Mobile - PMR

This section shows how our software tools can be applied to the general field of Private Mobile Radio (PMR) and specifically how our products can be used to design, optimise and roll out conventional and trunked mobile radio networks including technologies such as MPT1327 and TETRA.The methods and sub-tools developed within tools such asICS Telecom 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 mobile radio systems.

General PMR Planning Methods

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

• The ability to compute the coverage of ground area from a given transmitter type and specification to a given receiver type and specification.
• The ability to compute the degree of interference suffered by both mobiles (down link) and base stations (up link) from all on the same or adjacent channels.
• The degree of resilience built into a system allowing the network to be optimised for overlap, traffic demand or critical coverage.
• 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 Data Base Connectivity protocol to external database such as Oracle and MS Access allowing the sharing of engineering data across a multi-discipline project team.
• The counting of mobile population covered under a transmitter footprint with the addition of an irregular polygon limit.
• The counting of area under a transmitter footprint but showing the results over a variety of different urbanisation categories including roads, urban and suburban areas with the addition of an irregular polygon limit.

Specific PMR Planning Methods

The design and subsequently the roll out of PMR networks to cover both data and voice is a well established process. There is however very great scope for automation of the methods used and for optimisation of the engineering design to critically engineer the network to meet the customer requirement with the minimum base station and antenna system resources. The specific methods noted below are some of the tools employable to ensure that the planning engineer produces the most cost effective system.

The coverage calculated can be filtered to only display on specific ground use types such as roads or railways. This then allows the planner to focus on the desired target user for the service. Similarly, interference calculations over rural or open areas away from that target user can be ignored or reduced in significance.

Several views are possible once a coverage computation from a given site has been made. The best server view shows where on the ground mobile would vote or register on the basis of field strength. The simultaneous communications view shows which areas on the ground benefit from signal from several sites and where a radio dispatcher might be used to access several repeaters.

The computation of traffic capacity of a network will of course be dependant on the number of subscribers served by a given base station. Traffic analysis can be done using methods such as Erlang B or C. The traffic demand is made up in a demand file directly in the planning tool. ICS Telecom contains a host of sub-tools to be used in site finding.

This includes the ability to place a series of points and to reverse the planning process to request the locus of points where a useable signal will be received from those locations. Once established a site can be positioned there and the coverage probed. ICS Telecom allows the investigation of the lie of the land in three dimensions allowing the engineer to see directly the effect of positioning a site at a given location.

For quasi-synchronous systems including DQS ICS Telecom allows the user to analyse in both amplitude and phase the effects encountered by the mobile in overlap areas within the system. Once computed the planning engineer can introduce a launch delay at each transmitter and optimise the effects of overlap.

Once coverage has been assessed the operating frequency of each site can be assigned automatically from a frequency list. This is done primarily in the talk out path by selecting the best frequency to maximise the C/I ratio experienced by the mobiles.