11

Access NetworksAccess Networks

Types of Access Networks -Types of Access Networks -

- continue:- continue: other types:other types:

RRadio Access Networksadio Access Networks, , CATV – CATV – ANAN, , exploitation of power lines in exploitation of power lines in

ANAN

lecture No.5 and 6 -lecture No.5 and 6 - 200 20088/0/099- - w.t.w.t.

22

-radio broadcasting (LF, MF, HF), TV bands (VHF,UHF), bands of mobile teleph. networks, satellite lines, and finally tens of GHz for RR lines and broadband AN

- exclusively radiowave networks (or with retransmission stations) or combination with cable lines

-advantages: ...., disadvantages.....

-

3.4 Radio Access Networks - 3.4 Radio Access Networks - RANRAN-RITL – Radio In The Loop, and also other names (RLL-Radio Local Loop, WLL-Wireless Local Loop)

- general properties of RLL - in standard- ETSI ETR 139

33

Type of devidingType of deviding Types of radiocommunicationsTypes of radiocommunications

BandwidthBandwidth Narrow-bandNarrow-band Wide-bandWide-band

Transmission Transmission directiondirection

Broadcasting - Broadcasting - unidirectionalunidirectional

Bidirectional Bidirectional communicationscommunications

SystemSystem Point-to-multipointPoint-to-multipoint Poit-to-pointPoit-to-point

User mobilityUser mobility Fixed wireless Fixed wireless (cordless) user line(cordless) user line

MobilMobilee termin terminaall

Transmission Transmission mediamedia

terrestrialterrestrial Satellite (and Satellite (and others…)others…)

see also fig.3.4.2

Other classification – according to: services provided (teleph., data, ...)

method of sharing of information capacity ...modulation methods: ...private and public

Classification of radio wave media

Tab. 3.4.1

44

RLL

Fig.3.4.1 General RLL Reference Model. SS – switching system, BSC- Base Station Controller, BS – Base Station, RT- Radio termination, TE - Terminal equipment, IF – interfaces, OAM-Operation, Admin. and Maintenance functions, NMA-Network Management Agent

55

- possibilities of including of RITL into AN:

- cordless telephone

- wireless AN (RLL – Radio in the Local Loop)

- mobile cellular network

Fig.3.4.2 Radio wave network in AN: a) cordless telephone (CT) with individual connection, b) cordless telephone with common connection c) mobile cellular network (MS – mobile station)

RTTE

CT

RTTE

BS

BS

MS BS

Exchange

Cell

a)

b)

c)

user circuit

circuits trunk

trunk

TN

66

Fig.3.4.3 RLL (radio relay link) - point-to-point connection

Fig.3.4.4 RLL in the transport part of AN

Switching network SS

Switching network

77

CT – Cordless telephone and DECT system

- history: CT1, CT2, CT3 .... DECT

Fig.3.4.5 General reference model of DECT system

Fig.3.4.6 : DECT architecture in Access network

Legend:

FRT-Fixed Radio Termination

PRT- Portable Radio Termination

Global network

Local network

Switching network

cell 1

cell n

cell 2

Application

88

DECT - continue

- it is narrowband cordless access to public or private network

- there exist also P-MP type of DECT and complex applications similarly to mobile networks

- 3 generations

- it is the base for UMTS

99

• multipoint scheme named LMDS (Local Multipoint Distribution Systems) – fixed radiowave access – the alternative option to cable AN – there are cells, devided into the sectors operated from BS by means of radio termination, BS are connected to backbone network; mostly ATM technology, licenced bands (with guaranted QoS), without licence (so called general licence, WLAN); TDMA, FDMA and CDMA; unresistent to rain and vegetable disturbing• MMDS – (Multichannel Multipoint Distribution System) – or „wireless cable“ – utilised e.g. for TV signal distribution (DVB-C) in bands 2-3 GHz, LOS condition (Line-Of-Sight) must be satisfy for perfect receiving

• WLAN (Wireles Local Area Network): - radiowave type

- IR (infra-red) type

-fixed AP (access point) connected to LAN (e.g. Ethernet) + end station (client = power adapter, transmitter, receiver, antenna, etc.), but there can be also ad-hoc network without support infrastructure (stations communicate straightaway - each with another)

- standards IEEE 802.11, HIPERLAN, HomeRF: ...

