Broadband Wireless Technologies & Business

8/2/2019 Broadband Wireless Technologies & Business

http://slidepdf.com/reader/full/broadband-wireless-technologies-business 1/27

Broadband Wireless

Technologies, Standards and Service

Riaz EsmailzadehCarnegie Mellon University

[email protected]

27 July 2007 © Riaz Esmailzadeh 2

Overview

Broadband Wireless Technologies

Transmission Rates

Technology Differences

Throughput Calculations

Standards 3G to 4G

CDMA – Based

OFDMA – Based

Enhancing Technologies

Services

Revenue Flow Value Chain

Expected Growth






Transmission Rates

Technology Differences Throughput Calculations

3G to 4G Standards

CDMA – Based

OFDMA – Based


Services

Revenue Flow

Value Chain

Expected Growth


Edholm’s Law

Ex-CTO of Nortel, projected several years ago that with the presentrate of growth in both fixed and wireless transmission rates, in a fewyears the transmission rates will be comparable.

It would make more sense to roll-out a wireless network that a fixednetwork…

Source: IEEE Spectrum July 2004




Downlink Transmission Rate: 5 Giga-bit/sec

Japanese operator DoCoMo announced field test results in February

System parameters:

Multiplexing method: Variable Spreading Factor – Orthogonal

Frequency Division Multiple Access (VSF-OFDMA) Bandwidth: 100 MHz

Modulation: (256 QAM)

12 x 12 MIMO antennas

Single cell


There Are Challenges…

Propagation loss

From Hata-Okumura model

Path loss increases as a power of 2.6 or (f 1 /f 2)2.6

For f 1=2 GHz and f 2=5 GHz, the signal loss is almost 10 timeshigher at 5 GHz than 2 GHz

Required transmit power is a factor of transmission rate A 100 Kbps transmission requires 100 times more power than a 1

kbps

For a 4G vs. 3G system comparison:

10 times signal loss

10 times higher required transmission power due to higher bitrates

100 times more required peak transmission power

Available bandwidth

A chunk of 100 MHz needed

Go to the 5 GHz band?

Extra path loss of 10 dBcompared with the 2 GHz band

However, we have come a long way.10-3

0 4 8 12 16 20 24

Eb / N 0

BER

Fad ing channe l

Stat ic channel

10-2

10-1




Key Requirements for 4G

High data rate, low latency, packet-optimized radio access

100 Mbps peak DL rate in 20 MHz allocation

50 Mbps peak UL rate in 20 MHz allocation

Spectrum flexibility

Scalable bandwidths [1.25, 2.5, 5, 10, 15, 20MHz]

Support for paired and unpaired spectrum assignments

Support for high speed mobility (up to 350 km/h)

Flat backbone architecture (all IP)


Which Technologies

Two paths have emerged:

Evolution of CDMA – based system (3GPP)

Evolution of OFDMA – based systems (IEEE)

What is the difference?

Philosophical r eally!

How is the wireless channel equalised

(And how multi-user interference is dealt with).

How to operate in very wide-band channels




P o s i

t i o n

( c m

)

Frequency (MHz)

- 20

- 10

0

10

C h a n n e l

g a i n

( d B )

2 0 1 020 00 2 00 5

0

5 0

4 0

30

20

10

Fading in Two Domains

Wireless communications system performance is degraded due tosignal fading in two domains: frequency and time.

Wireless transmission technologies are designed to compensate for

these conditions Or Equalize the channel

*Source: Adachi, et al.


Shannon Theorem

In mobile communications, which re-use frequency resources, theamount of interference from other users must be taken into account

Shannon Theorem on capacity canbe approximated to include the

effect of interference, I

Throughput hereis calculated as afunction of SINR, or SIR

The efficiency of each technologycan be evaluated

based on thistheorem

0

1

2

3

4

5

6

7

8

9

-10 -5 0 5 10 15 20 25

S/ ( N + I ) ( d B )

N o r m a

l i s e d

C a p a c i t y

( b p s / H z )

Shannonlimit

⎟

⎠

⎞⎜

⎝

⎛

+

+≈ I N

S BC 1log 2




How to Equalise

For Time and Frequency domains fading:

