TRFHOE=TRUE :

Range TRUE, FALSEDefault FALSEObjectnya HAND (BASICS)

Traffic Handover Enabled, parameter ini enable atau memungkinkan fitur Handover disebabkan oleh criteria manajemen resource atau singkatnya disebut juga sebagai traffic handover. Jika fitur ini di"enable"kan maka BSC akan mencek situasi traffic load di sel tsb . Bila traffic load melebihi threshold TRFHITH , BSC enable traffic handover di BTS dengan mengirimkan pesan SET ATTRIBUTE dengan indikasi traffic handover ke BTS via link LPDLM (lihat pengertian LPDLM di posting yg lalu).

HOLTHLVDL=10 :Handover lower threshold level downlink Object HANDRange 0-63Default 10

Mendefinisikan threshold dari level sinyal yang diterima / Rxlev pada downlink untuk keputusan inter cell handover. Parameter ini hanya relevan jika RXLEVHO = TRUE (intercell handover is enable)

RXLEVMIN=12 :RX Level MinimumObject ADJCRange 0-63Default 12

Parameter ini menentukan pada Rx Lev minimum berapa suatu MS dapat melakukan handover ke adjacent cellnya. Semakin tinggi diset nilainya maka smakin lebih cepat dia akan handover ke adjnya.

HOM=69 :Handover MarginObject ADJC3Range 0-126Default 69

Handover margin for 2G-3G better cell handover , ini untuk mencegah terjadinya ping pong handover antar 2 sel. Parameter ini juga mendefinisikan cell yang lebih baik dari 2G ke 3G.

CRESOFF=1 :Cell reselection offsetObjectnyaRange 0-63Default 1

Ini dibutuhkan sebagai input dari nilai untuk kalkulasi C2. Parameter ini hanya diset jika CRESPARI diset 1. Sepertinya berhubungan dengan cell reselection yaitu saat MS idle yah, tapi C2nya itu apa ya? Tuh udh kejawab di bawah.

CRESPARI=1

object: BTS [BASICS]range: 0=C2 parameters not present1=C2 parameters presentdefault:1

Cell reselection parameter indicator, indikasikan kehadiran C2 (parameter reselection di BCCH) pada IE 'SI 4 Rest Octets'(SYSTEM INFORMATION TYPE 4) and the IE 'SI 3 Rest Octets'(SYSTEM INFORMATION TYPE 3); 0=not present, 1=present. C2 berguna buat konfigurasi microcell selama utk mencegah perpindahan cepat MS dan membuat terjadinya cell reselection yang tidak perlu.

Fromhttp://telecommunicationforall.blogspot.com/2009/02/sedikit-ttg-optim-2.html

HRACTT1 :

Bernilai rangenya 1 – 10000 dengan default 6000Bentuknya sbb: HRACTT1=6000Objectnya BTS

Half Rate Activation Threshold 1, Parameter ini mendefinisikan threshold yang digunakan oleh fitur” : Cell Load Dependent Activation of Half Rate dan Load-dependent AMR compression handover.

a) Cell Load Dependent Activation of Half Rate fitur ini diaplikasikan bila parameter EHRACT diset ke TRUE . Pada kasus ini, HRACTT1 mendefinisikan sebuah threshold load trafik yang dievaluasi untuk pemilihan versi forced speech utk incoming non-AMR TCH seizures. BSC membandingkan HRACTT1 dengan persen busy TCH (berhubungan dengan TCH yg available) dalam :-semua TRX / service layer yang tmsk dlm SLL untuk standard cell-semua TRX / service layer yang tmsk dlm SLL untuk concentric cell-semua TRX / service layer yang tmsk dlm SLL untuk extended cell

b) Load-dependent AMR compression handover tujuannya untuk mengkompres handover. Dalam kasus TCH load tinggi untuk mentransfer EFR call dengan quality radio link yang baik ke HR TCH dengan intrasel handover agar mencegah terjadinya TCH Blocking dengan menyediakan tambahan TCH resources.

RXLEVAMI=6 :Default 6Objectnya BTSRange 0-63 0=less than -110 dbm1= -110 dbm to -109 dbm2= -109 dbm to -108 dbm………..62 = -49 dbm to -48 dbm63 = greater than -48 dbm

Parameter ini mendefinisikan minimum DL receive level ,MS harus menerima dari sel yang melayani agar diijinkan mengakses jaringan via RACH. Menset RXLEVAMI ke nilai yang tinggi artinya yaitu hanya MS” tsb yang mencoba mengakses sel dimana

lokasinya terdapat kondisi coverage yang baik. Jadi jumlah permintaan handover dpt berkurang. Parameter ini dikirim lewat BCCH

Press Release

August 31, 2005

Indosat and Nokia Launch BlackBerry Connect with the Nokia 9300 smartphone and Nokia 9500 Communicator in Indonesia

Jakarta, Indonesia and Waterloo, ON - Indosat (JSX:ISAT; NYSE:IIT), Nokia (NYSE: NOK) and Research In Motion (RIM) (Nasdaq: RIMM; TSX: RIM) today introduced BlackBerry® Connect™ for the Nokia 9300 smartphone and Nokia 9500 Communicator to Indosat customers in Indonesia.

RIM’s BlackBerry Connect licensing program allows users of the Nokia 9300 and Nokia 9500 to connect to proven and popular BlackBerry services while maintaining the existing Nokia device capabilities. BlackBerry provides an efficient and reliable communications platform that can automatically deliver email to the Nokia devices with support for attachment viewing as well remote address lookup and up-to-date calendar information.

“Adding BlackBerry connectivity to Nokia’s high-end enterprise devices increases customer choices,” commented Wahyu Wijayadi, Director of Corporate Market at PT Indosat. “The ‘push’ based BlackBerry technology supported by Indosat’s strong signal, comprehensive national network and roaming capability will enable Matrix’s users to access their email using the Nokia 9300 and Nokia 9500.”

“The growth in the demand for mobility solutions has substantially expanded over the last year, driven by the fact that many of the Indonesia workforces are now mobile. Mobility has emerged as a priority investment area for business people and we believe that the form factor of the Nokia 9300 smartphone and Nokia 9500 Communicator with their large color screens, straightforward menu navigation and integrated QWERTY keyboards, coupled with BlackBerry service, makes them ideal handsets for mobile connectivity and email,” added Hasan Aula, General Manager Mobile Phones at Nokia Indonesia.

