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© 2013 Agilent Technologies
Wireless Communications
8x8 MIMO and Carrier
Aggregation Test Challenges
for LTE
Presented by
Iyappan Ramachandran
Agilent Technologies
© 2013 Agilent Technologies
Wireless Communications
2 © 2013 Agilent Technologies
Wireless Communications
Agenda
• Industry Background
• Design Issues and Test Challenges for LTE and
LTE-A
• LTE Transmission Modes
• LTE Signal Processing
• Test Solutions
© 2013 Agilent Technologies
Wireless Communications
New Broadband Applications Fuel the Drive
for Next Generation Wireless Technologies
Market trends • Mobile data traffic grows at high double-digit rates
each year
• High-speed applications fuel the drive for 4G
• Demand for smart phones and other mobile devices
• Increasing wireless technology complexity
• Fierce competition
• More functionality at lower cost
Agilent response • Participate, lead on wireless standards bodies and
industry forums
• Work with industry-leading customers to bring new
technologies to market faster
• Deliver multi-format solutions that simplify design and
test of complex devices
• Deliver integrated design simulation and test to reduce
cost, time, and risk
• Deliver cost-effective test solutions with scalable
performance Last decade was for mobile communication
This decade is for mobile broadband
-Advanced
LTE
(r)
a/g/n/ac
3
© 2013 Agilent Technologies
Wireless Communications
4 © 2013 Agilent Technologies
Wireless Communications
Cellular evolution 1990 - 2013
TD-SCDMA (China)
802.16e (Mobile WiMAX)
WiBRO (Korea)
802.16d (Fixed WiMAX)
802.11n
GSM (Europe)
IS-136 (US TDMA)
PDC (Japan)
IS-95A (US CDMA)
HSCSD GPRS iMODE IS-95B (US CDMA)
W-CDMA (FDD & TDD)
E-GPRS (EDGE)
HSDPA HSUPA
EDGE Evolution
1x EV-DO 0 A B
HSPA+ / E-HSPA
LTE (R8/9 FDD & TDD)
LTE-Advanced (R10 & beyond)
802.16m / WiMAX2 WirelessMAN-Advanced
802.11h
802.11ac 802.11ad
cdma2000 (1x RTT)
802.11a/g
802.11b 2G
W-LAN
2.5G
3G
3.5G
3.9G/ 4G
4G / IMT-Advanced
Inc
rea
sin
g e
fficie
nc
y, ba
nd
wid
th a
nd
da
ta ra
tes
Market evolution
Technology evolution
© 2013 Agilent Technologies
Wireless Communications
5 © 2013 Agilent Technologies
Wireless Communications
• Mobile penetration continues to grow:
>6.5 billion subscribers worldwide by end
of 2012; >92% of world population
• Mobile data traffic is growing exponentially
• Single Video Streaming = Around 500,000
Text Messages’ Traffic
• > 2 Billion App Downloads per Month
• In addition to subscriber growth, there is
parallel growth in cellular peak data rates
It’s All About More Data, Faster!
Source: LTE World Summit presentation 2011 and Portio research
384 kbps 14 Mbps 21-168 Mbps 150-300 Mbps
HSPA+ LTE
LTE-Advanced
W-CDMA HSPA
1 Gbps Growth in cellular peak data rates (theoretical) showing more than 2500 times higher data rate over a
period of 10 years
© 2013 Agilent Technologies
Wireless Communications
6 © 2013 Agilent Technologies
Wireless Communications
Agenda
• Industry Background
• Design Issues and Test Challenges for LTE and LTE-A
• LTE Transmission Modes
• LTE Signal Processing
• Test Solutions
© 2013 Agilent Technologies
Wireless Communications
7 © 2013 Agilent Technologies
Wireless Communications
3GPP Release 10 and Beyond
1. Carrier aggregation
2. Enhanced multiple antenna transmission a) Downlink 8 antennas, 8 streams
b) Uplink 4 antennas, 4 streams
3. Enhanced uplink multiple access a) Clustered SC-FDMA
b) Simultaneous Control (PUCCH) and Data (PUSCH)
4. Coordinated Multipoint (CoMP)
5. Relaying
6. Home eNB mobility enhancements
7. Heterogeneous network support
8. Self Optimizing networks (SON)
Rel-10 LTE-A
proposed to ITU
Other Rel-10
and beyond
LTE-Advanced Design & Test Challenges - Carrier Aggregation Webcast
© 2013 Agilent Technologies
Wireless Communications
Test Challenges for LTE-Advanced
Adds more complexity to the Physical Layer
Carrier Aggregation
• Simultaneous transceivers creates interference problems within the UE or Base Station
Clustered SC-FDMA
• Adds to amplifier design challenges
• Creates large opportunity for in-channel and adjacent channel spur generation
MIMO
• More antennas, more complexity
• Hard to design a multi-band, MIMO antenna in small space of the handset
Needs to co-exist with legacy 2G and 3G cellular systems worldwide
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© 2013 Agilent Technologies
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What is Carrier Aggregation?