CDMA systems equalise through

Diversity combining (rake, multiple antennas)

Power control OFDM systems equalise through

Narrow-band sub-carrier with flat fading

Power control

The other equalisation problem

Multi-user interference


Sources of Interference

In the uplink:All active mobile in the systemtransmit signals that areinterference to the desired usersignal

In the downlinkAll signals from other activebase stations, and signalsintended for other users withinthe same cell area areinterference




WCDMA (and HSDA)

The two systems differ in the way they treat interference

CDMA systems use frequency re-use factor of one

The sources of interference come from both within and without

the cell How these interference are minimised contributes to the

increase of WCDMA average throughput

The system may be equalised through joint detection techniques(interference mitigations, both inter- and intra-cell)

3

2

1


WiMAX

OFDMA-based systems use a TDMA system per sub-carrier, andtransmits to one user at a time

However, inter-cell interference remains

Therefore they need to have a frequency re-use factor of morethan one as the interference from neighbouring cell can be

destructive Adaptive array antenna systems, as well as adaptive

frequency re-sue factors are used to reduce interference andincrease the throughput efficiency

1




Peak t h r ou ghpu tAn example for a WCDMA system is calculated below. It shouldbe noted that peak throughput figures of up to 14 Mbps havebeen reported. These require higher coding rates and betterinformation efficiency than listed in this example.

1Spreading factor (chip per symbol)

4Data bits per symbol (16 QAM)

95%Information bits / transmitted bits10.944 MbpsPeak throughput

3/4Channel coding rate

3.84 McpsChip rate

Peak Throughput

Peak throughput is calculated similarly for all technologies

It is primarily a function of system bandwidth, and frequency re-usefactor


W iMAX peak t h r ough pu tAn example for a 5 MHZ WiMAX system is calculated below.

12 MbpsChannel coding rate 3/4

16 Mbps64-QAM modulation: 6 bits/symbol

8680Symbol rate per sub-carrier (1 / 115.2 μsec)

115.2 μsecOFDM symbol duration

9.766 kHzSub-carrier frequency spacing

384Number of sub-carriers

2.67 MspsInformation symbol ratio (80%)

12 MbpsPeak throughput

3.3 MspsTotal symbol rate (8680x384)

5 MHz McpsSystem bandwidth

WiMAX Peak Throughput

WiMAX peak throughput is similarly calculated. It is also directlyrelated to the system bandwidth




SIR = 12 dB

SIR = 9 dB

SIR = 6 dB

SIR = 0 dB

SIR = 3 dB

Average Throughput

Average throughput is calculated from SIR distribution and Shannontheorem

Various standards differ here on how they can minimize interference


t 1

t 3

t 4

t 2

Multi-hop Networking

With path loss and the required received power significantly higher,transmission range is significantly reduced.

To increase coverage, a user device may be used to relay signals to auser outside the coverage area




Fixed and wireless transmission rates are becoming more andmore comparable

The question of which technology to choose is answered bywhich way multi-user interference is handled

An operator should be most interested in average throughputrates for the system, rather than a marketing-oriented peakthroughput figure

To summarize …


3G to 4G Standards


Transmission Rates

Technology Differences

Throughput Calculations

3G to 4G Standards

CDMA – Based

OFDMA – Based


Services

Revenue Flow Value Chain

Expected Growth




Technologies: WCDMA-HSPA

WCDMA HSPA standard is in various stages of standardization withinITU, 3GPP and ARIB

3GPP has already made 5 formal releases of the CDMA standard

Most of these standards have been ratified by the ITU

June 2006Release 7

2 0 0 1Release 4

Dec 2002Release 5

Dec 2004Release 6

1 9 9 9Release 99

2 0 0 7/ 2 0 0 8Long Term Evolution

3GPP (Expected) Release Date


A Combination of…

It is a combination of FDD, CDMA and TDMA

The Duplex mode is Time Division

User simultaneously connect to the system in Code divisionmultiple access fashion

