Southern Methodist University

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Southern Methodist University EETS 8315 /
TC752-N Advanced Topics in Wireless
Communications Spring 2005 http//www.seas.smu.edu
/eets/8315 Lecture 9 UMTS Performance
Instructor Dr. Hossam Hmimy, Ericsson
Inc. hossam.hmimy_at_engr.smu.edu [phone]
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outline

• Link budget ch 8
• Interference margin, FF margin, SHO gain see also
  table 12.4,
• Calculate load UL/DL
• Soft capacity pp 205
• Gain from fast PC pp232
• Performance
• HSDPA
• Compare HSDPA/EVDO

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UL power and interference

• Pi UL Received power for one connection

Own cell Interference
4
UL loading

• Processing Gain (spreading Factor) Rchip /
  Rinfo
• g is the SIR own power / ( all power except
  own)
• AF is the activity factor.

Load per connection
Received power
Received Interference
Impact of other cells
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UL Noise rise and pole capacity

• Npole is at 100 load
• Assume all connections have same SIR and AF, for
  h UL100,

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DL power and interference

• P Node-B total power
• pi DL Transmitted power for one connection

Other cell interference
Own cell Interference
Total interference
Own cell interference
PLi
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DL TX Power calculation

• Orthogonality factor a (1 orthogonal, 0 not ?
  interference)

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DL Transmitted power calculation

• Orthogonality factor a (1 orthogonal, 0 not ?
  interference)

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DL Noise power

• P Node-B transmitted power at loaded system (
  for N users and thermal noise ? total
  interference )
• Pnoise is NodeB TX power at no load
• P-Pnoise Power needed for N users

Power received at no load
Power Tx at no load
Own cell Interference
PLi
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DL Loading
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DL Loading
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Examples Section 12.3.1.2 pp 362-363

• UL ( input)
• 64kbps
• Eb/No 2dB
• F 0.65
• h UL 60

• DL (input)
• 384kbps
• Eb/No 5dB
• F 0.65
• h DL 80
• a .5
• CCCH OH 15

• UL (results)
• Npole 23.5
• N 14.1
• Data rate 904kbps

• DL ( results)
• Npole 2.7
• N 2.1
• Data rate 718kbps

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UL linkbudget

• Well known

Noise rise 3 dB
PC margin 2 dB
Gain 17 dB
margin 8 dB
UE TX power 21 dBm
losses 4 dB
BS rx seni -112.16 dB
PL133.16dB
2dB 3dB ..
Thermal noise -174dBm/Hz
Noise figure UE ?10dB BS ? 3dB
64000 Hz 384000 Hz ..
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DL linkbudget
Noise rise 3 dB? N1.35
PC margin 2 dB
Gain 17 dB
margin 8 dB
losses 4 dB
Ptx 11 dBm
BS rx seni -103.16 dB
PL114.16dB
2dB 5dB ..
Thermal noise -174dBm/Hz
Noise figure UE ?10dB BS ? 3dB
64000 Hz 384000 Hz ..
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Coverage, Capacity and Service Flexibility

• Soft capacity gives flexibility between coverage,
  capacity and quality

Quality
Users
Coverage vs. capacity
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Uplink Capacity and Coverage

• Uplink interference level dB above noise as a
  function of the load

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10
8
Interference increase ?I dB
6
4
2
0
0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
Relative load M/Msystem_up
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Performance in trials table 12.15 pp 385

• Eb/No
• UL
• AMR 4.5- 5.9 dB (4.5dB)
• CS64 2.1-3.5 dB (2.0dB)
• 128 (1.5dB)
• 384 (2.0dB)
• DL
• AMR 6.1-7.4dB (6.7dB)
• CSD 64 4.6-7.9 (5.3dB)
• 128 (5.3dB)
• 384 2.6- 4.4dB (5.2dB)

• Pole capacity
• UL
• AMR 72-101
• CS64 video 16-23
• DL
• AMR 70-94
• CSD 64 7-14
• 384 2.5-3.9

3GPP performance requirement Multipath 3km/Hr,
1 BLER
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Example of Initial Radio Network Deployment

• Example of coverage and capacity for
• 64 kbps circuit data
• 128 kbps best effort packet data
• Speech

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Radio network design with a design tool

• Example of information
• given by the design tool
• Detailed coverage and traffic for each RBS and
  service
• Estimated load uplink and downlink
• Handover areas
• Interference levels