• Extends the maximum transmission bandwidth, up to 100 MHz, by aggregating
up to five LTE carriers – also known as component carriers (CCs)
• Lack of sufficient contiguous spectrum forces use of carrier aggregation to meet
peak data rate targets:
– 1 Gbps in the downlink and 500 Mbps in the uplink
• Motivation:
– Achieve wide bandwidth transmissions
– Facilitate efficient use of fragmented spectrum
– Efficient interference management for control channels in heterogeneous
networks
Component Carrier (CC)– up to 20 MHz BW
Reso
urc
e b
loc
k
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© 2013 Agilent Technologies
Wireless Communications
Band A Band B
Carrier Aggregation Modes
Intra -band
contiguous
allocation
Reso
urc
e b
lock
f
≈
Reso
urc
e b
lock
f
Intra-band
non-contiguous
allocation
Inter-band
non-contiguous
allocation
Component Carrier (CC)– up to 20 MHz BW
Reso
urc
e b
loc
k f
Band A
Band A
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© 2013 Agilent Technologies
Wireless Communications
Carrier Aggregation Band Combinations
•One of RAN WG4’s most intense activities is in the area of creating RF
requirements for specific band combinations.
• In theory there could be as many as 5 carriers but so far all the activity is
around dual carrier combinations
•The original CA work in Rel-10 was limited to three combinations
• In Rel-11 there are now up to 18 CA combinations being specified
Band
E-UTRA
operatin
g Band
Uplink (UL) band Downlink (DL) band
Duple
x
mode
UE transmit / BS receive Channel
BW
MHz
UE receive / BS
transmit Channel
BW
MHz FUL_low (MHz) – FUL_high
(MHz)
FDL_low (MHz) – FDL_high
(MHz)
CA_40 40 2300 – 2400 [TBD] 2300 – 2400 [TBD] TDD
CA_1-5 1 1920 – 1980 [TBD] 2110 – 2170 [TBD]
FDD 5 824 – 849 [TBD] 869 – 894 [TBD]
CA_3-7 3 1710 – 1788 20 1805 – 1880 20
FDD 7 2500 – 2570 20 2620 – 2690 20
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© 2013 Agilent Technologies
Wireless Communications
Rel-11 Carrier Aggregation Combinations
Band Lead company Uplink Downlink Uplink Downlink Mode
CA-B3_B7* TeliaSonera 1710 - 1785 1805 - 1880 2500 - 2570 2620 - 2690 FDD
CA-B4_B17 AT&T 1710 – 1755 2110 - 2155 704 – 716 734 - 746 FDD
CA-B4_B13 Ericsson (Verizon) 1710 – 1755 2110 - 2155 777 - 787 746 - 756 FDD
CA-B4_B12 Cox Communications 1710 – 1755 2110 - 2155 698 – 716 728 - 746 FDD
CA-B20_B7 Huawei (Orange) 832 – 862 791 - 821 2500 - 2570 2620 - 2690 FDD
CA-B2_B17 AT&T 1850 – 1910 1930 - 1990 704 – 716 734 - 746 FDD
CA-B4_B5 AT&T 1710 – 1755 2110 - 2155 824 – 849 869 - 894 FDD
CA-B5_B12 US Cellular 824 – 849 869 - 894 698 – 716 728 - 746 FDD
CA-B5_B17 AT&T 824 – 849 869 - 894 704 – 716 734 - 746 FDD
CA-B20_B3 Vodafone 832 – 862 791 - 821 1710 - 1785 1805 - 1880 FDD
CA-B20_B8 Vodafone 832 – 862 791 - 821 880 – 915 925 - 960 FDD
CA-B3_B5 SK Telecom 1710 - 1785 1805 - 1880 824 – 849 869 - 894 FDD
CA-B7 China Unicom 2500 - 2570 2620 - 2690 2500 - 2570 2620 - 2690 FDD
CA-B1_B7 China Telecomm 1920 - 1980 2110 - 2170 2500 - 2570 2620 - 2690 FDD
CA-B4_B7 Rogers Wireless 1710 – 1755 2110 - 2155 2500 - 2570 2620 - 2690 FDD
CA-B25_25 Sprint 1850 - 1915 1930 - 1995 1850 - 1915 1930 - 1995 FDD
CA-B38 Huawei (CMCC) 2570 - 2620 2570 - 2620 2570 - 2620 2570 - 2620 TDD
CA-B41 Clearwire 2496 - 2690 2496 - 2690 2496 - 2690 2496 - 2690 TDD
* Carried forwards from Rel-10
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© 2013 Agilent Technologies
Wireless Communications
Combinations of Carrier Aggregation