User traffic is also handled in a Frequency Division manner

The TDD mode is a complimentary component for the newstandard

FDD CDMA

TDMA

WCDMA-HSPA

Such as: GSM WCDMA

Such as: FOMA cdmaOne

Such as: GSM PDC




FDD and TDD

In FDD two different frequency bands are used for downlink anduplink transmissions

In TDD Uplink and

downlink transmissionsare carried out in thesame frequency band,but at different times

While CDMA systemshave been mainlyFDD, a joint TDD/FDDis being developed

While initially WiMAX

systems went the FDDway, they are nowfocusing on TDD

U p l i n k f r e q u e n c y b a n d

D o w n l i n k f r e q u e n c y b a n d

(FDD)

Base s tat ion

C o m m o n u p l i n k a n d d o w n l i n k f r e q u e n c y b a n d

(TDD)

Base s tat ionEnd-user dev ice

End-user dev ice


Technologies: WiMAX

WiMAX specifications are being developed under IEEE 802.16e group,with several other working group contributing to the final standard:Release dates have varied: the following was presented by Intel lastOctober: Definite Final Release 1 is expected this year...

*Source: Intel Presentation atWireless Broadband Technical Seminar,Tokyo, Japan, 31 October 2005




Uses OFDMA …

WiMAX is a combination of TDD OFDMA and TDMA

The Duplex is Time Division

User simultaneously connect to the system in an Orthogonal

Frequency Division Multiple Access fashion User traffic is also handled in a Time Division manner

TDD OFDMA

TDMA

WiMAX

Such as: DECT PHS

Similar to: 802.11a DAB/DVB

Such as: GSM PDC


WCDMA LTE: OFDMA with Spreading

Long term evolution of CDMA standards envisages usage of OFDMA

A combination of CDMA and OFDM as in the DoCoMo proposal

The OFDM part will use a scalable variable number of sub-carriers

Fixed sub-carrier spacing (15kHz)

Spectral compatibility for deployment in existing bands

20MHz

5MHz

10MHz

15 kHz




Frequency(sub-carriers)

Time(sub-frames)

code

Physical Layer: Resource Segmentation

Time, frequency and (possibly) code domain resource partitioning

Time domain

Accommodates bursty traffic profiles (packet data)

Enables channel dependent scheduling (multi-user diversity) Frequency domain

Further granularity, and channel dependent scheduling

Localised resources or distributed resources


System Parameters

Although both 3GPP WCDMA LTE and WIMAX evolution envisage arange of bandwidths, it is expected that mostly a 5 or 10 MHzbandwidth will be used

Both systems use similar coding and modulation schemes

The only difference between the two systems is the choice of access

technology This leads to different frequency re-use factor requirements

QPSK ~ 16 QAM

QPSK ~ 64 QAM

Uplink

Downlink QPSK ~ 64 QAM

1.25 ~ 20 MHz

OFDMA

QPSK ~ 64 QAM

Modulation

CDMA-OFDMAAccess Technology

Turbo and LDPC CodesCoding

1.25 ~ 20 MHzBandwidth

WiMAXWCDMA-HSPA




Key Parameters

The following table shows the general guidelines for the LTE

These are expected within 2009-2010 release

Paired & Unpaired

1.25, 2.5, 5, 10, 15, 20

< 5 ms

192-256 kbps

1 – 2 Mbps

0.48 – 0.72 b/s/Hz

1.2 – 1.6 b/s/Hz

2.5b/s/Hz

5b/s/Hz

Net Requirement Set By Operators

Duplex Modes

Cell Edge Rate - Downlink

Cell Edge Rate - Uplink

Parameter

Channel bandwidths (MHz)

Delay one way

(active state, single user, unloaded)

Spectral efficiency- Uplink

Spectral efficiency- Downlink

Uplink Peak User Throughput

Downlink Peak User Throughput


Frequency Re-Use

Usually the spectrum is re-used in many different base stations

If two base stations are sufficiently separated, they can re-use thesame spectrum to communicate with their mobiles

WiMAX systems propose a partial

frequency re-use, where areasin the centre of a cell can havere-use factor of 1, and cell-edgea re-use factor of 3.

