doc.: IEEE 802.15-15-0667-01-hrrc
Submission
September 2015
Junhyeong Kim, ETRI Slide 1
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [A Study on mmWave Beamforming for High-Speed Train Communication]
Date Submitted: [13 September, 2015]
Source: [Junhyeong Kim, Bing Hui, Hee-Sang Chung, JunHwan Lee] Company [ETRI]
Address [218 Gajeong-ro, Yuseong-gu, Daejeon, 305-700, KOREA]
Voice:[+82-42-860-6239], FAX: [+82-42-860-6732], E-Mail:[[email protected]]
Abstract: [A Study on mmWave Beamforming for High-Speed Train Communication]
Purpose: [For discussion]
Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for
discussion and is not binding on the contributing individual(s) or organization(s). The material in this
document is subject to change in form and content after further study. The contributor(s) reserve(s) the right
to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE
and may be made publicly available by P802.15.
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Contents
• Introduction
• Network Structure
• Beamforming
• Simulation
• Conclusions
• References
Junhyeong Kim, ETRI Slide 2
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Introduction
• Hierarchical two-hop network for fast moving vehicles
– Mobile wireless backhaul link • High rate rail communications Interest Group (IG HRRC) : a multi-gigabit-per-
second mobile wireless backhaul supporting high-mobility up to 500km/h
– Access link • Small cell (Wi-Fi and femto cell)
Junhyeong Kim, ETRI Slide 3
DU
GW
Public Internet
RU
GW : Gateway
DU : Digital Unit
RU : Radio Unit
TE : Terminal Equipment
RU
TE
Backhaul Link
mmWave
Backhaul Link
mmWave
Access Link
(inside vehicle)
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Introduction
• Various technical challenges and potential solutions
– Capacity improvement • Millimeter-wave due to its vast amount of underutilized spectrum
• MIMO techniques (polarized antenna)
– Path loss and atmospheric attenuation of millimeter-wave • coverage improvement by using beam-forming technique
– Inter-carrier interference (ICI) by Doppler effect • Proper sub-carrier spacing design for OFDM
• Millimeter-wave beam-forming techniques Doppler frequency shift in the
frequency domain can be simply overcome by automatic frequency control (AFC)
Junhyeong Kim, ETRI Slide 4
ETRI’s approach to physical layer design
Mobile Wireless Backhaul Link
(Outside Vehicle)
OFDM based on mmWave
Beamforming (2-link multi-flow)
Data throughput (DL) 2 Gbps using 500-MHz bandwidth
Spectral efficiency 4 bps/Hz
Mobility Support 500 km/h
User Access Link (Inside Vehicle) WiFi or Femto
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Network Structure
• Millimeter-wave beamforming for HST
communication
– Dual link multi-flow : same radio resources (time and
frequency) are assigned to both links
Junhyeong Kim, ETRI Slide 5
z
y
x(0, 0, 0)
fixed BF
adaptive BF
optical fiber
X2 interface
Public Internet
... ...
GW
DU #d+1DU #d
D-RU #mD-RU #m-1 D-RU #m+2D-RU #m+1 D-RU #m+4D-RU #m+3
direction of movement
T-RU #1 T-RU #2
z'
y'x'
DRUd DRUd
TRUd
DRU trackd
DRUh
TRUh
(0, dDRU-track, hDRU) (dDRU, dDRU-track, hDRU) (2 dDRU, dDRU-track, hDRU)
HST : (0, 0, 0) (x, 0, 0),
T-RU #1 (-dTRU/2, 0, hTRU) (-dTRU/2+x, 0, hTRU)
T-RU #2 (dTRU/2, 0, hTRU) (dTRU/2+x, 0, hTRU)
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
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Beamforming
• 3D beam radiation pattern
– Horizontal and vertical beam width (3dB) : approximately 8
degrees
– Maximum beamforming gain : 21.58 dBi
Junhyeong Kim, ETRI Slide 6
-200 -150 -100 -50 0 50 100 150 200-40
-30
-20
-10
0
10
20
30Beam Radiation Pattern
Degree ()
Gai
n (
dB
i)
=0
=90z
yx
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Beamforming
• Adaptive BF : require automatic tracking of signals of moving
targets by continuously updating their parameters based on the
received signals
– Control the beam direction with an accuracy 1˚
– Beam radiation pattern remains unchanged during beam steering
Junhyeong Kim, ETRI Slide 7
z
y
x(0, 0, 0)
optical fiber
X2 interface
Public Internet
... ...
