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The
main advantages of HSDPA are based on a beneficial consideration of the
actual radio conditions of all terminals to be served by one cell in a
very dynamic way:
- Link adaptation
with fast channel quality feedback
information ensures that modulation (QPSK and 16-QAM) and coding match
the varying channel conditions.
- Fast
retransmission of corrupted radio
blocks on Node B level reduce packet delay and resource allocation.
- Advanced MAC
layer procedures as C/I based scheduling and channel
sharing lead to an increased overall resource efficiency.
Thus
it is very clear that the performance of the HSDPA system is
closely related to the different radio channels of all mobiles and
their bursty traffic characteristics.
Obviously the main application
scenarios for HSDPA will be in dense urban and indoor areas with
corresponding high traffic demands. Especially for these environments
advanced ray-optical propagation models are available in ProMan. These deterministic
models can be used for the
important description of the radio channels in the HSDPA system
simulation.
Especially to exploit the benefits of the 16-QAM modulation (high
throughput on good channels) careful network planning is required.
Otherwise the probability to use these higher order modulation schemes
will be disappointingly small with all its effects on link and system
level performance.
System simulations help to evaluate mobile network performance in
different environments with different configurations or network
layouts. Performance indicators of interest are network capacity,
service availability and also service quality from the user point of
view. For HSDPA systems ProMan enables CPICH evaluation, a prediction
map indicating the maximum expected HSDPA data rate (see below), and
also
statistical analysis concerning packet delays, page throughput, sector
throughput, applied TFRC and others.
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