f 1+ f 2 + f 3

f 1

f 2

f 3

f 1+ f 2 + f 3

f 1+ f 2 + f 3




I MT Ex tens ion band :

Europe, Japan, KoreaTDD or FDDMMDS band:USA, CanadaTDD or FDD

2.5 ~ 2.69 GHz

I MT 2000 : FDD

Europe, Japan,Korea, China

2.11 ~ 2.17 GHz

I MT 2000 : TDD

Europe, Japan,Korea, China

2.01 ~ 2.025 GHz

I MT-2000 TDD

ChinaMobi l e I n t e rne tKorea

2.3 ~ 2.4 GHz

2

G H z B a n d

1.92 ~ 1.98 GHz

Pres en t l y us edfor 1 G, 2G

450 MHz800 MHz bandsTDD or FDDVarious Worldwide

Sub 1 GHz

I MT-2000 FDD1.72~1.78JapanCanada?

1.7 GHz

< 2

G H z B

a n d

Poss ib le BroadbandWireless5.470 – 5.725 :Asia, Americas, Europe

5.7 ~ 5.8 GHz

Broadband W i re l ess3.3- 3.4 GHz: China, India3.4-3.6 GHz: Worldwide3.6-3.8 GHz: USA, CanadaTDD or FDD

3.3 ~ 3.8 GHz

3

& 5

G H z B a n d

I MT-2000 TDDEurope, ChinaKorea

1.9 ~ 1.92 GHz

I MT 2000 : FDDEurope, Japan,Korea, China

Allocated Spectrum

Several frequency bands can be considered for future releases of 3Gstandards.


Switching Technology

Switching technologies have now also merged:

Data over wired network has long been packet switched

Voice communications over wire is now increasingly packetswitched: VoIP

Similarly in wireless

Data is now increasingly packet switched

Voice is also converging to packet switching: Wireless VoIP

Web

EmailCircuit

Switched

Voice

2 G

Email

Video

Voice

Web

Streaming

Packet

Switched

MMS

PacketSwitched

Email

Video

CircuitSwitched

Voice

Web

Streaming

MMS

3 GEar ly Releases

3 GRelease 5 ~




IP End-to-End

Services of the future will be packet switched

The backbone network will operate using IP

Offered services will also use IP

Using an end-to-end IP network design will reduce Design cost

Integration cost

Operating cost

Layout and expansion cost

Base station

IP Network

Server

Other Networks


LTE Architecture

The backbone is based on a flat all-IP architecture

I MS Serv iceN e t w o r k

“ P u b li c” I P W AN

I SPn e t w o r k

Pr i v a ten e t w o r k

PSTN

Signal l ing

User data

E-UTRAN

Opera to rManaged I P

bac k bone

E-Node BE-Node B

E-Node B

E-Node BE-Node B

LTE GW




Base station

User equipment

Antennaelements

Antennaelements

> λ/ 2

Using MIMO

MIMO (multiple-input multiple-output) technology is the usage of multiple antennas at both the transmitter and receiver sides

This in effect creates parallel channels. The channel capacity can

therefore be increased several times. For example the DoCoMo systems uses 12 antennas at each side

Under ideal conditions, this increases throughput 12 times

For this to work, antenna elements must be sufficiently apart


I n f o r m a t i o nb i t s

T r ans m i t t edpacket

N A C K

Buf fe r

Re- t ransmi tpunc t u r ed b i t

i f N ACK

I n f o r m a t i o nb i t s

Par i t yb i t s

Punc tu redpa r i t y b i t

Hybrid ARQ (Incremental Redundancy)

When “S” term is high in Shannon Theorem, higher transmission ratesmay be supported. This Hybrid ARQ scheme facilitates its realisation




0

50

100

150

200

250

300

350

-10 -5 0 5 10 15 20 25

T h r o u g h p u t

Eb / N 0

Mode 1

Mode 2

Mode 3

Mode 4

Mode 5

Mode 6

Mode 7

Adaptive Coding and Modulation

When channel conditions are good then channel coding rates andmodulation rates may be increased so more information is sentthrough the channel.