GW
DU #d+1DU #d
direction of movement
z'
y'x'
DRUd DRUd
TRUd
DRU trackd
HST : (0, 0, 0) (x, 0, 0),
T-RU #1 (-dTRU/2, 0, hTRU) (-dTRU/2+x, 0, hTRU)
T-RU #2 (dTRU/2, 0, hTRU) (dTRU/2+x, 0, hTRU)
(dDRU, dDRU-track, hDRU) (2 dDRU, dDRU-track, hDRU)
DRUh
(0, dDRU-track, hDRU) D-RU #mD-RU #m-1 D-RU #m+2D-RU #m+1 D-RU #m+4D-RU #m+3
TRUh
T-RU #1 T-RU #2
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Beamforming
• Fixed BF : BF parameters are fixed
– In the case of TX, the beam direction of m-th D-RU and m+1-th D-
RU is (dRU/2, 0, 0) and the beam direction of m+2-th D-RU and
m+3-th D-RU is (3∙dRU/2, 0, 0)
– In the case of RX, the beam directions of T-RU 1 and T-RU 2 are
simply set to direct in the negative and positive direction of the x-
axis respectively
Junhyeong Kim, ETRI Slide 8
z
y
x(0, 0, 0)
optical fiber
X2 interface
Public Internet
... ...
GW
DU #d+1DU #d
direction of movement
z'
y'x'
DRUd DRUd
TRUd
DRU trackd
HST : (0, 0, 0) (x, 0, 0),
T-RU #1 (-dTRU/2, 0, hTRU) (-dTRU/2+x, 0, hTRU)
T-RU #2 (dTRU/2, 0, hTRU) (dTRU/2+x, 0, hTRU)
(dDRU, dDRU-track, hDRU) (2 dDRU, dDRU-track, hDRU)
DRUh
(0, dDRU-track, hDRU) D-RU #mD-RU #m-1 D-RU #m+2D-RU #m+1 D-RU #m+4D-RU #m+3
TRUh
T-RU #1 T-RU #2
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Simulation
• Simulation scenarios
– adaptive BF (BS) + adaptive BF (TE)
– fixed BF (BS) + fixed BF (TE)
– fixed BF (BS) + adaptive BF (TE)
• Performance evaluation
– received signal quality
• 𝑆𝐼𝑁𝑅𝑑𝐵 1 = 10𝑙𝑜𝑔10𝑆𝑁𝑅 1,1
𝑆𝑁𝑅 2,1 +1, 𝑆𝐼𝑁𝑅𝑑𝐵 2 = 10𝑙𝑜𝑔10
𝑆𝑁𝑅 2,2
𝑆𝑁𝑅 1,2 +1
– 𝑆𝐼𝑁𝑅 𝑛 =𝑃𝑅𝑋,𝐷 𝑛
𝑃𝑅𝑋,𝐼 𝑛 +𝑁𝐹𝐿 𝑛=
𝑆𝑁𝑅𝐷 𝑛
𝑆𝑁𝑅𝐼 𝑛 +1
– 𝑆𝑁𝑅𝑑𝐵 𝑚, 𝑛 = 𝑅𝑆𝑆𝑑𝐵𝑚 𝑚, 𝑛 − 𝑁𝐹𝐿,𝑑𝐵𝑚(𝑛)
– 𝑅𝑆𝑆𝑑𝐵𝑚 𝑚, 𝑛 = 𝑃𝑇𝑋,𝑑𝐵𝑚 𝑚 + 𝐺𝑇𝑋,𝑑𝐵𝑖 𝑚, 𝑛 + 𝐺𝑇𝑋,𝑑𝐵𝑖 𝑚, 𝑛
– 𝑁𝐹𝐿,𝑑𝐵𝑚 𝑛 = −174 + 𝑁𝐹,𝑑𝐵 + 10𝑙𝑜𝑔10(𝑊)
Junhyeong Kim, ETRI Slide 9
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Simulation
• Major parameters
Junhyeong Kim, ETRI Slide 10
Parameters Values
Carrier frequency fc = 32 GHz
System bandwidth W = 125 MHz
Transmit power PTX,dBm = 20 dBm
Free space path loss [1] PLdB = 92.4 + 20 log fc,GHz
+ 20 log dkm (dB)
Noise figure NF,dB = 8 dB
D-RU height hDRU = 10 m
T-RU height hTRU = 3 m
Distance between
adjacent D-RUs dDRU = 1000 m
Distance between
adjacent T-RUs dTRU = 200 m
Distance between
Railway track and D-RUs
dDRU-track ∈
{10, 50, 100, 150} m
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Simulation
• Simulation results : received signal quality
– As the HST moves far away from the D-RU, the effect of
adaptive BF is negligible whereas it is important to use
adaptive BF if the T-RU is close to D-RU
Junhyeong Kim, ETRI Slide 11
0 100 200 300 400 500 600 700 800 900 1000-60
-40
-20
0
20
40
60SINR of Received Signal
HST Location (m)
SIN
R (
dB
)
TRU #1 (FXD TX BF, FXD RX BF)
TRU #2 (FXD TX BF, FXD RX BF)
TRU #1 (ADP TX BF, ADP RX BF)
TRU #2 (ADP TX BF, ADP RX BF)
TRU #1 (FXD TX BF, ADP RX BF)
TRU #2 (FXD TX BF, ADP RX BF)
September 2015
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Simulation
