In the presentations, slides containing the symbol ** in...

Week Jan. 27

Date L/E Time Content Notes

Jan. 27 E 10.15-11.15 Exercise on cellular system. Attached

Jan. 27 L 11.15-12.15 Overview on wireless systems. Attached

Jan. 28 E 16.15-18.15 Overview of LTE system.

Attached

[4,5]

[1] G. Tartara, L. Reggiani, "Sistemi di radiocomunicazione", Polipress 2009, Milano, marzo 2009.

[2] T. S. Rappaport, "Wireless Communications: Principles and Practice", 2nd edition, Prentice Hall.

[3] A. Goldsmith, “Wireless Communications”, Cambridge University Press, 2005.

[4] D. Astely, E. Dahlman, A. Furuskar, Y. Jading, M. Lindstrom, S. Parkvall, "LTE: the evolution of mobile

broadband," Communications Magazine, IEEE , vol.47, no.4, pp.44,51, April 2009. Available at

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4907406&isnumber=4907392

[5] A. Roessler, M. Kottkamp, “LTE- Advanced (3GPP Rel.11) Technology Introduction”, Rohde-Schwarz

white paper. Available at

http://cdn.rohde-

schwarz.com/dl_downloads/dl_application/application_notes/1ma232/1MA232_1E_LTE_Rel11.pdf

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[*] In the presentations, slides containing the symbol ** in the bottom right corner of the page are the most important. The others are supposed to be additional, already discussed or facultative material.

Ex3 - In a cellular system with reuse factor N, know the transmitted power PT[W], the equivalent noise figure of the receiver TE[oK], the antenna gains GTX and GRX in dB, the path loss propagation law versus

distance d, PL=(d/d0), the signal bandwidth B and the number of active users per cell M, express the

probability of error of

(a) the downlink of an FDMA system with modulation QPSK; (b) the downlink of a CDMA system with processing gain G and modulation QPSK; (c) the uplink of a CDMA system with processing gain G and modulation QPSK

SOLUTION

In a cellular system with reuse factor N, the ratio between D, the minimum distance between two interfering

base stations, and R, the radius of the cell, is equal to NRD 3 .

The bit error probability of QPSK modulation error is

.1038.1;2

)( 230

00EE

BB TTkN

IN

EQEP

Let’s express the quantities EB (the average received energy per bit) and I0 (the unilateral power spectral density of interference) for the two cases: (a) Downlink FDMA (assume the serving BS is at maximum distance R and the 6 cochannel interfering BSs

at distance D)

.

/106

;2

/10

010/)(

0

010/)(

B

DdPI

B

RdP

R

PE

TXRX

TXRX

GGT

GGT

B

RB

(b) Downlink CDMA (synchronous in the cell, so that the cochannel interference is only ‘external’, coming from M users for each cochannel BS):

.

/106

;2

/10

010/)(

0

010/)(

B

MDdPI

B

GRdP

R

PE

TXRX

TXRX

GGT

GGT

B

RB

(c) Uplink CDMA (the cochannel interference is both ‘external’ I0,ext , from outside the reference cell, or ‘internal’ I0,int , coming from the (M-1) users in the same cell).

In this case PT is the transmitted power from the user.

B

MDdPI

B

MRdPI

III

B

GRdP

R

PE

G

BRR

TXRX

TXRX

TXRX

GGT

ext

GGT

ext

GGT

B

RBSB

/106

.)1(/10

;

;2

/10;2

2

010/)(

,0

010/)(

int,0

int,0,0

010/)(

As the ratio between I0,int/I0,ext is proportional to (D/R), the external component of interference can be ignored w.r.t. the internal interference contribute. Ignoring also the AWGN contribute w.r.t. to interference, we can simplify the expression as

1)-2(Mint,000

G

I

E

IN

E BB

.

