LTE TechnologyPerofrmance Evaluation

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ITU/BDT Arab Regional Workshop on “ 4G Wireless Systems” - Tunis ia 2010

“4G Wireless Systems”LTE Technology

Session 5 : LTE

Technology Perofrmance

Speakers M.

Lazhar BELHOUCHET.

Date 27 – 29 January 2010

www.cert.tn1 LTE Technology Perofrmance Evaluation




Agenda

– Frequency Bands and Typical deployment areas

– Layer 1 Peak

Bit

Rates

– Terminal Categories

– Reference Sensitivity

– Link

Budgets – Propagation model

–

– Downlink link budgets

– Comparison between

GSM/HSPA/LTE

– Latency

– LTE Refarming to GSM Spectrum

www.cert.tn2

– Capacity Dimensioning

LTE Technology Perofrmance Evaluation




Introduction

• Performance evaluation : LTE capabilities from the end user’s

and from

the

o erator’s

oint

of

view

• The operator is interested in the network efficiency:

– how many customers can be served,

– how much

data

can

be

provided

and

how

many

base

station

sites

are

required.

• e en user app cat on per ormance epen s on :

– available bit rate,

–

– seamless mobility







Frequency Bands : Typical deployment areas

• Europe:

– Band 7:The

2.6

GHz

auctions

have

been

running

in

a few

countries

during

2007

and

2008, and continue during 2009/2010.

– Band 8:is currently used mostly by GSM. The band is attractive from a coverage

point of view due to the lower propagation losses. The band can be reused for LTE

or

for

HSPA. – Band 3: is also used by GSM, but in many cases Band 3 is not as heavily used by

GSM as Band 8. That makes refarming for LTE simpler.

– Digital dividend

• USA:

Bands

4,

12,

13,

14

and

17.

Bands

2

and

5

can

be

used

for

LTE

refarming.• Japan : Bands 1, 9, 11 and 18.

• LTE deployments globally will use several different frequency bands from the

start.





LTE Technolo Perofrmance Evaluation

PERFORMANCE

EVALUATION





Layer 1 Peak Bit Rates

sSubCarrier of Number Hz

bits

ms

SubFrame per symbolsof Number s Mbratebit Peak *)(*

1]/[ =

• control and reference signal overheads:

– PDCCH: takes one symbol out of 14 symbols. That is the minimum possible PDCCH

=. . .

– Downlink Reference

Signals

(RS)

depend

on

the

antenna

configuration

:Single

stream transmission uses 2 RS out of 14 in every 3rd sub‐carrier, 2 × 2 MIMO 4

. . . .

– Other downlink symbols Overhead: synchronization signal, PBCH, PCFICH, and one

group

of

PHICH.

The

overhead

depends

on

the

BW

ranging

from

below

1%

at

20

. .

– Uplink reference signals take 1 symbol out of 7 symbols resulting in an overhead of

14.3% = 1/7.





Layer 1 Peak Bit Rates – Cont.

BW RB/Sub‐carriers

Modulation

and coding

Bits/

symbol

MIMO usage 1.4 MHz

6/72

3.0 MHz

15/180

5.0 MHz

25/300

10 MHz

50/600

15 MHz

75/900

20 MHz

100/1200

QPSK 1/2 1 Single stream 0.9 2.2 3.6 7.2 10.8 14.4

16QAM 1/2 2 Single stream 1.7 4.3 7.2 14.4 21.6 28.8


64QAM 3/4 4.5 Single stream 3.9 9.7 16.2 32.4 48.6 64.8


64QAM 3/4 9 2 × 2 MIMO 7.8 19.4 32.4 64.8 97.2 129.6

64QAM 1 1 12 2 × 2 MIMO 10.4 25.9 43.2 86.4 129.6 172.8

64QAM 1/1 24 4 × 4 MIMO 20.7 51.8 86.4 172.8 259.2 345.6

Downlink eak bit rates Mb s





Layer 1 Peak Bit Rates – Cont.

BW RB/Sub‐carriers

and coding symbol

.

6/72

.

15/180

.

25/300

50/600

75/900

100/1200

QPSK 1/2 1 Single stream 0.9 2.2 3.6 7.2 10.8 14.4

16QAM

1/2 2 Single

stream 1.7 4.3 7.2 14.4 21.6 28.816QAM 3/4 3 Single stream 2.6 6.5 10.8 21.6 32.4 43.2

. . . . . .

