Towards 4G: Technical Overview of LTE & WiMAX

WCNC 20102010.04.18

Dr. Hyung G. MyungQualcomm / Flarion

Towards 4G: Technical Overview of LTE and WiMAX

Outline

1

Introduction and Background

Summary and References

3GPP Long Term Evolution (LTE)

WiMAX

4G Enabling Technologies

The Beginning

2


Wireless Evolution

3

Analog voice

Digital Voice + 7.2 Mbps data + GPS + Full Internet browsing + Multimedia messaging + Multimedia entertainment + …

1983: Motorola DynaTAC 8000X 2009: Apple iPhone 3G


Impact of Wireless Communications

4


Wireless Trends

5


Cellular Wireless Evolution

6

1G

2G

3G

4G

Analog speech | FDMA (’80s)AMPS

Digital modulation & roaming | TDMA & CDMA (’90s)GSM, IS-95, PDC

IMT-2000 global standard | Wideband CDMA (’00s)UMTS/WCDMA/HSPA, CDMA2000, TD-SCDMA

Systems beyond IMT-2000 (IMT-Advanced)LTE/LTE-Advanced, WiMAX (802.16m)


Towards 4G

• ITU’s Systems beyond IMT-2000 (IMT-Advanced) is set to introduce 4G.

• 3GPP is currently developing evolutionary/ revolutionary systems towards 4G: Long Term Evolution (LTE) and LTE-Advanced.

• IEEE 802.16-based WiMAX is also evolving towards 4G through 802.16m.

7


Wireless Backgrounds

• Fundamental limits

• Multiple access schemes

• Broadband wireless channel basics

• Cellular system

8


Fundamental Constraints

• Shannon’s capacity upper bound– Achievable data rate is fundamentally limited by bandwidth and signal

-to-noise ratio (SNR).

9

2log 1 [bits per second]S

C BWN

Signal power

Noise powerChannel bandwidth


Fundamental Constraints

• Fundamental constraints for high data rate communications

10

0.1 1 10 100-10

0

10

20

30

40

50

C/BW (Bandwidth efficiency)

Eb/N

0 [dB

] Power-limited Bandwidth-limited

2

2

0

0

log 1

log 1

2 1

b

CBW

b

C S

BW N

E C

N BW

E

CNBW

Noise power spectral density

Energyper bit

Bandwidth efficiency

- cont.


Challenges of Wireless Communications

• Multipath radio propagation

• Spectrum limitations

• Limited energy

• User mobility

• Resource management

11


Duplexing

• Two ways to duplex downlink (base station to mobile) and uplink (mobile to base station)– Frequency division duplexing (FDD)

– Time division duplexing (TDD)

12

Downlink (Forward link)

Uplink (Reverse link)


Multiple Access Schemes

• Multiple devices communicating to a single base station.– How do you resolve the problem of sharing a common

communication resource?

13


Multiple Access Schemes

• Access resources can be shared in time, frequency, code, and space.– Time division multiple access (TDMA): GSM

– Frequency division multiple access (FDMA): AMPS

– Code division multiple access (CDMA): IS-95, UMTS

– Spatial division multiple access (SDMA): iBurst

14


- cont.

Wireless Channel

• Wireless channel experiences multi-path radio propagation.

15


Multipath Radio Propagation

16

- cont.


Multi-Path Channel

• Multi-path channel causes:– Inter-symbol interference (ISI) and fading in the time domain.

– Frequency-selectivity in the frequency domain.

17

0 1 2 3 4 5 60

0.2

0.4

0.6

0.8

1

Time [sec]

Am

plit

ude [

linear]

3GPP 6-Tap Typical Urban (TU6) Channel Delay Profile

0 1 2 3 4 50

0.5

1

1.5

2

2.5

Frequency [MHz]

Channel G

ain

[lin

ear]

Frequency Response of 3GPP TU6 Channel in 5MHz Band


Multi-Path Channel

• For broadband wireless channel, ISI and frequency-selectivity become severe.

• To resolve the ISI and the frequency-selectivity in the channel, various measures are used.– Channel equalization in the time domain or frequency domain

– Multi-carrier multiplexing

• Orthogonal frequency division multiplexing (OFDM)

– Frequency hopping

– Channel-adaptive scheduling

– Channel coding

– Automatic repeat request (ARQ) and hybrid ARQ (H-ARQ)

18


- cont.

Mobile User

• When the user is mobile, the channel becomes time-varying.

• There is also Doppler shift in the carrier frequency.

19


Time-Varying Multi-path Channel

20

0

1

2

3

4

5

0

1

2

3

4

5

0

5

Time [msec]

Mobile speed = 60 km/h (111 Hz doppler)

Frequency [MHz]

Channel G

ain

[lin

ear]

0

1

2

3

4

5

0

1

2

3

4

5

0

5

Time [msec]

Mobile speed = 3 km/h (5.6 Hz doppler)

Frequency [MHz]

Channel G

ain

[lin

ear]


Wireless Spectrum

21


Cellular Wireless System

• A large geographical region is segmented intosmaller “cell”s.– Transmit power limitation

– Facilitates frequency spectrum re-use

• Cellular network designissues– Inter-cell synchronization

– Handoff mechanism

– Frequency planning

22



• Frequency re-use

23

F1

F1

F1

F1

F1

F1

F1

F1

F3

F2

F7

F6

F5

F4

Frequency re-use = 1- Higher spectral efficiency

- Higher interference for cell-edge users

Frequency re-use = 7- Lower interference for cell-edge users

- Lower spectral efficiency


- cont.


• Sectorized cells

24


- cont.


• Frequency re-use = 3

25


- cont.

Outline

26




WiMAX



• OFDM/OFDMA

• Frequency domain equalization

• SC-FDMA

• MIMO

• Fast channel-dependent resource scheduling

• Fractional frequency reuse

27


Orthogonal Frequency Division Multiplexing

• OFDM can be viewed as a form of frequency division multiplexing (FDM).– Divides the transmission bandwidth into narrower equally spaced

tones, or subcarriers.

– Individual information symbols are conveyed over the subcarriers.

28

Ser

ial-

to-p

ara

llel

02j f te

12j f te

12 Nj f te

Input data block

Output symbol


OFDM

• Use of orthogonal subcarriers makes OFDM spectrally efficient.– Because of the orthogonality among the subcarriers, they can

overlap with each other.

29

0 1 2 3 4 5 6 7 8 9Subcarrier

- cont.


OFDM

• Since the bandwidth of each subcarrier is much smaller than the coherence bandwidth of the transmission channel, each subcarrier sees flat fading.

