Difference between GSM and UMTS

GSM encompasses everything from the air interface to the way in which the switches interact with one another, as well as to the landlines to which they connect. However, in this context we are using GSM to refer to the old 2.5G service, UMTS is the new iteration of the GSM air interface.

The original GSM service was based on a TDMA (Time Division Multiple Access) scheme. This approach broke up a single channel into various “slots”, which phones took turns transmitting on in order to share the channel. The new UMTS service uses a CDMA (Code Division Multiple Access) scheme.

a big difference between a TDMA-based system and a CDMA-based system is how the phone deals with handing off from one cell site to another. In TDMA-based systems the phone must wholeheartedly switch from one channel to another in order to switch towers. There are no halfway measures here, it’s all or nothing. As a result, all TDMA-based GSM phones suffer from slight (but rather annoying) interruptions in the audio stream whenever a handoff occurs, and if one doesn’t occur in a timely fashion, the user can experience rather devastating degradation of the call quality. In short, UMTS is CDMA done right.

ps : need help and information of where to download MOSHELL (Ericsson RNC/Node-B)

MOshell
The Ericsson has developed a tool called MoShell for network management. The MoShell is a network tool used by Ericsson employees and it is the most important tool when there is need to integrate, upgrade, tune, troubleshoot or monitor the Radio Access Network. This chapter explains the Managed Object (MO) concept and main functionalities of MoShell.

Managed Object MO
MOs are small units for certain functionality in the Node. MOs are organized in a hierarchical tree structure. The Highest MO is so called ROOT MO and it represents the whole Node. Figure 15 illustrates ManagedElement as ROOT MO with some of it’s child MOs. Managed Object Model (MOM) explains the dependency and functions of managed objects. MOM is a list of all the MOs, their types, attributes, references and actions.

MOShell functionality
MOShell is used for radio access network management by including many useful services.

MoShell is text-based O&M (Operation and Maintenance) client providing access to the following services:
• Configuration Service (CS) • Alarm Service (AS)
• File Transfer (ftp/http)
• Log Service (LS)
• OSE shell (COLI) (Command Line Interface)
• Performance Management service (PM)

Configuration Service
The configuration service provides specifications and produces the configu-
ration data and software adaptations needed for the network elements to se-
cure high quality in network functions and end-user-services. Functions are
e.g. upgrade or integration of the nodes.

Alarm Service
Alarm service lists all active alarms from the network. The service indicates
the severity of the alarm, what specific problem is, what is causing it and
where the problem is located. The list of active alarms can be retrieved with

the commands ‘al’ or ‘ala’. Command ‘ala’ gives more detailed information of alarms.
File Transfer (ftp/http)
Files and directories can be downloaded or uploaded to/from node by using
http, ftp of sftp protocol.

Log Service (LS)
The log service is function which enable to read log-files from the node. Logfiles indicate all the alarms and failures which have occurred in RAN in certain time period. It is possible to see all the logs from the node, or at certain period of time. Minimum of time period is 30 minute, which includes two ROP xml-files.

Log-files can be found from MOShell by typing the command:
• Lgs (displays the system log from the whole period stored in system log.
It can be several months)
• Lgs year-month-day (displays logs from the following date)
• Lgasmi 30 (displays the last 30 days of the alarm and system logs)
• Lgaevs 5h (displays the last 5 hours of the alarm/event/availability/system
logs)
• Lgac 30m (display the last 30 min of the alarm log and print the output
into a default csv file)

Performance Management Service
All the main performance statistics information can be found with pmr command, which lists performance statistics from the node. The statistics are numbered from 1 to 25 and by entering the wanted number user can see desired counter values.