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Example Ec/Io for pilot
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Code planning
512 unique codes
By having codes from different code groups next
to each other,UE current consumption is reduced
64 groups with 8 codes each
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HSDPA
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Packet Data in WCDMA

• In R99/4, there are 3 DL channels for Packet data
• DCH Dedicated , fixed SF, reserve the code
  tree, power controlled
• DSCH shared, operated with DCH, dynamic varying
  SF on 10 msec frame basis. Fast power control,
  no SHO
• FACH Forward access carried on S-CCPCH, high
  power, fixed SF, no SHO, no PC

Max cell power
HS power
Admission control threshold
DL Power
Non-HS power
Time
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HSDPA Protocol Stack, data
IP
IP relay
IP relay
IP
GTP-U
PDCP
GTP-U
GTP-U
GTP-U
PDCP
UDP
UDP
UDP
UDP
RLC
IP
IP
IP
IP
RLC
MAC-d
L2
AAL5/2
L2
AAL5/2
MAC-hs
ATM
ATM
FP
MAC-hs
FP
Phy.
Phy.
Phy.
Phy.
Phy.
Phy.
Phy.
Phy.
Iu
RNC
Node B
UE
GGSN
SGSN
UTRAN
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• MAC-hs
• Handle ARQ
• Priority handling
• Scheduling ( vendor specific)

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HSDPA

• Two channels introduces HS-DSCH and HS-SCCH
• HS-DSCH (HS- DL shared channel)
• Supports link adaptation, hybrid ARQ and
  scheduling
• Always associated with a DPCH
• Never in soft handover
• Mapped to one or several channelization codes of
  SF16 ( up to 15).
•  HS-SCCH ( HS- shared control channel)
• Control signaling to the mobile(s) scheduled in a
  2 ms interval
• One (or a few) HS-SCCH per cell
• SF128

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• HS-DPCCH ( UL DPCCH)
• Ack/NAK
• DL Channel Quality indicator transport block
  size, modulation, codes.

ACK/NAK
CQI feedback
2560 chips
Pilot
TFCI
FBI
TPC



Slot 0

Slot 2









f
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HSDPA

• HS-SCCH channel structure
• of chips per slot Tslot 3.84Mcps2/3sec 2560
  chips, SF 128
• First slot (part) Time critical Info about
  Modulation, Codes
• 2nd part ( slot 2, 3) CRC, ARQ process, retx
  indicator.

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HSDPA ..

• HS-DSCH is carried by the physical channel
  HS-PDSCH
• Each HS-PDSCH corresponds to one Channalization
  code ( out of 15)
• Data rate M102k / (2/3 msec) 30M2(k-1),
  k4, M 2 QPSK, 4 16QAM.
• Data rate M102k / (2/3 msec)
• 30M2(k-1)
• QPSK ? 480kbps
• 16QAM ? 960kbps

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HSDPA

• Possible max. data rates with QPSK/ 16QAM
• 5 codes ? 4.8 Mbps (3.6 Mbps)
• 10 codes ? 9.6 Mbps (7.3 Mbps)
• 15 codes ? 14.4 Mbps (10 Mbps, 14 Mbps)

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Terminals
Soft IR Soft IR Soft IR Soft IR Soft IR Soft soft
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What is High Speed Downlink Packet Access (HSDPA)?

• Best-effort packet data
• Peak data rate 14 Mbit/s
• Reduced roundtrip delays
• Increased capacity
• An integral part of WCDMA Rel5 since March 2002
• Mobility, simultaneous voice services, no need
  for a separate carrier
• New HS-DSCH transport channel
• NO PC
• In WCDMA PC dynamic 20dB DL, 70dB UL
• In HSDPA ? Link adaptation
• Fixed SF
• WCDMA uses variable to match the different bearer
  data rates
• HSDPA ? HARQ multicode strong turbo coding

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Basic Principles
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Shared Channel Transmission

• A set of radio resources dynamically shared among
  multiple users, primarily in the time domain
• Efficient code utilization
• Efficient power utilization

TTI
Shared channelization codes
User 1
User 2
User 3
User 4
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Short 2 ms TTI (TTI Transmission Time Interval)

• Reduced air-interface delay
• Improved end-user performance
• Required by TCP at high data rates
• Necessary to benefit from other HS-DSCH features
• Fast Link Adaptation
• Fast hybrid ARQ with soft combining
• Fast Channel-dependent Scheduling