Broadband access systems FWA (Fixed Wireless Access)

1010

• WiFi – wireless technology, WiFi Alliance corporate mark; - for more possibilities of interconnections and connection in the frame of LAN (WLAN)

- standard IEEE 802.11b (the first utilized), 2.4 GHz band, disturbed by MW-ovens, cordless telephons and by Bluetooth; 802.11a – 5GHz – is not disturbed. (There are also other standards 802.11)

- unlicenced bands, for short distances (in the building or premise, up to 11 Mbps), (they say, that without obstacles up to tens of km; up to 54 Mbps), the longer distance the less data speed, ...

• WiMAX – Worldwide Interoperability for Microwave Access – system of WiMAX Forum company, this company certificates anything with WiMAX mark

- wireless broadband acces within the framework of the last mile, alternative possibility to cables and DSL systems

- standard IEEE 802.16 (latest 802.16-2004), transmission over the long distances, as similar technology as mobile telephony, licenc. and unlicenced spectrum

-...

1111

• WPAN (Wireless Personal Area Network)

- less reach than WLAN

- as such technologies as Bluetooth, ZigBee, HomeRF : ...

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Mobile Communications Network

Fig.3.4.7 Mobile communications system

- cellular architecture, frequence planning, frequences repetition

Generations: • 1. – analalogue. narrowband FM, only national systems, 450-900MHz• 2G – GSM, narrowb.TDMA, afterwards broadband CDMA, upstream 890-915, down 935-960MHz• 2.5G or GSM 2+ = GPRS• EDGE – between GSM and IMT-2000• 3G - UMTS and others (IMT-2000), in the 2nd phase IP supporting network (TCP/IP protocol, radio network UTRAN)•“3.9 G” – LTE (Long Term Evolution) • 4G - ?http://en.wikipedia.org/wiki/UTRAN

Access network

Supporting network

External systems

1313

Mobile Communications Network - continue

Fig.3.4.8 GSM network architecture or see next page

other BS

other MSC

BS

BSBS

public fixed network

other BS

BS- base station

Legend:

1414

Fig.3.4.9 Functional scheme of GSM network

Mobile Communications Network - continue

1515

Fig.3.4.10 GSM more detailed

Mobile Communications Network - continue

1616

GPRS (General Packet Radio Service) – mobile data service, accessible for GSM users (and for IS-136 mobil users) – for WAP services (Wireless Application Protocol), SMS, MMS and e-mail a www- access „2,5G“

UMTS – Universal Mobile Telcom. System – 3G mobile system, W-CDMA, access to web pages and to other data services, up to 14 Mbps

historical application:

paging – unidirectional radio systems (transport of data only in the direct to TE)– for both smaller private, but also greater public areas

1717

Fig.3.4.11 One of possible ideas of 4G network architecture concept - interoperability of several types of radiowaves networks

Mobile Communications Network - continue

satellites

cellular networks

radio and TV broadcasting

Support

network

WLAN

WPAN

WLL

1818

Fig.3.4.12: Classification of RRL systems (Radio Relay Link)

Radio-relay links - RRL- fixed access point + mostly also fixed user terminal (point-to-point)

- data speeds from E1 (2Mbps) up to STM1(155Mbps), 40-60 km, frequency bands and frequency channels, H/V polarizations of neighbour channels, QAM channel modulation

according to link length

system each-to-another

purpose

- portable

- fixed

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Tab. Frequency band for RRLs (point-to-poit)

core networks – up to 11 GHz

access networks – above 11 GHz notificatio

nnotification

2020

Tab. Bandwidths in RRLs and possible combinations of STM dig. streams

Fig.: Example: RR channels in band 6U

Digital streamBandwidth Nuber of states - modulation

XPIC – additional circuits for interference suppressing by utilizing different polarizations of waves of the same frequency