“We are pleased to work with Indosat to expand its BlackBerry portfolio in Indonesia. Customers around the world continue to choose BlackBerry for its unique architecture and its ability to keep mobile professionals connected to important communications and information,” said Norm Lo, Vice President, Asia Pacific at Research In Motion.  “BlackBerry Connect allows Indosat’s customers to leverage the BlackBerry architecture and infrastructure while also taking advantage of the robust features available on the Nokia 9300 and Nokia 9500 devices.”

Together, BlackBerry Connect and BlackBerry Enterprise Server™ enable:

• “Push” based wireless email access• Wireless email reconciliation• Remote address book look-up• Wireless calendar synchronization• Attachment viewing for many popular file formats including Word, Excel, PowerPoint, PDF and Zip files• Triple DES security

The Nokia 9300 smartphone and Nokia 9500 Communicator offer features such as:

• Advanced voice features: hands-free speakerphone, conference calling• Messaging options: Email with attachments, SMS, MMS• Organiser: Calendar, Contacts, Tasks with PC synchronisation via Nokia PC Suite• Large memory storage: 80MB built-in memory plus MultiMediaCard (MMC)• Tri-band (EGSM 900/1800/1900) for use on five continents• Bluetooth audio support for handsfree conversations, USB and Infrared connectivity for easy data transfer

and synchronization• Security features including SSL/TLS, IPsec VPN for secure mobile access.• High speed Internet browsing via HTML 4.01 and JavaScript 1.3• Built-in office tools supporting documents, spreadsheets, presentations and a PDF viewer

The Nokia 9300 and Nokia 9500 with BlackBerry Connect can be enjoyed by Matrix customers in Java and Bali and will be available in select Indosat retail outlets. Current owners of the devices are advised to contact a Nokia Professional Centre for information on how to upgrade their handsets to the appropriate version of phone software and BlackBerry software. The customers can also contact Indosat Gallery to get a BlackBerry-provisioned Matrix SIM Card.

For corporate customers, BlackBerry Enterprise Server™ tightly integrates with Microsoft® Exchange and IBM Lotus® Domino™ and works with existing enterprise systems to enable secure, push-based, wireless access to email and other corporate data.  For individuals and smaller businesses, BlackBerry Internet Service™ allows users to access up to ten corporate and/or personal email accounts (including Microsoft Exchange, IBM Lotus Domino and many popular ISP email accounts) from a single device.

About IndosatIndosat is a leading telecommunication and information provider in Indonesia, which provides: cellular, fixed telecommunication (including fixed wireless access services) and multimedia, data communication & internet (MIDI). After merging with its 2 subsidiaries, Indosat is well-positioned to be the telecommunication service provider with a comprehensive range of products offerings in Indonesia.Indosat is the second largest cellular operator in Indonesia and the primary provider of international telecommunications services.For further information, please visit Indosat website www.indosat.com.

About Nokia Enterprise SolutionsEnterprise Solutions is the arm of Nokia, which are dedicated to help businesses and institutions worldwide in improving their performance through extended mobility. Its end-to-end solution offerings range from business optimised mobile devices on the front end, to a robust portfolio of mobile business optimised gateways in the back end, including:  wireless email and internet, application mobility, virtual private networks, and firewalls. As the global leader in mobile enterprise voice, Nokia is well positioned to help companies to mobilise data and free their workforces, while ensuring the security and reliability of their networks. Nokia believes that business mobility will fundamentally change the way people work. www.nokia.com.

About Research In Motion (RIM)Research In Motion is a leading designer, manufacturer and marketer of innovative wireless solutions for the worldwide mobile communications market. Through the development of integrated hardware, software and services that support multiple wireless network standards, RIM provides platforms and solutions for seamless access to time-sensitive information including email, phone, SMS messaging, Internet and intranet-based applications. RIM technology also enables a broad array of third party developers and manufacturers to enhance their products and services with wireless connectivity to data. RIM’s portfolio of award-winning products, services and embedded technologies are used by thousands of organizations around wireless platform, the RIM Wirelessthe world and include the BlackBerry Handheld™ product line, software development tools, radio-modems and software/hardware licensing agreements. Founded in 1984 and based in Waterloo, Ontario, RIM operates offices in North America, Europe and Asia Pacific. RIM is listed on the Nasdaq Stock Market (Nasdaq: RIMM) and the Toronto Stock Exchange (TSX: RIM). For more information, visit www.rim.com or www.blackberry.com. 

Forward-looking statements in this news release are made pursuant to the "safe harbor" provisions of the United States Private Securities Litigation Reform Act of 1995. When used herein, words such as "intend" and similar expressions are intended to identify forward-looking statements. Forward-looking statements are based on assumptions made by and information available to Research In Motion Limited. Investors are cautioned that such forward-looking statements involve risks and uncertainties. Important factors that could cause actual results to differ materially from those expressed or implied by such forward looking statements include, without limitation, possible product defects and product liability, risks related to international sales and potential foreign currency exchange fluctuations, the initiation or outcome of litigation, acts or potential acts of terrorism, international conflicts, significant fluctuations of quarterly operating results, changes in

Canadian and foreign laws and regulations, continued acceptance of RIM's products, increased levels of competition, technological changes and the successful development of new products, dependence on third-party networks to provide services, dependence on intellectual property rights and other risks and factors detailed from time to time in RIM's periodic reports filed with the United States Securities and Exchange Commission, and other regulatory authorities. The Company has no intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

The BlackBerry and RIM families of related marks, images and symbols are the exclusive properties and trademarks of Research In Motion Limited. RIM, Research In Motion and BlackBerry are registered with the U.S. Patent and Trademark Office and may be pending or registered in other countries. All other brands, product names, company names, trademarks and service marks are the properties of their respective owners.

From :http://press.rim.com/release.jsp?id=937

Call Setup Successful Rate (%) = ((Total number of successful setup)/(Total number of calls attempt))*100 Total number of successful setup = Total number of mobile originating calls that are successfully assigned a traffic channel (TCH). Total number of calls attempt = Total number of times the test mobile attempts to make a mobile originating call.

