digital network lecturer5

DIT

Dar es Salaam institute of Technology (DIT)

ETU 08102

Digital Networks

Ally, J

[email protected]

DIT

Mobile Network Technologies

Important events in radio communications

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1855-1870: James Clerk Maxwell– Developed Maxwell’s equations relating electric and magnetic fields– Was laid off from Aberdeen University before publishing most notable works

1876: Alexander Graham Bell– Files the first patent on telephone in the US– Elisha Gray files his patent for the telephone just a few hours later than Bell– Later, Gray challenge Bell’s patent in court


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"we just have these mysterious electromagnetic waves that we cannot see with the naked eye. But

they are there“ Asked about the ramifications of his

discoveries, Hertz replied, "Nothing, I guess."

1888: Heinrich Hertz– Demonstrate the practical existence of radio communications, by generating and detecting a radio wave– “It's of no use whatsoever […] this is just an experiment that proves Maestro Maxwell was right”


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Guglielmo Marconi– March, 1897: Transmitted Morse codesignals over a distance of about 6 km.– 13th May, 1897: Sent the first ever wireless communication over open sea.– 17th December, 1902: A transmission from the Marconi station in Glace Bay, Nova Scotia, Canada, became the first radio message to cross the Atlantic.

Marconi was also an effective businessperson. The last lawsuit regardingMarconi's numerous radio patents wasresolved in the US in 1943 (six yearsafter his death)


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1947: The transistor is invented by J. Bardeen, W. Brattain, and W. Shockley (AT&T Bell Labs).1948: Shannon presents the famous channel capacity expression.1948: Radio relay system between New York and Boston, 4 GHz, 350 km, 7 hops.1956: Regular TV-broadcasts start in Finland. 1981: 1G cellular: NMT 450 in Scandinavia

1982: Start of GSM-specification. 1983: Start of the American AMPS (Advanced Mobile Phone System, analog)1983: AT&T introduces analog AMPS in Chicago and Washington D.C. (early cellular system)

Important events in radio communications 1991: 2G cellular: GSM, digital cellular phone 1993: DECT, digital cordless phone 1995: First CDMA (code-division multiple-access) based

wireless system available in Hong Kong 1997: Wireless LAN – IEEE 802.11 1998: Specification of UMTS (Universal Mobile

Telecommunication System) 1998: Iridium: portable satellite telephony (Low Earth

Orbit satellite constellation) 1999: WLAN standard IEEE 802.11b (WiFi). RF band: 2.4

GHz (ISM). Rate: 11 Mbps 1999: Bluetooth standard version 1.0 (WPAN). RF band:

2.4 GHz (ISM). Rate: 1 Mbps

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Important events in radio communications 2001: 3G cellular: First WCDMA system available

in Japan 2002: 1 billion mobile subscribers 2005: 3.5G cellular: HSDPA specifications 2007: 3 billion mobile subscribers 2008: LTE Release 8 specifications 2009: 4G cellular: First LTE networks deployed 2010: 5 billion mobile subscribers 2010: LTE-Advanced Release 10 specifications

completed 2012: 6 billion mobile subscribers

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Mobile Network Evolution Paths

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Simplified picture of most important evolution paths from 2G technologies (e.g., GSM) to 4G technologies

(e.g., LTE-Advanced)

Cellular Systems General requirements High capacity High data rate Wide service area (99% population coverage) Low cost Low power consumption (Terminal) High reliability Global

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Cell

Base station Mobile station

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GSM system overview The GSM system is a frequency- and time-division cellular

system, each physical channel is characterized by a carrier frequency and a time slot number

Cellular systems are designed to operate with groups of low-power radios spread out over the geographical service area. Each group of radios serve MSs presently located near them. The area served by each group of radios is called a CELL

Uplink and downlink signals for one user are assigned different frequencies, this kind of technique is called Frequency Division Duplex (FDD)

Data for different users is conveyed in time intervals called slots , several slots make up a frame. This kind of technique is called Time Division Multiple Access (TDMA)

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Multiple Access Technique Multiple Access Technique allows many subscribers to use

the same communication medium.

There are four kinds of basic Multiple Access Technique : FDMA , TDMA, CDMA and OFDMA.

GSM system adopt FDD-TDMA (FDMA and TDMA together).

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The Frequency Spectrum

Duplex Separation: 45MHzChannel Bandwidth: 200KHz

Duplex Separation: 95MHzChannel Bandwidth: 200KHz

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Frequency Reuse The frequency resource of mobile system is very limited. The different Subscribers can use the same frequency in

different places. The quality of communication must be ensured.

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GSM-GPRS Network Component

GSM /GPRS BSS

BTS

BSC

BTS

BSC

PCU

SS7

SMS system

PSTNISDN

Internet,Intranet

MSC/VLR GMSC

HLR/AUC

SGSN

CG BG

GGSN

GPRS backbone

Other PLMN

A

Gb

Gi

Gp

C/D/Gs

Gr/Gs/Gd/Ge Gc

Ga

Abis

Um

MS

MS

OMC

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Mobile Station (MS)MS=ME+SIM

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Subscriber Identity Module (SIM)

SIM is actually a database on the user’s side. Physically it’s a micro chip , which must be inserted

into a mobile phone before it can be used. Subscriber to a GSM system is determined not by the

identity of the ME, but by the SIM.

