A typical telecommunications system
today is composed of multiple distributed boxes (network elements), which
communicate with each other to realize the intended functionality of the
system. Dimetra-Sä is such a
system, comprised of multiple boxes which form two distinct and bifurcated
sub-systems: Dispatch and Telephony subsystems. The former provides dispatch and the
latter provides telephony services.
Although distinct, the boxes in both
sub-systems must interact to a certain degree to provide needed services. One such interaction is required during
the initial phase of a land-to-mobile telephony call.
The Tetra Site Controller (TSC) requires a particular
mobile subscriber identity to locate (page) the target mobile subscriber. The information is contained in
Dispatch Application Processor (DAP), which is part of the dispatch sub-system,
but the telephony page is initiated by the Base Site Controller (BSC), which
does not have the necessary identity information.
The telephony paging mechanism
typically involves multiple TSCs because, when the mobile subscriber is not
actively communicating with the system, the system can only isolate the
location of the mobile subscriber to a location area, and a location area is
typically comprised of multiple TSCs.
Thus, each TSC requires
identical information from the DAP.
The act of retrieving the needed information from the DAP incurs network
traffic and taxes the DAP’s processing capacity. Each TSC must request needed information from the DAP
individually as shown in Figure 1.
The resulting impact on
network traffic and DAP processing is potentially very high as the number of
TSCs involved may be large. The
impact on network traffic and DAP processing can be significantly improved by
employing the algorithm described below.
The application of the
algorithm requires that the following pre-requisites be met:
Multiple Clients (TSCs). One or more Servers (DAPs).
A triggering event (telephony page request), which
causes the multiple clients to request a given piece of information (mobile
subscriber ID) from the Servers at the same time. All requesting Clients know that the given information is
needed by other requesting Clients without communicating with one another. This means that the given event
implicitly ties all Clients together.
Similarly, the Server(s) knows which Client entities
(in this case, TSCs in the same location area) require a given piece of
information by virtue of a request by a single Client.
The required information lies within one of the
Servers, but which specific Server holds the information may not be known to
There are two parts to the solution as described below:
Part 1: Proxying the Request
As the requested information
is a common piece of information required by all Clients (TSCs), a requ...