Dropped Call Rate, also known as TCH drop rate Dropped Call Rate (%) = ((Call set-up Success) – (number of completed calls)) / (Call set-up Success)*100

HOSRHandover Success Rate (%) = ((Total number of successful handovers) / (Total number of handover attempts))*100

Handover per call = (Total number of Handover success / total number of call setup success)

GSM / UMTS Architecture

Prosedur Swap Nokia Flexi BTSNokia Siemens Network merupakan salah satu provider terbesar yang bergerak di bidang telekomunikasi.Salah satu produknya berupa perangkat yang disebut dengan 2G Flexi Nokia Edge dimana perangkat ini diklaim memiliki ketangguhan baik di indoor maupun outdoor serta modulnya yang bersifat flexibel.Proses swap BTS biasanya dilakukan untuk memenuhi kebutuhan dan kapasitas pengguna jaringan telekomunikasi.Proses ini secara umum dibagi menjadi empat bagian yaitu

1. Transmission shifting , 2. (BTS or RBS installation) Flexi BTS installation , 3. (Commisioning) Flexi BTS Commissioning ,

4. dan Cross-Connections antara BTS dan BSC.

Yang termasuk ke dalam Transmission shifting yaitu diawali dengan penggantian radio transmisi PDH lama dengan yang baru lalu dilakukan koneksi kembali untuk seluruh transmisi PDH yang baru (Cross-Patching Radios) dilanjutkan dengan pemesangan kabel interfaces lalu dilakukan loop-testing untuk pengecekan kembali transmisinya.Diakhiri dengan pengalokasian traffic E1.

Sedangkan untuk proses instalasi BTS flexi diawali dengan koneksi DTRX dengan DDU (ERGA duplexer untuk GSM dan ERDA duplexer untuk DCS) lalu koneksi ESMA (berlaku seperti prosesor) dengan DDU.Jika ada penambahan TRX maka bisa menggunakan ESEA.Kemudia dilanjutkan dengan koneksi kabel power ke DDU , DTRX , dan ESMA.Langkah selanjutnya yaitu mengukur VSWR (Voltage Standing Wave Ratio) dari kable feeder untuk mengecek adanya DTF (Distance to Fault) , lalu koneksi kabel feeder ke BTS Flexi melalui jumper , dan diakhiri dengan labeling alarm.

Berikutnya untuk proses Commissioning BTS Flexi diawali dengan koneksi BTS Flexi dengan perangkat laptop , lalu melakukan konfigurasi tiap TRX dan sector melalui software Flexi BTS , kemudian konfigurasi Abis Plan , Cross-Coonnection antara Flexi BTS dengan transmisi PDH , dilanjutkan dengan Cross connection untuk merubah BSC lama ke BSC baru , dan diakhiri dengan loop-testing untuk melakukan pengecekan transmisi baru dengan BSC Nokia.

Prosedur yang disampaikan ini merupakan prosedur secara umum untuk melakukan swap BTS.Masih banyak lagi hal-hal yang harus diperhatikan untuk menjamin keberhasilan dalam proses swap dan langkah-langkah apa yang harus diambil jika mengalami kegagalan dalam proses ini.

Sumber: http://id.shvoong.com/products/telecom/2019877-prosedur-swap-nokia-flexi-bts/#ixzz1Kn9W51hy

Common question for UMTS Interview :

1. Access Minimum 3G : qLevmin = -115dBm & qQualmin = -18dB2. CE :     PS 384 (SF8) consume berapa CE = 8 CE     PS128 (SF16) = 4 CE     PS64 (SF32) = 2 CE     CS64 - Video Call (SF32) = 2 CE     Voice AMR 12.2 = 1 CE     HSDPA consume brp CE?? HS-DSCH ga consume CE, yg consume CE HS-SCCH = 1 CE & UL A-DCH = 1 CE.3. IRAT Optim Improvement :     1. Cek External GSM Cell dan IRAT relation sudah dicreate atau belum.     2. Concheck LAC, NCC, BCC, BCCH 2G di 3G Network.

     3. Cek congestion 2G.     4. Cek alarm di 2G, terutama related ke clock reference.     5. Missing IRAT Neighbor karena coverrage overshoot.4. Improving CSSR 3G termasuk RAB & RRC     1. Cek CE Congestion, tambah CE kalau bisa.     2. Cek IuB Congestion, klo di huawei bisa setting priority IuB per service (Add trmfactor (RNC) & add FTI (cell level)).     3. Power congestion, reduce CPICH power, antenna tilting.     4. Code Congestion, huawei : turunin Guarantee Bit Rate (GBR)5. Improving CDR 3G      1. Missing Neighbor, make sure ga ada coverage overshoot.     2. Pilot pollution, tilting polluternya tilting penyebab polusinya,      3. Co-SC     4. IRAT (spt nomer 3)     5. High RTWP (biasanya HW)     6. Transmisi (Alarm, intermittent, high error second)     7. Hardware alarm

6. Lagi di trial di surabaya, be e awakmu ditakoni jg utk ngelanjutkan trialnya, cell reselection 3G - 2G.     Parameter yg mempengaruhi :     1. qLevmin     2. qQualmin     3. SsearchRAT     4. IdleQhyst1&2     5. QualMeas     6. Treselections

Hery B'Supriyanto: assalamu'alaikum...pakfastabiqul_khoirot: Wa alaikumsalamfastabiqul_khoirot: Piye pak?Hery B'Supriyanto: pak tau nge-trace MSISDN kan ? fastabiqul_khoirot: Maksude ngetrace nomer tah?Hery B'Supriyanto: iyo..nge-trace nomer lahfastabiqul_khoirot: Bagian core pakfastabiqul_khoirot: Awake dewe tidak punya priviledgeHery B'Supriyanto: tapi ngerti gak pak..nek lewat jaringan 2G karo 3G kan iso bedo kan ?fastabiqul_khoirot: Tergantung pak. Lek ngetrace teko mssfastabiqul_khoirot: Nek bsc ampek rnc ne sak mss mungkin bisa samafastabiqul_khoirot: Bedo apane pak?Hery B'Supriyanto: oo..iyo benerHery B'Supriyanto: kecuali bedo MSS yo ?Hery B'Supriyanto: eh..msc opo mss ? Hery B'Supriyanto: bedo kan mobile swistcing system karo center ? Hery B'Supriyanto: soale iki komplain, nek ganti nomer (operator yg sama bisa) , jarene wis di trace normal