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BTS

BSC

TC/SM

BSS

MSC

Base Station Subsystem (BSS) The Base Station Controller – BSC

The Base Transceiver Station – BTS

The Trans-coder – TC and Sub multiplexer (SM)

Base Station Subsystem is in charge of providing and managing the transmission path between the MS and the MSC. In particular the management of the radio interface.

BSC was defined with the intention of removing most of the radio related load from the MSC.

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Packet Control Unit (PCU)

Packet data switching

Bridge between SGSN and BSC

Provide Pb and Gb interface

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The Network Switching System

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Mobile-service Switching Center (MSC) Call Processing

Operations and Maintenance Support

Interface management

Inter-network & Inter-working Inter-network: communication between GSM

network and other network Inter-working : communication between different

entities inside the GSM network

Billing

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Home Location Register (HLR) Subscriber ID (IMSI and MSISDN)

Current subscriber VLR (current location)

Supplementary service information

Subscriber status (registered/deregistered)

Authentication key and AuC functionality

HLR is database used for the management of subscribers

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Visitor Location Register – VLR Mobile Status (IMSI attached / detached / busy /

idle etc.) Location Area Identity (LAI) Temporary Mobile Subscriber Identity (TMSI) Allocating the Roaming Number VLR stores subscriber information such as location

area when the subscriber is located in the area that the VLR is in charge of.

Some of the information that the VLR contains is a replica of the information in the HLR

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IMEI is Checked In White List

IMEI is Checked in Black/Grey List

If NOT foundEIR focus on the equipment , not the subscriber!!

Equipment Identity Register (EIR) White List

Black List Grey List

White list contains all equipment identity numbers that are permitted for use.

Black list consists of all equipment identity numbers that belong to equipment that need to be barred.

Grey list equipment are not barred, but tracked by the network for evaluation purposes.

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Echo takes place by GSM system delay caused by call processing, speech encoding and decoding etc.An Echo Canceller is used on the PSTN side of the MSC for all voice circuits

2-wire4-wire

2- wire

Hybrid Hybrid

Generation of Echo at 2-wire to 4-wire Interface

Echo Canceller － EC

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OMC Functional Architecture

OS

MMI

DB

Event/AlarmManagement

SecurityManagement

ConfigurationManagement

Performance Management

Fault Management

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LAI

Location Area IdentificationThe LAI is the international code for a location area.

MCC ： Mobile Country Code ， It consists of 3 digits . For example: The MCC of Tanzania is "640"MNC ： Mobile Network Code ， It consists of 2 digits . For example: The MNC of Zantel is "03"LAC ： Location Area Code ， It is a two bytes BCD

code(hex). The value 0000 and FFFF is invalid.For example: 640-03-0011

MCC MNC LAC

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CGI

The CGI is a unique international identification for a cell

The format is LAI+CILAI: Location Area IdentificationCI: Cell Identity. This code uses two bytes hex code to identify the cells within an LAI.

For example : 640-03-0011-0001

CGI: Cell Global Identification

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BSIC

NCC: PLMN network color code. It comprises 3 bit. It allows various neighboring PLMNs to be

distinguished.BCC: BTS color code. It comprises 3 bit, used to

distinguish different cells assigned the same frequency!

NCC BCC

BSIC

BSIC （ Base Station Identification Color Code)

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CC: Country Code. For example: The CC of Tanzania is “255".

NDC: National Destination Code. For example: The NDC of Vodacom is 755, 754, 764.

SN: Subscriber Number. Format:H0 H1 H2 H3 ABCDExample: 255-764-030690

MSISDN

CC NDC SNNational (significant)

Mobile numberMobile station international

ISDN number

MSISDN: Mobile Station International Standard Data Network

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MCC: Mobile Country Code, It consists of 3 digits . For example: The MCC of Tanzania is “640“.MNC: Mobile Network Code, It consists of 2 digits . For example: The MNC of Zantel is “03“.MSIN: Mobile Subscriber Identification Number. For example: 773-675000.NMSI: National Mobile Subscriber Identification ， MNC and MSIN form it together. For Example of IMSI : 640-03-773-675000

Not more than 15 digits3 digits 2 digits

IMSI

MCC MNC MSINNMSI

IMSI

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TMSI (Temporary Mobile Subscriber Identification)

The TMSI is assigned only after successful subscriber authentication.

The VLR controls the allocation of new TMSI numbers and notifies them to the HLR.

TMSI is used to ensure that the identity of the mobile subscriber on the air interface is kept secret.

The TMSI consists of 4 bytes (8 HEX numbers) and determined by the operator.

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IMEI (International Mobile Station Equipment

Identification)

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Physical Channel and Logical Channel

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Two types of Logical ChannelTraffic Channel (TCH) :

Transmits traffic information, include data and speech.

Control Channel (CCH) :Or Signaling Channel, transmits all kinds of control information.

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Traffic Channel (TCH)

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Control Channel (CCH)

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How to use these channels?

digital network lecturer5

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