Note that, assuming an Uplink Power Control that fixes the received power at the reference BS at a value PR, we would arrive to the same result considering that an interfering external user would again contribute with a

power PR(R/D) , so suggesting to ignore external interference w.r.t. the internal one.

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Wireless systems overview 1

Wireless systems: overview

Luca [email protected]@gmail.com


Outline

1. GSM

2. UMTS

3. HSPA

4. WiFi

5. ZigBee

6. UWB

7. Bluetooth

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GSM 1/4

[GSM 1800 Up – 1710-1785, Down 1805-1880 MHz ]


GSM 2/4

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GSM 3/4


GSM 4/4

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UMTS 1/8


UMTS 2/8

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UMTS 3/8


UMTS 4/8

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UMTS 5/8


UMTS 6/8

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UMTS 7/8


UMTS 8/8

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OVSF technique 2/2

WCDMA


HSPA 1/2

High Speed Downlink Packet Access (HSDPA) [2005]

High Speed Uplink Packet Access (HSUPA)

Evolved HSPA (HSPA+) [2008]

Shared-channel transmission

Shorter Transmission Time Interval (TTI) tracking of fast channel variations

Link adaptation

Fast scheduling

Fast retransmission and soft-combining, (H-ARQ)

16-QAM, 64-QAM

MIMO

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HSPA 2/2

HSDPA - 14 Mbit/s

HSUPA - 5.8 Mbit/s

Evolved HSPA (HSPA Evolution, HSPA+) With 2x2 MIMO, 64 QAM, aggregated carriers:up to 42 Mbit/s in the downlink up to 10.8 Mbit/s in the uplink (per 5 MHz carrier)

Dual-Cell HSDPA: a user can connect to two cells at the same time (2 x rate) [2009]

Dual-Cell HSUPA


WiFi 1/6

802.11 protocol

Release Frequency(GHz)

Modulation Data rate

(Mbit/s)

MIMO

a 1999 5 OFDM 6-54 1 x 1

b 1999 2.4 DSSS 1-11 1 x 1

g 2003 2.4 OFDM, DSSS

6-54 1 x 1

n 2009 2.4/5 OFDM 7.2 –72.2

/150(A)

4 x 4

ac [draft] 5 OFDM - 87.6 / 866.7(B)

8 x 8

(A) With 40 MHz bandwidth (instead of standard 20 MHz)(B) With 160 MHz bandwidth.

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WiFi 2/6


WiFi 3/6

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WiFi 4/6


WiFi 5/6

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WiFi 6/6

IEEE 802.11g [2003]

OFDM (802.11a) at 2.4 GHz

Max rate: 54 Mbit/s

IEEE 802.11n [2009]

+ MIMO (4 x 4), double bandwidth (40 MHz), aggregated frames

Max rate: from 54 to 600 Mbit/s

IEEE 802.11ac

Very high throughput (multi-stream, 256-QAM, 60 GHz)


ZigBee 1/6

IEEE 802.15.4

Global Standard

High density of nodes in a network

Simple protocol

Low Data rate

High data security

Flexibility

Very low power consumption (6 months – year of battery life)

Small size

Low cost

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ZigBee 2/6

Dual Physical layer: 2.4 GHz, 868-915 MHz

Data rates: 250 kbps (2.4 GHz), 40 kbps (915 MHz), 20 kbps (868 MHz)Direct-sequence spread spectrum coding (11 chips/ symbol)

Modulation: OQPSK (2.4 GHz), BPSK (868, 915 MHz)

Optimized for low duty cycle applications

CSMA / CA channel access

Multiple topologies

Star, peer-to-peer, mesh

Range: typically 50 m. (5 - 500 m.)


ZigBee 3/6

MASTER

SLAVE

ZigBee end device (RFD, FFD)

ZigBee router (FFD)

ZigBee coordinator (FFD)

Typical network organization

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ZigBee 4/6

Devices

FFD = full function device

The FFD can operate in three modes serving as a personal area network(PAN) coordinator, a coordinator, or a device. An FFD can talk to RFDs or other FFDs

RFD = reduced-function device

The RFD can talk only to a single FFD at a time. An RFD is intended for extremely simple applications (light switch or a passive infrared sensor) without need to send large amounts of data.


