Study On OFDM Performance Under LMS Channel Based On DVB-SH Standard

As an important part of global communications, communications satellites allow servicetransmissions to be sent to anywhere in the world including remote, undeveloped and sparselypopulated areas, which can also be useful while natural disasters or emergency events happen. Withhigh spectral efficiency and ability to cope with frequency-selective fading, OFDM(OrthogonalFrequency Division Multiplexing) modulation has become one of core transmission technologies inthe fourth generation mobile communications and WLAN systems. DVB-SH(Digital VideoBroadcasting-Satellite services to Handhelds) standard uses OFDM modulation in satellitecommunications to solve the spectrum limited problem while broadcasting signals carryingmultimedia services directly to a variety of mobile (handheld or vehicular) and fixed terminals. SoOFDM can also play an important role in satellite wideband communication systems.In this paper, the performance of the OFDM modulation under the LMS(Land Mobile Satellite)channel based on DVB-SH standard is analyzed through simulation. The main work is as follows.Firstly, the different characteristics and classifications of the channel fading are analysed andcompared in detail to simulate channel models; the simulation methods of models are present.Secondly, the main factors affecting the performance of OFDM system are discussed; BERperformance of the OFDM system under usual channel models is simulated. Thirdly, useful LMSmodels including single-state, multi-state narrowband and wideband models are described; thesimulation method of the most accurate and full environment suitable multi-state LMS widebandmodel is present for further analysis. Finally, all the OFDM modulation performance under differentenvironments, satellite elevation angles and frequency bands is simulated and compared.