Upload
sammy-yen
View
326
Download
3
Embed Size (px)
Citation preview
You take LTE forward. Agilent leads the way
3GPP LTE Technologies
JianHua Wu
Application Engineer
You take LTE forward. Agilent leads the way
LTE context and timeline
What is LTE?- LTE is a 3GPP project name for the evolution of UMTS- It is now linked with the development of a new air interface- Existed together the evolution of UMTS via HSDPA and HSUPA
Other names of LTE:- Evolved UTRA (E-UTRA) / Evolved UTRAN (E-UTRAN)- Evolved UMTS Terrestrial Radio Access- Evolved UMTS Terrestrial Radio Access Network
Related names:- 3.9G,Super 3G,HSOPA(Evolution of HSDPA/HSUPA with OFDM)- These terms are not standard, and may fade out soon.
LTE Core Network name:- It is called SAE (System Architecture Evolution).- It refers to the evolved core network.
You take LTE forward. Agilent leads the way
3GPP standards evolution (RAN & GERAN)
99
09
Release Commercial introduction
Main feature of Release
Rel-99 2003 Basic 3.84 Mcps W-CDMA (FDD & TDD)
Rel-4 Trials 1.28 Mcps TDD (aka TD-SCDMA) (LCR)
Rel-5 2006 HSDPA
Rel-6 2007 HSUPA (E-DCH)
Rel-7 2008+ HSPA+ (64QAM DL, MIMO, 16QAM UL). Many smaller features plus LTE & SAE Study items
Rel-8 HSPA+ 2009
LTE 2010+
LTE Work item – OFDMA air interface
SAE Work item New IP core network
Edge Evolution, more HSPA+
Rel-9 2011 – 2014 LTE Evolved MBMS, IMT-Advanced (4G)
Page 3
You take LTE forward. Agilent leads the way
IS-136TDMA
PDCGSMIS-95Acdma
Wireless evolution 1990 - 2010
2G
Incre
asin
g e
ffic
ien
cy,
ba
nd
wid
th a
nd
da
ta r
ate
s
2.5G
3G
3.5G
3.9G
4G
HSCSD iModeGPRSIS-95Bcdma
LTE-Advanced Rel-9/10
802.16m ?
E-GPRSEDGE
cdma2000W-CDMA
FDDW-CDMA
TDDTD-SCDMA
LCR-TDD
HSUPAFDD & TDD
1xEV-DORelease B
1xEV-DORelease A
1xEV-DORelease 0
HSDPAFDD & TDD
Edge Evolution
HSPA+
802.11g
802.11a
802.11b
802.16dFixed
WiMAXTM
802.11n
802.11h
WiBRO
Page 4
X
LTERel-8
802.16eMobile
WiMAXTMUMB
You take LTE forward. Agilent leads the way
LTE in context
5 major new 3.9G wireless technologies• 3GPP LTE
• 3GPP HSPA+
• 3GPP Edge Evolution
• 3GPP2 UMB (similar to 802.20)
• IEEE WiMAX – (802.16e / WiBRO)
3.9G Goals• Spectral efficiency
• Highest single user data rates
• Less robust higher order modulation schemes and multi-antenna technology ranging from basic Tx and Rx diversity through to full MIMO
3.9G Techniques:• HSPA+ and EDGE Evolution are natural extensions to existing technologies
• LTE, UMB and WiMAX are new OFDM systems with no technical precedent other than the early implementation of WiBRO which is now a WiMAX profile.
LTEE-UTRA
EDGE Evolution HSPA+
802.16eMobile
WiMAXTM
UMBcf 802.20
You take LTE forward. Agilent leads the way
LTE timeline for 3GPP, GCF & LSTI
2005 2006 2007 2008 2009 2010
Rel-7 Study Phase
Rel-8 Work Phase
Test Specs
Core specs drafted
1st Test Specs
drafted
Commercialrelease?
