The above
combination of the charging models is a simple
example and shows how a mobile
network operator
may choose to charge and invoice their subscribers. The illustration also shows
the
overlap between
the various pricing models and how the boundaries can be made flexible depending
on
the subscriber
usage profiles. For example, the mobile network operator may use Packet Charging in
both Fixed Price
and Metered Charging tariffs for some
subscribers but only use Packet Charging
with
a Fixed Price
charging model for other subscriber groups or
tariffs. Some subscribers may only want to
use limited
Internet services, for example only text email and no Web browsing. The mobile
networks
may choose to
implement charging models to take care of these
limited service requirements
The tariffs for
the subscriber may become complicated but may ultimately give the
subscribers
more control
over the way they are charged for using the mobile voice and Internet services
and the
Quality of
Service they receive from the network operator. The network operators will also
have the
advantage of
being able to charge the subscribers for different level of Quality of Service
for the
different
services and network provision.
Once experience
of realistic network traffic in the next generation GSM networks has been gained
and large
quantities of network usage statistics have been collected and analysed, then
more
comprehensive or
simplified charging models may be investigated,
developed and prototyped from the
ones discussed
above. There will always be a trade-off between the complexity of the billing
system to
be implemented
and supported and the advantage the network provider will receive for having
the
systems in
place. Fixed price charging schemes reduce the
overhead of the charging and
billing
systems
infrastructure, as they tend to provide the simplest charging scenarios. Usage based charging
models provide
incremental and harder to predict income for the network providers as well as
requiring
high investment
in the charging and billing infrastructure
required. This includes increased cost
in
network traffic
involved in the collection of the billing data required.
When the GPRS
networks are up and running and the charging
models are in place the economics
of the market
may take over and under- and/or over-provisioning of network resources may
become
apparent,
especially with the Internet gateway provision. Charging and billing may then be used for
congestion
control as already proposed for the Internet and not just for recovery of costs
for the
network
operators.
Further work in
this area should include the mathematical modelling of the various charging
models on
simulated mobile network data covering both voice and Internet data services.
This should
include
examining the combining of charging models and
the resultant effect on the income for the
GSM telephone network provider and also the cost impact on the different types of subscribers
using
the mobile
telephone networks.