ZigBee 5/6

Main functions

Network CoordinatorSets up a networkTransmits network beaconsManages network nodesStores network node informationRoutes messages between paired nodesTypically operates in the receive state

Network NodeDesigned for battery powered or high energy savings Searches for available networksTransfers data from its application as necessaryDetermines whether data is pendingRequests data from the network coordinatorCan sleep for extended periods

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ZigBee 6/6

Network topologies

Star

The PAN coordinator (usually mains powered) initiates, terminates, routes communications in the network.

Allowed intra-nodes communication. The network can be ad hoc, self-organizing, self-healing. Advanced multi-hop routing.

Each network selects a unique PAN identifier

Peer-to-peer


UWB 1/7

UWB : a signal whose bandwidth is greater than 500 MHz,

or such that its fractional bandwidth (fH, fL upper and lower -10 dB frequencies)

25.02

LH

LH

ff

ff

FCC emission limits

Aggregate interference from UWB transmissions should be “undetectable”

(or has minimal impact) to narrowband receivers

UWB EIRP Emission level[dBm/MHz]

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UWB 2/7

WPAN Low Rate (LR-WPAN)

IEEE 802.15.4

IEEE 802.15.4a -2007 “Wireless Medium Access Control (MAC) and Physical Layer(PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs)Amendment 1: Add Alternate PHYs”

The main interest is in providing communications and high-precision ranging/localizationcapability (<1 meter accuracy); as well as scalable data rates, low complexity, powerconsumption and cost

WPAN High Rate (HR-WPAN)

ECMA 368 – (3° edition, Dec. 2008)“High Rate Ultra Wideband PHY and MAC Standard” – based on MB-OFDM

WiMedia Alliance


UWB 3/7

• Impulse-radio based (pulse-shape independent)

• Support for different receiver architectures (coherent/non-coherent)

• Flexible modulation format

• Support for multiple rates

• Support for SOP (simultaneously operating piconets)

LDR-UWB

• Rates at 851 kb/s - 1000 kb/s.

• 16 channels in three UWB bands (500 MHz, and 3.1 - 10.6 GHz).

• Sub-GHz band group (250-750 MHz), the low band group (3.1-5 GHz) and the high band group (6-10.6 GHz).

• + ALOHA (UWB) channel access

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UWB 4/7

Technology: LDR-UWB key-points and strenghtnesses

Extremely wide bandwidth characteristics (UWB) that can provide very robust performance under harsh multipath and interference conditions.

Concatenated forward error correction (FEC) system to provide flexible and robust performance under harsh multipath conditions

Optional UWB pulse control features to provide improved performance under some channel conditions while supporting reliable communications and precision ranging capabilities.


UWB 5/7

Channel Assignment

-3 dB Bandwidth =494 or 1482 MHz

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UWB 6/7

● The UWB-PHY is required to support both coherent and non-coherentreceivers

● The modulation format is a combination of Pulse Position Modulation(PPM) and Binary Phase Shift Keying (BPSK)

● A UWB symbol is capable of carrying two bits of information: one bit is used to determine the position of a burst of pulses while an additional bit is used to modulate the phase (polarity) of this same burst

Technology: 802.15.4a main modulation characteristics


UWB 7/7

Symbol structure

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Bluetooth 1/4

Technology: IEEE 802.15.1 main features

Global Standard

‘Ad hoc’ connections.

Concept of ‘unconscious connectivity’.

