Gsm And Architecture

Elektrotehnički fakultet Univerzitet u Beogradu

Javni mobilni radio-sistemi

Prof. dr Đorđe Paunović Doc. dr Aleksandar Nešković Dr. Nataša Nešković

Javni mobilni radio sistemi - pregled stanja u svetu -

Konvergencija govornog saobraćaja ka mobilnim radio-sistemima

Procenat korisnika [%]

Javni mobilni radio sistemi - pregled stanja u svetu -

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

Javni mobilni radio sistemi - pregled stanja u svetu -

™ Osnovne

Teritorijalna raspodela različitih tipova javnih mobilnih sistema

Evolucija GSM standarda

™ 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).

Osnovni GSM 2G standard ™ ™ ™ ™ ™

1982 CEPT. početak formiranja standrda 1990. ETSI postavljeni standardi (faza 1) 1992. prve komercijalne GSM instalacije 1993. Australija se priključuje grupi zemalja koje planiraju GSM. .....

Tehničko-tehnološka koncepcija GSM sistema

™ Osnovni GSM 2G standard

Arhitektura GSM mreže

™ Osnovni GSMBSS2G BSS standard

MSC

• • •

BSS

• • •

MSC

• • • • • • • • • •

PSTN / ISDN

BSS

Second Generation Mobile Network Architecture

Tehničko-tehnološka koncepcija GSM sistema AUC Base Station Subsystem (BSS)

H EIR other BSSs

A-bis

A BTS Um

BSC

D

G

HLR F

BTS

other VLRs

C

VLR

OMC

B Mobile Services Switching Centre (MSC)

BTS E MS

Basic Architecture of GSM

PSTN ISDN CSPDN PSPDN

other MSCs BTS: BSC: HLR: VLR: OMC: EIR: AUC:

Base Transceiver Station Base Station Controller Home Location Register Visited Location Register Operation & Maintenance Centre Equipment Identity Register Authentication Centre

GSM sistema - frekvencijski opsezi -

™ Osnovni GSM 2G standard

GSM sistema - osnovne specifikacije -

™ Osnovni GSM 2G standard

GSM sistema - osnovne specifikacije -

™ Osnovni GSM 2G standard

Frekvencijski opsezi i radio-kanali - 900 MHz Uplink

890 – 915 MHz 25 MHz

Downlink

935 – 960 MHz 25 MHz 1

100 KHz

2

3

4

200 KHz

…………….

124 100 KHz

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

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

GSM sistem - radio interfejs (TDMA) -

Radio interfejs (TDMA) - problem vremenskog kašnjenja -

Radio interfejs (TDMA) - timing advance -

Blok dijagram GSM radio-sistema Mobile Station (MS)

Speech Encoder

FEC Encoder & Interleaving

Burst Former

Modulator

Base Station System (BSS)

Tx

Rx

Demodulator

Burst-to -Continous Rate Converter

FEC Dncoder & DeInterleaving

Transcoder

to MSC

Speech Decoder

FEC Dncoder & Delnterleaving

Burst-to -Continous Rate Converter

Demodulator

Rx

Tx

Modulator

Burst Former

FEC Encoder & Interleaving

Transcoder

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 units 3. Handheld units

Deleted

Class

GSM

1

20W

2

8W

3

5W

4

2W

5

0.8W

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.

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-channel interference • The MS will be capable of varying its transmit power form its maximum 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 of Voice activity detector) Advantages: •

The level of co-channel interference is, on average, reduced By about 3 dB

•

For a hand-held portable unit, the battery life can be significantly extended

2. Slow frequency hopping

Advantages: 1. The receive TDMA bursts with high error rates will be more spread in time 2. The co-channel interference is more evenly spread between all the MSs

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 the Mobile station.

Logical Channel Types Traffic Channels Traffic 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)

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

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

Logical Control Channels

Downlink

Uplink

Broadcast 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)

• Frequency Correction Channels (FCCH) – for mobiles for frequency correction. • Synchronization Channels (SCH) – for frame synchronization of mobiles and identification of the base station. • 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.

Common Control Channels

For downlink • Access Grant Channels (AGCH) – for assignment of a dedicated Channel after a successful random access. • Paging Channels (PCH) – for paging to mobiles. For uplink • Random Access Channels (RACH) – used for random access Attempts by mobiles.

