he cellular systems is made up of numerous transmitting and receiving sites, whose
individual coverage areas partially overlap. The concept of frequency re-use, same
frequency is used by several sites, allows a high traffic density in a wide area. Due to the
limited transmission range of the terminals, cellular systems are based on a large
number of base stations on the infrastructure side, scattered over the area to cover, with each
covering a fairly small geographical zone called cell. Cells are often represented by hexagons
(see figure 1.1.).
FIGURE 1.1 CELLULAR COVERAGE REPRESENTATION.
2
GSM Network Architecture.
GSM network can be broadly divided into three broad parts, namely:
1. Mobile Station(MS) carried by the subscriber,
2. Base Station Sub-system(BSS) which controls the radio link with the mobile station.
3. Mobile Switching Center(MSC) which performs the switching of calls between the mobile
users, and between mobile and fixed network users.
FIGURE 1.2 GSM ARCHITECTURE
Each mobile station is given a unique identity. As soon as the mobile phone is turned on, it
registers with the network and is authenticated; as such the network could always find the mobile
phone.
Larger amount of data is being exchanged to and from the following functional blocks in the MSC:
Visitor Location Register, VLR
Stores information about mobile subscribers that enter it coverage area, which is associated with
the geographical area where the mobile is currently roaming. When there is an incoming call for
the mobile, the HLR is interrogated about the present address of the VLR.
Home Location Register, HLR
A database that contains all data concerning the subscription of the mobile subscriber, i.e. their
access capabilities, subscribed services, and supplementary services. It also contains information
about the VLR that is handling the mobile station currently. When the mobile changes location,
the HLR is updated accordingly. It also provides the MSC with information about the MSC area
where the mobile is actually located to allow incoming calls to be routed immediately to the called
party.
Authentication Center, AUC
Stored information that is necessary to protect communication through the air interface against
any intrusions. The legitimacy of the subscriber is established through authentication and
ciphering, which protects the user information against unwanted disclosure.
Equipment Identity Register, EIR
An option the network operator can use to enforce security. With this feature the network can
identify defective or stolen mobile that may not be used in the network.
3
Subscriber Identity Module (SIM)
SIM is a smart card, which has a computer, and memory chip that is permanently installed in the
mobile equipment. It comes in either the size of a credit card or smaller version known as the
plug-in SIM.
The subscriber information, which includes a unique number called the International Mobile
Subscriber Identity (IMSI) is stored in the SIM card. SIM card identifies the subscriber to the
network.
To protect the SIM card from improper use, a security feature, a four digits personal identification
number (PIN), is built in. The PIN is stored in the SIM card and can be changed by the
subscriber. PIN2 is required for additional functions available with a special SIM card (Consult the
operator for more information about the PIN 2).
A code (PUK) is provided for unlocking the SIM card if the SIM card is blocked
.
4
SIM Application Toolkit
This is a new GSM feature that has been integrated into the GSM standards in Release 96, with
further enhancements added as part of the Release 97 feature set. This feature came about
because of a desire by Network Operators to offer differentiated services, without the need for the
Mobile Manufacturers having to build different variant for different customers. The unique service
offered by the Operator is placed as an application on the SIM and that could work on any mobile
that supports the Toolkit feature.
There is a distinct set of commands between the mobile and the SIM specifically for the Toolkit
that allows the SIM Toolkit and the mobile to communicate independently of the GSM
communication between the SIM and the mobile. Henceforth, the SIM Application Toolkit and
GSM functionality on the SIM are separated logically. The Toolkit can interact directly with the
mobile itself and adding itself to the mobile menu.
Currently, Toolkit application on the SIM and its “other half” communicate by using the Short
Message Service(SMS). “Proactive SIM” is a mechanism whereby the SIM can initiate actions to
be taken by the mobile. These actions include:
· Display text from the SIM on the Mobile display
· Send short message
· Set up a voice call to a number held by the SIM
· Set up a data call to a number and bearer capabilities held by the SIM
· Send a Supplementary Service (SS) control or Unstructured Supplementary Services Data
(USSD) string
· Play a tone in the mobile’s ear piece or ringer
· Initiate a dialogue with the user
· Provide local information from the mobile to the SIM.