64QAM 3/4 4.5 Single stream 3.9 9.7 16.2 32.4 48.6 64.8

64QAM

1/1 6 Single

stream 5.2 13.0 21.6 43.2 64.8 86.4

Uplink peak bit rates (Mbps)





Terminal Categories

Category 1 Category 2 Category 3 Category 4 Category 5

Peak rate downlink (approximately) 10 Mbps 50 Mbps 100 Mbps 150 Mbps 300 Mbps

Peak rate uplink (approximately) 5 Mbps 25 Mbps 50 Mbps 50 Mbps 75 Mbps

Max bits received within TTI 10 296 51 024 102 048 149 776 299 552

Max bits transmitted within TTI 5 160 25 456 51 024 51 024 75 376

RF bandwidth 20 MHz 20 MHz 20 MHz 20 MHz 20 MHz

Modulation uplink 16QAM 16QAM 16QAM 16QAM 64QAM

Receiver

diversity Yes Yes Yes Yes YesMIMO downlink Optional 2 × 2 2 × 2 2 × 2 4 × 4





Reference Sensitivity

• The reference sensitivity

level is the

minimum

mean

• kTB :thermal noise level , in units of

dBm, in

the

specified

bandwidth

(B),

received signal strength

applied to antenna ports at

• NF :noise figure for the receiver,

• SINR is the signal to interference plus

which

there

is

sufficient

SINR

for the specified modulation

modulation and

coding

scheme,

• IM is the implementation margin

throughput requirement of

95% of

the

maximum

• −3 dB represents the diversity gain.

possible.)(3Re dBm IM SINR NF KTB fSens −+++=





Reference Sensitivity

‐70.00

E‐UTRA reference sensitivity

‐85.00

‐80.00

‐75.00

‐100.00

‐95.00

‐90.00 d B m

‐110.00

‐105.00

1.4 3 5 10 15 20

QPSK 1/8 QPSK 1/5 QPSK 1/4 QPSK 1/3 QPSK 1/2

QPSK 2/3 QPSK 3/4 QPSK 4/5 16QAM 1/2 16QAM 2/3

16QAM 3/4 16QAM 4/5 64QAM 2/3 64QAM 3/4 64QAM 4/5





Link Budgets

• The link budget calculations estimate the maximum allowed

si nal attenuation

between

the

mobile

and

the

base

station

antenna. The maximum path loss allows the maximum cell

range to be estimated with a suitable propagation model.

• The cell

range

gives

the

number

of

base

station

sites

required

to cover the target geographical area.


E d i t e

d b y F ox i t R e a d er

C o p y

r i gh t ( C ) b y F ox i t C or p

or a t i on ,2 0 0 5 -2 0 0 9

F or E

v al u a t i on Onl .




Link Budgets ‐ Propagation model

• A propagation model describes the average signal

ro a ation

and it converts

the

maximum

allowed

propagation loss to the maximum cell range.

• It depends on:

– Environment : urban,

rural,

dense

urban,

suburban,

open,

forest,

sea…

– Distance

– Frequency

– atmospheric conditions

–

• Examples : Free space, Walfish–Ikegami, Okumura–Hata,

Lon le –Rice Lee Youn


E d i t e


C o p y


or a t i on ,2 0 0 5 -2 0 0 9

F or E





Link Budgets ‐ Propagation model –Cont.

• Hata Model for Urban Areas:

**** −−−=

• For small or medium sized city,

..... B H B

*** −−=

• For large cities,

−**

⎩⎨

≤−=

1500200,97.42))*75.11(log(*2.3

...

f if hC

M

H p

Parameters Unit Significance Parameters Unit Significance

Lu dB Path loss in Urban Areas f MHz Frequency of Transmission

hB m Height of base station Antenna CH dB Antenna height correction factor

hM m Height of mobile station Antenna d km Distance between Base station and MS





Link Budgets ‐ Propagation model –Cont.

