Wireless communication is a rapidly growing field with many of its aspects undergoing
constant enhancement. The use of cross-layer design (CLD) in current technologies has
improved system performance in terms of Quality-of-Services (QoS) guarantees. While
multimedia transmission is difficult to achieve, CLD is capable of incorporating techniques
to achieve multimedia transmission without high complexity. Many systems have
incorporated some form of adaptive transmission when using a cross-layer design approach.
Various challenges must be overcome when transmitting multimedia traffic; the main
challenge being that each traffic type, namely voice; image; and data, have their own
transmission QoS; delay; Symbol Error Rate (SER); throughput; and jitter requirements.
Recently cross-layer design has been proposed to exchange information between different
layers to optimize the overall system performance. Current literature has shown that the
application layer and physical layer can be used to adequately transmit multimedia over
fading channels. Using Reed-Solomon coding at the application layer and Rate Adaption at
the physical layer allows each media type to achieve its QoS requirement whilst being able
to transmit the different media within a single packet.
The following dissertation therefore strives to improve traffic through-put by introducing an
unconventional rate adaption scheme and by using power adaption to achieve Symbol Error
Rate (SER) QoS in multimedia transmission.
Firstly, we introduce a system which modulates two separate sets of information with
different modulation schemes. These two information sets are then concatenated and
transmitted across the fading channel. The receiver uses a technique called Blind Detection
to detect the modulation schemes used and then demodulates the information sets
accordingly. The system uses an application layer that encodes each media type such that
their QoS, in terms of SER, is achieved. Simulated results show an increase in spectral
efficiency and the system achieves the required Symbol Error Rate constraint at lower Signal
to Noise Ratio (SNR) values.
The second approach involves adapting the input power to the system rather than adapting
the modulation scheme. The two power adaptive schemes that are discussed are Water-
Filling and Channel Inversion. Channel Inversion allows the SER requirement to be
maintained for low SNR values, which is not possible with Rate Adaption. Furthermore, the
system uses an application layer to encode each media type such that their QoS is achieved.
Simulated results using this design show an improvement in through-put and the system
achieves the SER constraint at lower SNR values. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2013.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ukzn/oai:http://researchspace.ukzn.ac.za:10413/10404 |
| Date | January 2013 |
| Creators | Vieira, Ricardo. |
| Contributors | Xu, Hong-Jun. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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