Telecommunications in ITS

Access networks Wired, Wireless (WPAN, GSM)

Martin Šrotýř – srotyr@fd.cvut.cz

Categories in network hierarchy

Categories in network hierarchy

Classes of transmission media

Access Access networksnetworks

WiredWired

WirelessWireless

MetallicMetallic

OpticalOptical

StaticStatic

NomadicNomadic

MobileMobile

CATVCATV

xDSLxDSL

PLCPLC

AONAON

SatelliteSatellite

GSM,UMTSGSM,UMTS

WiMAXWiMAX

WiFiWiFi

PONPON

EthernetEthernet

Wired media

• metallic lines– Symmetrical pairs:

telephone pairs in local cables, internal wiring of buildings (CAT 5E)

– Coaxial cable: CATV networks, computer bus type network

– Power lines: currently in use for the media signals (PLC, Power Line Communication)

Wired media

• metallic lines– copper wires

– twisted pairs• unshielded

• shielded

– coaxial cables

Wired media

• optical lines– Optical fibres

– Singlemode– Multimode– Gradientmode

Wired access networksTypical representative of the entire spectrum of available

solutions:• CATV to connect customers to Internet via cable TV network

• PLC (PDSL/BPL) technology for transfer of the data via power cables

• xDSL technologies (such as HDSL, ADSL, VDSL etc.) using the access network of telecommunication networks mostly CAT 1.

• FTTx (Fiber To The X (Home / Building / Network))

• Ethernet networks using UTP cables

CATV• In the band of cable television networks (42 – 750 MHz) is usually

enough unfilled channels of 6 MHz wide. • In the upload direction are used „narrow“ channels

within 5 – 40 MHz• Connections is asymmetric, like e.g. the ADSL.• Through 6 MHz channel in „download“ direction can be achieved

data rate up to 27 Mbit/s or 36 Mbit/s. Depending on the type of modulation.

• The opposite direction is usually about hundreds of kilobits up to units of megabits.

• Every channel is shared by multiple participants – according to quality of service provided to users – it can be shared up to hundreds of users.

• Existing cable TV lines are fundamentally unidirectional, with one transmitter and many receivers in a tree architecture, ie. multiplexed media type „broadcast“.

• IP requires a two-way transmission (duplex).• It is necessary to rebuild wiring - active elements are

unidirectional.• Passive components (splitters, hubs) and coaxial cabling

are in principle duplex.• Nodal device to connect to the Internet are located at the

base of each analog segment whose IP connectivity are dealt separately from the television signal distribution.

CATV

Typical topology analog TV cable network

Node

Coaxial cableFiber optics

Splitter

Hub

Amplifier

PLC – Power Line Communication

Referred also as BPL (Broadband over Power Line)

• Designed for transmission of information over powerlines of LV and HV.

• Range in compliance with reference properties with „ideal“ cable is– up to 400m on LV distribution– up to 700m on HV distribution

• Data rate up to 200Mbit/s.• Possibility of repeating

(reinforcement)

PLC – Power Line Communication

Especially from a system perspective PLC is a truly high-tech access technology.

•QoS (802.1p) with multilevel priority of queues and programmatically adjusting mechanism of classification priorities for simultaneous multimedia applications in real time.•The possibility distribution of video and audio signals.

•Programmatically adjustable bandwidth.

Principle of PLC

It uses a metallic twisted pair where the usable frequency range is up to about 1.1 MHz.

Because the transfer characteristics of the transmission medium it does not guarantee comparable parameters in the whole frequency spectrum, the principle of the ADSL is based on band division to sub-bands, each of which is individually used based on the identification of its properties by the initialization of the modem.

ADSL – Asymetric Digital Subscriber Line

Allocation of spectrum for ADSL 1st gen.

The lowest 64 Khz band•is designed exclusively for the transmission of analog telephone service with separation zone 60 kilobytes / s, ie. a total of 64 kilobytes / s, or for 2B + D ISDN service.

Band from 64Khz to 1.1MHz•is divided into 256 sub-band. Each sub-band with a width of 4 kHz is an independent channel and is used with a define transmission capacity measured by at initialization of the modem parameters.

