Post on 07-Sep-2018
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3G Evolution –HSPA and LTE for Mobile Broadband
Dr Stefan ParkvallSenior Specialist, Adaptive Radio AccessEricsson Research
Ericsson Internal 2008-02-293
More Than 400* HSPA Devices!
203 HSPA phones, media players, camera (50%)161 PC with embedded HSPA, PC cards, USB modems (40%)39 wireless routers (10%)
*Commercially launched as of August 2007
Ericsson Internal 2008-02-295
Trend – Data is overtaking Voice
Data is overtaking voice......but previs cellular systems designed primarily for voice
Source: NetQB
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sep-06 okt-06 nov-06 dec-06 jan-07 feb-07 mar-07 apr-07 maj-07 jun-07 jul-07 aug-07 sep-07 okt-07 nov-07 dec-07
GBi
t/RN
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# R
NCs
Sum of Meas RNCs Sum of Total traffic (GBit/RNC/h) Sum of Speech traffic (GBit/RNC/h)Sum of Packet (DCH+HS) traffic (GBit/RNC/h) Sum of DCH Packet traffic (GBit/RNC/h) Sum of HS Packet traffic (GBit/RNC/h)Sum of CS64 traffic (GBit/RNC/h) Sum of Others traffic (GBit/RNC/h)
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Ctr l + Shi f t + E
PacketPacket
VoiceVoice
WCDMA & HSPA world average
Ericsson Internal 2008-02-296
HSPA and LTE = Mobile Broadband
HSPA – High-Speed Packet Access– Evolution of 3G/WCDMA – Gradually improved performance at a low additional cost– Data rates up to ~20 Mbit/s in 5 MHz
””4G4G””LTELTE LTE AdvancedLTE Advanced
R99 Rel4 Rel5 Rel6 Rel7 Rel8
HSPAHSPAWCDMAWCDMA HSPA evolutionHSPA evolutionHSDPAHSDPA
Rel10
LTE – Long-Term Evolution– Significantly improved performance in a wide range of spectrum allocations– Data rates up to ~300 Mbit/s in 20 MHz– First step towards IMT-Advanced (”4G”)
Different systems – but many basic principles are similar!
Ericsson Internal 2008-02-297
Wireless vs Wireline
Wireless seems simple…
∇×H
∇⋅D = ρ
∇⋅B = 0
∇×E = - ∂B∂t
= J + ∂D∂t
…so what’s the problem?
Ericsson Internal 2008-02-298
Radio Channels and Packet Data
Radio channel quality varies...– ...distance to base station– ... random variations in the
environment
Traffic pattern varies...– ...user behavior– ...server load
Adapt to and exploit channel and traffic variations!
Ericsson Internal 2008-02-299
Rate Control
Reliable reception requires a certain Eb/N0
How to control Eb?– Eb = P•T
Cha
nnel
Q
ualit
y
TxP
ower
Dat
a R
ate
Power Control
Dat
a R
ate
Cha
nnel
Q
ualit
y
TxP
ower
Rate Control
Rate control more efficient than power control!
Varying instantaneous data rate acceptable for packet-data services– Rapid – tracks fast fading
Ericsson Internal 2008-02-2910
Rate Control
Data rate controlled through...
...different channel coding rates– Advantageous channel conditions high code rate– Code rates from 1/3 to ~1
...different modulation schemes– Advantageous channel conditions higher-order modulation
...different multi-antenna schemes
QPSK 16QAM 64QAM
Ericsson Internal 2008-02-2911
Shared-Channel Transmission
Dedicated channel– User resources assigned
at ”call setup”– Independent of
instantaneous traffic situation
Shared channel– Dynamic sharing of
common rerouce– Adapts to instantaneous
traffic situation
Ericsson Internal 2008-02-2912
Channel-dependent Scheduling
Scheduling determines at each time instant…– …to whom to assign the shared channel– …which data rate to use
Basic idea: transmit at fading peaks– May lead to large variations in data rate between users– Tradeoff: fairness vs cell throughput
Cha
nnel
Qua
lity User #1
User #2
User #3
Time#1 #3 #2 #3 #1
Effective channel variations seen by the base station
Ericsson Internal 2008-02-2913
Channel-dependent Scheduling
Round Robin (RR)– Cyclically assign the channel to users without
taking channel conditions into account– Simple but poor performance
Max C/I– Assign the channel to the user with the best
channel quality– High system throughput but not fair
Proportional Fair (PF)– Assign the channel to the user with the best
relative channel quality– High throughput, fair
Rad
io L
ink
Qua
lity
Time
Rad
io L
ink
Qua
lity
Time
Rad
io L
ink
Qua
lity
Time
Ericsson Internal 2008-02-2914
data1data2data3data4
