Evolution of the Air Interface v0 - Frank Rayal · Evolution of the Air Interface ... GSM IS-95A...

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© 2012 Telesystem Innovations Inc. 1

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Evolution of the Air InterfaceFrom 2G Through 4G and Beyond…

Frank Rayal

BLiNQ Networks/

Telesystem Innovations

Presentation to IEEE Ottawa Section / Alliance of IEEE

Consultants Network (AICN) - 2nd May 2012

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Evolution of Wireless Systems

GSM

IS-95A

IS-136

PDC

GPRS

IS-95B

EDGE

cdma2000

UMTSHSDPA/

HSUPAHSPA+

1xEV-DO

1xEV-DV

LTE LTE-A

2G 2.5G 3G 4G

~1991 (GSM)

~1998(GPRS)

~2001(UMTS)

~2011(LTE)

Acronyms

GSM: Group Special Mobile/Global System for Mobilecommunications

UMTS: Universal Mobile Telecommunication System

PDC: Pacific Digital Cellular (Japan) HSxPA: High Speed (Downlink/Uplink) Packet Access

GPRS: General Packet Radio Service EV-Dx: Evolution – Data Only/Data and Voice

EDGE: Enhanced Data Rates for GSM Evolution LTE-(A): Long Term Evolution – (Advanced)

CDMA: Code Division Multiple Access

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Multiple Access Technologies

TDMA FDMA

CDMA OFDMA

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Performance Summary

System Modulation Bandwidth Theoretical Maximum Realistic

GSM GMSK 200 kHz ~ 40 kbps 9.6 kbps

GPRS GMSK 200 kHz 171.2 kbps 40 kbps

EDGE GMSK/8-PSK 200 kHz 384 kbps 60-70 kbps

UMTS

(R99)

QPSK 5 MHz DL: 384 kbps

UL: 384 kbps

100 kbps

HSDPA

(R5)

DL: QPSK - 16 QAM

UL: QPSK

5 MHz DL: 14.4 Mbps

UL: 384 kbps

DL: 800 kbps

UL: 100 kbps

HSUPA

(R7)

DL: QPSK - 64 QAM

UL: QPSK - 16 QAM

5 MHz DL: 14.4 Mbps

UL: 5.72 Mbps

DL: 4 Mbps

UL: 1 Mbps

HSPA+

(R8)

DL: QPSK - 64 QAM

UL: QPSK - 16 QAM

5 MHz DL: 14-42 Mbps

UL: 11.5 Mbps

DL: 4.5 Mbps

UL: 2 Mbps

LTE DL: QPSK-64QAM 5/10/20

MHz

DL: 150 Mbps

UL: 51 Mbps

DL: 37 Mbps

UL: 16 Mbps

HSPA+: MIMO or DC required for 42 Mbps. DC requires twice the bandwidth.

LTE: DL assumes 2x2 MIMO in 20 MHz, 64-QAM; UL assumes 1x2 SIMO in 20 MHz, 16-QAM.

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Next Generation Wireless Technologies (4G; +)

> OFDM-based air interface

> Common features to achieve high-data rates

– High Modulation & Coding Schemes (MCS)

– MIMO antenna systems

> Spatial Multiplexing

> Space Time/Frequency Coding

– Beamforming

> Common features for link integrity

– Turbo codes

– Hybrid-ARQ

– Adaptive Modulation/Link Adaptation

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3GPP Key Performance Targets for LTE

Parameter Absolute RequirementReference Base Line

(R6: HSDPA/HSUPA)Comment

Do

wn

lin

k

Peak transmission rate > 100 Mbps 7 x 14.4 Mbps LTE: 20 MHz FDD, 2x2 spatial multiplexing

Reference: HSDPA in 5 MHz FDD, single

antennaPeak spectral efficiency > 5 bps/Hz 3 bps/Hz

Average cell spectral

efficiency> 1.6 - 2.1 bps/Hz/cell 3 - 4 x 0.53 bps/Hz/cell

LTE: 2x2 spatial multiplexing, interference

rejection combining receiver.

Reference: HSDPA, Rake receiver, 2 receive

antennas

Cell edge spectral

efficiency> 0.04 - 0.06 bps/Hz/user 2 - 3 x 0.02 bps/Hz As above, 10 users assumed per cell

Broadcast spectral

efficiency> 1 bps/Hz N/A Dedicated carriers for broadcast mode

Up

lin

k

Peak transmission rate > 50 Mbps 5 x 11 Mbps LTE: 20 MHz FDD, 2x2 spatial multiplexing

Reference: HSUPA in 5 MHz FDD, single

antennaPeak spectral efficiency > 2.55 bps/Hz 2 bps/Hz

Average cell spectral

efficiency> 0.66 - 1.0 bps/Hz/cell 2 - 3 x 0.33 bps/Hz

LTE: single antenna transmission, IRC

receiver.