Transmission capacity of individual xDSL and ADSL versions

ADSL – Asymetric Digital Subscriber Line

Setup in xDSL

Setup in xDSL

Customer house detail

Wireless media

• WPAN (Bluetooth, UWB, ZigBee)

• WLAN (WiFi)

• WMAN (WiMAX)

• WWAN (GSM)

IEEE 802.15.1 – Bluetooth

• Since 1998 – SIG (Special Interest Group)• Bluetooth v1.1 has been adopted as the standard IEEE

802.15.1 in 2002• Maximal transfer rate:

V1.1 ~ 1 Mbit/s (720 kbit/s)V2.0 EDR ~ 2,1 Mbit/s (2007)V3.0 HS ~ 24 Mbit/s (2009)V4.2 ~ 24 Mbit/s (2014)

• It works on 2,4 GHz band with FHSS (Frequency Hopping Spread Spectrum)

• Aims to reduce consumption and the Internet of Things• Range 10 to 100 m (depending on power)

IEEE 802.15.3 – UWB (UltraWideBand)

IEEE 802.15.3 • Approved 06/2003 • Cooperation with 802.11b/g, 802.15.1 and 802.15.4• Low power consumption, data transper rate up to 55 Mbit/s

(5 types of modulation), TDMA, QoS

IEEE 802.15.3 – future

WiMedia Alliance (Intel) vs.

Freescale (Motorola)

UWB as a basis for further development:

• Wireless USB

• CableFree USB

• Wireless FireWire – IEEE 1394

• ECMA 368, 369 (WiMedia Alliance) (480 Mbit/s)

• Pulse~LINK CWave (890 Mbit/s, theoretically up to 1,35 Gbit/s)

IEEE 802.15.3

IEEE 802.15.3c • Wireless HD (WiHD)• WiMedia Alliance + others • 60 GHz• 2 ~ 3 Gbit/s (in the future 25 Gbit/s)• Smart antennas – NLOS• security against piracy

IEEE 802.15.4 – ZigBee

• 3 unlicensed bands: 2,4 GHz (worldwide, 16 channels spaced 5 MHz, 240

kbit/s/channel) 868 MHz (Europe, 1 channel, 20 kbit/s) 915 MHz (Amerika and Australia, 10 channels, 40

kbit/s/channel)• Range is units up to tens of meters, self-configuring network

with more jumps• RFD ( Reduced Functionality Device), FFD (Full Functional

Device)• Up to 65 000 devices• Very low energy consumption, low price

IEEE 802.15.4 – ZigBee

GSM• NMT

• GSM

• GPRS

• EDGE

• UMTS

NMT – Nordic Mobile Telephony (1 G)

– Finland, Sweden, Norway, Denmark

Analog cellular (radio)telephony network

It can transfer not only voice but also text messages DMS (Data and Messaging Service)

Classical telephony with circuit switching

What is NMT

NMT architecture and used techniques

FM – frequency modulation

FDMA – Frequency Division Multiple Access

• Transmitting bands BS: 463-467,5 MHz • Transmitting bands MS: 453-457,5 MHz • Channel width: 25 kHz • Number of channels: 180

NMT vs. GSM

NMT GSM analog. digital.

Channel width: 25 kHz 200 kHz

Number of users in 1 channel: 1 8

Max. transfer rate: 0,4 kbps 76,8 or 115,2kbps

+ large percentage of the area coverage – very good radio wave propagation

- Relatively low network capacity

- None encryption – easy tapping (listening)

NMT in Czech Republic

• Frequency: 450 MHz• Provider: Eurotel• Year of start: 1991• Year of end: 2006• Today: data transfers

via CDMA

What is GSM

GSM - Global System for Mobile communications (2 G)

Digital cellular (radio)telephony network

It can transmit not only voice but also text messages SMS and data (fax, pictures, internet, …)

Classical telephony with circuit switching

GSM history

1. In 1982, CEPT estabilish the GSM group (Group Special Mobile)

The proposed system had to meet these requirements: Quality and safe transmission of human speech Low price for service and device Possibility of international roaming Frequency efficiency ISDN compatibility Efficiency in future Compatibility with other Telco systems

GSM history

2. 1988 - CEPT began creating GSM specifications

3. 1989 – responsible for GSM standardizing was moved to the European Telecommunications Standards Institute (ETSI)