Proof of concept
GCF certification
Interoperability
Field trials
Page 6
You take LTE forward. Agilent leads the way
LTE at a glance
Page 7
You take LTE forward. Agilent leads the way
UE categories
UE Category
Max downlink data rate
Number of DL transmit data
streams
Modulation of DL
Max uplink data rate
Modulation of UL
RF Bandwidth
1 10 Mbps 1
QPSK
16QAM
64QAM
5 Mbps
QPSK
16QAM
20M
2 50 Mbps 2 25 Mbps
3 100 Mbps 2 50 Mbps
4 150 Mbps 2 50 Mbps
5 300 Mbps 4 75 Mbps
QPSK
16QAM
64QAM
Page 8
You take LTE forward. Agilent leads the way
Operating Band
DOCOMO
(Europe Bands)
TeliaSonera
Metro PCS ,
Verizon
You take LTE forward. Agilent leads the way
TX/RX Spacing
You take LTE forward. Agilent leads the way
Flexible Channel Bandwidth
You take LTE forward. Agilent leads the way
EARFCN
Channel Raster : 100k Hz
You take LTE forward. Agilent leads the way
LTE Network Architecture
•E-UTRAN (Evolved Universal Terrestrial Radio Access Network) –
3GPP TS 36.300
MME = Mobile
Management
entity
SAE = System
Architecture
Evolution
You take LTE forward. Agilent leads the way
Logical high level architecture for evolved systemEvolved IP packet core with multi-RAT integration
HSS - Home
subscriber server
IMS - IP
multimedia
subsystem
Inter AS anchor -
Inter access
system anchor
MME - Mobility
management
entity
Op. IP Serv. -
Operator IP
service
PCRF - Policy and
charging rule
control function
UPE - User plane
entity3GPP 23.882 Figure 4.2-1
WiMAX could
connect here
S5b
Evolved Packet Core
WLAN
3GPP IP Access
S2
non 3GPP
IP Access
S2
IASA
S5a
SAE Anchor
3GPP Anchor
S4
SGiEvolved RAN
S1
Op.IP
Serv.(IMS, PSS, etc…)
Rx+
GERAN
UTRAN
Gb
Iu
S3
MMEUPE
HSS
PCRF
S7
S6
SGSN GPRS Core
You take LTE forward. Agilent leads the way
• OFDM already widely used in non-cellular technologies and was considered by ETSI for UMTS in 1998
• CDMA was favoured since OFDM requires large amounts of baseband processing which was not commercially viable ten years ago
OFDM advantages• Wide channels are more resistant to fading and OFDM equalizers are much simpler to
implement than CDMA• Almost completely resistant to multi-path due to very long symbols• Ideally suited to MIMO due to easy matching of transmit signals to the uncorrelated
RF channels
OFDM disadvantages• Sensitive to frequency errors and phase noise due to close subcarrier spacing • Sensitive to Doppler shift which creates interference between subcarriers• Pure OFDM creates high PAR which is why SC-FDMA is used on UL• More complex than CDMA for handling inter-cell interference at cell edge
Why OFDM for the downlink?
You take LTE forward. Agilent leads the way
CDMA vs. OFDM
CDMA• All transmissions at full system bandwidth
• Symbol period is short – inverse of system bandwidth
• Users separated by orthogonal spreading codes
OFDM• Transmission variable up to system bandwidth
• Symbol period is long – defined by subcarrier
spacing and independent of system bandwidth
• Users separated by FDMA & TDMA on
the subcarriers
You take LTE forward. Agilent leads the way
LTE Air Interface OFDM: Orthogonal Carriers
• Closely spaced carriers overlap
• Nulls in each carrier’s spectrum land at
the center of all other carriers for Zero
Inter-Carrier Interference
Next
sub-carrier
You take LTE forward. Agilent leads the wayGroup/Prese
ntation Title
Agilent SeptemPage 18
• Closely spaced carriers overlap
• Nulls in each carrier’s spectrum land
at the center of all other carriers for
Zero Inter-Carrier Interference
LTE Air Interface Orthogonal Frequency Division Multiplexing
Tu=66.7us
△f=1/Tu=15kHz
△f
You take LTE forward. Agilent leads the way
Orthogonal Frequency Division Multiplexing
3GPP 25.892 Figure 1: Frequency-Time Representation of an OFDM Signal
OFDM is a digital multi-carrier modulation scheme, which uses a large number of closely-spaced orthogonal sub-carriers.
Each sub-carrier is modulated with a conventional modulation scheme (such as QPSK, 16QAM, 64QAM) at a low symbol rate similar to conventional single-carrier modulation schemes in the same bandwidth.
You take LTE forward. Agilent leads the way
OFDM vs. OFDMA
User 1
User 2
User 3
Subcarriers
Sym
bols
(Tim
e)
Subcarriers
Sym
bols
(Tim
e)
Orthogonal
Frequency
Division
Multiplexing
Orthogonal
Frequency
Division
Multiple
Access
OFDMA = OFDM + TDMA
User 1
User 2
User 3
OFDM
LTE uses OFDMA – a variation of basic OFDM
OFDMA’s dynamic allocation enables better use of the channel for multiple
low-rate users and for the avoidance of narrowband fading & interference.
You take LTE forward. Agilent leads the way
Why Single Carrier FDMA (SC-FDMA)?
• SC-FDMA is a new hybrid modulation technique combining the low PARsingle carrier methods of current systems with the frequency allocation flexibility and long symbol time of OFDM
• SC-FDMA is sometimes referred to as Discrete Fourier Transform Spread OFDM = DFT-SOFDM
TR 25.814 Figure 9.1.1-1 Transmitter structure for SC-FDMA.
