Peak to average power ratio reduction in OFDM systems by parallel branch selection method | |
| Author | Khan, Mohammad Enam Ur Rahman |
| Call Number | AIT Thesis no.TC-03-10 |
| Subject(s) | Multiplexing Discrete-time systems |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-03-10 |
| Abstract | The demand for multimedia over wireless link is growing rapidly. Because of its many advantages, Orthogonal Frequency Division Multiplexing (OFDM) is considered as a competent candidate for realizing this demand. But, occasional very high Peak to Average Power Ratio (PAPR) is a serious matter of concern in OFDM systems. To combat this problem many methods have been proposed by many researchers but to date no method justifies the ending of search for P APR reduction scheme. One of the best methods is Partial Transmit Sequences (PTS), proposed by Muller and Huber in 1997. This method has the drawback that it requires exhaustive search to find optimum combination of rotation factors giving minimum P APR. Later Cimini and Sollenberger proposed a suboptimum technique to reduce the number of searches. In the first part of this thesis, a new criterion has been introduced to decide suboptimum algorithm. In the second part of the thesis, Parallel Branch Selection (PBS) method is proposed that can work with arbitrary number of subcarriers without limitation to modulation schemes and incurs very little overhead. It has the advantage over PTS that at the receiver there is no need to derotate all the subcarrier phases which means a considerable saving in computation. Results show that the PBS can produce the same Complementary Cumulative Distribution Function (CCDF) as exhaustive PTS with 50% reduction in the number of trials. There are two drawbacks of PBS method. Firstly, it is difficult to manage the buffer and secondly, delay is introduced in the system. To handle the buffer underflow or overflow problem, during formation of a suitable OFDM symbol, a second criterion of maintaining minimum variance of buffer occupancy distribution is introduced. It is observed that inclusion of this second criterion gives propitious result. The amount of delay wholly depends upon initial number of OFDM symbols that is needed to be fed into buffer for smooth operation of PBS method. |
| Year | 2003 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-03-10 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Ahmed, Kazi M. ; |
| Examination Committee(s) | Erke, Tapio J. ;Teerapat Sanguankotchakorn; |
| Scholarship Donor(s) | Keihin Electric Express Railway Company Limited (KEIKYU), Japan; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2003 |