30

Frequency

Channel response

Subcarrier

- cont.


OFDM

• In the time domain, OFDM takes a high-rate serial data stream and transmits parallel low-rate substreams.

31

4 Input data symbols

TimeTimeF

req

uen

cy

Fre

qu

ency

OFDM symbol

- cont.


OFDM

• OFDM implementation using discrete Fourier transform (DFT)

32

Channel

Channel inversion

(equalization)

N-pointDFT

DetectRemove

CP

N-point IDFT

Add CP/ PS

*CP: Cyclic prefix*PS: Pulse shaping (windowing)

- cont.


OFDM

• Design issues of OFDM– Cyclic prefix (CP): To maintain orthogonality among subcarriers in the

presence of multi-path channel, CP longer than the channel impulse response is needed. Also CP converts linear convolution of the channel impulse response into a circular one.

– High peak-to-average power ratio (PAPR): Since the transmit signal is a composition of multiple subcarriers, high peaks occur.

– Carrier frequency offset: Frequency offset breaks the orthogonalityand causes inter-carrier interference.

– Adaptive scheme or channel coding is needed to overcome the spectral null in the channel.

33

- cont.


Orthogonal Frequency Division Multiple Access

• OFDMA is a multi-user access scheme using OFDM.– Each user occupies a different set of subcarriers.

– Scheduler can exploit frequency-selectivity and multi-user diversity.

34

subcarriers

User 1

User 2

User 3


Frequency Domain Equalization

• For broadband multi-path channels, conventional time domain equalizers are impractical because of complexity.– Very long channel impulse response in the time domain.

– Prohibitively large tap size for time domain filter.

• Using discrete Fourier transform (DFT), equalization can be done in the frequency domain.

• Because the DFT size does not grow linearly with the length of the channel response, the complexity of FDE is lower than that of the equivalent time domain equalizer for broadband channel.

35


FDE

36

hx y

1 *

y h x

x h y

1

Y H X

X H Y

Time domain

Frequency domain

Fouriertransform

Channel

- cont.


FDE

• In DFT, frequency domain multiplication is equivalent to time domain circular convolution.

• Cyclic prefix (CP) longer than the channel response length is needed to convert linear convolution to circular convolution.

37

CP Symbols

- cont.


FDE

• Most of the time domain equalization techniques can be implemented in the frequency domain.– MMSE equalizer, DFE, turbo equalizer, and so on.

• References– M. V. Clark, “Adaptive Frequency-Domain Equalization and

Diversity Combining for Broadband Wireless Communications,” IEEE J. Sel. Areas Commun., vol. 16, no. 8, Oct. 1998

– M. Tüchler et al., “Linear Time and Frequency Domain Turbo Equalization,” Proc. IEEE 53rd Veh. Technol. Conf. (VTC), vol. 2, May 2001

– F. Pancaldi et al., “Block Channel Equalization in the Frequency Domain,” IEEE Trans. Commun., vol. 53, no. 3, Mar. 2005

38

- cont.


Single Carrier with FDE

39

ChannelN-

point IDFT

EqualizationN-

pointDFT

SC/FDE

OFDM

DetectRemove

CP nxAdd CP/ PS

* CP: Cyclic Prefix, PS: Pulse Shaping

Channel EqualizationN-

pointDFT

DetectRemove

CP

N-point IDFT

Add CP/ PS

nx


SC/FDE

• SC/FDE delivers performance similar to OFDM with essentially the same overall complexity, even for long channel delay.

• SC/FDE has advantage over OFDM in terms of:– Low PAPR.

– Robustness to spectral null.

– Less sensitivity to carrier frequency offset.

• Disadvantage to OFDM is that channel-adaptive subcarrier bit and power loading is not possible.

40

- cont.


SC/FDE

• References– H. Sari et al., “Transmission Techniques for Digital Terrestrial TV

Broadcasting,” IEEE Commun. Mag., vol. 33, no. 2, Feb. 1995, pp. 100-109.

– D. Falconer et al., “Frequency Domain Equalization for Single-Carrier Broadband Wireless Systems,” IEEE Commun. Mag., vol. 40, no. 4, Apr. 2002, pp. 58-66.

• Single carrier FDMA (SC-FDMA) is an extension of SC/FDE to accommodate multiple-user access.

41

- cont.


CDMA with FDE

• Instead of a RAKE receiver, use frequency domain equalization for channel equalization.

• Reference– F. Adachi et al., “Broadband CDMA Techniques,” IEEE Wireless

Comm., vol. 12, no. 2, Apr. 2005, pp. 8-18.

42

Spreading ChannelM-

point IDFT

EqualizationM-

pointDFT

DetectRemove

CP nxAdd CP/ PS

De-spreading


Single Carrier FDMA

• SC-FDMA is a new multiple access technique.– Utilizes single carrier modulation, DFT-spread orthogonal frequency

multiplexing, and frequency domain equalization.

• It has similar structure and performance to OFDMA.

• SC-FDMA is currently adopted as the uplink multiple access scheme in 3GPP LTE.

43


TX & RX structure of SC-FDMA

44

Subcarrier Mapping

Channel

N-point IDFT

Subcarrier De-

mapping/ Equalization

M-pointDFT

DetectRemove

CP

N-point DFT

M-point IDFT

Add CP / PS

DAC/ RF

RF/ ADC

SC-FDMA:

OFDMA:

+* N < M* S-to-P: Serial-to-Parallel* P-to-S: Parallel-to-Serial

P-t

o-S

S-t

o-P

S-t

o-P

P-t

o-S


Why “Single Carrier” “FDMA”?

45

Subcarrier Mapping

N-point DFT

M-point IDFT

Add CP / PS

DAC/ RF

Timedomain

Frequencydomain

Timedomain

“FDMA”

“Single Carrier”

P-t

o-S

: Sequential transmission of the symbols over a single frequency carrier.

: User multiplexing in the frequency domain.


Subcarrier Mapping

• Two ways to map subcarriers; distributed and localized.

• Distributed mapping scheme for (total # of subcarriers) = (data block size) (bandwidth spreading factor) is called Interleaved FDMA (IFDMA).

46

Distributed Localized

0X

1NX

1X

Zeros

Zeros0X

1MX

Zeros

0X

Zeros

1X

2X

1NX

0X

1MX

Zeros


Subcarrier Mapping

• Data block size (N) = 4, Number of users (Q) = 3, Number of subcarriers (M) = 12.

47

subcarriers

Terminal 1

Terminal 2

Terminal 3

subcarriers

Distributed Mode Localized Mode

- cont.


