Mobile - Paging
This section shows how our software tools can be applied to the general field of radio paging
and specifically how our products can be used to design, optimize and roll out modern paging
networks employing technologies such as Flex 3200 or 6400, ERMES and POCSAG 2400.
The methods and sub-tools developed within tools such as ICS 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 high bit rate paging networks.
General Paging Methods
There are too many general sub-tools within ATDI products with application in this sector to mention
all of them here. Some of the most relevant however are:
- The ability to compute the coverage from a given transmitter type and specification to a given receiver type and specification.
- The ability to compute the degree of interference suffered by all parties, whether using the same or different modulation scheme.
- The degree of resilience built into a system allowing the network to be optimized for overlap or critical coverage.
- The ability to reverse the task and ask the tool to suggest the location of a transmitter in order to cover a given set of locations.
- 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 databases such as Oracle and MS Access allowing sharing of engineering data across a multi-discipline project team.
- The counting of 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 result over a variety of different urbanization categories including roads with the addition of an irregular polygon limit.
Specific Paging Methods
High bit rate iso-frequency or simulcast networks share one thing the
transmission of high bit rate data simultaneously from all transmitters.
The characteristics of the resultant composite signal at the overlap between transmitters and the use of distant,
dominant sites must be controlled carefully to avoid degradation of the perceived call
success rate by inter-symbol interference. The specific methods below indicate the
applications added to ATDI tools for this application.
Display on screen the condition 'if dominant site at that location, dominant
site prevails, else consider next two highest field strength sites, and
report the difference in propagation delay (time of arrival) greater
than DuS between arrivals from these sites.
Dominant sites are those where the field strength received from these sites is greater by EdB
than that from all others. Both D and E can be set by the user. Areas
victim to inter-symbol interference can be shown in color across the
area being planned.
The above condition considers that the modulation is launched
coincidentally from each site. To modify the effects of inter-symbol
interference on the ground there may be value in delaying the launch from
one or more transmitters by delays of between 0 and 100uS.
This fixed delay can be set in both ICS Telecom and HTZ Warfare.
Both the vertical and horizontal antenna responses can be changed
to illustrate the use of different antenna types. Standard antennas can
be called from equipment database. This allows the use of antenna tailoring
to direct areas victim to inter-symbol interference away from areas of key
interest such as towns and major roads.
Individual colors can be assigned to the best server footprint
of each site. This ability to differentiate between the coverage from each site
to the equi-signal loci can be used to develop an offset plan.
With color representation, +150 Hz, -150 Hz and channel center offsets can be assigned across the country.
In all ATDI planning tools the user has total control over the thresholds
and colours painted on screen to represent coverage. The user can
therefore set thresholds to represent given Call Success Rates in all
the various environments in which paging subscribers will operate.
Penetration loss can be assigned to each urbanisation or clutter category such that
this is added as an excess loss to each path loss assessment. This
automatically accounts for the fact that pager users in urban areas
will be located inside buildings.