Hery B'Supriyanto: mungkin pas ngetrace kayane teko 2G, lha aku yo gak eruh cutomer-e komplain 3G opo 2G ...ono info utowo saran ra pak ?fastabiqul_khoirot: Podo ae pakfastabiqul_khoirot: Yo podo pakfastabiqul_khoirot: Nek awakmu onok mgwne berarti mssfastabiqul_khoirot: Nek gak onok mgwne berarti mscfastabiqul_khoirot: Msc itu menggabungkan antara signalling ambek trunk trafficfastabiqul_khoirot: Lha nek sing kesini sini design msc dipecahfastabiqul_khoirot: Mss menangani signalling tokfastabiqul_khoirot: Lha traffic voice itu masuknya di mgwfastabiqul_khoirot: Mangkane wong2 ngarani msc lawas iku msc monolitikfastabiqul_khoirot: Soale disatukanfastabiqul_khoirot: Awakmu neng tsel yoh pak?Hery B'Supriyanto: ora pak..axisfastabiqul_khoirot: OalahHery B'Supriyanto: sik newbie kok nyekel tsel fastabiqul_khoirot: Nek sak ngertiku tsel ambek xl iku nduwe ss7 monitoringfastabiqul_khoirot: Berarti awakmu nek ngetrace nggae k15 pakfastabiqul_khoirot: Di tap neng msc/mss mau ikuHery B'Supriyanto: wah..aku ora iso pak ngetrace..wong kau ra iso mlebu omc-nefastabiqul_khoirot: Lha iyo pak. Awake dewe tidak punya priviledge pakfastabiqul_khoirot: Wong awake dewe wong radio kok fastabiqul_khoirot: Radio ngunu minangka pipafastabiqul_khoirot: Mek gae lewat tok. Tanpa ngerti opo sing lewat Hery B'Supriyanto: iyo pak...noc-ne mangkel no soale nang kene...koyo2ne rno tau segalanya end-to endHery B'Supriyanto: btw suwun pak penjelasane Hery B'Supriyanto: soale titik2 kongkon DT karo NOC, tiap komplain DT, masalahe nek sing komplain sak daerah iku akeh gak masalah...kadang cuman wong siji komplain, bareng diparani , cuma mbenakno seting modem-e ...asyemm tenan fastabiqul_khoirot: Walah pak. SabarHery B'Supriyanto: iyo pak...huawei iku sembarang2 di iya-ni...gak tau gak karo customer Hery B'Supriyanto: bedo nek vendor eropa..jual mahal..terutama eriksfastabiqul_khoirot: Wah... Bener jeh. Aku yo krungu2 perbuatane huawei teko konco2ku neng kene fastabiqul_khoirot: De-e tau projek axis huawei neng jktfastabiqul_khoirot: Wah ampun wis pokokeHery B'Supriyanto: hihihfastabiqul_khoirot: Wong huawei iku kesimpulane gak duwe udelHery B'Supriyanto: hihihi..Hery B'Supriyanto: pancen bedo pak standar-efastabiqul_khoirot is typing a message.fastabiqul_khoirot: Yoi... Yo gpp lah, asal bayaran lancar Hery B'Supriyanto: hihihi,,,iyo pakBookmark

General Packet Radio Service (GPRS)

Peng Chengyuan

 

Abstract

The new mobile data services are merging the Internet (data communications) and GSM (telecommunications). General packet radio service (GPRS) as one of the mobile data services is introduced in this paper. Subjects discussed are basic GPRS concepts, services, network architecture, and basic GPRS operations. QoS and possible applications are also presented.

1. Introduction

1.1 History of GSM/GPRSGSM, the most successful digital cellular network, is the European digital cellular standard published by ETSI (the European Telecommunications Standards Institute). There are three phases for GSM technology creation [5].

1. Introduction of commercial GSM services, including telephony, short message, fax and data services in 1992.

2. In 1996, phase 2 completed the original GSM design task and established a framework for ongoing technology enhancement.

3. GSM standardization is now in phase 2+, in this phase. It includes improved voice coding and advanced data transmission services. Two data services are high-speed circuit-switched data service (HSCSD) and the General Packet Radio Service (GPRS).

1.2 GSM services GSM has three types of services [13]: teleservices, bearer services, and supplementary services. Teleservices include telephony, fax, emergency calls, teletex, short Message services, fax mail, and voice mail. Supplementary services include call forwarding, call barring, etc. Bearer services are used for transporting user data. Some of the bearer services are listed below:

1. Asynchronous and synchronous data, 300-9600 bps. 2. Alternate speech and data, 300-9600 bps. 3. Asynchronous PAD (packet-switched, packet assembler/disassembler)

access, 300-9600 bps. 4. Synchronous dedicated packet data access, 2400-9600 bps.

Conventional GSM has limitations in data services [1]:

1. It does not provide direct connection to the Internet. In order to access to the Internet, GSM needs to call Internet Service Provider (ISP).

2. Uplink and downlink channels allocated for a user are for entire call period.

3. It has time-oriented charging, that is, payment is based on connection time, not on data volumes.

4. Connection setup takes about 20-25 seconds. 5. Limited capacity (9600 bps).

6. GSM was designed for speech, not for data, hence 50% radio capacity is wasted, and also there is no optimal channel coding for data.

1.3 The GSM System Architecture

The GSM system architecture[5], [13], [1] includes four subsystems (cf. Figure 1): Mobile Station (MS), Base Station Subsystem (BSS), Network and Switching Subsystem (NSS), and Operation Sub-System (OSS).

The MS subsystem involves a radio part, an interface, and a Subscriber Identity Module (SIM). The radio part carries out all the functions related to the radio interface (Um), e.g. receiving and transmitting radio signals, signal processing, frequency hopping, and channel management. The interface to terminal equipment acts as a gateway between the terminal and the radio part. The SIM contains all the subscriber-related information on the MS side of Um to identify a subscriber and take care of the security. The SIM is implemented as a smart card.

The BSS forms cell structure of GSM network. It includes two types of network elements: the Base Transceiver Station (BTS), and the Base Station Controller (BSC).