Frequency domain Time domainTime domain
LTE uses SC-FDMA in the uplink
DFTSub - carrier
MappingCP
insertion
Size -NTX Size -N FFT
Coded symbol rate= R
NTX symbols
IFFT
You take LTE forward. Agilent leads the way
OFDM modulationQPSK example using N=4 subcarriers
Each of N subcarriers
is encoded with one
QPSK symbol
N subcarriers can
transmit N QPSK
symbols in parallel
One symbol period
The amplitude of the combined 4 carrier signal varies widely
depending on the symbol data being transmittedWith many
subcarriers
the waveform
becomes
Gaussian not
sinusoidal
Null created by transmitting
1,1 -1,-1 -1,1 1,-1
1,1-1,1
1,-1-1,-1
I
Q
You take LTE forward. Agilent leads the way
SC-FDMA modulationQPSK example using N=4 subcarriers
To transmit the sequence:
1, 1 -1,-1 -1, 1 1,-1
using SC-FDMA first
create a time domain
representation of the IQ
baseband sequence
+1
-1
V(Q)
One SC-FDMA
symbol period
+1
-1
V(I)
One SC-FDMA
symbol period
Perform a DFT of length
N and sample rate
N/(symbol period) to
create N FFT bins
spaced by 15 kHz
V,Φ
Frequency
Shift the N
subcarriers to the
desired allocation
within the system
bandwidth
V,Φ
Frequency
Perform IFFT to create
time domain signal of
the frequency shifted
original
1,1-1,1
1,-1-1,-1
Insert cyclic prefix
between SC-FDMA
symbols and
transmit
Important Note:
PAR is same as
the original QPSK
modulation
1,1-1,1
1,-1-1,-1
I
Q
You take LTE forward. Agilent leads the way
Comparing OFDM and SC-FDMAQPSK example using N=4 subcarriers
1, 1 -1,-1 -1, 1 1, -1 1, 1 -1,-1 -1, 1 1, -1
SC-FDMAData symbols occupy N*15 kHz for
1/N SC-FDMA symbol periods
60 kHz Frequencyfc
V
CP
15 kHzFrequency
fc
V
CP
OFDMAData symbols occupy 15 kHz for
one OFDMA symbol period
These graphs show how this sequence of QPSK symbols is represented in frequency and time
You take LTE forward. Agilent leads the way
Physical Layer definitions – TS36.211Frame Structure
Ts = 1 / (15000x2048)=32.552nsec
Ts: Time clock unit for definitions
Frame Structure type 1 (FDD)
FDD: Uplink and downlink are transmitted separately
#0 #2 #3 #18#1 ………. #19
One subframe
One slot, Tslot = 15360 x Ts = 0.5 ms
One radio frame, Tf = 307200 x Ts = 10 ms
Subframe 0 Subframe 1 Subframe 9
You take LTE forward. Agilent leads the way
Physical Layer definitions – TS36.211Frame Structure- type 2 (TDD)
One slot,
Tslot=15360Ts
GP UpPTSDwPTS
One radio frame, Tf = 307200Ts = 10 ms
One half-frame, 153600Ts = 5 ms
30720Ts
One subframe,
30720Ts
GP UpPTSDwPTS
Subframe #2 Subframe #3 Subframe #4Subframe #0 Subframe #5 Subframe #7 Subframe #8 Subframe #9
5 ms switch-point periodicity
Uplink-downlink
configuration
Downlink-to-Uplink
Switch-point periodicity
Subframe number
0 1 2 3 4 5 6 7 8 9
0 5 ms D S U U U D S U U U
1 5 ms D S U U D D S U U D
2 5 ms D S U D D D S U D D
3 10 ms D S U U U D D D D D
4 10 ms D S U U D D D D D D
5 10 ms D S U D D D D D D D
6 5 ms D S U U U D S U U D
Uplink and downlink configurations
TDD: Subframe 0 and 5 for downlink, others are either downlink or uplink
You take LTE forward. Agilent leads the way
LTE downlink subframe and slot structure
You take LTE forward. Agilent leads the way
How OFDM Deals With MultiPath?
Problem: If transmitted symbol interval = receiver capture time the
system even a little delay spread causes problem.
Solution: extend the symbol interval time…..
You take LTE forward. Agilent leads the way
Cyclic Prefix – Each and every symbol has a guard time at the beginning of the symbol
which allows the receiver to collect multipath from the previous symbol
Tb = “useful” symbol time. Contains all
the information of the burst and is
created from the 256 Inverse-FFT
Ts=Tu + Tcp this is a “ready to
transmit” symbolCP
Tu
Tu
Tcp
Ts
The complete symbol is created in the time
domain by duplicating the back portion of the
useful symbol and transmitting this first. By
duplicating this portion of the time record, this
portion of the waveform is effectively transmitted
twice.
The cyclic-prefix length Tcp should cover the maximum length of the time-
dispersion expected to be experienced.
You take LTE forward. Agilent leads the way
How OFDM Deals With MultiPath?
1,Cyclic-prefix insertion makes an OFDM signal insensitive to time dispersion as
long as the span of the time dispersion.
2,More power loss in demodulation since only a fraction Tu/(Tu + Tcp) of receiver
power is actually utilized by OFDM demodulator.
You take LTE forward. Agilent leads the way
Frame Structure Type – generic view
Frequency
#0
#1
#2
#3
#4
#5
#19
#18
#17
#16
NBWDL subcarriers
NBWRB subcarriers (=12)
Po
wer
The minimum allocation
of resources is one
Resource Block
= 12 adjacent
subcarriers for one
0.5ms slot
You take LTE forward. Agilent leads the way
Downlink Resource Block
Channel bandwidth
[MHz]1.4 3 5 10 15 20
Number of
resource blocks6 15 25 50 75 100
3GPP TS 36.101
You take LTE forward. Agilent leads the way
Channel Bandwidth Vs Transmission Bandwidth
You take LTE forward. Agilent leads the way
Downlink RS and Signal Structure
• The mobile terminal used Reference Symbols to make the channel estimation of downlink for schedule optimization.
• Downlink reference symbols are inserted within the first and third last OFDM symbols of each slot and with a frequency-domain spacing of six subcarriers.