and Layers
There are multiple combinations of CA and layers that can meet the
data rates for the new and existing UE categories
The following tables define the most likely cases for which
performance requirements may be developed
UE category capability
[#CCs/BW(MHz)]
DL layers
[max #layers]
Category 6
1 / 20MHz 4
2 / 10+10MHz 4
2 / 20+20MHz 2
2 / 10+20MHz 4 (10MHz)
2(20MHz)
Category 7
1 / 20MHz 4
2 / 10+10MHz 4
2 / 20+20MHz 2
2 / 10+20MHz 4 (10MHz)
2(20MHz)
Category 8 [2 / 20+20MHz] [8]
UE category capability
[#CCs/BW(MHz)]
UL layers
[max #layers]
Category 6
1 / 20MHz 1
2 / 10+10MHz 1
1 / 10MHz 2
Category 7
2 / 20+20MHz 1
1 / 20MHz 2
2 / 10+20MHz 2 (10MHz)
1 ( 20MHz)
Category 8 [2 / 20+20MHz] [4]
Downlink Uplink
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© 2013 Agilent Technologies
Wireless Communications
Design Challenges – Intra-Band Carrier
Aggregation
• Not such an issue for the eNB
because already dealing with multi-
carriers
• Major challenge for the UE
• For Intra-band: Wider Carrier being
transmitted
– More stringent linearity requirements on the
power amplifier
– UE will need to use less transmitter power
for the amplifier to remain in the linear
region
Example of CCDF plot using N7624B LTE/LTE-
Advanced Signal Studio software
2 uplink contiguous CCs
Single uplink CC
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© 2013 Agilent Technologies
Wireless Communications
Design Challenges – Inter-Band Carrier
Aggregation
– Challenging radio environment in
terms of intermodulation and cross-
modulation within the UE device
– Need to design front-end
components that help reduce
harmonics, and other
intermodulation products, which
meet 3GPP requirements
Multiplex
1 BB
Multiplex
2 BB
IFFT
IFFT
D/A
D/A RF PA RF filter L2
L1 RF PA
RF filter
RF filter
• For Inter-Band: Multiple simultaneous transmit and
receive chains
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Wireless Communications
16 © 2013 Agilent Technologies
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Agenda
• Industry Background
• Design Issues and Test Challenges for LTE and LTE-A
• LTE Transmission Modes
• LTE Signal Processing
• Test Solutions
© 2013 Agilent Technologies
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17 © 2013 Agilent Technologies
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Multi-Antenna Techniques
Tx Diversity • Transmit orthogonally modified redundant copies
across multiple antenna’s
• Robustness to channel fading / noise
Tx0
Tx1
Frequency domain
Spatial Multiplexing • Transmit different data streams simultaneously
across multiple antenna’s
• Improved spectral efficiency / throughput
Tx0
Tx1
Beamforming • Transmit per antenna weighted signal copies
across multiple antenna’s
• Coherent beamforming gain (dB) at receiver
Tx0
Tx1
© 2013 Agilent Technologies
Wireless Communications
18 © 2013 Agilent Technologies
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LTE Downlink MIMO Terminology
Codeword - independent transport block of data to be transmitted
a maximum of 2 is supported in LTE
- codewords mapped to multiple layers by a serial to parallel
converter process
Layer - a stream of data to be transmitted
Rank - number of layers to be transmitted
Antenna Port - no definition of antenna port to physical antenna mapping
- example: one antenna port could be mapped to four physical
antennas, but the RX perceives the transmission originated from a single
antenna.
