Thesis Abstract and Dissertation Abstracts

As a promising technique, OFDM has been widely used in emerging broadband communication systems, such   as digital   audio   broadcasting   (DAB),   high-definition television (HDTV), wireless local area network (IEEE 802.11a and HIPERLAN/2).  However,  as  the  OFDM  signals  are  the sum  of  signals  with  random  amplitude  and  phase,  they  are likely  to have  large  PAPR that  requires  a  linear  high-power- amplifier (HPA) with an extremely high dynamic range, which is   expensive   and   inefficient.   Furthermore,   any   amplifier nonlinearity   causes   intermodulation   products   resulting   in unwanted out-of-band power. A number  of approaches have been  proposed to deal with the  PAPR  problem,  including  clipping,  clipping-and-filtering (CF),   coding,   companding   transform,   active   constellation extension  (ACE),  selected  mapping  (SLM),  partial  transmit sequence (PTS), and so on.

This thesis proposes an improvement in Selected Mapping technique and Simulation results are compared to existing techniques namely Exponential Companding Transform, Repeated Clipping and Filtering and Adaptive Active Constellation Extension. The improvements which are proposed in classical Selective Mapping technique satisfies the PAPR Reduction criteria with reducing the computational complexity. Also this new scheme has an important advantage of avoiding the extra bits along with the transmitted OFDM signal .This scheme can also be applied to the multiple transmitting antenna cases.