4. 1990 – specification of the GSM Phase 1 was declared as a standard

5. 1992 – first GSM provider “Oy Radiolinja Ab” in Finland

6. 1996 – first GSM network in CR (Eurotel)

7. 1999 – first GPRS network in CR (Eurotel)

GSM standards

Phase 1

• Basic voice and fax/data services

• International roaming• Call transfer and blocking• SMS service• SIM card and encryption

Phase 2

• Added specifications• Identification of the

called and calling• Call hold• Conference calls• Closed subscriber

groups• Data services extension

GSM standards

Phase 2+

• Added specifications• Private numbering plans• Connectivity with another mobile network standards• More service profiles• Multiple number

1989 1990 1991 1992 1993 1994 1995 1996 1997

Phase 1

Phase 2

Phase 2+

Idea Development Implementation

Type of GSM systems

GSM – 900 890 – 915 MHz 935 – 960 MHz

EGSM 880 – 915 MHz 925 – 960 MHz

GSM – 1800 1710 – 1785 MHz 1805 – 1880 MHz

DCS – 1800

GSM – 1900 1850 – 1910 MHz 1930 – 1990 MHz

DCS – 1900

PCS – 1900

Basic GSM characteristics

GSM 890 - 915 124 20 935 - 960 124EGSM 880 - 915 174 10 925 - 960 174DCS 1710 - 1785 374 20 1805 - 1880 374PCS 1850 - 1910 299 20 1930 - 1990 299

Number of channels

uplink downlinkType

BandwidthNumber of channels

Free zone

[MHz]Bandwidth

Channel width: 200 kHz

Number of users in 1 channel: as many of 8

Used techniques

FDD - Frequency Division Duplex• Creation of duplex pair (UPL/DWL)

TDMA – Time Division Multiple Access• Usage of repeating time period - timeslot (TS)• 1 frequency (channel) = 8 TS

Theoretical number of calls in one moment

GSM – 900 = 992

EGSM = 1392

DCS – 1800 = 2992

DCS – 1900 = 2392

Cellular network

allows you to reuse the same

frequencies after a certain distance

Between cells using the same

channels (frequencies) must be

distance c.

quintuple of the equivalent cell radius channel association to a periodical repeating clusters

Theoretically we need just 7 frequencies respectively 7 groups of radio channels for coverage of infinite area.

Type of cells

Principle of the cellular network is a division of the territory into small areas called cells. Area covered by a single antenna system is called cell.

Type of cell depends on population density in covered area:

• Pico cell (to 50 m) – for places with strong traffic, business centers, urban area, underground (DCS)• Micro cell (to 1 km) – for places with normal traffic, urban area (DCS, GSM)• Macro cell (max. 35 km) – for places with little traffic, rural area (GSM)

Type of cells

• Omnidirectional

BS has antenna system, which transmits around itself (typically macro cells)

• Segmentation

One antenna system transmits to the several (typically 3) cells (typically micro cells)

GSM network architecture

GSM network can be divided into 4 basic subsystems:

•Mobile Station (MS)•Base Station Subsystem (BSS)•Network and Switching Subsystem (NSS) •Operating and Maintenance Subsystem (OMS)

Mobile station

Mobil station (MS) consists of 2 parties:

• Terminal (mobile phone) provides „permanent“ radio connection with BSS communicates with subscribers and service realization encodes and decodes sent and received information

• SIM card (Subscriber Identity Module) brings subscriber´s independency from concrete

terminal provides authentication and partially participates in

encryption

MS

After switching on• MS must find network status in place where it is located

• Frequency scanning – MS do several measurement of BTS signal power

• Check old frequencies saved in memory from history

• Making table with 6 strongest (best) cells (frequencies)

• MS „move“ into the best cell

• After information exchange with cell is MS logged to the GSM network

MS

In stand-by mode• Every 5 seconds measures and compares BTS signal

power of nerby cells

• Periodically inform the network about its location

Base Station Subsystem

BTS (Base Transceiver Station)

ensure the radio connection with MSsignal modulation and demodulationencoding and error correctionsignal measurement etc.

Base Station Subsystem

BSC (Base Station Controller)

controls several BTS provides functions connected

with handover and subscriber mobility distributes subscriber on each physical

radio channels provides BTS performance

management etc.