Codebook - a predefined set of precoding weights
Precoding - complex weights used for each layer to match the
transmission to the propagation conditions of the channel.
- this process results in mapping each layer to one or more antenna ports
.
CRS
Cell-specific RS
UE1
Broadcast pattern
UE-specific pattern
UE-specific RS
Beamforming
weights
Physical
antennas
© 2013 Agilent Technologies
Wireless Communications
3GPP Release 8
TM1: SISO single antenna transmissions
TM2 : Tx Diversity using 2 or 4 antennas
TM3: Open-Loop SU-MIMO (Spatial Multiplexing) with CDD
TM4: Closed-Loop SU-MIMO
TM5: Closed-Loop MU-MIMO
TM6: Closed-Loop, Rank 1 Spatial Multiplexing
TM7: Rank 1 Spatial Multiplexing (Single-Layer Beamforming)
3GPP Release 9
TM8: Rank 2 Spatial Multiplexing (Dual-Layer Beamforming)
3GPP Release 10
TM9: Up to 8 layer transmissions using Ports 7 to 14
LTE DL Transmission Modes
Codebook
based precoding
Non-Codebook
based precoding
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Transmission Mode 3
Open-Loop SU-MIMO Spatial Multiplexing
• Requires no PMI feedback from UE
• Reduced overhead since Precoding Matrix Indicator is not signaled
• Rank information still transmitted
• Used in high mobility scenarios where it is not possible to get accurate feedback
• Which precoding matrix should be used?
• Uses predetermined precoding weights
• Always uses the 1st codebook index when in open-loop mode (this index not used in
closed-loop mode)
• Cyclic Delay Diversity – why do we add this?
• Applies an increasing delay to each antenna port, before the CP
• Results in linear phase offset for each subcarrier
• Adds additional diversity - each subcarrier experiences a different beamforming pattern
Layer
mapping Precoding
Tx1
Tx2
UE
CRS Cell-specific RS
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21 © 2013 Agilent Technologies
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Transmission Mode 4
Closed-Loop SU-MIMO Spatial Multiplexing
• Most used case for Release 8
• Precoding based on codebook
• UE reports rank and PMI to eNB, with rank and codebook index
most closely matching channel
Layer
mapping Precoding
Tx1
Tx2
UE
Precoding Matrix Indicator (PMI)
eNB
CRS Cell-specific RS
© 2013 Agilent Technologies
Wireless Communications
22 © 2013 Agilent Technologies
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Transmission Mode 5
Closed-Loop MU-MIMO
• Extension to TM4
• Concept is to direct each layer to a different user, rather than all layers to one UE
• Main difference is an additional power offset between PDSCH and CRS can be
signaled – necessary since the TX power can now be split between multiple users
and since UE uses RS for both amplitude & phase references. UE knows the
number of layers used in TM3 & TM4, so this information is not necessary to be
transmitted to UE’s in these cases.
• Power offset signaled in DCI Format 1D
Layer
mapping Precoding
Tx1
Tx2
UE 1
UE 2
eNB
CRS
Cell-specific RS
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Transmission Mode 6
Rank 1 Spatial Multiplexing
• Essentially beamforming using 1 layer, BUT with codebook-based precoding
• UE signals which precoding matrix should be used
• Why does this mode exist (seems to be a subset of TM4)?
• Reduced signaling overhead
• UE’s with low SINR (that can’t support multiple layers)
Layer
mapping Precoding
Tx1
Tx2
UE
Precoding Matrix Indicator (PMI)
eNB
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Transmission Mode 7
Single Layer Beamforming
• Available in R8 of standard
• Control channels utilize TX diversity, no beamforming
• Utilizes non-codebook based precoding
• UE still reports PMI using codebook based indexes, but eNB may or may not actually use them
• UE perceives the transmission originating from a single antenna port
• How does eNB know how to choose precoding weights?