Voice + data

Flexibility

Security

Low Consumption

Small size

Low cost

www.bluetooth.org


Bluetooth 2/4

Band: ISM at 2.4 GHz: 2400-2483.5 MHz

PowerClass

Maximum Output Power

Nominal Output Power

Minimum Output Power

Power Control

1 100 mW (20 dBm)

N/A 1 mW Pmin<4 dBm - Pmax

2 2.5 mW (4 dBm)

1 mW 0.25 mW (-6 dBm)

Optional

3 1 mW (0 dBm)

N/A N/A Optional

Countries Frequency RF channels

USA, Europa 2,400 - 2,4835 GHz f = 2402 + k MHzk = 0,…,78

Francia 2,4465 - 2,4835 GHz

f = 2454 + k MHzk = 0,…,22

Channels of 1MHz + guard bands of 2 and 3.5 MHz

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Bluetooth 3/4

Medium access

FH-CDMA (1600 hops / second)

Modulation

Gaussian frequency-shift keying (GFSK)Basic rate: 1 Mbit/s

[Bluetooth 2.0+] [2004] π/4-DQPSK, 8-DPSK modulation may also be used

Enhanced Data Rate (EDR): 2, 3 Mbit/s


Bluetooth 4/4

Two layers: Piconet and Scatternet

Piconet: two or more Bluetoothstations that share the same channelOne unit will be the MASTER and the others SLAVES (max 7).

More Piconet can create a Scatternet.

SLAVE can join more piconets in TDM and a MASTER can be SLAVE in anotherpiconet.

MASTER

SLAVE

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References

[1] www.3gpp.org

[2] F. Adachi, M. Sawahashi, K. Okawa, “Tree-structured generation of orthogonal spreading codes with different lengths for forward link of DS-CDMA mobile radio”, Electronics Letters, 2nd Jan. 1997, vol. 33, No. 1.

[3] IEEE 802.11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications http://standards.ieee.org/getieee802/

[4] IEEE 802.15: Wireless PAN Medium Access Control (MAC) and Physical Layer (PHY) Specificationshttp://standards.ieee.org/getieee802/

[5] http://www.zigbee.org

[6] Standard ECMA-368 High Rate Ultra Wideband PHY and MAC Standard http://www.ecma-international.org/publications/ standards/ Ecma-368. htm

[7] http://www.wimedia.org


Outline

1. The evolution of cellular networks

2. LTE Standard status

Enabling technologies

Network architectureSystem architecturePhysical layerRadio planning

3. LTE-Advanced

4. Next generation networks

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The evolution of cellular networks 1/5

Mobile traffic forecast

[Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2012–2017]

Combined annual growth rate



Mobile trafficforecast

[Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2012–2017]

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The mobile technology generations

2G 3G 4G … 5G

GSM

FDMA / TDMA

Macro-cellsR = 1 - 20 km

Micro-cells in dense urban areas

Data rate 10 … 100 kbit/s

?UMTS

CDMA

LTE-A

OFDMA

Macro-cellsR = 1 – 20 km

Increased use of micro-cells and DAS

Data rate 1 … 10 Mbit/s

Macro-cellsR = 1 – 20 km

Hetnets

Data rate 10 … 100 … 1000 Mbit/s

LTE

OFDMA

HSPAHSPA+

GPRSEDGE




ITU key features of IMT (International Mobile Telecommunications) – Advanced (4G)

- a high degree of commonality of functionality worldwide while retaining the flexibilityto support a wide range of services and applications in a cost efficient manner

- compatibility of services within IMT and with fixed networks- capability of interworking with other radio access systems- high quality mobile services- user equipment suitable for worldwide use- user-friendly applications, services and equipment- worldwide roaming capability- enhanced peak data rates to support advanced services and applications (100 Mbit/s

for high and 1 Gbit/s for low mobility).

[www.itu.int]

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5G (2020 ?)

No official definition for what comes beyond 4G is available yet.