• Within each resource block, consisting of 12 subcarriers during one slot, there are thus four reference symbols.
• The RS is always transmitted across the entire operation bandwidth, even if the downlink channel is not fully allocated
You take LTE forward. Agilent leads the way
Downlink Feature (Review)-Physical channel-
Downlink Physical Layer CapabilityReference Signal Cell-specific reference carries Cell-id
UE-specific reference, MBSFN reference
P-Sync Carries physical layer id (0~2)Zadoff-Chu sequence
S-Sync Carries cell-identity group (0~167)
P-BCH Broadcast Channel (1920bits@N_CP by 40ms)SFN control
PDCCH Carries DL Control Information (HARQ process#,MCS, TPC,MIMO precoding info etc.)
PCFICH Carries Control Format Information ((Num of OFDM symbols of PDCCH in a subframe; 1~4)
PHICH Carries HARQ Indicator (ACK/NACK)
PDSCH Carries data with QPSK, 16QAM or 64QAMLocalized/Distributed (VRB) allocation is possible
PMCH Multicast Channel
You take LTE forward. Agilent leads the way
Uplink Feature-Physical channel-
Uplink Physical Layer CapabilityPUSCH Carries data with QPSK, 16QAM or 64QAM
Localized/Distributed (Hopping) is possible
Demodulation reference signal for PUSCH
qth Zadoff-Chu sequenceGroup (u) /Sequence (v) Hopping, Cyclic shift change by DCI, Broadcast value and PRS
PUCCH Carries ACK/NACK, CQI with BPSK, QPSK or BPSK+QPSK by Format 1,1a,1b,2,2a,2b
Demodulation reference signal for PUCCH
qth Zadoff-Chu sequenceGroup (u) /Sequence (v) HoppingCyclic shift change at every slot and symbol
PRACH uth Zadoff-Chu sequence1.25kHz subcarrier spacingFormat 0 ~ 3 (FDD), Format 4 (TDD)
Sounding reference signal Used for UL timing adjustmentAllocated at first or last symbolCyclic shift change by higher layer
You take LTE forward. Agilent leads the wayAgilent T&M
Forum
Agilent
Agilent Confidential
Page 37
Downlink FDD Resource Mapping
NsymbDL OFDM symbols (=7 OFDM symbols @ Normal CP)
Cyclic Prefix
160 2048 144 2048 144 2048 144 2048 144 2048 144 2048 144 2048 (x Ts)
1slot = 15360 Ts
P-SCH
1 frame
13 Aug 2007
10 2 3 4 5 6 10 2 3 4 5 6
0 1 2 3 4 5 6
Subframe 0
10 2 3 4 5 61 0 2 3 4 5 6
PCFICH/PHICH/PDCCH
S-SCH
PBCH
Reference Signal – (Pilot)
No TransmissionSubframe 1
You take LTE forward. Agilent leads the way
LTE uplink subframe and slot structure
CP configuration for uplink
You take LTE forward. Agilent leads the wayGroup/Prese
ntation Title
Agilent SeptemPage 39
Agilent Confidential
Page 39
Frame Structure Type (UL)Slot / Subframe / Frame- PUSCH
NsymbDL OFDM symbols (=7 OFDM symbols @ Normal CP)
Cyclic Prefix
160 2048 144 2048 144 2048 144 2048 144 2048 144 2048 144 2048 (x Ts)
1slot = 15360
10 2 3 4 5 6
Reference Signal (Demodulation)
1 slot
#0 #1 #8#2 #3 #4 #5 #6 #7 #9 #10
0#11
1#12
2#19
3#13
4#14
5#15
6#16 #17 #18 1 frame
=10 sub-frames
=10 ms
10 2 3 4 5 6
1 sub-frame=2 slots
=1 ms
13 Aug 2007
PUSCH- Physical uplink shared channel
You take LTE forward. Agilent leads the way
Uplink Frame Structure Type (FDD)PUCCH Mapping (Formats 1, 1a, 1b )
[Syms 2-4 | Every Slot]
[Syms 0,1,5,6 | Every Slot]
1
You take LTE forward. Agilent leads the way
Unlike DL, UL DM-RS
Is confined only to User
Frame Structure Type (UL) - Physical Mapping
Note 1: When no PUCCH or PUSCH is scheduled in the uplink, the eNB can request transmission of the
Sounding Reference Signal (SRS), which allows the eNB to estimate the uplink channel characteristics
Note 2: PRACH and SRS not shown for clarity
OOK, BPSK
Rotated
QPSK
You take LTE forward. Agilent leads the wayPage 42
LTE / SAE Network Identifiers 3GPP TS 23.401 / TR25.813
PLMN ID
(MCC + MNC)
eUTRAN+EPC+Terminals=EPS(Evolved Packet System)
RNTI是UE的標識,不同的RNTI在不同範圍內標識UE,例如C-RNTI在Cell內,S-RNTI在RNC內,U-
RNTI在PLMN內
. RA-RNTI (Random Access Radio Network Temporary Identifier)- is used during the some transient states.