• Measure the Sounding RS
• Channel reciprocity in the case of TDD
• Direction of Arrival (DOA) estimates using a calibrated RX array
• UE informed to use UE-specific RS for as the phase reference in demod
• Why important: Eliminates need of UE to know how precoding was performed
• Where Transmitted: UE-specific RS only transmitted in RB’s of the PDSCH for a given UE
© 2013 Agilent Technologies
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MIMO in LTE Release 8
• Based on cell-specific RS
• Transmitted on antenna ports 0 through 3
• Support for up to 4x4 MIMO
• Transmit diversity or spatial multiplexing
• Codebook-based precoding
• Limited set of precoding matrices
• UE has to be informed of precoding used
Cell-specific RS
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26 © 2013 Agilent Technologies
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Transmission Mode 8
Dual Layer Beamforming
• Available in R9 of standard
• Similar to Transmission Mode 7
• but now uses 2 layers for increased throughput
• UE can send quantized PMI feedback to eNB, not ideal, but better than none
• CQI reports made using cell specific RS because UE-specific RS may not be allocated across entire channel – important for FDD where channel reciprocity does not work like in TDD
• Utilizes non-codebook based precoding
• UE perceives the transmission originating from a two antenna ports
• UE informed to use UE-specific RS for as the phase reference in demod
• UE-specific RS are orthogonal to enable separation of the 2 layers
• Transmitted on the same resource elements & symbols for each port
• Orthogonality provided via Walsh codes
• Enables MU-MIMO in TM8 & TM9: 2 cover codes & 2 UE-Specific RS = up to 4 unique users
• MU-MIMO operation transparent to UE through use of UE-specific RS. Power ratio between RS and data scales the same way for each layer.
© 2013 Agilent Technologies
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27 © 2013 Agilent Technologies
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MIMO in Release 9
• Based on UE-specific RS ports 5, 7 and 8
• Up to 2-layers (called TM8)
• Amenable to UE-specific beamforming
• Non-codebook-based precoding
• UE-RS undergoes the same precoding
• Channel estimation/equalization based on UE-RS
• No need to inform UE of precoding
UE-specific RS
Beamforming
weights
Physical
antennas
UE-specific
pattern
© 2013 Agilent Technologies
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28 © 2013 Agilent Technologies
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Transmission Mode 9
8-Layer Transmissions
• Available in R10 of standard
• Non-codebook based precoding used
• Extension from 2-layers in TM8 (introduced in R9) for up to 8-layers in R10
• Codewords still limited to 2. Additional codeword support adds little benefit and comes at cost of additional
signaling to support each transport block
• New CSI-RS introduced
• Used for channel estimation by the higher layers
• Relatively sparse in density since they are used for feedback only
• Can be ‘muted’ to enable reception of CSI-RS from other cells, important for COMP & Hetnet interference
management
• UE-specific RS updated to enable additional layers/antenna ports while remaining backward compatible with R9
transmissions
© 2013 Agilent Technologies
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29 © 2013 Agilent Technologies
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Antenna Ports in LTE/LTE-A
• Ports are not the same as physical antennas
• Cell-specific RS
• Ports 0 – 3
• UE-specific RS
• Port 5 defined in Rel 8
• Ports 7 and 8 defined in Rel 9
• Ports 9-14 defined in Rel 10
• MBSFN-RS (Multicast-Broadcast Single Frequency Network Reference Signal)
• Port 4
• Positioning RS
• Port 6 defined in Rel 9
• CSI-RS (Channel State Information Reference Signal)
• Ports 15-22 defined in Rel 10
© 2013 Agilent Technologies
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30 © 2013 Agilent Technologies
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Agenda
• Industry Background
• Design Issues and Test Challenges for LTE and LTE-A
• LTE Transmission Modes
• LTE Signal Processing
• Test Solutions
© 2013 Agilent Technologies