Let us guess …

- Further increase in network capacity, spectral efficiency, energy efficiency- pervasive user connectivity- high service quality - User personalization- High context awareness


1/3

Long Term EvolutionRel see Work Plan for Features in each Release

Spec version number(see note 4)

Functional freeze date, indicative only (see note 3)

Rel-12 12.x.y Stage 1 freeze March 2013

Stage 2 freeze December 2013

Stage 3 freeze June 2014 (RAN protocols: September 2014)

Rel-11 11.x.y Stage 1 freeze September 2011

Stage 2 freeze March 2012

Stage 3 freeze September 2012 (core network protocols stable December 2012, radio access protocols stable March 2013 -though performance parts of RAN work items may not be complete before June 2013)


Stage 2 freeze September 2010

Stage 3 freeze March 2011 (protocols stable three months later)

Rel-9 9.x.y Stage 1 freeze December 2008

Stage 2 freeze June 2009



Stage 2 freeze June 2008


LTE Standard status

“LTE”

“LTE-Advanced”

150 Mbps with 20 MHz, 2x2

1 Gbps with 40 MHz, 8x8

Small enhancements including VoIP, femto handovers, …

[www.3gpp.org]

Enhancements including CoMP, HetNets

…

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2/3LTE Standard status

[www.3gpp.org]

"Stage 1" refers to the service description from a service-user’s point of view.

"Stage 2" is a logical analysis, breaking the problem down into functional elements and the information flows amongst them across reference points between functional entities.

"Stage 3" is the concrete implementation of the protocols appearing at physical interfaces between physical elements onto which the functional elements have been mapped.

ITU-T (originally CCITT) method for categorizing specifications (Recommendation I.130).


Long Term Evolution - Advanced

Release 10

Higher capacity for fulfilling ITU 4G requirements

- Increased peak data rate, DL 3 Gbps, UL 1.5 Gbps- Higher spectral efficiency, from a maximum of 16 bps/Hz in R8 to 30 bps/Hz in R10- Increased number of simultaneously active subscribers- Improved performance at cell edges (e.g. for DL 2x2 MIMO at least 2.40 bps/Hz/cell)

Main new functionalities introduced in LTE-Advanced

- Carrier Aggregation (CA)- Enhanced use of multi-antenna techniques (MIMO)- Support for Relay Nodes (RN).

LTE-A 3/3LTE Standard status

[www.3gpp.org]

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Network architecture

More functionality in the base station (eNodeB)

Packet switched domain

System architecture

Channel dependant scheduling

Physical layer

OFDMA in downlink

SC-FDMA in uplink

MIMO (multiple antenna technologies)

Radio Planning

Frequency Reuse 1

(No frequency planning)

Fractional frequency reuse (FFR)

Enabling technologies 1/1


Physical layer 1/16

Uplink resource allocation: SC-OFDM x frame

Downlink resource allocation: OFDMA x frame

The downlink and uplink (time, frequency) grids are composed by resource blocks of 12 sub-carriers (frequency spacing = 15 kHz) x 0.5 ms ( = 1 timeslot).

FDD: Timeframe structure 1 TDD: Timeframe structure 2

Frequency flexibility and bandwidth scalability

Bandwidths: 1.4 , 3, 5, 10, 15, 20 MHz

Carriers for FDD and TDD: 698 – 915 MHz, 1.4 GHz, 1.7 – 2 GHz, 2.3 – 2.6 GHz

Peak data rates: 75 (UL) / 300 (DL) Mbps

Reduced latency: < 10 ms

Basic parameters

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LTE and next generation mobile networks

3/16

6/7 OFDM symbols

Sub carrier spacing = 15 kHzCP length = 5.2 - 4.7 s / 16.7 s

Frame structure[10 TTI]

TTI = 1 ms

2 time-slots

Physical layer

Time organization

Modulation

(DL) QPSK, 16-QAM, 64-QAM(UL) QPSK, 16-QAM, (64-QAM)

TTI

slot

sym

frame


OFDMA: Orthogonal Frequency Division Multiple Access

The signal is based on OFDM, i.e. a superposition of N orthogonal channels, each one associated to a sub-carrier. A resource block (RB) occupies 12 adjacent sub-carriers.