TimeFrequency
User #1 scheduled
User #2 scheduled
1 ms
180 kHz
Time-frequency fading, user #1
Time-frequency fading, user #2
Channel-dependent Scheduling
HSPA – channel-dependent scheduling in time-domain onlyLTE – channel-dependent scheduling in time and frequency domains
Ericsson Internal 2008-02-2915
Channel Quality Indication
Scheduling and rate control adapts to channel variations
Problem: need channel knowledge at the base stationSolution: terminals transmit channel-quality reports to base station
Reporting rate configurable– HSPA – reports as often as every 2 ms– LTE – reprots as often as every 1 ms
Ericsson Internal 2008-02-2916
Hybrid ARQ with Soft Combining
Retransmsision of erroneously received packets– Fast no disturbance of TCP behavior
Soft combining of multiple transmission attempts– Soft combining improved performance
NAK
ACK
NACK
ACK
ACK
+ +
Transmitter
Receiver
P1,1 P1,2 P2,1 P2,2 P3,1
P1,1 P1,1 P2,1 P2,2 P3,1
P1,2 P2,2
Ericsson Internal 2008-02-2917
R=3/4
redundancy version 1
Initial transmission
Transmitted bits
Bits input to decoder
Resulting code rate
Accumulated energy
Eb
CRC insertion,Turbo coding
Data
Puncturing to• generate different redundancy versions
• match the number of coded bits to the channel
redundancy version 2
R=3/8
First retransmission
2Eb
redundancy version 3
R=1/4
Second retransmission
3Eb
Hybrid ARQ with Soft Combining
Incremental redundancy
R=1/4
Third retransmission
redundancy version 1
4Eb
Ericsson Internal 2008-02-2918
Basic Principles – Summary
Shared channel transmission
Channel-dependent scheduling
Rate control
Hybrid-ARQ with soft combining
Ericsson Internal 2008-02-2919
Summary
Adapt to and exploit– variations in radio channel quality– variations in the traffic pattern
…instead of combating them!
Traffic pattern is time varying
Radio channel quality is time varying
Ericsson Internal 2008-02-2921
History
NMT, ...NMT, ...Analog, speechAnalog, speech
1980 1990 2000 2010
GSM, ...GSM, ...Digital, speech and lowDigital, speech and low--rate datarate data
HighHigh--speed data speed data (up to ~20 Mbps)(up to ~20 Mbps)
WCDMA/HSPAWCDMA/HSPA
20 MHz
5 MHz
200 kHz
HighHigh--speed data speed data (up to 300 Mbps)(up to 300 Mbps)
LTELTE
30 kHz
Research and standardization
Research and standardization
Research and standardization
Ericsson Internal 2008-02-2922
””4G4G””
3G Evolution
R99 Rel4 Rel5 Rel6 Rel7 Rel8
LTELTE
HSPAHSPAWCDMAWCDMA HSPA evolutionHSPA evolutionHSDPAHSDPA
HSPA evolution– gradually improved performance at a low additional cost
in 5MHz spectrum allocation
LTE– significantly improved performance in a wide range of spectrum
allocations– further evolved into IMT-Advanced
LTE AdvancedLTE Advanced
Rel10
1999 2002 2005 2007 2008
Ericsson Internal 2008-02-2923
PCG(Project coordination
group)
TSG GERAN(GSM EDGE
Radio Access Network)
TSG RAN(Radio Access Network)
WG2Radio Layer 2 &
Layer 3 RR
WG1Radio Layer 1
WG3Iub, Iuc, Iur &
UTRAN GSM Req.
WG4Radio Performance& Protocol Aspects.
WG2Protocol aspects
WG1Radio Aspects
WG3Terminal testing
TSG SA(Services &
System Aspects)
WG2Architecture
WG1Services
WG3Security
WG4Codec
TSG CT(Core Network &
Terminals)
WG3Interworking withExternal Networks
WG1MM/CC/SM (Iu)
WG4MAP/GTP/BCH/SS
WG5OSA
Open Services Access
WG5Mobile Terminal
Conformance Test
WG5Telecom
Management
WG6Smart Card
Application Aspects
3GPP
International organization– Vendors and operators co-operate– Develop specifications for GSM, WCDMA/HSPA, LTE
Ericsson Internal 2008-02-2924
Standardization – a Flying Circus?
RAN1 meetings held ~8 times a year– Meetings run from Monday to Friday– Held in various countries in Europe, North America, and Asia
Meeting schedule 2007– January 15-19, Sorrento, Italy– February 12-16, St Louis, USA– March 26-30, St Juliens, Malta– April 17-20, Beijing, China– May 7-11, Kobe, Japan– June 25-29, Orlando, USA– August 20-24, Athens, Greece– October 8-12, Shanghai China– November 5-9, Seoul Korea
Ericsson Internal 2008-02-2925
Typical RAN1 Meeting
Approx 200 delegates attending and ~550 documents submitted...Number of Contributions per Agenda Item
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