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31 © 2013 Agilent Technologies
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LTE Signal Processing (TM7 & TM8) (Adapted from 3GPP 36.211 and 36.212)
Channel coding
Rate matching
Code block
concatenation
110 ,...,, Aaaa
110 ,...,, Bbbb
110 ,...,, rKrrr ccc
)(
1)(
1)(
0 ,...,, iDr
ir
ir r
ddd
110 ,...,, rErrr eee
110 ,...,, Gfff
Transport block
CRC attachment
Code block segmentation
Code block CRC attachment
ScramblingModulation
mapper
Layer
mapperPrecoding
Resource element
mapper
OFDM signal
generation
Resource element
mapper
OFDM signal
generationScrambling
Modulation
mapper
layers antenna portscodewords
CRS (Cell-specific Reference Signal)
Can be weighted to produce sector wide common control Broadcast pattern
Possible when Num Physical Ports > Num CRS Ports
CRS
Cell-specific RS Broadcast pattern
PDSCH (Data)
Channel encoded as 1 or 2 codewords per Subframe (TTI)
Mapped to 1 layer for TM7 and 1 or 2 layers for TM8
BF precoding is non-codebook based
BF precoding can vary per RB & per Subframe (TTI)
UERS (UE-specific Reference Signal)
Mapped to associated TM7/TM8 PDSCH RB allocations
Same BF precoding as each associated PDSCH RB
UERS
UE-specific RS
UE-specific pattern
UE1
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32 © 2013 Agilent Technologies
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TM8
Dual Layer
UERS
LTE Signal Processing R8 & R9 Reference Signals: Common CRS and UE-Specific RS
TM7
Single Layer
UERS
Common
CRS
Port 0
Port 1
Port 2
Port 3
Port 7
Port 8
Port 5
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33 © 2013 Agilent Technologies
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MIMO in LTE-A Release 10
• Extension of MIMO based on UE-specific RS
• Up to 8 layers (8x8 MIMO) supported (called TM9)
• Transmission on ports 7 through 14
• The 8 UE-RS ports are orthogonal
• Either on time/freq grid or in code domain
Port 7 Port 8 Port 9 Port 10
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34 © 2013 Agilent Technologies
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LTE Signal Processing R10 Reference Signals: Common CRS and UE-Specific RS
TM8
UERS
TM9
UERS
TM7
Single Layer
UERS
Common
CRS
Port 0
Port 1
Port 2
Port 3
Port 9
Port 10
Port 7
Port 8
Port 5
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35 © 2013 Agilent Technologies
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CSI-RS in LTE-A Release 10
• To be used by UE to measure Channel State Information
• Fed back to eNB through CQI
• 8 ports defined : ports 15 through 22
• Relatively sparse in the time-freq grid
Port 15 Port 16 Port 17 Port 18
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36 © 2013 Agilent Technologies
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LTE Signal Processing
What really happens…
CRS
Cell-specific RS
UERS
UE-specific RS
Serial
to
Parallel
Converter
Mapping to physical Antennas Layer Mapper Receiver Precoding
CW1
CW2
L2
L3
P2
L1
P4
P6
P1
A2
A3
A5
A1
P…
P5
P3
MIMO Channel
A4
© 2013 Agilent Technologies
Wireless Communications
37 © 2013 Agilent Technologies
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Agenda
• Industry Background
• Design Issues and Test Challenges for LTE and LTE-A
• LTE Transmission Modes
• LTE Signal Processing
• Test Solutions
© 2013 Agilent Technologies
Wireless Communications
38 © 2013 Agilent Technologies
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Design Issues for MIMO
DSP
TRANSMITTER
DSP
RECEIVER
• Receiver needs to differentiate/
recover simultaneous multiple
signals coming at it - Requires a
wide range of test conditions/
scenarios
• Need to adequately stress
amplifiers, I/Q modulators, filters,
etc - Need to simulate real-world
signals including fading
• Receivers must deal with
complex interference - Need to
provide the ability to add
impairments to the test signals.
• Cross Coupling through power
supplies, poor grounding etc -
Requires analyzer to pick out the
right signal and look at power
characteristics
• It gets worse for picocells &
femtocells
• Signal Coding Verification - Need
the analyzer to figure out what all
the signals are before making
measurements. • Distortion in Power Amplifiers -
Needs out of band spectrum measurements.