Subcarrier Mapping

48

0 0 0 0 0 0 0 0X0 X1 X2 X3

frequency

0 0 0 0 0 0 0 0X0 X1 X2 X3

:kX X0 X1 X2 X3

:nx x0 x1 x2 x3

DFT

21

0

, 4N j nk

Nk n

n

X x e N

IFDMAlX ,

~

0 0 00 0 0 0 0X0 X1 X2 X3 DFDMAlX ,

~

LFDMAlX ,

~ Current implementationin 3GPP LTE

- cont.


Time Domain Representation

49

x0 x1 x2 x3

x0 x1 x2 x3

nx

x0 x1 x2 x3 x0 x1 x2 x3

* * * * * * * *x0 x2 x0 x2

time

* * * * * * * *x0 x1 x2 x3

,m IFDMAQ x

,m DFDMAQ x

,m LFDMAQ x

3

, ,

0

* , : complex weightk m k k m

k

c x c


Amplitude of SC-FDMA Symbols

50

10 20 30 40 50 600

0.1

0.2

0.3

0.4

0.5

Symbol

Am

plit

ude

[lin

ea

r]

IFDMA

LFDMA

DFDMA

QPSK


SC-FDMA and OFDMA

• Similarities– Block-based modulation and use of CP.

– Divides the transmission bandwidth into smaller subcarriers.

– Channel inversion/equalization is done in the frequency domain.

– SC-FDMA is regarded as DFT-precoded or DFT-spread OFDMA.

51


SC-FDMA and OFDMA

• Difference in time domain signal

52

OFDMA symbol

SC-FDMA symbols*

Input data symbols

* Bandwidth spreading factor : 4time

- cont.


SC-FDMA and OFDMA

• Different equalization aspects

53

Subcarrier De-

mapping

Equalizer

Equalizer

Equalizer

Subcarrier De-

mapping

Detect

Detect

Detect

Equalizer IDFT DetectSC-FDMA

OFDMA DFT

DFT

- cont.


SC-FDMA and DS-CDMA

• In terms of bandwidth expansion, SC-FDMA is very similar to DS-CDMA system using orthogonal spreading codes.– Both spread narrowband data into broader band.

– Time symbols are compressed into “chips” after modulation.

– Spreading gain (processing gain) is achieved.

54


SC-FDMA and DS-CDMA

• Conventional spreading

55

x1 x2 x3

1 1 1

x1 x1 x1 x1 x2 x2 x2 x2 x3 x3 x3 x3

1 1 1 1 1 1 1 1 1

Signature Sequence

Data Sequence

time

x0 x0 x0 x0

1 1 1 1

x0

- cont.


SC-FDMA and DS-CDMA

• Exchanged spreading

56

time

1

x0 x1 x2 x3

1 1

x0 x1 x2 x3 x0 x1 x2 x3

x0 x1 x2 x3 x0 x1 x2 x3 x0 x1 x2 x3

Data Sequence

Signature Sequence

x0 x1 x2 x3

x0 x1 x2 x3

1

IFDMA

- cont.


SC-FDMA and Other Schemes

57

SC-FDMA

OFDMADS-CDMA

/FDE* DFT-based FDE

* Block-based processing & CP

* SC transmission: Low PAPR

* Time-compressed “chip” symbols

* Time-domain detection

* Subcarrier mapping: Frequency-selective scheduling


PAPR Characteristics of SC-FDMA

58

0 2 4 6 8 10 1210

-4

10-3

10-2

10-1

100

Pr(

PA

PR

>P

AP

R0)

PAPR0 [dB]

CCDF of PAPR: 16-QAM, Rolloff = 0.22, Nfft

= 512, Noccupied

= 128

Dotted lines: no PS

Dashed lines: RRC PS

Solid lines: RC PS

IFDMA

DFDMA

LFDMA

OFDMA

(a) QPSK (b) 16-QAM

0 2 4 6 8 10 1210

-4

10-3

10-2

10-1

100

Pr(

PA

PR

>P

AP

R0)

PAPR0 [dB]

CCDF of PAPR: QPSK, Rolloff = 0.22, Nfft

= 512, Noccupied

= 128

Dotted lines: no PS

Dashed lines: RRC PS

Solid lines: RC PS

IFDMA

DFDMA

LFDMA

OFDMA

H. G. Myung et al., “Peak-to-Average Power Ratio of Single Carrier FDMA Signals with Pulse Shaping", IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) 2006.


MIMO

• Multiple input multiple output (MIMO) technique improves communication link quality and capacity by using multiple transmit and receive antennas.

• Two types of gain; spatial diversity gain and spatial multiplexing gain.

59

Transmitter Receiver

MIMO channel


MIMO

• Spatial diversity– Improves link quality (SNR) by combining multiple independently

faded signal replicas.

– With Nt Tx and Nr Rx antennas, NtNr diversity gain is achievable.

– Smart antenna, Alamouti transmit diversity, and space-time coding.

• Spatial multiplexing– Increases data throughput by sending multiple streams of data

through parallel spatial channels.

– With Nt Tx and Nr Rx antennas, min(Nt,Nr) multiplexing gain is achievable.

– BLAST (Bell Labs Space-Time Architecture) and unitary precoding.

60

- cont.


Basic Idea of Spatial Diversity

• Coherent combining of multiple copies

61

1x

1y

2y

rNy

1h

* Narrowband channel

2h

rNh

Coherentcombining 1x


Basic Idea of Spatial Multiplexing

• Parallel decomposition of a MIMO channel

62

1x

2x

tNx

1y

2y

rNy

11h

21h

1rNh

r tN Nh

* Narrowband channel



63

11 11 1 1

1

t

r r r t t r

N

N N N N N N

h hy x n

y h h x n

y H x n

H H

H H H H

I

H H H

x ny

H UDV y UDV x n

U y U U DV x U n

U y D

y x

U

D

V n

n

x

Diagonal matrix

Singular value decomposition (SVD)

- cont.



64

1x

2x

tNx

1y

2y

rNy

11h

21h

1rNh

r tN Nh

1x

2x

tNx

1y

2y

rNy

11d

21d

t tN Nd

* Nt < Nr

- cont.