64-QAM

16-QAM

16-QAM

16-QAM

QPSK

QPSK

QPSK

Modulation

1/32

1/24

3/43

1/21

3/47

3/46

1/35

CodingRate

Mode


T ime

A

m

p l i t u d e

l e v e l

P o w

e r l e v e l

Average

power

Peak power

T ime

T ime

T ime

T ime

()2

Peak-to-Average Power Ratio (PAPR)

Multi-carriersystems suffer fromlarge PAPR problem

This is significantparticularly in

regards to poweramplification as non-linearity can causeclipping




Power Amplifier Efficiency

Power amplifiers have a saturation level

With PAPR, the device need to operate

at well below saturation level

This leads

Less efficient operation (morebattery power required, more heatgenerated)

Cost/Battery usage can beprohibitive for handsets.

This is the reason

OFDM/Multi-carrier isnot used in Uplink

I npu t l e v el

Ou t pu tleve l

3 0 %6 - 9 d B

4 4 %3 d B

6 0 %0 d B

Ef f ic iencyI n p u t b a ck o f f


To summarize …

“3G” standards evolution (both 3GPP and IEEE – based) intendto provide

Higher transmission rates

Flexible bandwidth allocation

Full IP backbone architecture

Advanced antenna MIMO, and error control coding technologieshelps increase the transmission rate

However, concerns remain with the electronics design aspects,specially PAPR issues for OFDM systems




Services


Transmission Rates

Technology Differences Throughput Calculations

3G to 4G Standards

CDMA – Based

OFDMA – Based


Services

Revenue Flow

Value Chain

Expected Growth


End-User device

The services that can be provided are very much a factor of the end-user device capability, core purpose, and mobility

Mob i l i t y

Mini PCLap t op PC PDA Mob i le




UserMob i le

Opera to r

Th i rd par t i es

RevenueFlow

RevenueFlow

RevenueFlow

UserMob i le

Opera to r

RevenueFlow

Revenue Flow

Service models, and revenue flows are also changing as many newplayers are entering the value chain

With the introduction of new services in 2G and 3G, the flow of

revenue has become more complex It is expected to be more complex with (4G) broadband wireless

services


Non-Por ta lContent

Aggrega t i onand Creators

Non-Por ta lAppl icat ion

P la t f o rm

Por ta lContent

Aggrega t i on

Th i r dPar t y

Bi l l ing

Por ta lAccess

End-userBi l l ing

I PN e t w o r k

Access

Mobi leN e t w o r k

Access

3. Access Focused App roach

2. Por ta l Focused Approach

1. Mob i le Specia l i sed Serv ices

Value Chain

A value chain, based on 3G services and applications has beendeveloped by UMTS Forum

They classify services into three groups:

*Source: UMTS Forum




CustomizedI n f o t a i n m e n t

Mu l t imed iaMessaging

Serv ice

(MMS)

Locat ionBased

Serv ices

Rich/ SimpleVoice

Mobi leI n t e r n e tAccess

Mobi leI n t r a n e t / Ex t r ane t

Access

Access FocusedApproach

Por ta lFocused

Approach

Mobi le Spec ia l ized Serv ices

Conten t Connec t i v i t y( I n t e r n e t )

Mob i l i t y

I n f o r m a t i on and Con t en t(Non-Vo ice)

Voice

Service Classification

Using this classification, service categories are defined by UMTSForum

*Source: UMTS Forum


Required Transmission Rates

Required transmission rates vary for different services

Moreover they are expected to be different for downlink and uplink

These help the decision making process: what amount of totaltransmission rates are needed for a certain customer base.