2121

Fig.3.4.13 Examples of shapes and dimensions of several satellites orbit types

Satellite networks

- advantages, disadvantages

- VSAT technology(Very Small Aperture Terminal – for both narrowband and broadband data (Internet, VoIP a video)

LEO: Argos, Orbcomm, Iridium, Teledesic, Globalstar, SkybridgeGEO: Thuraya (, Inmarsat (maritime - communications), cca 36000km above equator

2222

3.5 3.5 CATV CATV in the role of access in the role of access networksnetworks

2323

specifications:

- DVB-C dig. signal, MPEG-2 compress encoding, resp. MPEG-4 AVC (H.264)

- 4 or 5 dig. channels in previous 1 analogue one carrier is modulated by transport stream by means of QAM

- central node – previously with distribution role – now is transformed for bidirectional transport (interactive services) – down 65 -850 MHz with 8 MHz per channel; up 5-65 MHz (in USA 42-850 MHz / 5-42 MHz and 6 MHz channels)

- possibility of POTS – the main station must be interconnected with PSTN (see the next figure)

- needed modernization of whole network (several hierarchy level of network, amplifiers, optical sections, O/E convertors, freq. splitters,....)

-comunications standards based on IP protocol (Ethernet-frames with variable word length, resp. ATM technology):

• DOCSIS - Data Over Cable Service Interface Specification

= international standard for communications via CATV

(DOCSIS 3.0) – is also for cabel modems

• DVB/DAVIC Euromodem – standard developed in Europe (by ETSI)

Fig.3.5.1 Architecture of CATV- AN with optical network in the primary segment (primary level)

splitter

the components of distribution system see e.g. in: http://www.blondertongue.com/distribution/Distribution.pdf

splitter

- user splitter (tap?) / coupler

tap / coupler

Main Station – there are antenna combiners, convertors , amplifiers, splitters

distrib.node

centr.office

2-way amplifier

- user wall outlet

splitter (or band separator) of down- and up- directions

primary optical PON section

aerial (antennas) system

secondary – coaxial section

Fig.3.5.2 Functional scheme of cable modem and its implemenation into network (it can be integrated in Set-Top-Box) – upstream is realized by telephone line

HF

CATV modem

MAC – Medium Access Controll

telephone subscriber

line

return channel realization in the case of 1-directional

CATV network

64/256-QAM demodulator,

error correction

interface (Ethernet, USB, PCI)

control (CPU)

splitter

telephone

modem

CATV subscriber

line

2626

3.6 PLC

- Power Line Communication

- utilizing of power lines in the role of broadband AN

-advantages:

or: PDSL- Power DSL

2727

-2-phase wires for providing of BB services

- LF, HF filters

- high security required

Base unit

HF

LF

HFLF

LAN

Internet

4 x 400 V customer

User terminal

customercustomer

kWh

Power transformer station

Fig.3.6.1 Principle of using power network for broadband (BB) access

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Tab.3.6.1 : Frequence bands previously permited by european norm for communications

BandBand Frequencies[kHz]Frequencies[kHz] NoteNote

3 – 9 Only for power contractors

AA 9 – 95 For power contractor, and with their agreement for customers

BB 95 – 125 For private pusposes of customers

CC 125 – 140 For customers – there is required the protocol about agreement

DD 140 – 148,5 Private purposes of customers

-but – for PDSL – there are allowable bands up to tens MHz (the larger distance the less transported frequencies)

- development in area e-m compatibility and mutual interferences of different tel-com systems and disturbing by power network (there are stated some treshold values… )

2929

IPTV and Internet via convenience outlet (in the frame of home network)- architecture:

- Internet connecting

- router (or DSL modem) connected to both Internet and power network

- adaptors of Powerline technology connected to outlets in residence (behind transformer station, in the same phase circuit)

- in the reach of 101 m data speeds up to 200 Mbps

- undesirable: overvoltage defence (protect) and filters (!)