Multicarrier MIMO Spatial Multiplexing

• Frequency domain for kth subcarrier

65

11, 1 ,1, 1, 1,

, 1, , , ,

t

r r r t t r

k kkk

k N kk k k

N k N k N N k N k N k

Y NXH

k k k k

H

k k k

H

k k k

H

k

k k k k

k k

H HY X N

Y H H X N

Y H X N

Y U Y

X V X

N U

Y D X N

N


Unitary Precoding

66

UnitaryPrecoding

MIMO ChannelHk

Receiver

kXkX

k kH X

kN

kY

kZ

kV

k k kX V X

H

k k k k k

k k k

U D V V X

U D X


Channel-Dependent Scheduling

67

Subcarriers

Frequency

User 1

User 2

Channel gain



• Assign subcarriers to a user in good channel condition.

• Two subcarrier mapping schemes have advantages over each other.– Distributed: Frequency diversity.

– Localized: Frequency selective gain with CDS.

• CDS is a scheme to find an optimal set of subcarriers that are allocated to each user that maximizes some utility based on each user’s channel response.

68

- cont.



69

0 50 100 150 200 2500

0.5

1

1.5

2

2.5

3

Subcarriers

|Channel gain

| 2

256 total subcarriers, 16 chunks, 16 subcarriers per chunk

User 1

User 2

Chunk allocated to user 1

Chunk allocated to user 2

- cont.


Distributed vs. Localized Subcarrier Mapping

• Two subcarrier mappings have advantages over each other.– Distributed: Frequency

diversity, lower PAPR in case of IFDMA.

– Localized: Frequency selective gain with channel dependent scheduling (CDS), higher PAPR than the case of IFDMA but similar PAPR to the case of DFDMA.

70

* J. Lim, H. G. Myung, K. Oh, and D. J. Goodman, "Proportional Fair Scheduling of Uplink Single-Carrier FDMA Systems", IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC) 2006.

4 8 16 32 64 1285

10

15

20

25

30

35

40

45

Number of users

Ag

gre

ga

te th

rou

gh

pu

t [M

bp

s]

LFDMA: Static

LFDMA: CDS

IFDMA: Static

IFDMA: CDS


Fractional Frequency Re-use

71

F F1 F2 F3= + +

Cell-center users:

Cell-edge users:

Cell-center users:

Cell-edge users:


FFR

72

Cell-center users:

Cell-edge users:

F F1 F2 F3= + +

- cont.


FFR

• Frequency re-use improves cell-edge performance but sacrifices the cell-center performance.

• Fractional frequency re-use (FFR)– Frequency re-use = 1 at cell center: Improves overall cell capacity.

– Higher re-use factor at the cell edge to reduce interference: Improves cell-edge performance.

73

- cont.


Outline

74




WiMAX


3GPP Evolution

• Release 99 (2000): UMTS/WCDMA

• Rel-5 (2002): HSDPA

• Rel-6 (2005): HSUPA

• Rel-7 (2007) and beyond: HSPA+

• Long Term Evolution (LTE)– 3GPP work on the Evolution started in November 2004.

– Standardized in the form of Rel-8 (Dec. 2008).

• LTE-Advanced– More bandwidth (up to 100 MHz) and backward compatible with LTE.

– Standardization in progress (targeted for Rel-10).

75

3GPP LTE

Requirements of LTE

• Peak data rate– 100 Mbps DL/ 50 Mbps UL within 20 MHz bandwidth.

• Up to 200 active users in a cell (5 MHz)

• Less than 5 ms user-plane latency

• Mobility– Optimized for 0 ~ 15 km/h.– 15 ~ 120 km/h supported with high performance.– Supported up to 350 km/h or even up to 500 km/h.

• Enhanced multimedia broadcast multicast service (E-MBMS)

• Spectrum flexibility: 1.25 ~ 20 MHz

• Enhanced support for end-to-end QoS

76

3GPP LTE

Key Features of LTE

• Multiple access scheme– DL: OFDMA with CP.

– UL: Single Carrier FDMA (SC-FDMA) with CP.

• Adaptive modulation and coding– DL/UL modulations: QPSK, 16QAM, and 64QAM

– Turbo coding

• Advanced MIMO spatial multiplexing techniques– (2 or 4)x(2 or 4) downlink and uplink supported.

– Multi-user MIMO also supported.

• Support for both FDD and TDD

• H-ARQ, mobility support, rate control, security, and etc.

77

3GPP LTE

Release 10

LTE-Advanced

LTE Standardization Status

78

2008 2009 2010

Release 8

First version of LTE

Release 9

Enhancements to LTE

Source: 3GPP

3GPP LTE

2011

LTE Standard Specifications

• Freely downloadable from http://www.3gpp.org/ftp/Specs/html-info/36-series.htm

79

Specification index Description of contents

TS 36.1xx Equipment requirements: Terminals, base stations, and repeaters.

TS 36.2xx Physical layer.

TS 36.3xxLayers 2 and 3: Medium access control, radio link control, and radio resource control.

TS 36.4xxInfrastructure communications (UTRAN = UTRA Network) including base stations and mobile management entities.

TS 36.5xx Conformance testing.

3GPP LTE

http://www.3gpp.org/ftp/Specs/html-info/36-series.htm





Protocol Architecture

80

PHY: Physical layer

MAC: Medium Access Control

RLC: Radio Link Control

Logical channels

Transport channels

Co

ntr

ol

/ m

ea

su

re

me

nts

Layer 3

Layer 2

Layer 1

RRC: Radio Resource Control

Physical channels

Transceiver

3GPP LTE

LTE Network Architecture

• E-UTRAN (Evolved Universal Terrestrial Radio Access Network)

81

NB: NodeB (base station)RNC: Radio Network ControllerSGSN: Serving GPRS Support NodeGGSN: Gateway GPRS Support Node

RNC RNC

SGSN

GGSN

NB NB NB NB

UMTS 3G: UTRAN

* 3GPP TS 36.300

eNB

MMES-GW/P-GW

MMES-GW/P-GW

S1

X2

E-UTRAN

EPC (Evolved Packet Core)

eNB eNB

eNB

eNB: E-UTRAN NodeBMME: Mobility Management EntityS-GW: Serving GatewayP-GW: PDN (Packet Data Network) Gateway

* 3GPP TS 36.300

3GPP LTE


• eNB– All radio interface-related

functions

• MME– Manages mobility, UE

identity, and security parameters.

• S-GW– Node that terminates the

interface towards E-UTRAN.

• P-GW– Node that terminates the

interface towards PDN.

82

* 3GPP TS 36.300

eNB

MMES-GW/P-GW

MMES-GW/P-GW

S1

X2

E-UTRAN

EPC (Evolved Packet Core)

eNB eNB

eNB

eNB: E-UTRAN NodeBMME: Mobility Management EntityS-GW: Serving GatewayP-GW: PDN (Packet Data Network) Gateway

* 3GPP TS 36.300

3GPP LTE

- cont.


