PAPR reduction by combining selected mapping and selected spreading code in MC-CDMA systems | |
| Author | Supachai Ruangsuthinarupap |
| Call Number | AIT Thesis no.TC-03-17 |
| Subject(s) | Code division multiple access Multiplexing |
| 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-03-17 |
| Abstract | MC-CDMA is a combination technique of Orthogonal Frequency Division Multiplexing (OFDM) and Code Division Multiple Access (CDMA). MC-CDMA has several advantages such as, high rate data transmission, high bandwidth efficiency, frequency diversity and interference reduction. The main drawback is high Peak to Average Power Ratio (PAPR). Therefore, PAPR reduction methods are researched extensively. In this thesis, the effect of spreading sequences on PAPR by using three different Walsh Hadamard code allocations have been studied. The result shows that PAPR variation depends on the way the Walsh sequences are allocated to different users especially for a small number of active users. A code selection method is introduced for PAPR reduction. However, the achieved PAPR reduction by this technique is insignificant for large number of active users. To reduce PAPR further, PAPR reduction by combining selected mapping and selected spreading code is proposed. From the simulation results, it is observed that PAPR can be reduced significantly at a cost of increased system complexity proportional to the number of different phase sequences. The BER performances for multipath fading of three systems, the original system, the proposed system, and PTS are almost the same. Finally, four orthogonal sets of sequences namely, Walsh Hadamard sequences, Golay complementary sequences, Orthogonal Gold sequences, and Shapiro-Rudin sequences, are employed for spreading to study PAPR characteristic with different number of active users. The simulation result shows that Golay complementary sequences offer best PAPR reduction gain among the four types of sequences. |
| Year | 2003 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-03-17 |
| 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) | TOT Corporation Public Company Limited; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2003 |