• Coverage

evaluation

will

be

based

on

the

the

umura– a a propaga on mo e w e

parameters shown below:

Urban indoor Suburban indoor Rural outdoor Rural outdoor fixed

Base station antenna height (m) 30 50 80 80

Mobile antenna height (m) 1.5 1.5 1.5 5

Mobile antenna gain (dBi) 0 0 0 0

Slow fading standard deviation (dB) 8 8 8 8

Location probability 95% 95% 95% 95%

Correction factor dB 0 −5 −15 −15

Indoor loss (dB) 20 15 0 0

Slow fading margin (dB) 8.8 8.8 8.8 8.8


E d i t e


C o p y


or a t i on ,2 0 0 5 -2 0 0 9

F or E





Uplink link budgets

GSM voice HSPA LTE

Data rate (kbps) 12.2 64 64

Transmitter – UE

Source :

LTE for UMTS –a Max tx power (dBm) 33 23 23

b Tx antenna gain (dBi) 0 0 0

c Body loss (dB) 3 0 0

d EIRP (dBm) 30 23 23

OFDMA and SC-FDMA

Based Radio AccessHarri Holma and Antti Toskala

Receiver – BTS/Node B/eNB

e Node B noise figure (dB) – 2 2

f Thermal noise (dB) – ‐108.2 ‐118.4

Receiver noise dBm – ‐106.2 ‐116.4

h SINR (dB) – ‐17.3 ‐7

i Receiver sensitivity ‐114 ‐123.4 ‐123.4

j Interference margin (dB) 0 3 1

l Rx antenna gain (dBi) 18 18 18

m Fast fade margin (dB) 0 1.8 0

n Soft handover gain (dB) 0 2 0


ax mum pat oss . .

E d i t e


C o p y


or a t i on ,2 0 0 5 -2 0 0 9

F or E





Downlink link budgets

Downlink GSM voice HSPA LTE

Data rate (kbps) 12.2 1024 1024

Transmitter – Node B

Source :

LTE for UMTS –

a Tx power (dBm) 44.5 46 46

b Tx antenna gain (dBi) 18 18 18

c Cable loss (dB) 2 2 2

OFDMA and SC-FDMA

Based Radio AccessHarri Holma and Antti Toskala

.

Receiver

– UEe UE noise figure (dB) – 7 7

f Thermal noise (dB) ‐119.7 ‐108.2 ‐104.5

g Receiver noise fl oor (dBm) – ‐101.2 ‐97.5

h SINR (dB) – ‐5.2 ‐9

i Receiver sensitivity (dBm) ‐104 ‐106.4 ‐106.5

Interference mar in dB 0 4 4

k Control channel overhead (%) 0 20 20

l Rx antenna gain (dBi) 0 0 0

m Body loss (dB) 3 0 0


ax mum pat oss . . .

E d i t e


C o p y


or a t i on ,2 0 0 5 -2 0 0 9

F or E





Link budgets Comparison GSM/HSPA/LTE

180

Maximum path loss values for GSM voice and HSPA and LTE data

170

175

160

165

dB

145

150

140

GSM voice HSPA 1Mbps/64kbps LTE 1Mbps/64kbps

Uplink Downlink


E d i t e


C o p y


or a t i on ,2 0 0 5 -2 0 0 9

F or E







Cell range Comparison

• The urban cell range varies from

0.6 km

to

1.4

km

and

suburban

Cell

ranges

with

Okumura–Hata

from 1.5 km to 3.4 km.

• Such cell ranges are also typically

found in existin GSM and UMTS

100

networks.

• The rural case shows clearly

10

K m

outdoor mobile coverage and

even

up

to

50

km

for

the

rural

1

ixe insta ation at 900 MHz. 0.1

900 MHz 1800 MHz 2100 MHz 2600 MHz

Urban indoor Suburban indoor

Rural outdoor Rural outdoor fixed


E d i t e d b y F ox i t R e a d er

C o p y


or a t i on ,2 0 0 5 -2 0 0 9

F or E





Difference between 900 MHz and 2600 MHz

Urban Rural Rural fixed

wireless

• 1 :According to Okumura–Hata.

• 2 :Shared

1.3

m

antenna

for

Propagation loss (1) +14 dB +14 dB +14 dB

‐

900 2600 giving 15 and 18 dBi

gain at 900 vs 2600 MHz.