Network and Switching Subsystem

NSS system is similar to the ISDN network.•MSC (Mobile Switching Centre) - PBX (exchange) as we know from the fixed networks•MSC (Gateway MSC) ensures connection with external telco and data networks

Network and Switching Subsystem

VLR (Visitor Location Register) database of mobile "visitors" who are now in the area of the MSC

AuC (Authentication Center) by using keys from HLR verifies subscriber (key in the SIM card)

EIR (Equipement Identity Center) is a database of all phone which operate in mobile network, it offers phone blocking after theft

HLR (Home Location Register) - central database of all subscriber using network

•Contains IMSI (International Mobile Subscriber Identity)•MSISDN (Mobile Station ISDN Number) •VLR address, •Other information about subscriber (pre-paid services, etc.)

GSM architecture

Operating and Maintenance Subsystem

Is a central computer system that communicates with most elements of the GSM network and allows to operator central management of the network and its functions.

•OMC (Operating and Maintanance Center) Network management and maintenance (regional

character) Realizes NMC decisions

•NMC (Network Management Center) longer-term management and network planning (does

statistics and measurement)

Collets network alarms Does load monitoring and planning capacity expansion

Data services in GSM (2G)

CSD - Circuit Switched Data • oldest type of data transfers in GSM works on circuit

switching principle -> same priority as voice call • scheme 1+1 (1 TS for upload a 1 TS for download)• low transfer rates 9,6 kbps resp. 14,4 kbps

HSCSD - High Speed Circuit Switched Data (2G/ 2,5G)• same principle as CSD -> same priority as voice call • TS grouping + efficient use of available TS• possibility of asymetric data transfers • 18 HSCSD class - class 6 2+2, 3+1

CSD vs. HSCSD

CSD HSCSD occupancy of the whole channel

Possibility of TS grouping:

no yes

Transfer schemes (upl + dwl):

1+1 according to class max. 8+8

Max. transfer rate:

9,6 resp. 14,4 kbps 76,8 resp.115,2 kbps

Process of data connection based on circuit switching (CSD/HSCSD)

What is GPRS

GPRS - General Packet Radio Service (2,5 G)

• Packet data transfer in GSM network

• Easy implementation – necessity of new MS

• Transfer rate and capacity increasing

• Channel grouping

• Voice call has priority over data

GSM vs. GPRS

GSM GPRS occupancy of the whole channel packet data transfer

Ideal:

pro voice and video transfers for „burst“ transfers

Paid:

for all allocated channels (TSs) for transfered data

Network capacity – 1 channel can use:

1 subscriber max. 12 subscribers

Max transfer rate:

76,8 kbps 171,2 kbps

Used techniques

• GMSK modulation

• variable transfer schemes – TS grouping 3+1, 2+2, 4+1, 3+2 etc.

• TS alocation only during data transfer

• 4 coding schemes

Class transfer rate user transfer rate

CS-1 9,05 kbps 6,7 kbps

CS-2 13,4 kbps 10 kbps

CS-3 15,6 kbps 12 kbps

CS-4 21,4 kbps 16,7 kbps

GPRS architecture

SGSN – Serving GPRS Support Node

Device controls GPRS traffic in GSM network (identity verification, encryption and pricing)

•Has same function as MSC•It is connected with BSC•Counts transfered data for billing•Translates protocols of GSM network to „IP“•Communicates with GGSN to open the requirements for subscriber data transfers

GGSN – Gateway GPRS Support Node

Gateway between GPRS network and Internet

• Data routing in Internet or corporate networks• Packet routing from external networks to MS• Collects charging data and traffic statistics• Allocates IP address based on customer

requirements, resp. settings in the HLR

What is EDGE

EDGE – Enhanced Data for GSM Evolution (2,5 G)

- sometimes known as EGPRS (enhanced GPRS)

• Packet data transfer in GSM network

• Transfer rate and capacity increasing in comparison with GPRS

• Voice call has priority over data

Used techniques

• 8-PSK modulation

• 9 coding classes MCS-1 až MCS-9

• variable transfer schemes – TS grouping 3+1, 2+2, 4+1, 3+2 etc.