Reference: HSUPA, Rake receiver, 2 receive

antennas

Cell edge spectral

efficiency> 0.02 - 0.03 bps/Hz/user 2 - 3 x 0.01 bps/Hz As above, 10 users assumed per cell

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LTE Air Interface

eNB UE

> Downlink

– OFDMA based access, with QPSK, 16QAM and 64QAM modulation (adaptive selection)

– MIMO and transmit diversity

– Scheduling, link adaptation, HARQ

> Uplink

– Single Carrier FDMA (SC-FDMA) access with QPSK, 16QAM and 64QAM (optional)

> Scheduling, link adaptation, HARQ

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Orthogonal Frequency Division Multiplexing (OFDM)

FDMA

OFDM

Bandwidth Saving

> Narrowband sub-carriers fade independently

> Does not require sophisticated frequency equalizers at the receiver

> Overlapping carriers increases spectral efficiency compared to

conventional FDM

> Orthogonality between carriers mitigates interference

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Modulation Schemes

> Higher order modulation schemes result in highest spectral efficiency

BPSK: 1bps/Hz QPSK: 2bps/Hz ππππ/4-QPSK: 2bps/Hz

8-PSK: 3bps/Hz 16-QAM: 4bps/Hz 64-QAM: 6bps/Hz

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��Digital Modulation Reach Comparison

> Higher order modulation schemes require higher signal quality to demodulate

– Higher SNR results in reduced range; hence higher order modulation schemes have shorter range

> Control signaling typically uses BPSK or QPSK with low code rate

1% PER; 100 Byte Packet; PB Channel.

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��Spatial Multiplexing

Increases channel capacity by creating multiple parallel channels

with no additional power or BW requirements:

Capacity Gain = Min (Tx , Rx) antennas

S4S2

S3S1

TX RX

h11

h22

h21

h12

Y = H S + n

S1

S2

y1

y2

=

2212

2111

hh

hhH

S3S4 S2S1

S3

S4

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LTE-Advanced

LTE (R8) LTE-Advanced (R10)

Peak Data Rate (Mbps)Downlink 300 1000

Uplink 75 500

Bandwidth (MHz) 20 100

Peak Spectral Efficiency

(bit/s/Hz)

Downlink 16.3(1) 30(2)

Uplink 4.32(3) 15(4)

Spectral Efficiency

(bit/s/Hz/cell), 3 km/h,

500 m ISD

Downlink

2 x 2 1.69 2.4

4 x 2 1.87 2.6

4 x 4 2.67 3.7

Uplink1 x 2 0.74 1.2

2 x 4 -- 2.0

Cell-edge User

Throughput

(bit/s/Hz/cell/user),

5 percentile, 10 users,

500 m ISD

Downlink

2 x 2 0.05 0.07

4 x 2 0.06 0.09

4 x 4 0.08 0.12

Uplink1 x 2 0.02 0.04

2 x 4 -- 0.07

(1) 4x4 MIMO; (2) Up to 8x8 MIMO; (3) 64QAM SISO; (4) Up to 4x4 MIMO

ISD: Inter-site distance

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Reaching the Limits of Technology?

Source: Qualcomm; LTE-Advanced: Heterogeneous Networks, Feb 2010

Network Topology Key To Capacity Enhancements

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Fractional Frequency Reuse

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LTE-A Radio Interface Technologies

LTE-Advanced Maximum Bandwidth

Carrier 1 Carrier 2 Carrier 3 Carrier 4 Carrier 5

100 MHz

Joint transmission: DL/UL cooperative MIMO;

Joint processing of received signals

Coordinated Multiple Point

Transmission and Reception (CoMP)

Carrier Aggregation

�� Peak Data Rate

�� Spectral Efficiency

�� Cell-edge Performance

�� Coverage

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Heterogeneous Networks

Enhanced ICIC (R10) Combined With Heterogeneous Networks

Pico-BS

Relay RF

Backhaul

C-RAN/RRH

Femto

(Indoor)

RelayCoverage

Hole



�� Coverage



�� Coverage�� Cell-edge Performance

�� Coverage

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Key Take-Aways

> To maximize capacity, wireless technologies incorporate the

latest in physical layer innovations; BUT we are soon reaching

the limit in terms of peak link-level capacity from both

technology and practical perspectives

> Next generation wireless systems (LTE-Advanced) will

leverage ‘network-level’ techniques to maximize average

capacity

> Enhancements in capacity and performance will shift to

network topology and architecture

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[email protected]

http://www.frankrayal.com

Telesystem Innovations

Evolution of the Air Interface v0 - Frank Rayal · Evolution of the Air Interface ... GSM IS-95A...

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