83

* Non-roaming architecture* 3GPP TS 23.401

SGi

S12

S3

S1-MME

PCRF

S7

S6a

HSS

Operator's IP Services (e.g. IMS, PSS etc.)

Rx+

S10

UE

SGSN

"LTE-Uu"

E-UTRAN

MME

S11

S5 Serving Gateway

PDN Gateway

S1-U

S4

UTRAN

GERAN

3GPP LTE

- cont.


84

* 3GPP TS 36.300

internet

eNB

RB Control

Connection Mobility Cont.

eNB Measurement

Configuration & Provision

Dynamic Resource

Allocation (Scheduler)

PDCP

PHY

MME

S-GW

S1

MAC

Inter Cell RRM

Radio Admission Control

RLC

E-UTRAN EPC

RRC

Mobility

Anchoring

EPS Bearer Control

Idle State Mobility

Handling

NAS Security

P-GW

UE IP address

allocation

Packet Filtering

RRM: Radio Resource ManagementRB: Radio BearerRRC: Radio Resource ControlPDCP: Packet Data Convergence ProtocolNAS: Non-Access StratumEPS: Evolved Packet System

3GPP LTE

- cont.


85

User-PlaneProtocolStack

Control-PlaneProtocolStack

* 3GPP TS 36.300

eNB

PHY

UE

PHY

MAC

RLC

MAC

PDCPPDCP

RLC

eNB

PHY

UE

PHY

MAC

RLC

MAC

MME

RLC

NAS NAS

RRC RRC

PDCP PDCP

3GPP LTE

- cont.

Frame Structure

• Two radio frame structures defined.– Frame structure type 1 (FS1): FDD.

– Frame structure type 2 (FS2): TDD.

• A radio frame has duration of 10 ms.

• A resource block (RB) spans 12 subcarriers over a slot duration of 0.5 ms. One subcarrier has bandwidth of 15 kHz, thus 180 kHz per RB.

86

3GPP LTE

Frame Structure Type 1

• FDD frame structure

87

One subframe = TTI (Transmission Time Interval)

#0 #1 #2 #3 #18 #19

One slot = 0.5 ms

One radio frame = 10 ms

3GPP LTE

Frame Structure Type 2

• TDD frame structure

88

Subframe #0 Subframe #2 Subframe #3 Subframe #4 Subframe #5 Subframe #7 Subframe #8 Subframe #9

DwPTS GP UpPTS DwPTS GP UpPTS

One subframe = 1 ms

One half-frame = 5 ms

One radio frame = 10 ms

One slot = 0.5 ms

3GPP LTE

Resource Grid

89

Slot #0 #19

One radio frame

Su

bca

rrie

r (f

req

uen

cy)

OFDM/SC-FDMA symbol (time)

RB

RB scN N

12

RB

scN

symbN

Resource block

Resource element

RB

symb scN N resource elements

3GPP LTE

Length of CP

90

symbNConfiguration

Normal CP 7

Extended CP 6

Extended CP (Df = 7.5 kHz)† 3

Configuration CP length NCP,l [samples]

Normal CP160 ( 5.21 s) for l = 0144 ( 4.69 s) for l = 1, 2, …, 6

Extended CP 512 ( 16.67 s) for l = 0, 1, …, 5

Extended CP (Df = 7.5 kHz) † 1024 ( 33.33 s) for l = 0, 1, 2

† Only in downlink

3GPP LTE

LTE Bandwidth/Resource Configuration

91

Channelbandwidth [MHz]

1.4 3 5 10 15 20

Number of resource blocks (NRB)

6 15 25 50 75 100

Number of occupied subcarriers

72 180 300 600 900 1200

IDFT(Tx)/DFT(Rx) size 128 256 512 1024 1536 2048

Sample rate [MHz] 1.92 3.84 7.68 15.36 23.04 30.72

Samples per slot 960 1920 3840 7680 11520 15360

*3GPP TS 36.104

3GPP LTE

Bandwidth Configuration

92

freq

uen

cy

time

300

UL RB

RB scN N

12

RB

scN

(7.68 MHz)

512

M

(4.5 MHz)(180 kHz)

Resourceblock

Zeros

Zeros

1 slot

DL or UL symbol

* 5 MHz system withframe structure type 1

3GPP LTE

LTE Physical Channels

• DL– Physical Downlink Shared Channel (PDSCH)

– Physical Broadcast Channel (PBCH)

– Physical Multicast Channel (PMCH)

– Physical Control Format Indicator Channel (PCFICH)

– Physical Downlink Control Channel (PDCCH)

– Physical Hybrid ARQ Indicator Channel (PHICH)

• UL– Physical Uplink Shared Channel (PUSCH)

– Physical Uplink Control Channel (PUCCH)

– Physical Random Access Channel (PRACH)

93

3GPP LTE

LTE Transport Channels

• Physical layer transport channels offer information transfer to medium access control (MAC) and higher layers.

• DL– Broadcast Channel (BCH)

– Downlink Shared Channel (DL-SCH)

– Paging Channel (PCH)

– Multicast Channel (MCH)

• UL– Uplink Shared Channel (UL-SCH)

– Random Access Channel (RACH)

94

3GPP LTE

LTE Logical Channels

• Logical channels are offered by the MAC layer.

• Control Channels: Control-plane information– Broadcast Control Channel (BCCH)

– Paging Control Channel (PCCH)

– Common Control Channel (CCCH)

– Multicast Control Channel (MCCH)

– Dedicated Control Channel (DCCH)

• Traffic Channels: User-plane information– Dedicated Traffic Channel (DTCH)

– Multicast Traffic Channel (MTCH)

95

3GPP LTE

Channel Mappings

96

PCCH BCCH CCCH DCCH DTCH MCCH MTCH Logicalchannels

PMCH PDCCHPBCHPDSCH

PCH DL-SCH MCH

CCCH DCCH DTCH

PUSCH PUCCHPRACH

RACHBCH UL-SCHTransportchannels

Physicalchannels

Downlink Uplink

3GPP LTE

LTE Layer 2

• Layer 2 has three sublayers– MAC (Medium Access Control)

– RLC (Radio Link Control)

– PDCP (Packet Data Convergence Protocol)

97

DL UL

ROHC: Robust Header Compression * 3GPP TS 36.300

Segm.

ARQ etc

Multiplexing UE1

Segm.

ARQ etc...

HARQ

Multiplexing UEn

HARQ

BCCH PCCH

Scheduling / Priority Handling

Logical Channels

Transport Channels

MAC

RLCSegm.

ARQ etc

Segm.

