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| 099 | 9 | _aAIT Thesis no.TC-00-06 | |
| 100 | 0 | _aNanthawan Ruangsurat | |
| 245 | 1 | 3 | _aAn investigation of peak to average power ratio in MC-CDMA combined with partial transmit sequence |
| 260 |
_aBangkok : _bAsian Institute of Technology, _c2000 |
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| 300 | _a72 p. | ||
| 490 | 1 |
_aThesis ; _vno. TC-00-06 |
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| 500 | _aA thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology | ||
| 502 | _aThesis (M.Eng.) - Asian Institute of Technology, 2000 | ||
| 520 | _aMulticarrier code division multiple access (MC-CDMA) is a technique that combines orthogonal frequency division multiplexing (OFDM) and code division multiple access (CDMA). Since MC-CDMA system provides an efficient method of frequency diversity, it is suitable to a frequency selective rayleigh fading environment. This technique becomes a potential technique for future wireless networks. In addition, MC-CDMA is especially useful in the downlink transmission. However, similar to OFDM system, the transmitted signal from MC-CDMA system also exhibits a very high Peak to Average Power Ratio (PAPR) when using a large number of subcarriers. Therefore, the amplifiers should be operated in large linear ranges to avoid nonlinear distortion. This leads to very inefficient amplification and very expensive transmitters. Thus, P APR reduction techniques are very significant for multicarrier transmission systems. Consequently, several P APR reduction methods have been proposed, but most of techniques are considered with single user OFDM such as Clipping, Selected Mapping, Partial Transmit Sequence, and so on. In MC-CDMA systems, the P APR reduction technique is mostly based on the type of spreading sequences. Partial Transmit Sequence (PTS) technique is an efficient approach and a distortionless scheme for reducing P APR. Due to its flexibility, the PTS technique works with an arbitrary number of subcarriers. In addition, it works without restriction on the type of modulation scheme. Thus, the investigation of P APR in MC-CDMA system combined with PTS technique is very attractive. In this thesis, the P APR reduction in synchronous downlink MC-CDMA using PTS technique is investigated with a different number of active users. Moreover, WalshHadamard (WH) sequence and Orthogonal Gold (OG) sequence are used as the spreading sequences in MC-CDMA system. From the simulation results, when the number of active users is varied, P APR reduction of this system also varies depending on the P APR characteristics of spreading sequence. Although PTS technique is very efficient in reducing PAPR, high PAPR reduction is achieved at a cost of increased system complexity. Furthermore, to compromise between P APR reduction and system complexity, the suboptimal algorithms are used for combining partial transmit sequences. Based on simulation results, we can reduce system complexity by more than 90% at the expense of little P APR performance degradation. | ||
| 650 | 1 | 0 | _aCode division multiple access |
| 700 | 1 |
_aRajatheva, R.M.A.P, _eChairperson |
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| 700 | 1 |
_aErke, Tapio J., _eExamination Committee |
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| 700 | 0 |
_aTeerapat Sanguankotchakorn, _eExamination Committee |
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| 710 | 2 |
_aNokia Telecommunications (Thailand) Ltd., _eScholarship Donor |
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| 810 | 2 |
_aAsian Institute of Technology. _tThesis ; _vno. TC-00-06 |
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| 856 |
_3Full-Text _uhttp://203.159.5.9/ait-thesis/detail.php?q=B06530 |
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