Orthogonal frequency division multiple access (OFDMA) systems use the same concept of orthogonal frequency division multiplexing, assign different subcarriers to different users for multiple access requirements. Since the received signals from different users have different carrier frequency offsets (CFOs) induced by Doppler effect and frequency mismatching between transmitter¡¦s and receiver¡¦s oscillators, the system performance will be degraded by the multiple access interference (MAI). In this thesis, we present iterative interference cancellation by signal classification (IICSC) and interference cancellation by user and signal classification (ICUSC) algorithm for QPSK and 16QAM modulation schemes. We investigate the method to select significantly reliable signals and then cancel the corresponding MAI from other signals in frequency domain. In 16QAM modulation scheme, the system is more sensitive to MAI. Therefore, we propose a criterion to choose the users with less MAI and then select reliable signals from these users. Since these reliable signals are not required interference cancellation, we can reduce the total number of interference cancellation operations. From simulation results, the performance of our proposed methods is similar to that of parallel interference cancellation method, but the computational complexity of our proposed method is lower.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0701110-213603 |
| Date | 01 July 2010 |
| Creators | Tseng, Po-kai |
| Contributors | Ching-Pia Hong, Ru-Ya Chen, Ming-da Hsieh, Jieh-Chia Wu, Jih-Ching Chiu |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | Cholon |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0701110-213603 |
| Rights | not_available, Copyright information available at source archive |
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