ARQ etc

PDCP

ROHC ROHC ROHC ROHC

Radio Bearers

Security Security Security Security

...

Multiplexing

...

HARQ

Scheduling / Priority Handling

Transport Channels

MAC

RLC

PDCP

Segm.

ARQ etc

Segm.

ARQ etc

Logical Channels

ROHC ROHC

Radio Bearers

Security Security

3GPP LTE

RRC Layer

• Terminated in eNB on the network side.

• Functions– Broadcast

– Paging

– RRC connection management

– RB (Radio Bearer) management

– Mobility functions

– UE measurement reporting and control

• RRC states– RRC_IDLE

– RRC_CONNECTED

98

3GPP LTE

Resource Scheduling of Shared Channels

• Dynamic resource scheduler resides in eNB on MAC layer.

• Radio resource assignment based on radio condition, traffic volume, and QoS requirements.

• Radio resource assignment consists of:– Physical Resource Block (PRB)

– Modulation and Coding Scheme (MCS)

99

3GPP LTE

Radio Resource Management

• Radio bearer control (RBC)

• Radio admission control (RAC)

• Connection mobility control (CMC)

• Dynamic resource allocation (DRA) or packet scheduling (PS)

• Inter-cell interference coordination (ICIC)

• Load balancing (LB)

100

3GPP LTE

Other Features

• ARQ (RLC) and H-ARQ (MAC)

• Mobility

• Rate control

• DRX (Discontinuous Reception)

• MBMS

• QoS

• Security

101

3GPP LTE

DL Overview

• DL physical channels– Physical Downlink Shared Channel (PDSCH)

– Physical Broadcast Channel (PBCH)

– Physical Multicast Channel (PMCH)

– Physical Control Format Indicator Channel (PCFICH)

– Physical Downlink Control Channel (PDCCH)

– Physical Hybrid ARQ Indicator Channel (PHICH)

• DL physical signals– Reference signal (RS)

– Synchronization signal

• Available modulation for data channel– QPSK, 16-QAM, and 64-QAM

102

3GPP LTE

DL Physical Channel Processing

103

Scrambling

Modulation mapping

Layer mapping

OFDM signal generation

Resource element mapping

MIMO-relatedprocessing

Precoding

Mapping onto one or more transmission layers

Generation of signals for each antenna port

IDFT operation

3GPP LTE

DL Reference Signal

• Three types of DL reference signals– Cell-specific reference signals

• Associated with non-MBSFN transmission

– MBSFN reference signals

• Associated with MBSFN transmission

– UE-specific reference signals

104

3GPP LTE

DL Reference Signal

• Cell-specific 2D RS sequence is generated as the symbol-by-symbol product of a 2D orthogonal sequence (OS) and a 2D pseudo-random sequence (PRS).– 3 different 2D OS and ~170 different PRS.

– Each cell (sector) ID corresponds to a unique combination of one OS and one PRS ~510 unique cell IDs.

• CDM of RS for cells (sectors) of the same eNodeB (BS)– Use complex orthogonal spreading codes.

• FDM of RS for each antenna in case of MIMO

105

3GPP LTE

- cont.

DL Reference Signal

106

*With normal CP*3GPP TS 36.211

0l

0R

0R

0R

0R

6l 0l

0R

0R

0R

0R

6l

On

e an

ten

na

po

rtT

wo

an

ten

na

po

rts

Resource element (k,l)

Not used for transmission on this antenan port

Reference symbols on this antenna port

0l

0R

0R

0R

0R

6l 0l

0R

0R

0R

0R

6l 0l

1R

1R

1R

1R

6l 0l

1R

1R

1R

1R

6l

0l

0R

0R

0R

0R

6l 0l

0R

0R

0R

0R

6l 0l

1R

1R

1R

1R

6l 0l

1R

1R

1R

1R

6l

Fo

ur

ante

nn

a p

ort

s

0l 6l 0l

2R

6l 0l 6l 0l 6l

2R

2R

2R

3R 3R

3R 3R

even-numbered slots odd-numbered slots

Antenna port 0


Antenna port 1


Antenna port 2


Antenna port 3

3GPP LTE

- cont.

DL MIMO

• Supported up to 4x4 configuration.

• Support for both spatial multiplexing (SM) and Tx diversity (TxD).– SM

• Unitary precoding based scheme with codebook based feedbackfrom user.

• Multiple codewords (up to two).

– TxD: SFBC and CDD (Cyclic Delay Diversity).

• MU-MIMO supported.

• 3G Americas, “MIMO Transmission Schemes for LTE and HSPA Networks,” Jun. 2009, available at http://3gamericas.org

107

3GPP LTE

http://3gamericas.org/

UL Overview

• UL physical channels– Physical Uplink Shared Channel (PUSCH)

– Physical Uplink Control Channel (PUCCH)

– Physical Random Access Channel (PRACH)

• UL physical signals– Reference signal (RS)

• Available modulation for data channel– QPSK, 16-QAM, and 64-QAM

• Single user MIMO not supported in Release 8.– But it will be addressed in the future release.

– Multi-user collaborative MIMO supported.

108

3GPP LTE

UL Resource Block

109

1 slot (0.5 ms)

Resourceblock (RB)

Fre

qu

ency

Time

One SC-FDMA symbol

Su

bca

rrie

r

Referencesymbols (RS)

*PUSCH with normal CP

3GPP LTE

UL Physical Channel Processing

110

Scrambling

Modulation mapping

Transform precoding

SC-FDMA signal generation

Resource element mappingSC-FDMA

modulation

DFT-precoding

IDFT operation

3GPP LTE

SC-FDMA Modulation in LTE UL

111

Serial-to-

Parallel

M-IDFT

N-DFT

Zeros

0 1 1, , Nx x x

Parallel-to-

Serial

0 1 1, , Mx x x

Subcarrier Mapping

sub

carr

ier

0M

-1Zeros

One SC-FDMA symbol

Localized mapping with an option of adaptive scheduling or random hopping.

3GPP LTE

UL Reference Signal

• Two types of UL RS

– Demodulation (DM) RS Narrowband.

– Sounding RS: Used for UL resource scheduling Broadband.

• RS based on Zadoff-Chu CAZAC (Constant Amplitude Zero Auto-Correlation) polyphase sequence– CAZAC sequence: Constant amplitude, zero circular auto-

correlation, flat frequency response, and low circular cross-correlation between two different sequences.

112

2

2 , 0,1,2, , 1; for even2

( 1)2 , 0,1,2, , 1; for odd

2

k

r kj qk k L L

L

r k kj qk k L L

L

ea

e

* r is any integer relatively prime with L and q is any integer.