The S-TMSI (SAE Temporary Mobile Subscriber Identity) is replacing TMSI & P-TMSI in 2G & 3G networks
The TAI is replacing the URA ID, LAI and RAI
You take LTE forward. Agilent leads the way
Basic channel access modes
Transmit
Antennas
Receive
Antennas
SISO
The Radio
Channel
MISO
Single Input Single Output
Multiple Input Single Output
(Transmit diversity)
Receive
Antennas
Transmit
Antennas
MIMO
The Radio
Channel
SIMO
Single Input Multiple Output
(Receive diversity)
Multiple Input Multiple Output
(Multiple data streams)
You take LTE forward. Agilent leads the way
MIMO principles
•Transmitting multiple data streams in the same space and time used to be called interference!
•So how does MIMO work?1. MIMO capacity gains come from taking advantage of spatial
diversity in the radio channel
2. Depending on channel conditions and noise levels, the rank (number of simultaneous streams) can be varied
3. The performance can be optimized using precoding
•These three MIMO principles can seem complex to understand particularly abstract mathematical descriptions
•But we intuitively already know these MIMO principles in the way they apply to our perception of audio
You take LTE forward. Agilent leads the wayPage 45
Understanding MIMO spatial diversity through Audio -Single Stream (Mono)
Page 45
Note, the combination of SIMO and MISO further improves
robustness but does not provide any MIMO capacity gain
since there is only one stream of data
SISO
M
MISOSIMO
M
SIMO + MISO
≠ MIMO
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 46
Understanding MIMO spatial diversity through Audio -Dual Stream (Stereo)
Page 46
Interference!
• For MIMO to work:• Must have at least as many receivers as transmitted streams
• Must have spatial separation at both transmit and receive antennas
• More transmitters enables beamforming in addition to MIMO
Interference! MIMO!
Interference!
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 47
Understanding MIMO precoding through Audio
• MIMO Precoding is a pre-emphasis technique used to improve the separation of the streams at the receiver due to unhelpful coupling in the channel
• In audio systems precoding is similar to stereo “balance”
• If the receiver is not positioned directly between the speakers the received streams will be at different levels
• Adjusting the balance at the transmitter can mitigate the problem
• Balancing requires feedback from the receiver to the transmitter
Page 47
Not enough Right
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 48
Understanding MIMO precoding through Audio
• The receiver could just amplify the right channel but in the presence of noise the corrected signal would degrade:
• Precoding the transmission as L, 5R optimizes signal recovery
Page 48
L + NL, 0.2 R + NR
L + NL, R + 5*NR
L + NL, R + NR
Problem!
Solution!
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 49
Understanding MIMO Rank adaptation through Audio
•In good radio conditions an FM stereo receiver will attempt to decode both the left and right signals (streams)
•When the noise gets too high the receiver switches to mono and the quality improves although stereo is lost
•This is the audio equivalent of rank adaptation where the number of streams is reduced under poor conditions
•Transmit matrix encoded FM stereo as L + R, L – R
•Receive (L + R) + N1, (L – R) + N2
•Since N1 and N2 are largely correlated, adding the two streams (maximum ratio combining) cancels most of the noise
Page 49
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 50
The role of channel correlation and noise in system performance
• In a ideal 2x2 system the potential capacity gain is 2x
• The actual gain depends on how easily the receiver can descramble the simultaneous transmissions – this depends on the amount of unwanted correlation and noise
• In audio systems channel correlation and noise also affects perceived stereo performance
– Spaced living room speakers - lots of correlation degrades stereo, susceptible to external noise
– Open headphones – zero correlation, good stereo but still susceptible to noise
– Closed headphones – zero correlation, minimal noise
Page 50
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 51
So what makes a good channel for MIMO?
• A perfect MIMO channel islike the closed headphones: channels 2 and 3 don’t exist
• By simple observation it follows that R0 = T0 and R1 = T1
• This is one case that creates double the capacity
• But suppose we create a simple static channel like this:
• How do we know if it will provide capacity gain?
• This requires deeper analysis
Page 51
1 0
0 1
Channel H
0.8 0.2
0.3 -0.9
Channel H
ch1
ch4
T0
T1
R0
R1
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 52
The MIMO challenge: Recovering the signal
• If all four channels are the same the original signal cannotbe recovered since R0 = R1
• R0 = T0 + T1 and R1 = T0 + T1
• But put in a phase inversion e.g. on ch3 we get:
• R0 = T0 - T1 and R1 = T1 + T0
• thus T0 = (R0 + R1)/2 and T1 = -(R0 - R1)/2
• The original signal is completely recovered even though the apparently unwanted ch2 and ch3 exist
Page 52
1 1
1 1
Channel H
1 1
-1 1
Channel H
ch1
ch4
T0
T1
R0
R1
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 53
The MIMO challenge: Recovering the signal
• So is the earlier example good or bad for MIMO?
• We can recover the original signal
• In fact any H matrix other than the unity matrix can be resolved PROVIDED there is no external or internal noise!
• So what kinds of channels are robust to noise?