• 3 :2.5 m antenna giving 18 dBi gain at

BTS cable loss (4) +1 dB +3 dB +3 dB

900 MHz.

• 4 :Cable 1/2’. Urban 30 m and rural

100 m.

UE antenna gain ‐5 dB (5) ‐5 dB (5) 0 dB (6)• 5 :Based on 3GPP RAN4

contributions.

• 6 :External

fixed

antenna

assumed.

UE sensitivity (7) ‐1 dB ‐1 dB ‐1 dB

Total +6 dB +11 dB +16 dB

• 7 :UE sensitivity can be up to 3 dB

worse at 900 MHz but the

www.cert.tn22

LTE Technology Perofrmance Evaluation




Cell range Limitation

• The earth’s curvature limits the maximum cell range to

a roximatel

40 km

with

an

80

m

hi h

base

station

antenna

assuming that the terminal is at ground level.

• The maximum cell range can be calculated with Equation

below• To achieve 100 km cell range, the required antenna height is

580 m!!!

R = 8650 km 222

(Effective earth radius for

radio propagation is

4/3 larger than real radius) Rd Rh −+= 22



C o p y r i gh t ( C ) b y F ox i t C or p

or a t i on ,2 0 0 5 -2 0 0 9

F or E





Latency

• User plane latency is relevant for the performance of many

a lications.

• There are several applications that do not require a very high

data rate, but they do require very low latency: voice, real

time gaming,

interactive

applications.





Latency : End‐to‐end delay budget

Delay component Delay value

Transmission

time

uplink +

2 ms

• On average, the packet needs to wait

for

0.5

ms

for

the

start

of

the

next

Buffering time (0.5 ×

transmission time) 2 × 0.5 × 1 ms = 1 ms

Retransmissions 10% 2 × 0.1 × 8 ms = 1.6 ms

.

• The retransmissions take 8 ms at best

• the assumed retransmission

Uplink scheduling request 0.5 × 5 ms = 2.5 ms

Uplink scheduling grant 4 msprobability

is 10%.

• The average delay for sending the

UE e ay est mate 4 ms

eNodeB delay estimated 4 ms

Core network 1 ms

.

• Scheduling grant : 4 ms.

• UE

rocessin

dela

: 4 ms,

Total delay with pre‐allocated

resources 13.6 ms

Total delay with scheduling 20.1 ms

• eNodeB processing delay :4 ms

• core network delay :1 ms.





End‐to‐end round trip time including scheduling latency

25

LTE round trip time

20

Core

15

eNB

UE

Uplink scheduling grant

5

10

Retransmissions

Buffering time

Transmission

time

0

Delay value





LTE Refarming to GSM Spectrum

• LTE could be deployed in the existing GSM spectrum

.

• The flexible LTE bandwidth makes refarming easier

an w ecause can s ar w .

MHz or 3.0 MHz bandwidths and then grow later w en e ra c as ecrease .



C o p y r i gh t ( C ) b y F ox i t C or p or a t i on ,2 0 0 5 -2 0 0 9

F or E v al u a t i on Onl .




LTE refarming to GSM spectrum ‐ Example





Dimensioning Capacity ‐ Traffic volume based approach

• The busy hour is assumed to carry

15%

of

the

daily

traffic

• t e usy our average oading is 50%.

• The calculation shows that the total

site throughput per month is 4600

GB.

• To offer 5 GB data for every subscriber per month, the number of

subscribers per site will be 920.





Dimensioning Capacity ‐ Data rate based approach

• Target : 1 Mbps per subscriber.

• Since only

some

of

the

subscribers are downloading data

simultaneously, we can apply an

overbookin factor for exam le

20.

• It means that the average busy

subscriber.

• The number

of

subscribers

per

site using this approach is 1050.


E d i t e d

b y F ox i t R e a d er

C o p y r i gh t ( C ) b y F ox i t C or p or a t i on ,2 0 0 5 -2 0 0 9

F or E v al u a t i on Onl .








LTE Technolo Perofrmance Evaluation

ANNEXES





UL link budget parameters for LTE – Parameters‐1


Ref. LTE for UMTS – OFDMA and SC-FDMA Based Radio Access Harri Holma and Antti Toskala


















DL link budget parameters for LTE – Parameters‐2



LTE TechnologyPerofrmance Evaluation

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