B. M. Popovic, “Generalized Chirp-like Polyphase Sequences with Optimal Correlation Properties,” IEEE Trans. Info. Theory, vol. 38, Jul. 1992, pp. 1406-1409.

3GPP LTE

UL RS Multiplexing

113

subcarriers

User 1

User 2

User 3

subcarriers

FDM Pilots CDM Pilots

3GPP LTE

UL RS Multiplexing

• DM RS: Associated with PUSCH or PUCCH– For SIMO: FDM between different users.

– For SU-MIMO: CDM between RS from each antenna

– For MU-MIMO: CDM between RS from each antenna

• Sounding RS: Not associated with PUSCH or PUCCH– CDM when there is only one sounding bandwidth.

– CDM/FDM when there are multiple sounding bandwidths.

114

3GPP LTE

- cont.

Cell Search

• Cell search: Mobile terminal or user equipment (UE) acquirestime and frequency synchronization with a cell and detectsthe cell ID of that cell.– Based on hierarchical synchronization signals.

• Primary SS (PSS) and secondary SS (SSS) are transmitted twice per radio frame (10 ms) for FDD.

• Cell search procedure1. 5 ms timing identified using PSS.

2. Radio timing and group ID found from SSS.

3. Full cell ID found from DL RS.

4. Decode BCH.

115

3GPP LTE

Random Access

• Non-synchronized random access.

• Open loop power controlled with power ramping similar toWCDMA.

• RACH signal bandwidth: 1.08 MHz (6 RBs)

• Preamble based on CAZAC sequence.

116

UE eNB

Random Access Preamble1

Random Access Response 2

Scheduled Transmission3

Contention Resolution 4CP Preamble

TCP TGP

RA slot = 1 ms

* TCP = 0.1 ms, TGP = 0.1 ms

3GPP LTE

Other Procedures

• Power control

• Uplink synchronization and uplink timing control

• Hybrid ARQ related procedures

117

3GPP LTE

LTE-Advanced Requirements

• Peak data rate: – 1 Gbps DL and 500 Mbps UL

• Latency– Less than 10 ms within Connected mode

– Less than 50 ms from Idle to Connected mode

• Spectrum– Up to 100 MHz bandwidth

– Support for non-consecutive bands (spectrum aggregation)

• Peak spectrum efficiency– 30 bps/Hz DL and 15 bps/Hz UL

118

3GPP LTE

LTE-A Features

• Carrier aggregation

• Enhanced MIMO

• Coordinated multi-point (CoMP) transmission and reception

• Relaying

119

3GPP LTE

- cont.

LTE-A: Carrier Aggregation

• In order to support up to 100 MHz bandwidth, two or more component carriers aggregated– Component carrier (CC): Basic frequency block which comply with R8

LTE numerology

– Each CC is limited to 20 MHz bandwidth (110 resource blocks).

– Maintains backward compatibility with R8 LTE.

• Supports both contiguous and non-contiguous spectrum.

• Also supports asymmetric bandwidth for FDD.

120

3GPP LTE

- cont.


121

3GPP LTE

- cont.

20 MHz

100 MHz

CC

60 MHzNon-contiguous

20 MHzR8 LTE

60 MHzContiguous


• Downlink multiple access scheme– OFDMA with CC-based structure: Re-use R8 spec for low cost & fast

development

– One transport block is mapped within one CC.

• Uplink multiple access scheme– N-times DFT-spread OFDM: Clustered DFT spreading

122

3GPP LTE

- cont.

LTE-A: Enhanced MIMO

• Downlink MIMO– Up to 8x8 (8 layer) configuration

– Additional RS: CSI-RS and UE-specific DM RS

– Support for MU-MIMO

– Enhancements to CSI feedback

• Uplink MIMO– Introduction of UL transmit diversity

– Introduction of up to 4x4 SU-MIMO

– Use of turbo serial interference canceller

123

3GPP LTE

LTE-A: CoMP TX & RX

• Improves coverage, cell-edge performance, and system throughput– DL: Joint processing, coordinated scheduling/beamforming

– UL: Multi-point reception

124

3GPP LTE

LTE-A: Relaying

• Improves coverage and cell-edge performance.

• Relay node is wirelessly connected to RAN via a donor cell.

125

Relay nodeDonor cell

3GPP LTE

LTE-A Documentations

• Ongoing progress highlighted in:– 3GPP TR 36.913, Requirements for Further Advancements for E-UTRA

(LTE-Advanced)

– 3GPP TR 36.814, Further Advancements for E-UTRA Physical Layer Aspects

126

3GPP LTE

- cont.

Outline

127




WiMAX


What is WiMAX?

• Worldwide Interoperability for Microwave Access

• IEEE 802.16-based system profile maintained by WiMAXForum– IEEE 802.16 standards only specify PHY and MAC layers. WiMAX

specifies overall system profile based on 802.16 air interface.

– WiMAX Forum certifies system components to ensure inter-operability.

• Mobile WiMAX– Based on IEEE 802.16e-2005 and IEEE 802.16-2004 standards.

128

WiMAX

IEEE 802.16 Evolution

• 802.16 (2002): Line-of-sight fixed operation in 10 to 66 GHz

• 802.16a (2003): Air interface support for 2 to 11 GHz

• 802.16d (2004): Minor improvements to fixes to 16a

• 802.16e (2006): Support for vehicular mobility and asymmetrical link

• 802.16m (in progress): Higher data rate, reduced latency, and efficient security mechanism

129

WiMAX

Mobile WiMAX System Profile

130

System profile

Release 1.0 Release 1.5 Release 2.0

IEEE Standard

802.16-2004 802.16e-2005

802.16Rev2802.16j

802.16m

CertificationWave 1Wave 2

Comments

•TDD only•1x2 SIMO in Wave 1•2x2 MIMO & beamformingin Wave 2•Bandwidth: 5, 8.75, & 10 MHz

•TDD & (H)FDD•Higher VoIP capacity•2x2 UL MIMO•UL 64-QAM•Bandwidth: up to 20 MHz•Multi-hop relay

•TDD & FDD•Candidate for IMT-Advanced

WiMAX

Source: WiMAX Forum

Mobile WiMAX Network Architecture

131

Mobileterminals

MobileWiMAX

base stationASN-GW CSN

ASN-GW: Access Service Network GatewayASN: Access Service NetworkCSN: Core Service Network

ASN

ASN

WiMAX

Mobile WiMAX Network Architecture

• Security– Strong mutual device authentication based on IEEE 802.16

security framework.