The BTS is a transmission component. It carries out radio signal transmission and reception, signal processing, speech encoding and decoding, and transmission rate adaptation. The BSC is a managing component. It is responsible for all

the management of the Um, e.g. channel allocation and deallocation, handover, and timing of radio signals. One BTS implements one cell in GSM. A BSC can manage several BTSs.

The NSS comprises the main switching functions of GSM and all the databases needed for subscriber information, mobility management, and interworking. It contains the following databases: Home Location Register (HLR), Visitor Location Register (VLR), Authentication Center (AUC), and Equipment Identity Register (EIR).

The MSC performs the basic switching function by setting up calls to/from MSs.

The GSM system also communicates with other networks such as the Public Switched Telephone Network (PSTN), Integrated Services digital Network(ISDN), Circuit-Switched Public Data Network (CSPDN), and packet-switched public data network (PSPDN).

1.4 The GSM radio interface

The radio interface [13] is the interface between the mobile stations and the fixed infrastructure. It is one of the most important interfaces of the GSM system.

The Radio Interface (Um) is split into several channels: traffic channels and signaling channels. The traffic channels carry user data. The signaling channels carry management and control information.

1.4.1 Frequency allocation

Two frequency bands, of 25 Mhz each one, have been allocated for the GSM system:

� The band 890-915 Mhz has been allocated for the uplink direction (transmitting from the mobile station to the base station).

� The band 935-960 Mhz has been allocated for the downlink direction (transmitting from the base station to the mobile station).

1.4.2 Multiple access scheme

The multiple access scheme defines how different simultaneous communications, among different mobile stations located in some different cells, share the GSM radio spectrum. A mix of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA), combined with frequency hopping, has been adopted as the multiple access scheme for GSM.

1.4.2.1 FDMA and TDMA

Using FDMA, a frequency is assigned to a user. So, the larger the number of users in a FDMA system, the larger the number of available frequencies must be.

The limited available radio spectrum and the fact that a user will not free its assigned frequency until he does not need it longer, explain why the number of users in a FDMA system can be "quickly" limited.

On the other hand, TDMA allows several users to share the same channel. Each of the users, sharing the common channel, are assigned their own burst within a group of bursts called a frame. Usually TDMA is used with a FDMA structure.

In GSM, a 25 Mhz frequency band is divided, using a FDMA scheme, into 125 carrier frequencies spaced one from each other by a 200 khz frequency band.

Normally a 25 Mhz frequency band can provide 125 carrier frequencies. Each carrier frequency is then divided in time using a TDMA scheme. This scheme splits the radio channel, with a width of 200 khz, into 8 bursts. A burst is the unit of time in a TDMA system. A TDMA frame is formed with 8 bursts. Each of the eight bursts, that form a TDMA frame, is then assigned to a single user.

1.4.2.2 Channel structure

A channel corresponds to the recurrence of one burst every frame. It is defined by its frequency and the position of its corresponding burst within a TDMA frame. In GSM, there are two types of channels:

� The traffic channels used to transport speech and data information.

� The control channels used for management messages and some channel maintenance tasks.

2. The GPRS Network Architecture

2.1 Elements:

GPRS network elements are SGSN, GGSN, Border Gateway (BG), Backbone network (intra-PLMN and Inter-PLMN), HLR, MSC/VLR, SMS-GSMC

GPRS requires major changes in the network infrastructure. In addition to the current GSM entities, a number of new network elements are introduced in order to create an end-to-end packet transfer mode. The HLR is enhanced with GPRS subscriber information of every MS.

The serving GPRS support node (SGSN) is responsible for the delivery of packets to/from the MSs within its service area and communicates with the Gateway GPRS Support Node (GGSN). It also keeps track of the mobiles within its service area. The GGSN acts as a logical interface to external packet data networks (such as the Internet, X.25 networks or private networks) and maintains routing information used to tunnel Protocol Data Units (PDU) to the SGSN that is currently serving the MS.

A GPRS networks can use multiple serving nodes, but requires only one gateway node for connecting to an external network (e.g., the Internet).

The GPRS phone communicates with GSM base stations, (but unlike circuit-switched data calls which are connected to voice networks by mobile switching center), GPRS packets are sent from BSS to a Serving GPRS Support Node (SGSN).

When the mobile station sends packets of data, it is via the SGSN to the GGSN, which converts them for transmission over the desired networks (the Internet, X.25 networks or private networks). IP packets from the Internet addressed for mobile station are received by the GGSN, forwarded to the SGSN and then transmitted to the mobile station.

2.2 Radio Interface

A new radio interface is needed to handle packet traffic, new security features for the GPRS backbone and a new ciphering algorithm, new Mobile Application Part (MAP) and GPRS-specific signaling should be added.

2.3 Protocols

The GPRS data communication architecture [1], [5], [6] adheres to the principle of protocol layering and has two protocol planes, signaling plane and transmission plane. The signaling plane consists of protocols that control and support the transmission of user information. The transmission plane covers the protocols for user information transmission and associated control procedures like flow control or error handling.

Between SGSN and GGSN (cf. Figure 3), the GPRS tunnel protocol (GTP) tunnels the PDUs through the GPRS backbone network. The GTP header contains mobile�s identity and PDP context identifier. In addition, QoS parameter is included in the PDP context activation and modification. It is not included in every packet.

Below GTP, the Transmission Control Protocol/User Datagram Protocol (TCP/UDP) and IP are used as GPRS backbone network-layer protocols. Any IP based network protocols can be used below IP, e.g. Ethernet cabling, integrated services digital network (ISDN) links, or ATM-based protocols.

Between the SGSN and MS, the Subnetwork-Dependent Convergence Protocol (SNDCP) maps network-level protocol characteristics onto the underlying logical link control and provides functionality like multiplexing of network-layer messages onto a single virtual logical link connection. Furthermore, segmentation and compression functionality are covered by SNDCP. The BSS GPRS protocol (BSSGP) has been derived from the BSSAP used in GSM, and conveys routing and QoS-related information between the BSS and SGSN.

Radio communication between the MS and the GPRS network covers physical and data link layer functionality.

Between MS and BSS the physical layer is split up into a Physical Link sublayer (PLL) and a Physical RF sublayer (RFL). The RFL performs the modulation and demodulation of the physical waveforms. The carrier frequencies, radio channel structures, and raw channel data rates are specified, as well as transmitter and receiver characteristics and performance requirements. The PLL provides services for information transfer over a physical channel between the MS and the network. These functions include data unit framing, data coding, and the detection and correction of physical medium transmission errors.