•
Page 53
0.8 0.2
0.3 -0.9
Channel H
R0 = 0.8 T0 + 0.3 T1
R1 = 0.2 T0 - 0.9 T1
T0 = 1.15 R0 + 0.39 R1
T1 = 0.26 R0 - 1.03 R1
Giving:
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 54
The MIMO challenge: Recovering the signal
• The receiver can untangle the two signals because it knows the coupling coefficients, based on the reference signals
• The RS transmits a known amplitude and phase at different subcarriers and times for each MIMO antenna from which the receiver can calculate the complex channel matrix H
Page 54
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 55
The MIMO challenge: Recovering the signal
• But RS estimation is susceptible to noise
• If the H estimate is wrong the recovered signal is impaired
• Consider these equations for T0 from different channels:
• Errors in T0 recovery happen due to estimation errors in the coefficients or large coefficients amplifying noise N0 and N1
• It is possible to analyze the channel matrix H to determine the sensitivity to noise for signal recovery
Page 55
T0 = 1.15 (R0 + N0) + 0.39 (R1 + N1)
T0 = 27.3 (R0 + N0) + 16.5 (R1 + N1)
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 56
Condition Number: Measures the short term MIMO channel performance
R0 = 0.8 T0 + 0.3 T1
R1 = -0.9 T1 + 0.2 T0
0.8 0.2
0.3 -0.9
Channel H
0.8 0.3
0.2 -0.9
Channel HT
0.73 -0.11
-0.11 0.85
Channel HTH Eigenvalues
0.914
0.666
Singular values
0.957
0.815
К = Condition number
0.957 / 0.815 = 1.17
The condition number is the ratio of the singular values of HHT
The dB value of К approximates the increase in SNR required
to recover the signal
Page 56Page 56Page 56
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 57
MIMO needs better SNR than SISO
High К increases SNR requirements further
•The extra SNR required to achieve the same recovered signal quality as SISO rises as the condition number rises
Page 57Page 57Page 57
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the wayPage 58
Ped. A Channel Condition Number vs. Freq.
Page 58
Condition number and channel response across 10 MHz, 10 ms
0 dB
Taking LTE MIMO from
Standards to Starbucks
Moray Rumney 10th June 2009
You take LTE forward. Agilent leads the way
Handover
CELL_PCH
URA_PCH
CELL_DCH
UTRA_Idle
E-UTRA
RRC_CONNECTED
E-UTRA
RRC_IDLE
GSM_Idle/GPRS
Packet_Idle
GPRS Packet
transfer mode
GSM_Connected
Handover
Reselection Reselection
Reselection
Connection
establishment/release
Connection
establishment/release
Connection
establishment/release
CCO,
Reselection
CCO with
optional
NACC
CELL_FACH
CCO, Reselection
Diagram of the various UE states
Idle Mode
Cell selection
System
Information
Call/data
setup
Paging
RACH
Connected
Call/data
control
Data flowFrom 3GPP 36.331
You take LTE forward. Agilent leads the way
LTE – eHRPD HandoversCell reselection and Handover Types
IDLE
2G
CONNECTED
Connection
Establish/
release
Handover
Cell Re-selection
Optimized Handover
(eNodeB decision)
eNB
eHRPD LTE
Cell Re-selection
(UE decision)
eHRPD LTE
1
1
3
3Non-optimized Handover
(eNodeB decision)2
2 Connection
Establish/
release
You take LTE forward. Agilent leads the way
LTE Cell Re-Selection
UE Serving eNB
Broadcast neighbour cell info
Attach with Serving eNB
Initiate cell reselection
RRC release with no re-direction
Establish eHRPD session with target AN
eHRPD AN
You take LTE forward. Agilent leads the way
LRE – eHRPD Handover Architecture
• S2a provides a data plane tunnel for forwarding IP data traffic
• S101 provides a control plane tunnel for establishing an eHRPD session
You take LTE forward. Agilent leads the way
LTE – CDMA non-Optimized Handover
UE Serving eNB eHRPD AN
Broadcast neighbour cell info
Attach with Serving eNB
Configure measurement reports
Send measurement reports
Initiate handover
RRC release with re-direction to target eNB
S2a data plane tunnel
Establish data plane tunnel
Establish eHRPD session with target AN
S2a data plane tunnel
Forward IP Data traffic
You take LTE forward. Agilent leads the way
LTE – CDMA Optimized Handover
UE Serving eNBBroadcast neighbour cell info
Attach with Serving eNB
Configure measurement reports
Send measurement reports
Initiate handover
Agree handover parameters with target cell
E-UTRA Handover (rrc_conn_reconfig)
S101 control plane tunnel
S2a data plane tunnel
eHRPD AN
Forward IP data traffic
Created eHRPD session with AN
S101 control plane tunnel
S2a data plane tunnel
Establish data plane tunnel
You take LTE forward. Agilent leads the way
Agilent E6621A PXT, 8960 & IFT software
Agilent is working in collaboration with Verizon to implement the LTE – CDMA (eHRPD) Compliance (Performance) Test Plan•The plan is being implemented with Agilent IFT and operates with the E6621A PXT and 8960•The automated test package will enable Verizon to qualify LTE UE for use on their network•Agilent will make the test scripts available to UE makers to pre-qualify UE before submission to Verizon•During the development phase, Agilent is collaborating with UE vendors with leading InterRAT UE capability.