• Mobility and handover– Vertical (inter-technology) handover

– IPv4 or IPv6-based mobility management

– Dynamic and static home address configuration

– Dynamic assignment of Home Agent

• QoS– Support for different levels of QoS

– Admission control

– Implementation of policies

132

WiMAX

- cont.

Frame Structure

133

*IEEE Std 802.16e-2005

WiMAX

Frame Structure

• Preamble: Used for synchronization.

• FCH (Frame Control Header): Provides frame configuration information such as MAP (Media Access Protocol) message length, coding scheme, and usable sub-channel.

• DL-MAP and UL-MAP: Provide sub-channel allocation information.

• UL Ranging: Used to perform closed-loop time, frequency, and power adjustment as well as bandwidth requests.

• UL CQICH (Channel Quality Indicator Channel): Used to feedback channel state information.

• UL ACK: Used to feedback DL H-ARQ acknowledgement.

134

WiMAX

- cont.

Subchannelization and Slots

• Subchannelization schemes: Ways to divide frequency/time resources among users– PUSC (Partial Usage Subchannelization)

– FUSC (Full Usage Subchannelization)

– TUSC (Tile Usage Subchannelization)

– AMC (Adaptive Modulation and Coding)

• Slot is the basic unit of time/frequency grid.– Slot contains 48 data subcarriers.

• Localized and distributed resource allocation

135

WiMAX

Advanced PHY Layer Features

• Adaptive modulation and coding

• Hybrid ARQ

• Fast channel feedback via CQICH

• Support for QPSK, 16-QAM, and 64-QAM (optional in UL)

136

WiMAX

MAC Features

• QoS Support– 5 Categories of QoS: Unsolicited grant service (UGS), real-time

polling service (rtPS), extended real-time polling service (ErtPS), non-real-time polling service (nrtPS), and best-effort service (BE).

• Scheduling service– Fast data scheduler for both DL and UL

– Dynamic resource allocation

– QoS oriented

– Frequency-selective scheduling

• Mobility management

• Security

137

WiMAX

MIMO Features

• Beamforming– Improves coverage and capacity and reduces outage

probability.

• Space-time code– Provides spatial diversity and reduces fade margin.

• Spatial multiplexing– Achieves higher data rate.

– Up to 2x2 MIMO.

• Adaptive switching among beamforming, space-time coding, and spatial multiplexing

138

WiMAX

Other Features

• Fractional frequency re-use.

• Ranging: Closed-loop adjustments of time, frequency, and power.

• Power management through periodic sleep and listen.

139

WiMAX

802.16m Minimum Requirements

• OFDMA for both DL and DL

• Scalable bandwidth– 5 MHz to 40 MHz as a single RF carrier.– Higher bandwidth supported by carrier aggregation.

• Full duplex FDD, half-duplex FDD, and TDD

• Data latency: Less than 10 ms

• Up to 8x8 MIMO

• Integrated relay

• IEEE 802.16m working document– System requirements document (IEEE 802.16m-07/002r6)– System description document (IEEE 802.16m-07/003r6)

140

WiMAX

Outline

141




WiMAX


Summary

• Key technologies of 4G systems– Multicarrier-based radio air interface

• OFDMA and SC-FDMA

– Frequency domain equalization

– IP-based flat network architecture

– Multi-input multi-output (MIMO)

– Active interference avoidance and coordination

• Fractional frequency re-use (FFR)

– Fast multi-carrier frequency-selective resource scheduling

142


References and Resources

• 4G enabling technologies

– OFDM/OFDMA

• R. van Nee and R. Prasad, OFDM for Wireless Multimedia Communications, Artech House, 2000.

– Frequency domain equalization

• D. Falconer et al., “Frequency Domain Equalization for Single-Carrier Broadband Wireless Systems,” IEEE Commun. Mag., vol. 40, no. 4, Apr. 2002, pp. 58-66.

• H. Sari et al., “Transmission Techniques for Digital Terrestrial TV Broadcasting,” IEEE Commun. Mag., vol. 33, no. 2, Feb. 1995, pp. 100-109.

– SC-FDMA

• H. G. Myung & D. Goodman, Single Carrier FDMA: A New Air Interface for Long Term Evolution, John Wiley & Sons, Nov. 2008

• H. G. Myung et al., “Single Carrier FDMA for Uplink Wireless Transmission,” IEEE Vehicular Technology Mag., vol. 1, no. 3, Sep. 2006.

• http://hgmyung.googlepages.com/scfdma

143


http://hgmyung.googlepages.com/scfdma


– MIMO

• A. Paulraj et al., Introduction to Space-Time Wireless Communications, Cambridge University Press, May 2003.

• G. L. Stüber et al., “Broadband MIMO-OFDM Wireless Communications,” Proceedings of the IEEE, Feb. 2004, vol. 92, no. 2, pp. 271-294.

– Multicarrier scheduling

• G. Song and Y. Li, “Utility-based Resource Allocation and Scheduling in OFDM-based Wireless Broadband Networks,” IEEE Commun. Mag., vol. 43, no. 12, Dec. 2005, pp. 127-134.

144


- cont.


• 3GPP LTE – Spec

• http://www.3gpp.org/ftp/Specs/html-info/36-series.htm

• http://www.3gpp.org/ftp/Specs/html-info/25814.htm (old)

– 3G Americas

• http://3gamericas.org

– http://www.LTEwatch.com

145


- cont.


• WiMAX– IEEE 802.16e Spec

• http://standards.ieee.org/getieee802/download/802.16e-2005.pdf

– IEEE 802.16m working document (http://wirelessman.org/tgm/index.html)

• System requirements document (IEEE 802.16m-07/002r6)

• System description document (IEEE 802.16m-07/003r6)

• Evaluation methodology document (IEEE 802.16m-07/004r4)

– WiMAX Forum, “Mobile WiMAX - Part I: A Technical Overview and Performance Evaluation,” available at http://www.wimaxforum.org/sites/wimaxforum.org/files/documentation/2009/mobile_wimax_part1_overview_and_performance.pdf

146


- cont.

http://standards.ieee.org/getieee802/download/802.16e-2005.pdf



http://wirelessman.org/tgm/index.html

http://wirelessman.org/tgm/index.html

http://www.wimaxforum.org/sites/wimaxforum.org/files/documentation/2009/mobile_wimax_part1_overview_and_performance.pdf



WCNC 20102010.04.18

Dr. Hyung G. MyungQualcomm / Flarion

Questions? Thank you!

Towards 4G: Technical Overview of LTE & WiMAX

Documents