The data link layer has been separated into two distinct sublayers. The Radio Link Control/Medium Access Control (RLC/MAC) sublayer arbitrates access to the shared medium between a multitude of MSs and the network. The RLC/MAC layer encompasses the efficient multiplexing of data and signaling information, and performs contention resolution, QoS control(limited), and error handling. The MAC itself is derived from a slotted reservation ALOHA protocol, and operates between the MS and BSS. For retransmission of erroneous frames, an automatic selective repeat request (SREJ-ARQ) mechanism is applied.

The Logical Link Control (LLC) layer operates above the MAC layer, and provides a logical link between the MS and SGSN. To allow introduction of alternative radio solutions without major changes to NSS, it is independent of the

RLC/MAC protocol as far as possible. Protocol functionality is based on LAPD as used within the GSM signaling plane, but supports point-to-multipoint transmission.

For signaling plane, between the MS, BSS, and SGSN (cf. Figure 4), the same protocols are used as for data transmission up to the SNDCP protocol. Only at the network layer, a GPRS-specific mobility management protocol (GMM) is required within MS and SGSN to support the mobility functionality.

2.4 GPRS Design

The initial work on GPRS began in 1994. Its design objectives [1] are

1. Uses packet-switched resource allocation, that is, resources allocated only when data is to be sent or received.

2. Flexible channel allocation: one to eight time slots; available resources shared by active users; up and down link channels are reserved separately; GPRS and circuit switched GSM services can use the same time slots.

3. Seamless, immediate connection with data networks(IP network, X.25, GPRS's own protocols)

4. Efficiently delivery of SMSs over the GPRS radio interface 5. GPRS uses radio resources only when there is data to be sent or received

(well adapted to the very busty nature of data applications)

Its basic design rules and goals [1] are:

1. No HW change is needed in BTSs 2. Scalability of GPRS network, that is no "big bang" to introduce GPRS, no

one-to-one relation for GPRS network element and MSC. 3. Support of GPRS only mobile( so called C-Class MS) 4. High throughput over the air, that is up to 21.4 kbps per TS, up to 8 TS

utilization per MS 5. Short access time to network 6. GPRS vs. existing GSM services

GPRS services traditional GSM services

connection with external packet data networks connection with circuit switched networks

typical connection can last several hours typically one call per hour, average call 2 minutes

data transmission bursty continuous flow of data in both direction

uplink and downlink transmissions independent  

no need to access HLR for every GPRS packet every MT call causes query to HLR

user can activate services separately all services activated at IMSI attach

charging is based on amount of transmitted data charging is based on time

every network element knows where to route packets further

 

GPRS support the "service specific attach" principle  

packets are short(typically 500-1000 octets)  

every packet treated as independent entity  

2.5 GPRS characteristics [1]:

1. transmission modes: send and receive data in packet transfer mode; cost effective and efficient use of network resources

2. traffic characteristics: intermittent, bursty data transmissions; frequent transmissions of small volumes of data; infrequent transmission of large volumes of data

3. transmission: four level of radio priorities and five classes of QoS supported; point-to-point (PTP) or point-to-multipoint (PTM)

2.6 GPRS Services

From the user's point of view, GPRS is a wireless extension of data networks. It can access to data networks, such as IP-based networks (public internet, private intranet, IPv4 and IPv6 protocols) and X.25 based networks.

GPRS upgrades GSM data services and provides the following services [1]:

1. Point-to-point (PTP) service: internetworking with the Internet (IP protocols) and X.25 networks.

2. Point-to-multipoint (PTM) service: point-to-multipoint multicast and point-to-multipoint group calls.

3. SMS service: bearer for SMS 4. Anonymous service: anonymous access to predefined services 5. Future enhancements: flexible to add new functions, such as more

capacity, more users, new accesses, new protocols, new radio networks

3. GPRS Operations

3.1 Session Management

In order to send and receive data, the MS shall activate the packet data address (IP address) that it wants to use. This operation lets the corresponding GGSN know the MS, and then interworking with external data networks can start.

PDP context consists of PDP type, PDP address(optional), QoS parameters (optional), access point name, etc. The optional means that when activating a context, these are optional; when context is active, they have some negotiated or subscribed value.

GPRS uses the concept of non-anonymous and anonymous PDP contexts [1].

The no-anonymous PDP context means that:

1. MS must have a subscription for this operation 2. Network verifies that no unauthorized PDP context activation is done 3. Network knows who holds each PDP context 4. No limitations on mobility (MS may move freely in the network)

The anonymous PDP context means that:

1. No subscription is needed, no need to attach first 2. Network does not know who uses PDP context 3. Limited mobility (only within limited area)

The user may have several subscribed contexts which are used to access to external data networks. Any of the contexts can be activated or deactivated independently. When context is activated, user can send and receive data packets from MS to fixed network, from fixed network to MS, or form MS to MS. When a context is not activated, the network drops the packets.

There are two kinds of activation, Anonymous PDP context activation and Non-anonymous PDP context activation. Here only Non-anonymous PDP context activation is given (with defined address), see Figure 5.

The main procedures are:

1. MS informs the network that it wants to activate this PDP context 2. SGSN checks that MS is allowed to activate the context. Also SGSN

fills/defines missing (=optional) parameters 3. SGSN selects GGSN to be used

4. QoS negotiation: MS requests some QoS level ( or default); SGSN may downgrade the QoS (if it can not handle that high); GGSN may downgrade even further

In order to communicate with network, the MS shall activate one or more PDP contexts. Once the MS has been attached to the network, the PDP context can be negotiated with the SGSN. If access is permitted, the SGSN informs the GGSN to update the context for the MS. The GGSN context includes the address of the SGSN that is currently serving the MS and tunneling information. The PDP context activation is completed by an acknowledgement from the network to the MS.

3.2 Routing(Data Transmission) [1], [6]

The data transmission can be Mobile oriented data transmission, Mobile terminated data transmission, and Mobile originated and terminated data transmission.

In the case of a mobile-originated transmission (cf. Figure 6), the SGSN encapsulates the incoming packets from MS and routes them to the appropriate GGSN, where they are forwarded to the correct PDN. Inside PDN, PDN-specific routing procedures are applied to send the packets to the corresponding host.