LTE-CDMA_InterRAT_Performance_Test_Plan.doc
Verizon InterRAT Compliance Test Plan
You take LTE forward. Agilent leads the way
3.1 CELL SELECTION DUE TO LTE SYSTEM LOST – WITH PREVIOUS SESSION ON TARGET EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE
3.2 CELL SELECTION DUE TO LTE SYSTEM LOST – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 AVAILABLE
3.3 CELL SELECTION DUE TO LTE SYSTEM LOST – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 NOT AVAILABLE
3.4 CELL SELECTION DUE TO LTE SYSTEM LOST – WITH PREVIOUS SESSION ON TARGET EHRPD AND NO SAVED PARTIAL HSGW CONTEXT
3.5 CELL SELECTION DUE TO LTE SYSTEM LOST – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 AVAILABLE
3.6 CELL SELECTION DUE TO LTE SYSTEM LOST – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 NOT AVAILABLE
3.7 CELL SELECTION DUE TO LTE SYSTEM LOST – WITH NO PREVIOUS SESSION ON EHRPD
3.8 CELL RESELECTION – WITH PREVIOUS SESSION ON TARGET EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE
3.9 CELL SELECTION – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 AVAILABLE
3.10 CELL RESELECTION – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 NOT AVAILABLE
3.11 CELL RESELECTION – WITH PREVIOUS SESSION ON TARGET EHRPD AND NO SAVED PARTIAL HSGW CONTEXT
3.12 CELL RESELECTION – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 AVAILABLE
3.13 CELL RESELECTION – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 NOT AVAILABLE
3.14 CELL RESELECTION – WITH NO PREVIOUS SESSION ON EHRPD
4.1 CELL SELECTION TO 1XRTT DUE TO LTE SYSTEM LOST
4.2 CELL SELECTION TO 1XRTT/HRPD DUE TO LTE SYSTEM LOST
5.1 RRC RELEASE WITH REDIRECTION AND MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON TARGET EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE
5.2 RRC RELEASE WITH REDIRECTION AND MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 AVAILABLE
5.3 RRC RELEASE WITH REDIRECTION AND MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 NOT AVAILABLE
5.4 RRC RELEASE WITH REDIRECTION AND MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON TARGET EHRPD AND NO SAVED PARTIAL HSGW CONTEXT
5.5 RRC RELEASE WITH REDIRECTION AND MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 AVAILABLE
5.6 RRC RELEASE WITH REDIRECTION AND MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 NOT AVAILABLE
5.7 RRC RELEASE WITH REDIRECTION AND MEASUREMENT GAPS SCHEDULED – – WITH NO PREVIOUS SESSION ON EHRPD
5.8 RRC RELEASE WITH REDIRECTION NO MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON TARGET EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE
5.9 RRC RELEASE WITH REDIRECTION NO MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 AVAILABLE
5.10 RRC RELEASE WITH REDIRECTION NO MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD AND PARTIAL HSGW CONTEXT AVAILABLE – A13 NOT AVAILABLE
5.11 RRC RELEASE WITH REDIRECTION NO MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON TARGET EHRPD AND NO SAVED PARTIAL HSGW CONTEXT
5.12 RRC RELEASE WITH REDIRECTION NO MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 AVAILABLE
5.13 RRC RELEASE WITH REDIRECTION NO MEASUREMENT GAPS SCHEDULED – WITH PREVIOUS SESSION ON SOURCE EHRPD WITH NO SAVED PARTIAL HSGW CONTEXT – A13 NOT AVAILABLE
5.14 RRC RELEASE WITH REDIRECTION NO MEASUREMENT GAPS SCHEDULED – – WITH NO PREVIOUS SESSION ON EHRPD
6 LTE ACTIVE TO 1XRTT/HRPD IDLE
6.1 CELL SELECTION TO 1XRTT DUE TO LTE SYSTEM LOST
6.2 CELL SELECTION TO 1XRTT/HRPD DUE TO LTE SYSTEM LOST
7 EHRPD DORMANT TO LTE IDLE
7.1 MORE PREFERRED SYSTEM RESELECTION
7.2 CELL RESELECTION
8 HRPD/1XRTT DORMANT TO LTE IDLE
8.1 MORE PREFERRED SYSTEM RESELECTION
9 LTE DATA THROUGHPUT PERFORMANCE WITH INTERRAT OPERATIONS - FUTURE
10 LTE SUPPLEMENTARY SIGNALING CONFORMANCE FOR LTE-CDMA INTERRAT CAPABLE DEVICES
10.1 RRC UE FEATURE GROUP SUPPORT
Verizon InterRAT Compliance Test Plan
You take LTE forward. Agilent leads the way
LTE - eHRPD handover demo
SERVER(s)
• SMS
• MMS
• SIP v6
• HTTP
• FTPRF
Proprietary
i/f
UE under test
8960 eHRPD cell
LAN
CLIENT
• DUT control
• IFT - test case script(s)
USB
Single DRB
SISO 10MHz channelPXT LTE cell
You take LTE forward. Agilent leads the way
LTE - eHRPD handover demo
SERVER(s)
• SMS
• MMS
• SIP v6
• HTTP
• FTPRF
Proprietary
i/f
UE under test
PXT LTE cell
8960 eHRPD cell
LAN
CLIENT
• DUT control
• IFT - test case script(s)
USB
Step 1: setup of an LTE end to end IP connection
You take LTE forward. Agilent leads the way
LTE - eHRPD handover demo
SERVER(s)
• SMS
• MMS
• SIP v6
• HTTP
• FTPRF
Proprietary
i/f
UE under test
8960 eHRPD cell
LAN
CLIENT
• DUT control
• IFT - test case script(s)
USB
Step 2: verification of LTE end to end IP connection
PXT LTE cell
You take LTE forward. Agilent leads the way
LTE - eHRPD handover demo
SERVER(s)
• SMS
• MMS
• SIP v6
• HTTP
• FTPRF
Proprietary
i/f
UE under test
8960 eHRPD cell
LAN
CLIENT
• DUT control
• IFT - test case script(s)
USB
Step 3: handover to eHRPD serving cell
PXT LTE cell
You take LTE forward. Agilent leads the way
LTE - eHRPD handover demo
SERVER(s)
• SMS
• MMS
• SIP v6
• HTTP
• FTPRF
Proprietary
i/f
UE under test
8960 eHRPD cell
LAN
CLIENT
• DUT control
• IFT - test case script(s)
USB
Step 4: verification of e2e IP in eHRPD serving cell
PXT LTE cell
You take LTE forward. Agilent leads the way
Verizon Wireless LTE-eHRPD Inter-RATCompliance Testing with IFT
You take LTE forward. Agilent leads the way
What is LTE voice ?