Sub-carriers are separated by a fixed frequency spacing f = 15 kHz

Symbol duration T = 1/ f = 66.67 s

Each symbol is completed by the cyclic prefix (CP), for a duration = T + TCP = 71.35 s

Normal cyclic prefix TCP = 5.2 s, 4.7 s

Extended cyclic prefix TCP = 16.7 s

DownlinkOFDMA

Physical layer

Bandwidth [MHz] 1.4 3 5 10 15 20

N (RB) 72 (6) 180 (15) 300 (25) 600 (50) 900 (75) 1200 (100)

DL band [MHz] 1.095 2.715 4.515 9.015 13.515 18.015

UL band [MHz] 1.080 2.7 4.5 9 13.5 18

Sampling rate [Mbaud] 0.5 x 3.84 1 x 3.84 2 x 3.84 4 x 3.84 6 x 3.84 8 x 3.84

FFT size 128 256 512 1024 1536 2048

4/16

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SC-FDMA Single Carrier FDMA

5/16UplinkSC-FDMA

OFDM has a high PAPR (Peak Average Power Ratio)

This requires highly nonlinear power amplifiers, i.e. energy consuming and expensive at UE side …

Reduced PAPR means lower RF hardware requirements.

SC-FDMA combines the PAPR of single-carrier system with the multipath resistance and flexible subcarrier frequency allocation of OFDM.

While OFDMA transmits data in parallel across multiple subcarriers, SC-FDMA transmitsdata in series employing multiple subcarriers

Physical layer


6/16UplinkSC-FDMA

OFDMA : parallel transmission of multiple symbols

S / P IFFT P/SRF up conv.

R (sym/s) an sk

D/A

fC

+CP

SC- FDMA : modulation symbols go through another FFT block before IFFT

IFFT P/SRF up conv.R

(sym/s)

sk

D/A

fC

+CP

TX

FFT(n)

an

TX

This process reduces PAPR considerably.

Physical layer

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7/16

0

resourceblock (RB) …..

Slotnumber 1 2 18 19

Subframe (TTI)

Radio frame 1 = 10 ms

resource element = 1 sub-carrier x 1 OFDMA symbol time

1 RB = 12 sc x 7 OFDMA symbols (normal CP)

12 sc x 6 OFDMA symbols (extended CP)…..N

sub

carr

iers

Downlink / UplinkFrame - FDD

12 sc

A user is assigned a set of resource blocks.

Physical layer

180

KH

z


Extended CP

7 symbols = 0.5 ms 6 symbols = 0.5 ms

12

su

bca

rrie

rs =

18

0 k

Hz

Resource ElementPhysical layerResource block

Each RB has 84 or 72 resource elements.

Normal CP

Each resource element is loaded by 2, 4 or 6 bits (QPSK, 16-QAM, 64-QAM).

The assignment for an UE of an RB corresponds to 144 ksps or 168 ksps288-864 or 336-1008 kbit/s

8/16

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9/16Downlink / UplinkFrame - FDD

Coding: Turbo parallel code, R = 1/3Tailbiting convolutional code, R = 1/3

Rates: 0.35, 0.45, …, 0.95 associated to QPSK, 16-QAM, 64-QAM

Physical layer

Control channels, reference symbols.

PSCH = Primary Synchronization ChannelSSCH = Secondary Synchronization ChannelPBCH = Physical Broadcast ChannelRS = cell-specific Reference Signal (for each Tx antenna)PCFICH = Physical Control Format Indicator ChannelPHICH = Physical Hybrid ARQ Indicator ChannelPDCCH = Physical Downlink Control Channel

[see … http://paul.wad.homepage.dk/LTE/lte_resource_grid.html]


10/16

0

resource block (RB)

Slotnumber 1

Subframe

Radio frame 2 = 2 half-frames = 2 x 5 ms

…..

