL Control LLRU
– UL Control LLRU consists of Nsc consecutive subcarriers by Nsym
consecutive OFDMA symbols.
– UL Control LLRU is used for the transmission of ranging channel, etc.
4/13
Fast Feedback Channel Structure
• Fast feedback channel
– A UL Control LDRU consists of multiple logical fast feedback channels.
A logical fast feedback channel is a unit of a transmission of fast
feedback information and consists of three tiles and a code [CDM] or a
subcarrier index [FDM].
• Feedback information to UL resource mapping process
1) The information to signals mapping
– The information is encoded to 24 bits by punctured and masked RM
code, and the bits are modulated to 12 QPSK signals.
2) Channel multiplexing
– [FDM] The signals are mapped to subcarriers by FDM. Each logical
channel has own subcarrier index.
– [CDM] The signals are mapped to subcarriers and spread over 6
contiguous subcarriers by orthogonal code. Each logical channel has
own code.
– To avoid ICI, the subcarrier location (FDM) or the code (CDM) of each
tile is permutated depending on Cell_ID. The details are FFS.
5/13
Fast Feedback Channel Structure (Cont’d)
In CDM, logical channels are
distinguished by spreading code index
In FDM, logical channels are distinguished
by the used subcarrier index
OFDM Symbol
OFDM Symbol
S0
S1
S2
S3
Tile 0
S0
S1
S2
S3
S4
S5
S6
S7
S8
S9
S10
S11
S5
S6
S7
Tile 1
S8
S9
S10
Tile 1
S11
Tile 2
Tile 2
Pilot subcarrier
Data subcarrier
Assigned
subcarriers in a
logical channel
of FDM
6/13
Subcarrier
S4
Subcarrier
Tile 0
Fast Feedback Information
Usage
Reported information
Required bits
Wide band
feedback
• WB CQI
• WB PMI
• Rank information
• 4-5
• 4-6
• 1-2
Narrow band
feedback
• Selected NB CQI
• Selected NB PMI
• Selected Band information
• Rank information
• (4-5) * N
• (4-6) * N
• variable (3-12?)
• 1-2
• Case1: Under 10bits information
– MS uses a logical fast feedback channel.
– The feedback channel is robust because any user can feedback this information.
• Case2: Over 10bits information
– MS uses several logical fast feedback channels but the channels are located in a
LDRU.
– Total transmission power is the same between a logical channel and several
logical channels to MS. Because the symbol power per logical channel is N
times lower when a MS uses N logical channels. Therefore the performance of
case 2 is worse than case1 and it is suitable to medium and high SNR user.
7/13
The Simulation Conditions
Parameters
Values
Channel Bandwidth
10MHz
Over-sampling Factor
28/25
FFT Size
1024
Cyclic prefix (CP) ratio
1/8
Resource
Three distributed tiles (6x6 tile)
Multiplexing scheme
CDM, FDM
Information size
5bits~10bits in a logical channel
Coding & Modulation
RM code (5~10, 24) & QPSK
Channel condition
PedB 3km/h, VehA 120km/h
The number of antennas
1 Tx MS, 2 Rx BS
Impairments
- time offset: -8~8 sample
- freq offset: -2%~2% of subcarrier spacing
Tx Power
Identical transmit power per OFDM symbol
regardless of CDM or FDM.
8/13
The Simulation Results
• The simulation result according to multiplexing scheme
and time/freq offset
* X-axis: SNR per tone (dB)
 The performances of CDM and FDM are similar. There is no
performance loss according to freq/time offset.
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The Simulation Results (Cont’d)
• The simulation result according to information size
 The performance is about 0.5dB worse as adding one more
information bit. But Fast feedback channel with 10bits
information is enough to satisfy the CQI requirement as below
1% PER in 0dB. (see Appendix in C80216m-08_726r1.)
10/13
Conclusions
• UL Control Structure
– Use one of freq parts as UL control part in figure 33.
– The UL control part consists of UL control LDRU and UL control
LLRU.
• Fast feedback channel structure
– A logical fast feedback channel is a unit of a transmission of fast
feedback information and consists of three tiles and a code index [CDM]
or a subcarrier index [FDM].
– The tile size is 6 subcarriers by 6 OFDM symbols.
– MS can transmit several logical channels according to fast feedback
information size.
11/13
The proposed text in SDD
Remedy 1.
[Modify the text in line 15, page 51 as below]
11.6 Uplink Physical Structure
Each frequency partition can be used for different purposes such as fractional
frequency reuse (FFR) or uplink control channel.
[Add the below text between line 1 and line 2 in the page 74.]
11.9
UL Control Structure
One frequency part of figure 33 is used for UL control part. The UL control part is divided
into UL Control LLRUs and UL Control LDRUs.
UL Control LDRU consists of three distributed tiles, each of which comprises Nsc(=6)
consecutive subcarriers by Nsym(=6) consecutive OFDMA symbols.
Details of the UL control structure are described in the following sections.
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The proposed text in SDD (Cont’d)
Remedy 2.
[Add the below text in line 25, the page 76.]
11.9.2.1.2 PHY structure
The structure of the resource blocks, pilots and resource mapping for the UL fast
feedback channel are TBD.
A UL Control LDRU consists of multiple logical fast feedback channels. A logical fast
feedback channel is a unit of a transmission of fast feedback information and consists of
three tiles and [a code / a subcarrier index]. MS may use several logical channels
according to fast feedback information.
11.9.2.1.2 The information to signals mapping
The information is encoded to 24 bits by RM code, and the bits are modulated to 12
QPSK signals.
11.9.2.1.2 Channel multiplexing
Option1: [FDM] The signals are mapped to subcarriers by FDM. Each logical channel
has own subcarrier index. The subcarrier location of each tile is permutated based on
Cell_ID. The details are FFS.
Option2: [CDM] The signals are mapped to subcarriers and spread over 6 contiguous
subcarriers by orthogonal code. Each logical channel has own code. The code of each
tile is permutated based on Cell_ID. The details are FFS.
13/13