ATDI Software and Point to Point Technologies.

Microwave links

This note describes how ATDI software can be used across current Microwave Link technologies in the bands 1.5GHz to 55GHz to design, optimise and roll out networks either in support of mobile and radio fixed access or to carry trunk telephone traffic as a network in their own right.

The methods and sub-tools within tools such as ICS telecom nG have come from our work with various customers. These companies have either used our tools or have contracted ATDI to carry out work on their behalf to further their development of their fixed link networks.

General Microwave Link Planning Methods

The following general modelling methods have application in microwave radio links and are included in ATDI planning tools.

• The ability to draw a radio path profile between any two points on the loaded terrain showing the Fresnel zone and Fresnel zone fraction and the Earth Radius factor.
• The ability to edit this path profile in light of visual clearance surveys adding buildings and trees to the profile at the correct heights.
• The ability to account for both terrain and buildings/trees in the path loss calculation.
• The ability to link the planning tools via a network to develop the system using a number of planners each with privilege to change their own zone yet compute the effects of those adjacent.
• The ability to link the planning tools via an Open DataBase Connectivity protocol to external database such as Oracle and MS Access allowing the sharing of engineering data across a multi-discipline project team.
• The ability to search for likely sites by carrying out area coverage plots only showing 'coverage' where a free space path exists.

Specific Microwave Links Planning Methods

Using ICS Telecom the microwave planner can search for potential sites gaining very quick assessment of the viability of the various optional paths across the terrain.

On fixing the sites the planner then proceeds to design the hops from his pre-configured equipment database probing each in the desired band for reliability. To conclude the design the network can be assigned operating frequencies and the resulting interference is computed.

• The ability to select the terminal, feeder and antenna types from an equipment database. This speeds up characterisation. Antenna types can be input directly from manufacturers files or from administration masks.
• ICS telecom nG can automatically assign frequencies around the network considering the terminal specification laid down. The channels are taken from a sub-band frequency list obeying the high-low rule if appropriate.

Once subscriber frequencies are assigned either manually or automatically ICS Telecom can assess the interference to every receiver considering all active transmitters using either the C/I - or wanted to unwanted - method or the 'drop in threshold' method. Interference assessments consider both co-channel and adjacent channel (including adj+1 to infinity).

• The consideration of both rainfall and atmospheric multi-path (considering path roughness/inclination) in computing reliability for link paths world-wide.
• The ability to design and view the complete nation-wide link plan on screen with links tagged by their idents and terminal call signs. Selection of links for analysis is then from a database listing.
• The ability to place sites statistically across the area with bias toward stated ground use categories. This allows future performance to be simulated according to different network growth profiles.
• ICS Telecom also calculates margins, clearances, reliability, interference and other parameters writing the results for the whole network to file for transfer to external management packages.