© 2013 Agilent Technologies
Wireless Communications
Test Challenges in LTE systems (1 of 2)
Some specific challenges for LTE:
• Six channel bandwidths from 1.4 to 20 MHz
• Different transmission schemes for the downlink (OFDMA) and uplink (SC-
FDMA)
• Flexible transmission schemes where the physical configuration impacts RF
performance
• Specifications that include both FDD and TDD transmission modes
• Challenging measurement configurations caused by spectral, power, and time
variations due to traffic
• Multi-antenna techniques such as TX diversity, spatial multiplexing (MIMO), and
beamsteering
• Complex tradeoffs between in-channel, out-of-channel, and out-of-band
performance
• New multi-standard radio (MSR) base station transmitter requirements
• LTE-Advanced requirements including carrier aggregation (CA) for both
downlink and uplink
39
© 2013 Agilent Technologies
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Test Challenges in LTE systems (2 of 2)
Some specific challenges for LTE:
• Receiver co-channel interference
• Receiver testing under propagation impairment conditions:
• Faded channel performance
• MIMO performance testing
• UE reports (CQI. HARQ, ...)
• Throughput
40
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41 © 2013 Agilent Technologies
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SystemVue: Simulation-Based 8x8 MIMO PHY Modeling A versatile design & verification tool that bridges early R&D gaps
• Explore open TX/RX baseband reference
designs for UE & eNB, with MIMO fading
• Versatile modeling environment: includes
many technologies, RF/BB models, effects
• Simulate missing system pieces and
environments for earlier R&D validation
• Leverage simulation for scripting and easy
creation of arbitrary payloads, scenarios
• Measure using 89600 VSA for consistency
Working 8x8 MIMO Reference Design
with TX, RX, MIMO Channel, and RF
8x8 MIMO Channel modeling Throughput vs. D patterns
Basestation beamforming Pattern synthesis and signal gen
Download
to/from Agilent
Sources/Analyzers
Agilent Solutions: • W1461 SystemVue
• W1918 LTE-Advanced Library
• W1715 MIMO Channel models
© 2013 Agilent Technologies
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42 © 2013 Agilent Technologies
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Test Challenges for 8x8 MIMO: Analyze
Signals from Multiple Antennas Simultaneously
Test Challenge: The signals from the multiple antennas must be aligned to within 90ns.
This requires measuring time delay between the signals from the multiple transmit
antennas with enough margin.
Agilent Solutions:
89600 VSA software
Up to 8x8 MIMO support for FDD and
TDD with time alignment error
measurement result.
Hardware: N7109A multi-channel
signal analyzer
© 2013 Agilent Technologies
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43 © 2013 Agilent Technologies
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Test Challenges
MIMO plus Carrier Aggregation for UE Rx Tests
Agilent Solution – Signal Studio for LTE-Advanced
• Create FDD or TDD signals
• Inter-band carrier aggregation in 2 RF bands
• Up to 5 component carriers
• Independent configuration for each CC
• Up to 8x8 MIMO capability
• Transport channel coding
• Cross-carrier scheduling enables control information to be carried on
another carrier
• Signal Studio synchronizes and automatically controls up to 16 signal
generators
Inter-band 1 (Up to 8x8) Inter-band 2 (Up to 8x8)
Test Challenge: Test UE’s ability to decode signals with component carriers in two separate
RF bands. Additional challenges result if each component carrier is configured for MIMO
Select RF band for each
component carrier
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Snapshot of 8x8 MIMO Demod in VSA
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SISO and MIMO Solutions for R&D and Design Validation
Signal Studio
89600 VSA
Software
SystemVue
Infiniium
Oscilloscopes
(13GHz BW)
X-Series
Signal Analyzer
Single Channel 2x2 MIMO 3x3, 4x4 MIMO
• Up to 8x8 MIMO
MXG/EXG Signal Generator
Wideband MIMO PXI VSA
(800 MHz BW)
Infiniium
Oscilloscopes
(13GHz BW)
Wideband MIMO PXI VSA
(800 MHz BW) (2) MXG/EXG
Signal Generators
(N) MXG/EXG Signal Generators
M9381A PXIe RF Vector
Signal Generator
8x8 MIMO
N7109 Multi-channel Signal
Analyzer
(N) MXG/EXG Signal Generators
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(2) MXA/EXA Signal Analyzers
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46 © 2013 Agilent Technologies
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Agenda
• Industry Background
• Design Issues and Test Challenges for LTE and LTE-A
• LTE Transmission Modes
• LTE Signal Processing
• Test Solutions
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47 © 2013 Agilent Technologies
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For More Information
Agilent Resources
• LTE-Advanced application and product information:
www.agilent.com/find/lteadvanced
• 8x8 LTE MIMO analysis YouTube video:
http://www.youtube.com/watch?v=8TDaVMsKPP8
• Solutions for design and test of downlink 8x8 LTE MIMO, Application
Note: http://cp.literature.agilent.com/litweb/pdf/5991-1878EN.pdf
• 89600 VSA product information: www.agilent.com/find/vsa
• N7109A multi-channel signal analyzer information:
www.agilent.com/find/N7109A
• X-Series signal analyzer product information:
www.agilent.com/find/xseries
• Signal Studio product information: www.agilent.com/find/signalstudio
© 2013 Agilent Technologies
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Thanks for Listening!