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 rate of 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 frames From the TCH. The bit rate of this channel is 9.2 kbits/s.

GSM sistem - osnovna jedinica je ćelija-

™ Osnovni GSM 2G standard

GSM sistem - Location Area & Service Area -

™ Osnovni GSM 2G standard

GSM sistem - Location Area & Service Area -

™ Osnovni GSM 2G standard

GSM sistem - fizička struktura mreže -

™ Osnovni GSM 2G standard

GSM sistem - softverska struktura mreže -

™ Osnovni GSM 2G standard

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 -

™ Osnovni GSM 2G standard

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

™ Osnovni GSM 2G standard

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

™ Osnovni GSM 2G standard

GSM sistem - MS aktivna -

™ Osnovni GSM 2G standard

Iniciranje poziva - MS prema PSTN -

™ Osnovni GSM 2G standard

Iniciranje poziva - PSTN prema MS -

™ Osnovni GSM 2G standard

Handover

™ Osnovni GSM 2G standard

Handover - u okviru istog BSC-a -

™ Osnovni GSM 2G standard

Handover - u okviru istog MSC-a -

™ Osnovni GSM 2G standard

Handover - u okviru različitih MSC -

™ Osnovni GSM 2G standard

Roaming

™ Osnovni GSM 2G standard

Short message service - SMS (slanje poruke)

™ Osnovni GSM 2G standard

Short message service - SMS (prijem poruke)

™ Osnovni GSM 2G standard

GSM servisi

™ Više desetina postojećih servisa i stalni razvoj novih servisa. ™ Teleservisi - pre-paid telefonija, - post-paid telefonija, - fax, - SMS, ... ™ Bearer servisi - više tipova prenosa podataka do 9600bps, ...

™ 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), i TELEKOM – 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%.

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

Novembar 2003

Merenje GSM mreža Telekom Srbije

Upravljačkokomutacioni sistem - 3 500 000 korisnika

Plan razvoja GSM mreže Telekom Srbija do kraja 2006.

Prikaz pokrivenosti teritorije prema fazama realizacije

Povećanje pokrivenosti teritorije upotrebom repeatera ™ Nekoliko repeater-a se može povezati na jednu 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.

GPRS (General Packet Radio Services) • • • • •

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

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

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

GPRS servisi ™ Paketski prenos podataka do maks. 115kbps (tipično do 50kbps), ™ MMS, ™ E-mail, ™ Pretraživanje WEB-a, ™ File Transfer, ™ Prenos audio informacija, ™ Prenos slika, ™ Itd.

EDGE (Enhanced Data for GSM Evolution) •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, Novembar 2003 prenos pokretnih slika, itd.)

EDGE (Enhanced Data for GSM Evolution) Izmena načina modulacije na radio-interfejsu – povećanje protoka!

Novembar 2003 Uporedni prikaz GMSK i 8PSK modulacija.

Novembar 2003

GPRS (General Packet Radio Services) • GPRS omogućava veće protoke podataka u okviru postojećih GSM mreža! • GPRS se označava kao 2.5G tehnologija. • 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).

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

Novi dopunski GPRS servisi (mobile Internet technology) ™ 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 wellknown 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 video conferencing. ™ Tele-action services, which are characterized by short transactions and are required for services such as SMS, electronic monitoring, surveillance systems, and lottery transactions.

Prenos podataka – tipovi i karakteristike ™ 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 a response of the request (e.g., WEB/WAP browser).

Zahtevi u pogledu kvaliteta servisa (QoS)

Novembar 2003

Definicija klasa saobraćaja

End User Performance ExpectationsConversational/Real-Time Services

Novembar 2003

End User Performance ExpectationsStreaming Services

End User Performance ExpectationsInteractive Services

Novembar 2003

Uvođenje GPRS-a u postojeću GSM mrežu •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.

SGSN - Serving GPRS Support Nodes Novembar 2003 GGSN - Gateway GPRS Support Node

GPRS - arhitektira

Novembar 2003

Klase mobilnih GPRS uređaja ™ 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 GPRS communication 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.

EDGE (Enhanced Data for GSM Evolution) • 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 (Enhanced Data for GSM Evolution) • 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 2003

Uporedni prikaz GMSK i 8PSK modulacija.