• TS alocation only during data transfe

EDGE vs. GPRS

• Change in coding

• Hard implementation

(change of BTS)

• Higher transfer rates

GPRS EDGE

Transfer rate in (1 TS): 22,8 kbps 62,9 kbps

User transfer rate in (1 TS): 20 kbps (CS-4) 59,2 (MCS-9)

Max. uses transfer rate in (8 TS): 160 kbps 473,6 kbps

Process of data connection based on packet switching (GPRS/EDGE)

• GPRS attach

• PDP context

• GPRS detach

What is UMTS

UMTS – Universal Mobile Telecommunications System (3G)

• for high-speed packet data transfers

• voice call / videocall is data

• higher capacity than in GSM

• possibility of handover between UMTS a GSM

• while GSM network is out of order or overloaded, UMTS network can take GSM calls

UMTS bands

• Paired bands 1920 – 1980 MHz

and

2110 – 2170 MHz

• Unpaired bands 1910 – 1920 MHz

and

2010 – 2025 MHz

• Channel width: 5 MHz

Used techniques

• WCDMA – Wideband Code Division Multiple Access

• FDD - Frequency Division Duplex for paired band

1920 - 1980 MHz (upl)2110 - 2170 MHz (dwl)

• TDD – Time Division Multiple Duplex for unpaired band

GSM + GPRS vs. UMTS

GSM + GPRS UMTS

Ideal:

for calls and data transfers for high-speed data transfers

Advantages:

expansion and costs new services and applications

Disadvantages :

transfer rates costs

Coverage:

full area local „islands“

Transfer rates:

max. 384 kbps 2 Mbps(HSDPA up to 14,4 Mbps)

UMTS architecture

UMTS GSM

Node-B BTS

RNC BSC

Interconnection UTRAN with existing GSM network

Every RNC is connected with SGSN MSC - upgrade is necessary

UMTS Core Network (CN)

• connection functions (subscriber connection, packet routing etc.)

• maintains and updates the relevant user information (location, security, billing etc.)

• provides connections to another networks (ISDN, X.25, PSTN, Internet, ...)

2 domains

• Circuit Switched Domain

• Packet Switched Domain works on IP protocol firewall

Data services - summary

Tarification for spent time• CSD - one channel and transfer rate 9,6 kbit/s • HSCSD - grouping of several chanels (timeslots) within GSM network

- transfer rate 43,2 kbps downlink, 14,4 kbps uplink in case (3+1)

Tarification for transfered data• GPRS - packet data transfers

- teoretical transfer rate 172 kbps, real around 53,6 kbps• EDGE - increases the possible transfer rate (in 1TS) on 48 kbps,

- teoretical transfer rate 384 kbit/s • UMTS - from 384 kbps to 2 Mbps (fast moved subscribers 144 kbps)

- HSDPA to 14,4 Mbps

Data services – development, requirements

Development of IT and multimedia services increases the requirements for transfer of technology

It leads to accelerating the pace of development of mobile technology

The advent of fourth generation

Definitions 4th generation according to ITU:

• download speeds of 100 Mb/s on the move and 1Gb/s on a still stand

4. generation - LTELTE – Long Term Evolution (3,9G)

• downlink 172,8 Mbps, uplink 57,6 Mbps

LTE Advanced (4G)• achieving the objectives of ITU - over 1Gbps downlink

(theoretically)

The development of mobile networks from separate areas of circuit-switched (CS) and packet switched (PS) to a single common network IP (VoIP usage)

OFDM (Orthogonal Freqency Division Multiplexing)• The signal is transmitted on multiple carrier frequencies,

thereby increasing its resistance to interference (interference). • Other uses OFDM: DVB –T, A DSL, PLC, WiMAX

Architecture of LTE

LTE - EPC

EPC – Evolvent Packet Core

• new backbone LTE network on the packet connection principle

• basis for the transformation IP technology into mobile networks

• supports voice over IP - VoIP

Auction of LTE frequencies in the Czech Republic

Auction of frequencies for LTE in the Czech Republic was in 2013.

Overall, the company obtained for the frequency spectrum of pay:•Telefónica: 2.802 billion crowns•T-Mobile: 2614000000 crowns•Vodafone: 3.113 billion crowns•Total profit to the state budget: 8.529 billion czech crowns

•Current coverage is approx. 94% of the population.

Thank you for your attention.