· Data download to the SIM from network
· Call control by the SIM.
SIM Applications Toolkit (SAT) allows the flexibility to update the SIM, to change the services and
download new services over the air. In the SAT specification, the short message service is a key
mechanism for personalizing the SIM in each user’s GSM phone. It is designed as a client-server
application. A50 series supports SAT Class 3 specification.
When active, the name of the service may appear in the menu, and there will be sub-menu if
more than one application is active. Figure 1.4 is the SAT icon.
FIGURE 1.4 SAT ICON
Extended GSM 900, E-GSM
This is a new standard that allows Network Operators to increase their capacity through an
extended frequency. The frequency range of E-GSM is as follows:
· Mobile Transmit: 880,2 - 914,8 MHz
· Mobile Receive: 925,2 - 959,8 MHz
A50/1168 series is a GSM Phase 2 / Phase 2+ Dualband E-GSM / GSM 1800 mobile phone.
5
Wireless Application Protocol, WAP.
Wireless Application Protocol takes a client-server approach that uses the in-built micro-browser
to make a request, in wireless markup language (WML), for information or service. The request is
passed to a WAP Gateway, which then retrieves the information from a Internet server, in HTML
format, and translate it into WML. The requested information is then sent to from the WAP
Gateway to WAP client (mobile) using the available and most appropriate mobile network bearer
services.
Defines the user interface on the phone. WAE contains the WML,WML script and the
wireless telephony application (WTA).
2. Wireless Session Protocol
Link the WAE to two session services – one connection oriented operating above the WTP
and a connectionless service operating above WDP.
3. Wireless Transaction Protocol
Runs on top of the datagram service and part of the standard suite of TCP/IP protocols, to
provide a simplified protocol suitable for low bandwidth mobile station.
4. Wireless Transport Layer Security
WTLS incorporates security features that are based upon the established Transport layer
Security (TLS) protocol standard, that include data integrity checks, privacy on the WAP
Gateway to client leg and authentication.
5. Wireless Datagram Protocol
Allows WAP to be bearer independent by adapting the transport layer of the under-laying
bearer. WDP presents a consistent data format to the higher layer on the WAP stack.
WAP Internet access via the A50 is possible with the inclusion of Wireless Application Protocol
(WAP) browser 1.2.1.
Note: The Asian variant phone (1168) does not support WAP.
6
Ch
r
apte
Level 2 Service Guide
Introduction
The chapter is intended to help you carry out repair up to Level 2 on the A50 mobile phone.
General Information
A50/1168 is a dual band (GSM 900 and GSM 1800) Siemens GSM Smart handset.
Due to different requirements of the markets, the A50 has different variants, which broadly
classified under International version and Asian version. Marketing name for international version
is A50, whereas Asian version is 1168.
The A50 and 1168 share the same phone accessories.
Difference between A50 and 1168
The differences between the A50 and 1168 are the phone hardware code and the phone
software.
1168 is a Asian variant of A50 phone for the China, Taiwan, Hong Kong, Singapore and Malaysia
markets featuring support for English, Simplified Chinese and Traditional Chinese language.
The repair for international version A50 and the Asian variants 1168 are identical unless
otherwise noted, therefore the description herein is confined to A50 only.
All repairs have to be carried out in an environment set up
according to ESD regulations defined in international standards.
1
7
A50/1168 Technical Information
System GSM Phase 2, Dual Band
EGSM 900, Class 4(2 Watt)
GSM 1800, Class 1(1 Watt)
Operating Voltage 3.6V
Size (LxWxH)
Volume 85 cm
109 x 46 x 23 mm (L x W x H)
3
including battery (approx)
Weight 97g including battery (approx)
Battery 650mAH Li-ion Battery (A50 Standard)
Standby time
Talk time
1
up to 250 hours (standard battery)
1
up to 300 minutes (standard battery)
Charging Time < 2 hours for 100%
SIM support Plug in card 1.8 V or 3V, SIM Application Tool Kit Class 3
For the updated list, please refer to the list in e-Commerce from time to time
URL address: https://communication-market.siemens.de/so/welcome.lookup.asp
Data Cable S45/ME45/C45/M45/S25/C35/C35i/
M35/S35i/SL42/SL45
.
10
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