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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.
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-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
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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
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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
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- 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
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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
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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
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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
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• 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)
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• 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
-...
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• 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
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Fig.3.4.10 GSM more detailed
Mobile Communications Network - continue
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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
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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
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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
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3.6 PLC
- Power Line Communication
- utilizing of power lines in the role of broadband AN
-advantages:
or: PDSL- Power DSL
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-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… )
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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 (!)
Recommended