Through LTE network?
Through legacy 2G/3G?
You take LTE forward. Agilent leads the way
Support for Voice
• 3GPPs long term solution for voice is to use VoIP and an IMS based core network
• It will take time for all networks to support this
• For networks which do not support IMS several technologies are being considered, namely:-
– CSFB (Circuit Switched Fall Back)
– SVLTE (Simultaneous Voice and Data LTE)
– VoLGA (Voice over LTE Generic Access)
• VoLGA involves sending the CS data over an LTE PS bearer- this is not discussed further in this paper
• SRVCC will be natural in 3GPP through IMS ,also named as “Voice over LTE “,” VoLTE” strongly supported by GSMA
SRVCC : Single Radio Voice Call Continuity
You take LTE forward. Agilent leads the way
Circuit switched Fallback to 1xRTT
1xCSFB UE
1xRTT CS Access
1xRTT
MSC
1xCS WS
MME
1xCSFB UE
E-UTRANServing/PD
N GW
A1
A1
S102
S1-U
S11
S102 SGi
S1-MME
cdma Network
LTE Network
Tunneled 1xRTT messages*CS Fallback to 1xRTT and IMS-Based services shall be able to co-exist in the same operator’s network
You take LTE forward. Agilent leads the way
SVLTE
CDMA BTS
BSC/ MSC
E-UTRAN MME
CS Core Network
IP
LTE
Data
CDMA
Voice
• Supports simultaneous voice and data
• UE has 2 complete radios
• Voice provided through CDMA
• Data provided via LTE link
• No interworking required
• SVLTE may be the preferred choice for CS voice on CDMA/LTE networks
You take LTE forward. Agilent leads the way
CSFB (Requires S102 control plane tunnel)
• Requires 2 baseband ICs (LTE + CDMA)
• Some opportunity to share RF resources
• Significant additional protocol complexity
• Control plane tunnel required for establishing pre-registration with the CDMA cell (via LTE signaling)
• More complex than 2G/3G CSFB due to the lack of interworking at the core network level
• CSFB may be the preferred choice for CS voice on 2G/3G/LTE networks
UEServing eNB
Broadcast neighbour cell info
Attach with Serving eNB
Configure measurement reports
Send measurement reports
Tunnel paging info from CDMA BTS to LTE enBRRC release with re-direction to CDMA BTS
S102control plane tunnel
CDMA BTS
register UE with 1x cdma2000 base
station
S102 control plane tunnel
Establish voice call between UE and CDMA cell
Page UE
You take LTE forward. Agilent leads the way
Circuit switched Fallback to GERAN/UTRAN
LTE/UMTS UE
UTRAN
GERAN
E-UTRAN
SGSN
MME
MSC server
LTE/UMTS UE
S1-MMELTE-Uu
Uu
Um
Lu-PS
Gb Gs
Lu-CS
SGs
S
3
A
UMTS Network
LTE Network
*CS Fallback and IMS-Based services shall be able to co-exist in the same operator’s network
You take LTE forward. Agilent leads the way
Single radio voice Call Continuity (SRVCC)
• The continuity of voice when a customer moves from LTE to where LTE coverage is not available
• In 2009 ,the consortium includes AT&T,Orange, Verizon,Vodafone,Alcatel-Lucent,Ericsson ,and other key players announced “One Voice” initiative
• GSMA VoLTE initiative was formally announced at MWC in 2010
• It is voice over IMS network
• SR-VCC is in 3GPP TS 23.216 in R9
You take LTE forward. Agilent leads the way
Single radio voice Call Continuity (SRVCC)
LTE/UMTS UE
GERAN/UTRAN
E-UTRAN
SGSN
MME
MSC server
LTE/UMTS UE
S1-MME
LTE-Uu
Uu/Um
Gb/Lu-PS
Lu-CS/A
SGi
S3
IMS
Serving/
PDN GW
HSS
S1-U
S6a
Sv
S11
Bearer path before HO
Bearer path after HO
SIP Signaling path before HO
You take LTE forward. Agilent leads the wayPage 81
Thanks!