IEEE 802.16m-08/374
Project
IEEE 802.16 Broadband Wireless Access Working Group <http://ieee802.org/16>
Title
Network Coordinated Beamforming
Date
Submitted
2008-05-06
Source(s)
Choong Il Yeh, Young Seok Song, Seung Joon Lee,
Byung-Jae Kwak, Jihyung Kim, Wooram Shin, Dong Seung
Kwon
ETRI 161 Gajeong-dong Yuseong-gu, Taejeon 305-700,
Korea
Re:
IEEE 802.16m-08/016r1: Call for Contributions on Project 802.16m System Description Document (SDD) (2008-03-20), Downlink
MIMO schemes.
Abstract
In order to improve spectral efficiency, this contribution proposes network coordinated beamforming focusing on downlink
dedicated/control channels.
Purpose
Adoption of proposed text into SDD
Notice
This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups . It represents only
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 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.
Patent Policy
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>.
Voice: +82 42 860 4895 (Choong Il Yeh)
+82 42 860 5936 (Dong Seung Kwon)
E-mail: ciyeh@etri.re.kr (Choong Il Yeh)
dskwon@etri.re.kr ((Dong Seung Kwon)
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.
1
IEEE 802.16m-08/374
CONTENTS


Rationale
Mechanism of Network Coordinated BF






Measurement
Feedback
MS location recognition by network
Network coordinated BF associated with FFR
Advantages
Text Proposals
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IEEE 802.16m-08/374
Rationale

Antenna Configuration



Target Channels



Narrow spacing (~0.5) multiple transmit antennas (array antenna)
Wide spacing (> 4l) multiple transmit antennas
Downlink dedicated data channels
Downlink dedicated control channels
Purposes



To improve cell-edge performance
To reduce feedback overhead
To reduce pilot overhead
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IEEE 802.16m-08/374
Mechanism of Network Coordinated BF

Measurements & Feedback by MSs


CINR
Preferred beam index (n)
i  arg max hˆ c
1 j  N
j
h
hˆ 
, h  C1K , K  the number of transmit antennas at BS
h
c j  c1 , c 2 ,, c N   Codebook


Cell ID
Coordinated BF by Network Cooperation



BSs are sharing feedback information (measurements) from MSs via
network interface.
Network recognizes user (MS) locations in the network
Coordinated BF by network cooperation
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IEEE 802.16m-08/374
MS Location Recognition & Network Coordinated BF
User Location Recognition by Network using Feedback Parameters


Network Coordinated BF

To mitigates inter-cell interference
To obtain macro diversity
BS2
Cell boundary
BS2
8
1
7
6
MS2
5
BS1
8
2
4
3
5
4
3
2
a1
Dat
Dat
a
7
1
4
2
2
Data3
3
6
3

Dat
a

MS1: High CINR, Preferred beam index 7, Cell ID 1
MS2: Low CINR, Preferred beam index 6, Cell ID 3
D
at
a1

5
1
6
BS3
MS1
7
a2
at
D
BS1
8
BS3
-5-
Suitable Antenna Configuration
for Network Coordinated BF
High CINR Users Group (Cell center region)

Multiple transmit antennas with wide spacing (AntennaSpacing > 4l)
•
•

Array antenna with narrow spacing (AntennaSpacing  0.5l)
•
Low CINR Users Group (Cell edge region)
Narrow antenna spacing (0.5l)
•
•
BF and Macro diversity gain by Network cooperation
Inter-cell interference mitigation by arranging beams using the same
spectrum from neighboring cells not to collide
Cell boundary
Preference for Antenna Configuration

High CINR Cell Center Region
•
•
Low CINR Cell Edge Region
•
a1
Dat
Dat
a
2
a2
at
D
Narrow space for both urban & rural
BS1
Data3

Urban: Wide space (rich scattering)
Rural: Narrow space (LOS)
BS2
3


Space Division Multiple Access (SDMA)
Dat
a

Multiuser MIMO (MU-MIMO)
Spatial Multiplexing (SM)
D
at
a1

IEEE 802.16m-08/374
-6BS3
IEEE 802.16m-08/374
Network Coordinated BF & FFR

FFR Group 1 for Coordinated BF (Reuse 1: spectrum fully reused)

High CINR users group (cell center region)
•
•

FFR Group 2 for Coordinated BF (Reuse 1: spectrum fully reused)

Low CINR users group (not-clustered users in the cell edge region)
•
•

Cooperation with neighbor cells is not required
MU-MIMO, SM or SDMA can be implemented in terms of only serving cell point of view
Cooperation with neighbor cells is required
Multiple single streams using the same spectrum from neighboring cells by the help of both coordinated
BF and Macro diversity
FFR Group 3 for Coordinated BF (Reuse N: spectrum flexibly reused)

Low CINR users group (clustered users in the cell edge region)
•
•
Cooperation with neighbor cells is required
Common subcarrier permutation may be required
BS2
Cell boundary
BS2
Cell boundary
BS2
Cell boundary
Data1
Data6
Data1
Data2
Data4
Data5
BS1
Data1
Data3
Data1
Data2
Data3
Data9
Data3
Data3
Data1
Data2
Data8
Data7
Data3
Data1
Data3
BS1
BS1
BS3
BS3
High CINR Cell-center
Reuse 1 multi-stream
BS3
Low CINR Cell-edge not
clustered
Reuse 1 single stream
Low CINR Cell-edge clustered
Reuse N
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IEEE 802.16m-08/374
Advantages

Reduced Feedback Overhead

Low Pilot Density

Cell-edge Performance

Inter-cell Interference Mitigation

Low Deployment Cost
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IEEE 802.16m-08/374
Text Proposal
11.X
Downlink Network Coordinated BF
In order to improve spectral efficiency of downlink dedicated data and control
channels, network coordinated BF can be used. Such parameters as CINR and preferred
beam index should be measured at MS and reported to the BS. Then BSs will share
these feedback information. Depending on the feedback parameters from MSs, Access
Service Network (ASN) can recognize the locations of MSs. MU-MIMO, SM or SDMA
should be applied to MSs located at cell center regions in terms of only serving cell
point of view. For MSs located at cell-edge regions and spaced apart enough to neglect
inter-beam interference, network will arrange beams using the same spectrum from
neighboring BSs not to collide each other as well as to obtain macro diversity. In case
where users are located in the cell-edge regions, the network should use Reuse N to
mitigate inter-cell interference.
-9-