City Research Online

Abstract

This thesis describes a novel type of family of LANs, that is characterised by high performance, security and survivability. These qualities are of great importance for a lot of applications, especially in environments where uninterrupted operation and low overall time delay for message delivery are required. Such environments can be the military ones, airports, crucial industrial areas, etc.

For this family of LANs a mesh topology with physical separation of the subscribers into intercommunicating groups, according to their properties and security demands, in combination with a modular structure is suggested. On this mesh topology a continuous retransmission of any received signal in any direction (flooding routing), together with the spread spectrum techniques, as a media multiple access method (Code Division Multiple Access) are used. This architecture guarantees survivability, offers security, gives possibility of simultaneous communication and similar performance to all the communication channels. The synchronisation and signalling problem of the LAN and the selection of the family of the spreading codes is solved through the use of known protocols, methods and technology. Many different architectures can be designed according to the above principles. Among them the idea of using a separate signalling and timing channel (e.g. a TDM channel) in a universal timing system improves the reliability, without affecting the performance.

A survivable and secure LAN topology, a member of this family, is described. The architecture and operation of two spread spectrum mesh topology LANs that use a signalling TDM channel and the maximal length binary sequences are examined and analysed.

The distributed design of the system in combination with the used code division multiple access method reduces greatly the collision probability and consequently the created delays. The statistical properties of the used packet switching method improves considerably the overall performance of the system. The selection of the spreading code bit rate defines the final bit error rate. Performance estimates for the flooding idea regarding the bit error rate and the collision probabilities have been evaluated. These estimates have been taken through the solution of a simplified mathematical model and verified from simulation tools that have been developed. These simulation tools compose an environment for the study of mesh topology networks.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science
Departments:	School of Science & Technology > Computer Science School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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