Cellular One 832 CO-IIE Bedienungsanleitung PDF herunterladen

LECTURE 5

AMPS and GSM

1G Cellular Systems

!  Goal: Provide basic voice service to mobile users over a large

area

!  1 G Systems developed in late 70’s/early 80’s – deployed in

80’s

!  Advanced Mobile Phone System (AMPS) - USA

!  Total Access Communications Systems (TACS) - UK

!  Nordic Mobile Telephone (NMT) System – Scandinavian PTTs

!  C450 - W. Germany

!  NTT System - Nippon Telephone & Telegraph (NTT) – Japan

!  Incompatible systems using different frequencies!

!  Have similar characteristics though

Characteristics of 1G Cellular Systems

!  Use Cellular Concept to provide service to a

geographic area (i.e. number of small adjacent cells to

provide coverage)

!  Frequency Reuse

!  Handoff/Handover

!  FDMA/FDD systems

!  Common Air Interface standards only

"  Analog Voice communications using FM

"  Digital Control channels for signaling

!  Adjustable Mobile Power levels

!  Macro Cells : 1-40 km radius

!  Focus on AMPS system

Characteristics of 1G Cellular Systems

(continued)

!  First generation systems targeted to few subscribers with car phones

!  Rapid growth in demand for cellular services

!  Availability of low cost, lightweight, portable handsets

!  → Growing demand for system capacity

!  Capacity can be increased by smaller cells but:

!  More difficult to place base stations at locations for necessary radio

coverage

!  Increased signaling for handoffs, and more frequent handoffs

!  Base stations handle more access requests and registrations

!  Analog technology has limited options to combat interference effects

from smaller cells

!  Demand for 2G digital cellular

!  Also, incompatible first generation (analog) standards in Europe

motivated new pan-European digital standard

1 2 3 4 5 6 ... 13 14

Inhaltsverzeichnis

Seite 1 - 1G Cellular Systems

LECTURE 5 AMPS and GSM 1 1G Cellular Systems 2 !  Goal: Provide basic voice service to mobile users over a large area !  1 G Systems developed in la

Seite 2 - MSAs and RSAs

GSM: FDD Channels 37 0 1 2 3 4 5 6 7 0 1.73 ms Frame= 4.62 ms BS to MS Downlink MS to BS Uplink 200 KHz 1 2 5 6 7 0 1 2 3 4 5 6 7

Seite 3 - Mobility Management in AMPS

Common Control Channels (Unidirectional) 41 !  Used for all connection set up purposes !  The paging channel (PCH) is used for paging a mobile when it

Seite 4 - Functional Architecture

Mobile Terminated Call 45 1)  User dials a phone number of a GSM subscriber 2)  PSTN forwards the call set up to the GMSC 3)  GMSC identifies the HLR

Seite 5 - Base Station Subsystem (BSS)

Mobile Assisted Handoff (MAHO) 49 !  The BTS provides the MS a list of available channels in neighbouring cells via the BCCH !  MS monitors the RSS fr

Seite 6 - BSC Vs BTS Functions

Handoff Executed with an MSC 53 MS BSS 1 MSC BSS 2 Measurement Report Handoff Required Handoff Command Handoff Complete Clear Command Clear Complet

Seite 7 - Visitor Location Register

Summary of 1G systems 5 Japan North America England Scandinavia Germany System NTT AMPS TACS NMT C450 Dwnlink Freq (MHz) Uplink Freq (MHz) 870

Seite 8 - Air Interface

Frequency Allocation in AMPS 9 !  Originally 40 MHz of spectrum separated into two bands of 20 MHz each (A and B band). Later expanded to 25 MHz each

Seite 9 - Types of Time Slots

GSM: Global System of Mobile Communications 13 !  A heterogeneous analog cellular implementation was observed in Europe in the 1980s !  United Kingdom

Seite 10 - Traffic Channel

Radio Subsystem 17 !  It is made of the Mobile Station (MS) and the Base Station Subsystem (BSS) !  It deals with the radio part of the GSM system MS

Seite 11 - Pre-registration

Base Station Controller (BSC) 21 !  Performs all functions necessary to maintain radio connections to an MS !  Manages several BTSs !  It multiplexes

Seite 12 - Handoff in GSM

Mobile Services Switching Center (MSC) 25 !  High performance digital ISDN switches !  Manages several BSCs !  A Gateway MSC (GMSC) connects different

Seite 13 - Handoff Criteria

radio LAPDm RRM MM CM radio LAPDm 64 kbps LAPD RRM 64 kbps LAPD 64 kbps MTP SCCP RRM 64 kbps MTP SCCP RRM MM CM Um Air Interface A-bis A MS BTS MSC

Seite 14 - Data Services in GSM

Framing Scheme in GSM (Control Channels) 33 1 2 3 4 2048 1 2 3 4 26 1 2 3 4 51 TB TB Data (57 bits) TS GP Data (57 bits) 1 2 3 5 6