N s

ubca

rrie

rs

Downlink / UplinkFrame - TDD

4 9Subframenumber 0

DwPTS, GP, UpPTS DwPTS, GP, UpPTS

Several uplink/downlink divisions of subframes

resource element = 1 sub-carrier x 1 SC-OFDM symbol time

Physical layer

DwPTS = Downlink Pilot Time SlotGP = Guard PeriodUpPTS = Uplink Pilot Time Slot

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TX architecture

Main operations for downlink signal generation

Scrambling Modulation

Layermapper

Precoder

Encoding Elementmapper

OFDMmodulator

Scrambling ModulationEncoding Elementmapper

OFDMmodulator

….. …..

Physical layer

x multiple antennas

11/16

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Physical layer 2/16

Italy

Bandwidth assignments in Sept. 2011:

- 800 MHz: 2 blocks (1 block = 5 MHz FDD) to Vodafone Italia, Telecom Italia, Wind Telecomunicazioni

- 1800 MHz: 1 block (1 block = 5 MHz FDD) to Vodafone Italia, Telecom Italia, 3 Italia

- 2000 MHz: no offers

- 2600 MHz: 4 blocks (1 block = 5 MHz FDD) to 3 Italia and Wind Telecomunicazioni, 3 blocks to Telecom Italia and Vodafone Italia.


Spatial mutiplexing

SU-MIMO [DL]

Open loop [from UE: RI + CQI]

2 x 2 [Capacity x2 during a subframe]

4 x 4 [Capacity x2, x3, x4]

Closed loop [from UE: RI + CQI + PMI]

2 x 2 [Capacity x1 or x2]

4 x 4 [Capacity x1, x2, x3, x4]

N. layers <= N. antennas

Multiple antennasPhysical layer 14/16

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Spatial mutiplexing

MU-MIMO [typically 2 users]

MU-MIMO is transparent to the UEs.

Each layer is addressed to one UE

More users share the same RB !

Precoding provides a beamforming effect

MU-MIMO increases cell capacity

SU-MIMO increases peak UE data rate

Physical layerMultiple antennas

15/16


Performance

[T. Nakamura (3GPP TSG‐RAN Chairman), «3GPP LTE Radio Access Network», GSMA Americas Conf., June2010]

Rel. 8 LTE Performance Verification

Physical layer 16/16

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LTE-Advanced 1/2

Main objectives

- Peak data rate: DL 3 Gbps – UL 1.5 Gbps

1 Gbps data rate will be achieved by 4-by-4 MIMO and transmission bandwidth wider than approximately 70 MHz

- Peak spectrum efficiency: 30 bps/Hz in Rel. 10

DL: Rel. 8 LTE satisfies IMT-Advanced requirement (15 bps/Hz)UL: Need to double from Release 8 to satisfy IMT-Advanced requirement

(3.75 bps/Hz vs 6.75)

- Increased number of simultaneously active subscribers

- Improved performance at cell edges


LTE-Advanced 2/2

Main features

- Improved MIMO: improved codebook/feedback for MU-MIMO (up to 50% spectral efficiency gain), added 8x8 DL and 4x4 UL

- CA: Carrier aggregation to achieve wider bandwidth. Support of spectrum aggregation for peak data rate and spectrum flexibility.

- Relay Nodes (RN)

- Coordinated multipoint transmission and reception (CoMP) for cell-edge user throughput, coverage, deployment flexibility

[Rel. 10]

[Rel. 11]

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Next generation networks 1/8

Cooperation

CoMP: Coordinated multipoint transmission and reception

Key factors

Multiple transmit and receive antennas from

multiple sites

Enhance the received signal quality and decrease

the received interference

3GPP CoMP techniques classification

- Coordinated scheduling and coordinated beamforming (CS/CB)Multiple coordinated TPs share only CSI for multiple UEs, while data packets are available onlyat one TP.

