gsm and architecture

Elektrotehnički fakultetUniverzitet u Beogradu

Javni mobilni radio-sistemi

Prof. dr Đorđe PaunovićDoc. dr Aleksandar Nešković

Dr. Nataša Nešković

Javni mobilni radio sistemi - pregled stanja u svetu -

Konvergencija govornog saobraćaja ka mobilnim radio-sistemima

Razvoj javnih mobilnih radio-sistema do 2007. god. (predviđanje)

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Osnovne


Teritorijalna raspodela različitih tipova javnih mobilnih sistema

Osnovni GSM 2G standard

GPRS (General Packet Radio Services),

EDGE (Enhanced Data for GSM Evolution), i

3GSM (tehnologija 3G mobilnih sistema primenjena na evoluiranoj GSM strukturi).

Evolucija GSM standarda

1982 CEPT. početak formiranja standrda1990. ETSI postavljeni standardi (faza 1)1992. prve komercijalne GSM instalacije1993. Australija se priključuje grupi zemalja koje planiraju GSM......



Tehničko-tehnološka koncepcija GSM sistema


Arhitektura GSM mreže

Second Generation Mobile Network Architecture

PSTN / ISDN

• • • • • • • • • •MSC MSC

BSSBSS BSS BSS• • • • • •

Tehničko-tehnološka koncepcija GSM sistema

BTS

MS

Um

BTS

BTSBSC

Base Station Subsystem (BSS)

A-bisA

Basic Architecture of GSM

BTS: Base Transceiver StationBSC: Base Station ControllerHLR: Home Location RegisterVLR: Visited Location RegisterOMC: Operation & Maintenance CentreEIR: Equipment Identity RegisterAUC: Authentication Centre

MobileServicesSwitchingCentre(MSC)

HLREIR VLR OMC

AUC

F

H G

BC

other MSCs

E

PSTNISDNCSPDN PSPDN

other VLRs

other BSSs

D


GSM sistema- frekvencijski opsezi -


GSM sistema- osnovne specifikacije -

Frekvencijski opsezi i radio-kanali- 900 MHz -

Uplink 890 – 915 MHz 25 MHz

Downlink 935 – 960 MHz 25 MHz

100 KHz 200 KHz 100 KHz

1 43 1242 …………….

A 200 KHz carrier spacing has been chosen. Excluding 2x100 KHz edges ofthe band, this gives 124 possible carriers for the uplink and downlink. The use of carrier 1 and 124 are optional for operators.

Multiple Access TechniqueFDMA/TDMA. The total band is divided into 124x200 KHz bands (FDMA).Each group of 8 users transmit through a 200 KHz band sharingtransmission time (TDMA).

GSM sistem- radio interfejs (TDMA) -

Radio interfejs (TDMA)- problem vremenskog kašnjenja -

Radio interfejs (TDMA)- timing advance -

Blok dijagram GSM radio-sistema

SpeechEncoder

FEC Encoder&

InterleavingBurstFormer

Modulator Tx RxDe-modulator

Burst-to-ContinousRateConverter

FEC Dncoder&

DeInterleaving Transcoder

RxSpeechDecoder

FEC Dncoder&

Delnterleaving

Burst-to-ContinousRateConverter

De-modulator

Mobile Station (MS) Base Station System (BSS)

Tx Modulator BurstFormer

FEC Encoder&

Interleaving

Transcoder

to MSC

from MSC

GSM sistem

GMSK(Gaussian Minimum

Shift Keying)modulacija

Tipovi mobilnih uređaja

Mobile station can have three forms:

1. Vehicle – Mounted units 2. Portable units3. Handheld units

0.8W52W45W38W220W1

GSMClass

Mobile Station Power Class

Base stations are also classified in a similar way to mobile stations with 8 classes in 3 dB steps from 2.5 watts to 320 watts.

Deleted

Power control

• RF power control will be used in the GSM MS and BS to reduce the transmit power to the minimum required to achieve the minimum quality objective and hence reduce the level of co-channelinterference

• The MS will be capable of varying its transmit power form itsmaximum output down to 20 mW in steps of nominally 2 dB

• The BS calculates the RF Power level to be used by the MS and sends a 4 bit number instruction to the corresponding MS

GSM mandatory features

1. Discontinuous transmission and reception (with the aid ofVoice activity detector)

• The level of co-channel interference is, on average, reducedBy about 3 dB

• For a hand-held portable unit, the battery life can be significantlyextended

Advantages:

2. Slow frequency hopping

1. The receive TDMA bursts with high error rates will be more spread in time

2. The co-channel interference is more evenly spread betweenall the MSs

Advantages:

Channel Types

1. Traffic channels (TCHs)

The traffic channels are intended to carry encoded speech or user data.

