Previous generations of cellular networks was built for telephone calls and
slow data transmission. Due to the rapid changes in information technology,
these factors do not meet the requirements of today's wireless revolution.
The first specifications for the 3rd generation system (3G) was released
2000 from the 3GPP collaboration group. WCDMA is one of the air interfaces in
the specifications.
In 2001 the first phase of HSDPA, High Speed Downlink Packet Access, was
introduced to the specifications. Instead of sending the data on a dedicated
channel to each user the radio resources are used more efficiently in HSDPA
by using shared channels in the downlink. A control channel signals which
users that is to receive data in each time instance.
This master thesis has been carried out at DBP IoV (Downlink Baseband
Processing Integration and Verification) at Ericsson, Lindholmen in
Gothenburg. This department is responsible for realtime target integration
and verification of the baseband processing system in WCDMA, including
testenvironment development and testcase design. Currently tests are in most
cases executed and recorded for offline analysis. The memory available for
recording on the test hardware limits the maximum run-time of the tests. To
be able to run long tests data has to be decoded and analyzed in real-time.
The purpose of this thesis was to design and implement a realtime decoder for
a subset of WCDMA, namely the downlink HSDPA channels. It should be
investigated how much that can be done in software on a DSP and how much, if
at all, that needs to be done in hardware on an FPGA. This was then to be
implemented on and integrated into existing test environments.
A comprehensive study of WCDMA in general and HSDPA in particular has been
carried out. The specifications define in detail how encoding is done, so the
core part of the thesis was to design a decoder based on these. During the
project there was a need to verify parts of the implementation so an encoder
was programmed in Matlab, enabling control of all parameters.
It was concluded that decoding could be done entirely on the DSP, and a
working...