UplinkDownlink

Simple Voice

Rich Voice

Location Based Services

Multimedia Messaging Service

Customised Infotainment

Mobile Intranet/Extranet Access

Mobile Internet Access

8 kbps ~ 16 kbps16 kbps ~ 64 kbps




8 kbps ~ 16 kbps

128 kbps ~ 256 kbps

32 kbps ~ 64 kbps

64 kbps ~ 128 kbps

500 kbps ~ 1 Mbps

500 kbps ~ 1 Mbps

*Source: UMTS Forum




Uplink and Downlink Asymmetry

The amount of traffic in the uplink and downlink are going to bedifferent

TDD systems are more flexible in traffic allocation

U p l i n k f r e q u e n c y b a n d

D o w n l i n k f r e q u e n c y b a n d

(FDD)

C o m m o n u p l i n k a n d d o w n l i n k f r e q u e n c y b a n d

(TDD)

One slot

One frame

0

5 0 0

1 0 0 0

1 5 0 0

2 0 0 0

2 5 0 0

1 9 9 7 2 0 0 2 2 0 07Year

K b p s

D o w n l in kUp l ink

Maximum throughput for D/L and U/L per User


Simple and Rich Voice

This is the traditional voice service, and voice enriched by video andother functions

While the revenue from simple voice service is expected to decrease,revenue from rich voice service is expected to increase

Transmission rates are moderate

Source:Esmailzadeh basedon UMTS Forum data 0

20

40

60

80

100

120

2005 2006 2007 2008 2009 20100

100

200

300

400

500

600

700

Rich Voice revenue ($B)Simple Voice revenue ($B)Simple voice subscribers (M)

Year

R e v e n u e

( $ B )

S u b s c r i b e r s ( M )




Customized Infotainment

Information and entertainment services are going to be a majorrevenue growth for operators

Moderate transmission

rates

0

10

20

30

40

50

60

70

80

90

100

2005 2006 2007 2008 2009 2010Year

R e v e n u e

( $ B )

0

50

100

150

200

250

300

350


Customised Infotainment revenue ($B)Customised Infotainment Subscribers (M)

Source:Esmailzadeh basedon UMTS Forum data


Mobile Intranet/Extranet

Wireless ADSL type of services, specially for the business segment isexpected to grow.

High transmission rates, perhaps counting for the lion share of inforamtion transfer

However, revenues are not expected to be correspondingly high

0

10

20

30

40

50

60

70

2005 2006 2007 2008 2009 2010Year

R e v e n u e

( $ B )

0

50

100

150

200

250

300


Intranet/Extranet revenue ($B)

Intranet/Extranet subscribers (M)





Multimedia Messaging Service

Short messaging services, enhanced by multimedia features isexpected to grow

MMS services for business, including machine-to-machine services are

expected to grow rapidly. Transmission rates are expected to be low

0

5

10

15

20

25

30

35

40

45

2005 2006 2007 2008 2009 20100

20

40

60

80

100

120

140MMS business segement revenue ($B)MMS consumer segment revenue ($B)MMS consumer segment subscribers (M)

Year

R e v e n u e

( $ B )

S u b s

c r i b e r s ( M )



Location Based Services

Location based services, including both consumer and businesssegments (asset tracking etc.) will show significant growth

Low transmission rates

0

2

4

6

8

10

12

2005 2006 2007 2008 2009 2010Year

R e v e n u e

( $ B )

1 01Bus iness asse t t rack ing

1 8 01 8Consumer t h i r d pa r t y

1 94LBS t r ansact ion s

1 1 73 9LBS adver t is ing

1 8 72 2Consumer nav iga t ion

Un i t ( M)2 0 1 0

Un i t ( M)2 0 0 5





To summarize …

A good classification of the future services have been done bythe UMTS forum

Based on this classification a value chain and market forecasthas been made

It is expected that a mixture high and low data rates will exist,and generate revenues unrelated to their transmission rates

The future wireless technology needs to be flexible to provide

these service mixture

Overall Summary

There appears to be convergence between CDMA and OFDMA camps

Perhaps driven by the 3GPP camp to remove any differentiationWiMAX camp may have

Although provision of high transmission rates is being addressed, the

two camps still are in the marketing mode: Peak transmission rates are bragged

Service provision is not really addressed

Essential problems are still ignored

The end-user major present-and-now need is wireless DSL–typeservices

Which neither technology with their present capacities can provide

And which may be best provided by proprietary technologies

The challenge of transmission of higher rates at higher frequencybands and reduced transmission range also needs to be addressed.

Documents

Broadband Wireless Technologies & Business