Any Questions?
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Back-Up
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What’s New: LTE-Advanced at a Glance
1
2
3
Carrier aggregation
• Support for up to 5 Aggregated Carriers
• Up to 100 MHz Bandwidth
Enhanced uplink multiple access
• Clustered SC-FDMA
• Simultaneous Control and Data
Higher order MIMO
• Downlink 8x8
• Uplink 4x4
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UE Carrier Aggregation Bandwidth Classes
There is a total of six different carrier aggregation bandwidth classes
being defined.
Carrier
aggregation
bandwidth class
Maximum
number of CC
Aggregated
transmission bandwidth
configuration
3GPP
Release
A 1 NRB ≤ 100 R10
B 2 NRB ≤ 100 R10
C 2 100 < NRB ≤ 200 R10
D,E,F For future study 200 < NRB ≤ [500] Beyond R10
20 MHz BW = 100 RB (resource block)
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Carrier Aggregation Solution
Generate and analyze:
• Up to 5 component carriers
simultaneously
• All aggregation types: Inter-band
and intra-band (both contiguous
and non-contiguous)
• Uplink and downlink signals
• FDD and TDD frame structure
Two CCs at 800 MHz Three CCs at 2100 MHz
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LTE/LTE-Advanced Specifications Documents
The LTE and LTE-Advanced specifications are defined in the 36-series documents of 3GPP Standard
There are six major groups of documents
• 36.8XX & 36.9XX Technical reports (background information)
• 36.1XX Radio specifications (and eNB conformance testing)
• 36.2XX Layer 1 baseband
• 36.3XX Layer 2/3 air interface signalling
• 36.4XX Network signalling
• 36.5XX UE Conformance Testing
The latest versions of most of the documents can be found at
www.3gpp.org/ftp/Specs/html-info/36-series.htm
•The LTE-Advanced specifications are now drafted in the
Release 10 specifications
• ftp.3gpp.org/specs/latest/Rel-10/
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LTE Signal Processing
What really happens…
Serial
to
Parallel
Converter
Mapping to physical Antennas Layer Mapper Receiver Precoding
CW1
CW2
L2
L3
P1
L1
P3
P4
P1
A2
A3
A4
A1
CRS
Cell-specific RS
UERS
UE-specific RS
MIMO Channel
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55 © 2013 Agilent Technologies
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LTE Signal Processing
What really happens…
Serial
to
Parallel
Converter
Mapping to physical Antennas Layer Mapper Receiver Precoding
CW1
CW2
L2
L3
P1
L1
P3
P4
P1
A2
A3
A4
A1
CRS
Cell-specific RS
UERS
UE-specific RS
MIMO Channel
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56 © 2013 Agilent Technologies
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LTE Signal Processing
What really happens…
CRS
Cell-specific RS
UERS
UE-specific RS
Serial
to
Parallel
Converter
Mapping to physical Antennas Layer Mapper Receiver Precoding
CW1
CW2
L2
L3
P2
L1
P4
P6
P1
A2
A3
A5
A1
P…
P5
P3
MIMO Channel
A4