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E13 Mux: Study and prototyping
KTH, Superseded Departments, Teleinformatics. (CCSlab)
1996 (English)Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
Abstract [en]

Even though this thesis-project never reached the goal, a fully equipped and working prototype, it is possible to make a few important and valuable conclusions for further implementation of a prototype handling multiplexing and demultiplexing of timeslots in primary rate, E1 level and third rate, E3 level.

This `stripped' prototype is designed to multiplex timeslots from two E1 links into one E3 link, demultiplex timeslots from one E3 link into to two E1 links, also detect and generate basic alarms such as AIS, RAI and Loss of Signal. It is equipped with one dualdirected E3 interface and a dualdirected interface for two DL-2 connections. DL-2 is an Ericsson internal format. A conversion from DL-2 to E1 is made on the board. Since there are only two actual DL-2 connections and the remaining fourteen connections simulates AIS when multiplexed and not taken care of when demultiplexed, the prototype is considered as `stripped'. The wired prototype is easily controlled from an ANSI terminal, through the V.24 interface. When prototyping is finished and the construction is installed in AXE-10 environment, the V.24 interface will be unnecessary. The reason is the command interpreter that the V.24 interface is built upon. A command interpreter is not needed in AXE-10 environment, since the multiplexer unit will be controlled by DEVCB-signals from a regional processor and not by user commands.

The hardware is built up around the Motorola 68HC11F1. The multiplexors are very simple and are controlled by pins and not registers. This makes them easy to integrate in a system, but on the other hand it calls for higher performance of the device processor. The 68HC11F1 is not suitable for a fully equipped construction. The device processor must be able to handle alarms and produce statistics from a total of seventeen links, because the multiplexors doesn't support much more than a few alarm functions.

The software is written with processes and signals using OS11 operative system. The software is mostly written in C. The tasks that the processes preforms are distinct and logically separated, and will not be a cause of concern when reading the programs. Redesign of one process' functionality will have no or moderate impact on other processes, since the processes communicates through well defined signals.

Place, publisher, year, edition, pages
National Category
Communication Systems
URN: urn:nbn:se:kth:diva-98048OAI: diva2:534662
1996-04-26, Seminar room at floor 5, elevator B, Isafjordsgatan 22, Kista, 17:00 (English)
Available from: 2012-06-18 Created: 2012-06-18 Last updated: 2013-09-09Bibliographically approved

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