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Fast Link Adaptation

• Adjust transmission parameters to match
  instantaneous channel conditions
• Path loss and shadowing
• Interference variations
• Fast multi-path fading
• HS-DSCH Rate control (constant power)
• Adaptive coding
• Adaptive modulation
• Adapt on 2 ms TTI basis ? fast
• Release 99 Power control (constant rate)

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Fast Link Adaptation Higher Order Modulation

• 16QAM allows for twice the data rate compared to
  QPSK (used in R99)
• 16QAM more sensitive to interference ? useful
  mainly in good channel conditions (high C/I)
• Close to cell site
• Low speed
• Little or no dispersion
• Channel Coding
• Only Turbo code rate 1/3
• 2 ms interleaving.
• Followed by HARQ. Support IR or soft combining.

2 bits
4 bits
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Fast Hybrid ARQ with Soft Combining

• Rapid retransmissions of erroneous data
• Hybrid ARQ protocol terminated in Node B? short
  RTT (typical example 12 ms)
• Soft combining in UE of multiple transmission
  attempts? reduced error rates for retransmissions

P1,1
P1,2
P2,1
P2,2
P3,1
NACK
ACK
NACK
ACK
ACK
P1,2
P2,2


P1,1
P2,1
P1,1
P2,1
P3,1
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Fast Channel-dependent Scheduling

• Implemented in Node-B
• Quality feedback
• UE capability
• Resource availability
• Buffer status
• QoS and priority
• Scheduling which UE to transmit to at a given
  time instant
• Basic idea transmit at fading peaks
• May lead to large variations in data rate between
  users
• Tradeoff fairness vs cell throughput

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Fast Channel-dependent Scheduling (II)

• Examples of scheduling algorithms
• 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

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HSDPA Operation procedure

• Scheduler evaluate ch condition and data pending
  for each user
• Node-B identifies HS-DSCH parameters for ready UE
• Node-B transmit the HS-SCCH 2 slots before the
  HS-DSCH TTI
• UE monitors the HS-SCCH. Once 1st part decoded,
  then decode rest of HS_SCCH and buffer the needed
  codes
• Decoding the 2nd part of HS-SCCH ? UE knows the
  ARQ process need to be combined with buffered
  data
• UE sends UL ACK/NACK on HS-DPCCH
• UE use same HS-SCCH while receives consecutive
  TTIs

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(No Transcript)
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Traffic and spectrum utilization comparison

• Cdma2000 1xRTT and 1x EV-DO
• do not share the same frequency ? inefficient
  utilization of spectrum.
• WCDMA
• Voice and data share same frequency and air
  interface ? efficient traffic and capacity
  utilization.
• Flexible with mixed services.

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Performance comparison

• Within 5MHz deployment.
• Capacity derived from multicell system level
  simulations
• NRT packet data

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Network comparison

• GERAN/WCDMA

Cdma2000 1x EV-DO does not use R-P
interface Needs 1x EV-DO access router in CN
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Evolution path

• cdmaOne, TDMA, GSM, PDC

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Migration path for TDMA operators
GERAN/WCDMA

• cdma2000

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CDMA2000 EV-DO

• Forward link ( figure shows 16 frames 426.67
  msec)
• Frame 26.6 msec with 16 slots ( slot time 1.67
  msec 2048 chips)
• CCH on ½ frames ( 8 slots)

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CDMA2000 EV-DO

• Forward link Modulation
• QPSK up to ? 1.229Mbps
• 8PSK up to ? 1.843 Mbps
• 16 QAM up to ? 2.457 Mbps

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CDMA2000 EV-DO

• Reverse link
• 16 slots per frame. Slot 1.67msec
• Access channel
• Pilot channel
• Data channel
• Traffic channel
• Pilot channel
• ACK channel
• Data channel
• MAC channel (Reverse rate indicator RRI, data
  rate control DRC)
• Uses SHO

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CDMA2000 EVDV forward

• Turbo code rate 1/5
• Use up to 28 32 chip walsh codes to increase
  data rate

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Cdma2000 EVDV reverse

• packet data channel
• 10 m sec frame
• Turbo 1/5
• BPSK, QPSK, 8PSK
• Max BR RC7 QPSK 1.538Mbps, 8PSK 1.845mbps

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Reading assignment

• Ch8
• 8.2.1,
• 8.2.2,
• 8.6
• Ch 11
• Ch 12
• 12.3.1.2,
• 12.4.3,
• 12.5