Packets coming from a corresponding host are routed the GGSN through the PDN based on the examination of the destination address. The GGSN checks the routing context associated with this destination address and determines the serving SSGN address and tunneling information. The packet is encapsulated and forwarded to the SGSN, which delivers it to the mobile station.

3.3 Mobility management

Mobility management [1], [4], [6] is also needed in GPRS. There are three activities related to mobility management, that is attach, detach, and location update. Attach means entering/joining the system. Detach means leaving the system. Location update includes routing area (RA) update and cell update.

Before an MS is able to send data to a corresponding host, it has to attach to the GPRS system. During the attachment procedure, the GPRS shall do the following things:

1. Inform the network for the MS's request to be active 2. Network check the MS's identity and initiate ciphering mode for data

communication 3. If SGSN does not already have the MS�s subscription info, download the

information from HLR to SGSN 4. Update MSC/VLR 5. Signal between the MS and SGSN

As a result of this attachment, a logical link control context, including a temporary logical link identity (TLLI), is established between the MS and SGSN.

A cell update is performed implicitly on the logical link control level. In cell update, the following information needs to be updated:

1. Specific cell update message 2. Any valid signaling message 3. Any user data sent uplink

When MS changes RA, the GPRS needs to update routing area (cf. Figure 7). The MS sends a routing update request containing the cell identity and the identity of the previous routing area (RA) to the SGSNn. If the RA is served by the same SGSN, the location information is updated and an acknowledge is sent back to the MS. There is no need to inform the GGSN, because the SGSN and tunneling information are not changed. However if the previous RA is served by another SGSN, the GGSN must be informed. The GGSN address and tunneling information can be requested from the previous SGSNo. Simultaneously, the SGSNo is requested to transmit the undelivered data packets to the new SGSN. Afterwards, the information context of the MS is deleted from the memory of the SGSNo. As soon as the address and tunneling information is received from the SGSNo, the new SGSN address and tunneling information is delivered to GGSN.

4. GPRS Applications

GPRS supports standard data network protocol (TCP/IP, X.25) based applications [4], such as www, ftp, telnet, email, video, audio for wireless PCs or mobile offices. There are also GPRS specific protocol based applications, e.g. point-to-point application (Toll road system, UIC train control system, etc.) and point-to-multipoint application (weather info, road traffic info, news, fleet management).

Recently, an important industry trend is remote access, a new technology, referred to as a virtual private network (VPN) [2]. With this new technology, companies will be able to let their remote workers wirelessly access to corporate resources and stay in touch with their work teams.

5. Quality of Service (QoS)

A QoS parameter [15] is associated with each service request primitive received at an Network Service Access Point (NSAP). This is a set of parameters that collectively specify the performance of the network service that the network service user expects the network provider in relation this request. In addition, QoS is also used to specify the optional services to be used with this request. The QoS may vary from one network to another.

GPRS supports Quality of Service. The QoS profile attributes in GPRS [1], [8] are:

1. Precedence class---indicates the importance of the packet with regard to discarding it in case of problems and degradation of QoS when necessary)

2. Reliability class---specifies the mode of operation for various error detection and recovery protocols, how securely the data should be delived.

3. Delay class---the transfer delay includes the uplink radio channel access or downlink radio channel scheduling delay, the radio channel transit delay, and GPRS network transit delay

4. Peak throughput class --- define the maximum allowed transfer rate 5. Mean throughput class --- define long term average transfer rate

In GPRS, the default QoS profile is defined in HLR. The SGSN and GGSN control QoS in GPRS, but mainly in the SGSN.

One of the problems of GPRS is relatively low bandwidth and the lack of capability to perform packet multiplexing between LLC packets with different QoS requirement of same PDP context. Another problem is regarding the packets discarding when the MS moves from one BSS to another.

6. Conclusion

In this presentation, only some basic GPRS operations are introduced. There are so many GPRS related issues, such as radio interface, service subscription roaming, security, billing, etc. Interested readers may reference to the materials [1].

GPRS is standardized in SMG of ETSI [2]. The first version of GPRS standard has been improved in 1998, while the next version of the standard that adds advanced features such as point-to-multipoint communications is in development. Most GSM vendors such as Alcatel, Ericsson, Lucent, Motorola, Nokia, Nortel, and Siemens have been active in the standards process. Four companies, Ericsson, Motorola, Nokia and Siemens have announced their products. But the commercial networks are not available yet. Field trials are expected in 1999 and deployment will begin in the year 2000. Though the GPRS standard specifies support for both X.25 and IP, it is likely that vendors and operators will emphasize IP service. At this time no cellphones or modems that support GPRS have been announced but it is possible that eventually all new GSM phones will support GPRS.

The future of the GPRS will evolve towards wireless LAN(WLAN) and the Universal Mobile Telecommunications System (UMTS) (the 3rd generation wireless personal communications) [9], [11]. The WLAN now is available. It offers 4 different transfer rate: 2 Mbps, 1 Mbps, 5.5 Mbps and 11 Mbps. The UTMS will offer at least 144 kb/s for high-mobility users with wide area coverage and 2 Mbps for low-mobility users with local coverage, and support a large variety of services over a large variety of radio conditions.

Acknowledgement

I would like to thank Dr. Hannu H. Kari for his guidance, providing valuable materials, and even corrections on the presentation. I would like to thank prof. Petri Vuorimaa for his comments.

References[1] Hannu K. Kari, http://www.cs.hut.fi/~hhk/GPRS/gprs_own.html

[2] Peter Rysavy, General Packet Radio Service (GPRS). Journal of PCS Data Today, 1998. http://www.pcsdata.com/paprysavy.htm

[3] Timo Sivula, General Packet Radio Service. Nokia's vision for a service platform supporting packet-switched applications, 1998.

[4] G�tz Brasche and Bernhard Walke, Concepts, Services, and Protocols of the New GSM Phase 2+ General Packet Radio Service. IEEE Communications Magazine, Aug. 1997.

[5] Jian Cai and David J.Goodman, General Packet Radio Service in GSM. IEEE Communications Magazine, Oct.1997.

[6] Jari H�m�l�inen, Design of GSM High Speed Data Services. Tampere University of Technology, Oct. 1996.

[7] Heimo Laamanen, Serveability Issues in Mobile Distributed Systems. University of Helsinki, 1998.