• Simulation results : received signal quality
– Received signal strength < 2 dB in the HST location from
200m to 800m
• If the T-RUs are placed sufficiently far away from each other, inter-D-RU
interference at each T-RU is significantly reduced with a properly sharp
beam pattern designed for both TX and RX side
Junhyeong Kim, ETRI Slide 12
0 100 200 300 400 500 600 700 800 900 10000
2
4
6
8
10
12
14
16
18Degradation of Received Signal Strength
HST Location (m)
Deg
radat
ion (
dB
)
TRU #1 (FXD TX BF, FXD RX BF)
TRU #2 (FXD TX BF, FXD RX BF)
TRU #1 (ADP TX BF, ADP RX BF)
TRU #2 (ADP TX BF, ADP RX BF)
TRU #1 (FXD TX BF, ADP RX BF)
TRU #2 (FXD TX BF, ADP RX BF)
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Simulation
• Simulation results : AoD, AoA
– Both vary according to 𝑑𝐷𝑅𝑈−𝑡𝑟𝑎𝑐𝑘
– 𝑑𝐷𝑅𝑈−𝑡𝑟𝑎𝑐𝑘 : distance between DRU and railway track
Junhyeong Kim, ETRI Slide 13
0 100 200 300 400 500 600 700 800 900 10000
50
100
150
200Angle of Departure (Transmit Beamforming)
HST Location (m)
(
Deg
ree)
0 100 200 300 400 500 600 700 800 900 10000
50
100
150
200Angle of Arrival (Receive Beamforming)
HST Location (m)
(
Deg
ree)
dDRU-track
=10m
dDRU-track
=50m
dDRU-track
=100m
dDRU-track
=150m
• AoD : Angle of Departure
(transmit beamforming)
• AoA : Angle of Arrival
(receive beamforming)
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Simulation
• Simulation results
– 𝑑𝐷𝑅𝑈−𝑡𝑟𝑎𝑐𝑘 = 10 𝑚
Junhyeong Kim, ETRI Slide 14
0 100 200 300 400 500 600 700 800 900 10000
50
100
150
200Zenith Angle ()
HST Location (m)
Angle
(D
egre
e)
AoD (TX BF)
AoA (RX BF)
0 100 200 300 400 500 600 700 800 900 1000-100
0
100
200Azimuth Angle ()
HST Location (m)
Angle
(D
egre
e)
0 2 4 6 8 10 12 14 16 18 20105
110
115
120
HST moves from (94,0,0) meters to (104,0,0) meters
Velocity of HST = 400 km/h
Zenith Angle ()
Elapsed Time (msec)A
ngle
(D
egre
e)
AoD
AoA
AoD (round-off)
AoA (round-off)
0 2 4 6 8 10 12 14 16 18 20-20
0
20
40
60Azimuth Angle ()
Elapsed Time (msec)
Angle
(D
egre
e)
• AoD : Angle of Departure
(transmit beamforming)
• AoA : Angle of Arrival
(receive beamforming)
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
Conclusions
• Different BF schemes are appropriate for different
HST location
• The fixed BF can achieve very similar performance to
that of adaptive BF in most of time
– giving a valuable insight into designing the mmWave BF
based HST communication system from feasibility and
implementation perspective
• As future works, it is worth to study the performance
of adaptive BF in the presence of calibration error
and the HST communication system in various
environments including the case of HST running
along the curved line.
Junhyeong Kim, ETRI Slide 15
September 2015
doc.: IEEE 802.15-15-0667-01-hrrc
Submission
References
1. ITU-R P.525-2, “Calculation of free-space
attenuation”
Junhyeong Kim, ETRI Slide 16
September 2015
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