2. Control Channels (CCHs)

The control channels are intended to carry signalling and synchronization data between the base station and theMobile station.

Traffic ChannelsTraffic channels are intended to carry encoded speech and user data.• Full rate traffic channels at a net bit rate of 22.8 Kb/s (TCH/F)• Half rate traffic channels at a net bit rate of 11.4 Kb/s (TCH/H)

Data Channels

Speech ChannelsSpeech channels are defined for both full rate and half ratetraffic channels. The latter for the future system.

Data channels support a variety of data rates (2.4, 4.8 and9.6 Kb/s) on both half and full rate traffic channels. The 9.6Kb/s data rate is only defined for full rate application.

Logical Channel Types

Logical Control Channels

Downlink UplinkBroadcast Control Channels• Frequency Correction - FCCH• Synchronization – SCH• Broadcast - BCCH

-

Common Control Channels• Access Grant - AGCH• Paging - PCH

Common Control Channels• Random Access - RACH

Dedicated Control Channels• Stand – alone Dedicated - SDCCH• Slow Associated – SACCH• Fast Associated - FACCH

Broadcast Control Channels (Downlink only Channels)

• Broadcast Control Channels (BCCH) – Broadcasts to all mobiles general information regarding their own cell as well as the neighbouring (up to 16) cells, e.g. information used for cell selection and for describing the current control channel structure.

• Frequency Correction Channels (FCCH) – for mobiles for frequency correction.

• Synchronization Channels (SCH) – for frame synchronization ofmobiles and identification of the base station.

Common Control Channels

• Access Grant Channels (AGCH) – for assignment of a dedicatedChannel after a successful random access.

• Paging Channels (PCH) – for paging to mobiles.

For downlink

• Random Access Channels (RACH) – used for random access Attempts by mobiles.

For uplink

Dedicated Control Channels

• Stand-alone Dedicated Control Channels (SDCCH) – are major signalling channels used for location updating, registration,point-to-point SMS and handover preparation.

8 SDCCH sent through one physical channel each having a bit rateof approximately 782 bits/s.

• Slow Associated Control Channels (SACCH) – always associated with TCH, SDCCH or FACH and carry timing advance and power control measurement results and information.

The bit rate per channel is 391 bits/s.

• Fast Associated Control Channels (FACCH) – carry the same Signalling data as SDCCH. They are used in the case when a very fast exchange of information is needed, e.g. , in the case of a hand-over. It accesses to the physical resource by stealing framesFrom the TCH.

The bit rate of this channel is 9.2 kbits/s.


GSM sistem- osnovna jedinica je ćelija-


GSM sistem- Location Area & Service Area -


GSM sistem- fizička struktura mreže -


GSM sistem- softverska struktura mreže -

GSM- Saobraćajne procedure -

• Mobilna stanica u neaktivnom modu • Mobilna stanica u aktivnom modu• Roaming• Slanje i prijem kratkih poruka - SMS

GSM - MS neaktivna -


GSM sistem- prijavljivanje -


GSM sistem- location updating (isti MSC/VLR) -


GSM sistem- location updating (novi MSC/VLR) -


GSM sistem- MS aktivna -


Iniciranje poziva- MS prema PSTN -


Iniciranje poziva- PSTN prema MS -


Handover


Handover- u okviru istog BSC-a -


Handover- u okviru istog MSC-a -


Handover- u okviru različitih MSC -


Roaming


Short message service - SMS(slanje poruke)


Short message service - SMS(prijem poruke)

Teleservisi- pre-paid telefonija,- post-paid telefonija, - fax, - SMS, ...

Bearer servisi- više tipova prenosa

podataka do 9600bps, ...

GSM servisi

Više desetina postojećih servisa i stalni razvoj novih servisa.

Dodatni servisi- razne kontrole poziva, - konferencijska veza, - govorna pošta, - faks-pošta,

- međunarodni roaming, - virtualne privatne mreže (VPN)- Direktna veza PABX ↔ MSC, ...

Javni mobilni radio sistemi - pregled stanja u Srbiji -

Dva GSM operatora u opsezima GSM900 i GSM1800:MOBTEL – 063 (od 1996.god), iTELEKOM – 064 (od 1998.god).

Teritorijalna pokrivenost GSM servisom oko 82% teritorije i oko 93% stanovništva.

TELEKOM I MOBTEL imaju oko 3 miliona korisnika, svaki.Ambiciozni planovi razvoja u narednim godinama.Do kraja 2006.god treba očekivati

- pokrivenost teritorije od oko 85%,- pokrivenost stanovništva do 95%.