- Joint transmission (JT)The same data transmission from multiple coordinated TPs with appropriate beamformingweights.

- Transmission Point selection (TPS)Transmission of beamformed data for a given UE is performed at a single TP at each timeinstance, while the data is available at multiple coordinated TPs.


2/8

Broadcast MIMO Network MIMO

Next generation networksKey factors

eNB

UE

UE

UE

eNB 1

eNB 2

eNB 3

UE

UE

UE

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3/8

Heterogeneous networks

Macrocell [N. users > 256]

Microcells [N. users > 100]

Small cells complement macrocells for improving throughputand coverage.

The approach can include theuse of micro-cells, pico-cells,low-power remote radio units(RRH, DAS) and othertechnologies (e.g. Wi-Fi).

Picocells[N. users = 30 - 100]

Femtocells[N. users < 10-30]



4/8

Relay nodes (RN)

RN improve the possibility for efficient heterogeneous network planning. RN is connected tothe Donor Macro Base Station (DeNB in LTE) via a radio interface (Un in LTE-A).

In the Donor cell, radio resources are shared among UEs served directly by the Donor BSand the Relay Nodes. In general RNs work in a frequency or time division schememanaged by the donor BS.

Macrocell

RN1

RN2

DeNB

UE1

UE2


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5/8

SON - Self Organizing Networks

SON is a set of solutions and technologies for making

planning (e.g. frequency reuse), configuration ("plug-and-play" paradigm), management (e.g. a SON establishes neighbor relations automatically), optimization (e.g. BS parameters), healing (e.g. in case of a BS failure)

of mobile radio access networks easier, more efficient and less expensive.



6/8

Centralized processing

The trend for next generation networks is to separate RF function in the remote radio heads (RRH)from baseband processing, performed in central units (CU). RF signals are down converted,digitalized and transmitted to the CU for demodulation.

The existing solutions are CPRI (Common Public Radio interface) or OBSAI (Open Base Station Architecture Initiative).

RRH A1

RRH A2

RRH A3

RRH B1

RRH B2

RRH B3

BBU B1

BBU B2

BBU B3

…

BBU A1

BBU A2

BBU A3

MU

X /

DE

MU

X

Basebandcentralprocessing


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7/8

DAS – Distributed antenna systems

They are an evolution of RRHs since they represent the implementation of a more integrated, at thephysical layer, system with multiphe RRHs that share baseband processing.

Transport networks

In this context, front-hauling, as the last mile of radio access networks, is a crucial issue for nextgeneration networks.

Backhaul

networkCU

RRH

…

Fronthaul

network

Internet



8/8

HW

Dense networks with smaller cells

More spatial dimensions (antennas)

… More connections

SW

More cooperation

Automatic and adaptive configurations according to the radio environment (channels, traffic, …)

… More Smartness


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References

[1] 3GPP TS 36.201: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer; General description".[2] 3GPP TS 36.211: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation "[3] 3GPP TS 36.212: "Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding"[4] 3GPP TS 36.213: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures"[5] 3GPP TS 36.302: "Evolved Universal Terrestrial Radio Access (E-UTRA); Services provided by the physical layer"[6] 3GPP TS 36.306: "Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio access

capabilities"[7] 3GPP TS 36.321: "Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Acces Control (MAC) protocol

specification"[8] 3GPP TS 36.322: "Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Link Control (RLC) protocol

specification"[9] 3GPP TS 36.323: "Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol

(PDCP) specification"[10] 3GPP TS 36.331: "Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC) protocol

specification".

Books

[*] E. Dahlman, S. Parkvall, J.Sköld ,P. Beming, «3G Evolution: HSPA and LTE for Mobile Broadband», AcademicPress, 2010.

[*] H. Holma, A. Toskala, « LTE for UMTS: Evolution to LTE-Advanced», Wiley, 2011.[*] C. Johnson, «Long Term Evolution in Bullets», CreateSpace Independent Publishing Platform, 2012.

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