[8] Jouni Mikkonen, Matti Turunen, An Integrated QoS Architecture for GSM Networks. October, 1997.

[9] Tero Ojanper�, Ramjee, An Overview of Third-Generation Wireless Personal Communications: A European Perspective. IEEE Personal Communications. December 1998, p59-65.

[10] Takehiro Murase, Minoru Ohyama, Evolution of Personal Multimedia Communications Services in Japan. IEEE Personal Communications.

December 1998, p66-74.

[11] Fabrizio Sestini, Thomas Y.C.Woo, 3RD Acts Mobile Communications Summit. IEEE Personal Communications. December 1998.

[12] Olivier Verscheure, et al, User-Oriented QoS in Packet Video Delivery. IEEE Network. November/December 1998. p12-21.

[13] Javier Goz�lvez Sempere, An overview of the GSM system. http://www.comms.eee.strath.ac.uk/~gozalvez/gsm/gsm.html#6

[14] Jouni Mikkonen, QoS Support in Wireless Access Networks. February, 1998.

[15] Fred Halsall, Data Communications, Computer networks and Open Systems. Fourth Edition.

Abbreviations [1]

AA Anonymous Access. Network does not know the real identity of the mobile. Opposite to non-anonymous access.

AUCAuthentication Center BG Border Gateway. Logical box that connects two (or more) operators together via Inter-PLMN backbone. BG protects operator's intra- PLMN

network against intruders.

BSC Base Station Controller

BSS Base Station Subsystem

BSSAP+ Base Station System Application Part+. Protocol between SGSN and MSC/VLR

BSSGP Base Station System GPRS Protocol. Protocol between SGSN and BSS.

BTS Base Transceiver Station

EIR Equipment Identity Register

ETSI European Telecommunications Standards Institute

GGSN Gateway GPRS Support Node. One of the new key functional elements of GPRS.

GMM/SM GPRS Mobility Management and Session Management Protocol stack between MS and SGSN that handles GPRS attach/detach, PDP

context activation/deactivation, etc.

GGSN Gateway GPRS Support Node

GPRS General Packet Radio Service

GSM Global System for Mobile Communications

GTP GPRS Tunnel Protocol

GTP GPRS Tunneling Protocol. Protocol between SGSN and GGSN to encapsulate user data and to carry GPRS signaling.

HLR Home Location Register

HPLMN Home Public Land Mobile Network. The home network.

HSCSD High Speed Circuit Switched Data. New GSM service for circuit switched connections

ICMP Internet Control Message Protocol. IP network control protocol.

IMSI International mobile subscriber identity. User's unique ID in GSM/GPRS networks.

IPv4 Internet Protocol version 4. The currently used IP version.

IPv6 Internet Protocol version 6. Next generation IP protocol, not yet widely used.

ISP Internet Service Provider. The organization or operator that sells Internet access.

LLC Logical Link Control. Protocol layer between MS and SGSN.

MAC Medium Access Control. Protocol in the radio level that is used to allocated the radio channel.

MS Mobile station . The phone (in general).

MSC Mobile Switching Center

NS Network Service. Protocol layer between BSS and SGSN.

NSAPI Network layer Service Access Point Identifier that specifies the PDP context in MS and in SGSN.

NSS Network SubSystem. Network part of the network (in GPRS it means SGSN and GGSN).

PCU Packet Control Unit. Functional element in BSS that handles upper level GPRS control in radio.

PDA Personal Digital Assistant. A gadget that fits in hand and has limited services.

PDN Packet Data Network. Network that carries user data in packets (e.g., Internet and X.25)

PDP Packet Data Protocol, e.g., IP or X.25. Protocol that is used by user.

PDU Protocol Data Unit. One data packet.

PLMN Public Land Mobile Network

PPP Point-to-Point protocol. Widely used protocol under IP to connect, e.g., PC and ISP via modems.

PSTN Public Switched Telephone Network

PTM Point To Multipoint. One sender, multiple receivers.

PTP Point To Point. One sender, one receiver.

QoS Quality of Service. Definition of the service class of the connection between MS and the network.

RA Routing Area. A set of cells that belongs to one group. RA is always a subset of a LA (location area).

RLC Radio Link Control. A protocol between MS and BSS to handled retransmission and other radio related issues.

SGSN Serving GPRS Support Node. Second new functional element of the GPRS network.

SM Short Message. Service to send/receive 140 bytes (160 characters) messages.

SM-SC Short Message service Service Center. A computer that handles short messages.

SMS-GMSC Short Message Service Gateway MSC. MSC that is used to deliver data to/from SGSN.

SMS-IWMSC Short Message Service Interworking MSC. MSC that is used to deliver data to/from SGSN.

SNDC SubNetwork Dependent Convergence. Protocol layer between MS and SGSN.

SNDCP SubNetwork Dependent Convergence Protocol. Protocol of the SNDC.

TCP Transmission Control Protocol. Protocol layer on top of conventional IP protocol.

TE Terminal equipment. Typically a computer, host.

TID Tunnel Identifier that identifies uniquely the MS and also the PDP context in the GPRS backbone network (between SGSN and GGSN).

TLLITemporary Logical Link Identity. Identifier of the mobile used between MS and SGSN, UDP User Datagram Protocol. Another protocol on top of IP.

UMTSUniversal Mobile Telecommunications Services VLR Visitor Location Register

VPLMN Visited Public Land Mobile Network. The network where mobile is currently located.

WLAN wireless local area network

List of interfaces [1]

Gb Interface between an SGSN and a BSS.

Gc Interface between a GGSN and an HLR.

Gd Interface between a SMS-GMSC and an SGSN, and between a SMS-IWMSC and an SGSN.

Gf Interface between an SGSN and an EIR.

Gi Reference point between GPRS and an external packet data network.

Gn Interface between two GSNs within the same PLMN.

Gp Interface between two GSNs in different PLMNs. The Gp interface allows to support of GPRS network services across areas served

by the co-operating GPRS PLMNs.

Gr Interface between an SGSN and an HLR.

Gs Interface between an SGSN and an MSC/VLR.

kbit/s Kilobits per second.

R Reference point between a non-ISDN compatible TE and MT. Typically this reference point supports a standard serial interface.

Um Radio interface between MS and the network side.