Novembar 2003

Javni mobilni radio sistemi

( pregled stanja u Srbiji )

900MHz

30.03.2006

Novembar 2003

Javni mobilni radio sistemi

( pregled stanja u Srbiji )

1800MHz

30.03.2006

MerenjeGSM mreža

Telekom Srbije

Upravljačko-komutacioni sistem

- 3 500 000 -korisnika

Plan razvojaGSM mreže

Telekom Srbijado kraja 2006.

Prikaz pokrivenosti

teritorije prema fazama realizacije

Povećanje pokrivenosti teritorije upotrebom repeatera

Nekoliko repeater-a se može povezati najednu baznu stanicu i na taj način pokriti “rupe” u zoni pokrivanja bazne stanice.

Realizacija indoor sistema upotrebom GSM tehnologije

U slučaju nadzemnih objekata GSM radio-servis je najčešće već obezbeđen unutar objekta i bez fizičkih indoor instalacija.Podzemne instalacije se realizuju mikro-baznim stanicama.Veliki broj ovih sistema je realizovan (TC “City Passage”, podzemna stanica “Vukov Spomenik”, hotel “Intercontinental”, hotel “Hyatt”, TC “Merkator”, itd. )Korišćenjem VPN servisa formiranje indoor poslovnog mobilnog sistema najčešće se može sprovesti za manje od 1h.Za poslovne VPN sisteme primenjuje se posebna niža tarifa.

• Princip udruživanja vremenskih slotova u okviru jednog radio-nosioca.• Kroz GPRS uvodi se paketski prenos podataka na radio-ineterfejsu.• Teorijski, maksimalan protok iznosi 160kbs (za korisnika 115kbs).• U praksi raspoloživi protoci znatno manji (tipično 40-50kbps). • Brza uspostava veze (ne uspostavlja tzv. dial-up veza).

•QoS profili:

Novembar 2003

GPRS (General Packet Radio Services)

•Relativno jednostavna i elegantna instalacija•Koristiti ista postojeća ćelijska struktura. •Nije neophodno ni novo frekvencijsko planiranje.•Zahtevaju se izmene samo u upravljačko-komutacionim čvorištima

Novembar 2003

Uvođenja GPRS-a u postojeću GSM mrežu

•Oko 190 GSM operatora u svetu investiralo je u GPRS. •TELEKOM i MOBTEL GPRS servis započeli su tokom 2003.god.

Paketski prenos podataka do maks. 115kbps (tipično do 50kbps),

MMS, E-mail, Pretraživanje WEB-a, File Transfer,Prenos audio informacija,Prenos slika,Itd.

GPRS servisi

•Promena na osnovnom fizičkom nivou radio-interfejsa.•Povećanje protoka iznosi oko tri puta u odnosu na GPRS protoke.•Struktura i načini realizacije servisa praktično se ne menjaju. •Novi tip modulacije i novi tip kanalskog kodovanja na radio-interfejsu.•Striktno se poštuju TDMA struktura rama, širina radio-kanala (200kHz).

struktura logičkih kanala, kao i sistemski GPRS mehanizmi.•Maksimalni protok podataka za korisnika 384kbs (GPRS - 115kbs).•Teorijski protok na fizičkom nivou 473.6kbs (GPRS – 160kbs). •EDGE u pogledu komutaciono-upravljačkog sistema,

u potpunosti koristi strukturu definisanu u okviru GPRS-a. •Zahteva se zamena primo-predajnih jedinica u okviru baznih stanica. •Nedostatak, zahteva se veći odnos C/I nego u slučaju GPRS-a. •Neminovno uvođenje novih baznih stanica u radio-mrežu. •Očekuje se pun razvoj multimedijalnih servisa, brzi pristup Internetu,

prenos pokretnih slika, itd.) Novembar 2003

EDGE (Enhanced Data for GSM Evolution)

Izmena načina modulacije na radio-interfejsu – povećanje protoka!

Novembar 2003Uporedni prikaz GMSK i 8PSK modulacija.


Novembar 2003

• GPRS omogućava veće protoke podataka u okviru postojećih GSM mreža!• GPRS se označava kao 2.5G tehnologija.

• Princip udruživanja vremenskih slotova u okvirujednog radio-nosioca.

• Kroz GPRS uvodi se paketski prenos podataka na radio-ineterfejsu.• Teorijski, maksimalan protok iznosi 160kbs (za korisnika 115kbs).• U praksi raspoloživi protoci znatno manji (tipično 40-50kbps). • Brza uspostava veze (ne uspostavlja tzv. dial-up veza).

GPRS (General Packet Radio Services)

• Oko 190 GSM operatora u svetu investiralo je u GPRS. • TELEKOM i MOBTEL GPRS servis započeli su tokom 2003.god.

Client-server services, which enable access to data stored in databases. The most famous example of this is access to the World Wide Web (WWW) through a browser.Messaging services, intended for user-to-user communication between individual users via storage servers for message handling. Multimedia Messaging Service (MMS) is an example of a well-known messaging application.Real-time conversational services, which provide bidirectional communication in real-time. A number of Internet and multimedia applications require this scheme such as voice over IP and videoconferencing.Tele-action services, which are characterized by short transactions and are required for services such as SMS, electronic monitoring, surveillance systems, and lottery transactions.

Novi dopunski GPRS servisi(mobile Internet technology)

Infrequent data transmission, as when the time between two transmissions exceeds the average transfer delay (e.g., messaging services);Frequent transmission of small data blocks, in processes of several transactions of less than 500 octets per minute (e.g., downloading of several HTML pages from a browsing application);Infrequent transmission of larger data blocks, in processes of several transactions per hour (e.g., access of information stored in database centers);Asymmetrical throughput between uplink and downlink, such as for data retrieval in a server where the uplink is used to send signaling commands and the downlink is used to receive data as aresponse of the request (e.g., WEB/WAP browser).

Prenos podataka – tipovi i karakteristike

Novembar 2003

Zahtevi u pogledu kvaliteta servisa (QoS)

Definicija klasa saobraćaja

Novembar 2003

End User Performance Expectations-Conversational/Real-Time Services

End User Performance Expectations-Streaming Services

Novembar 2003

End User Performance Expectations-Interactive Services

•Relativno jednostavna i elegantna instalacija•Koristiti ista postojeća ćelijska struktura. •Radio-pokrivanje je približno isto kao i za govorne servise.•Nije neophodno novo frekvencijsko planiranje.•Zahtevaju se izmene samo u upravljačko-komutacionim čvorištima.

Novembar 2003

Uvođenje GPRS-a u postojeću GSM mrežu

SGSN - Serving GPRS Support NodesGGSN - Gateway GPRS Support Node

Novembar 2003

GPRS - arhitektira

The class A mobile can support simultaneously a communication in circuit-switched mode and another one in packet-switched mode. It is also capable of detecting in idle mode an incoming call in circuit or packet-switched mode.The class B mobile can detect an incoming call in circuit-switched mode or in packet-switched mode during the idle mode but cannot support them simultaneously. The circuit and packet calls are performed sequentially. In some configurations desired by the user, a GPRScommunication may be suspended in order to perform a communication in circuit-switched mode and then may be resumed after the communication release in circuit-switched mode.The class C mobile supports either a communication in circuit-switched mode or in packet-switched mode but is not capable of simultaneously supporting communications in both modes. It is not capable of simultaneously detecting the incoming calls in circuit-switched and packet-switched mode during idle mode. Thus a class C mobile is configured either in circuit-switched mode or in packet-switched mode. The mode configuration is selected either manually by the user or automatically by an application.

Klase mobilnih GPRS uređaja

• Promena na osnovnom fizičkom nivou radio-interfejsa.

• Povećanje protoka iznosi oko tri puta u odnosu na GPRS protoke.

• Struktura i načini realizacije servisa praktično se ne menjaju.

• Novi tip modulacije i novi tip kanalskog kodovanja na radio-interfejsu.

• Striktno se poštuju TDMA struktura rama, širina radio-kanala (200kHz).struktura logičkih kanala, kao i sistemski GPRS mehanizmi.

•Maksimalni protok podataka za korisnika 384kbs (GPRS - 115kbs).

•Teorijski protok na fizičkom nivou 473.6kbs (GPRS – 160kbs). Novembar 2003


• EDGE u pogledu komutaciono-upravljačkog sistema, u potpunosti koristi strukturu definisanu u okviru GPRS-a.

• Zahteva se zamena primo-predajnih jedinica u okviru baznih stanica.

• Nedostatak, zahteva se veći odnos C/I nego u slučaju GPRS-a.

• Neminovno uvođenje novih baznih stanica u radio-mrežu.

• Očekuje se pun razvoj multimedijalnih servisa, brzi pristupInternetu, prenos pokretnih slika, itd.

Novembar 2003


Izmena načina modulacije na radio-interfejsu – povećanje protoka!

Novembar 2003Uporedni prikaz GMSK i 8PSK modulacija.


gsm and architecture

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