Abstract
Spread spectrum technique modifies the signal spectrum to spread it out and increase its bandwidth. There are two major methods in spread spectrum technique: direct sequence and frequency hopping. The resistance capability of jamming signal for frequency hopping system is better than that for direct sequence system. Two types of frequency hopping techniques can be distinguished. In ¡§fast frequency hopping¡¨ the period of a frequency-hop is smaller than a data symbol-period while in ¡§slow frequency hopping¡¨ the period of a frequency-hop is larger than a data symbol-period. Fast frequency hopping systems have the advantages that the error correction codes are not needed and diversity can be applied. The disadvantage of fast frequency hopping system is that coherent data detection is not possible because of phase discontinuities.
Traveling wave tube amplifier is often used in satellite communications. It has nonlinear characteristics which can be classified as nonlinear amplitude and phase distortions toward the output signals. Certain backoff input power makes the amplifier work within the linear region. However, in order to have more output power, the amplifier usually operates in the saturation region and in consequence serious nonlinear signal distortion would be introduced.
In this thesis, the effect of nonlinear amplifier on a frequency hopping multiple access (FHMA) system with binary frequency shift keying is discussed. In the simulation, two types of nonlinear amplifiers, traveling wave tube amplifier and solid state power amplifier, are applied to the FHMA system. Tradeoff between power efficiency and performance degradation is determined by the index of total performance degradation, which is obtained from simulation. With known single carrier output power, third-order intermodulation, and same input power, the bit error rate performance is also analyzed.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0902103-191323 |
| Date | 02 September 2003 |
| Creators | Guo, Han-Yu |
| Contributors | Shiunn-Jang Chern, Chin-Der Wann, Ju-Ya Chen, Miin-Jong Hao |
| 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-0902103-191323 |
| Rights | unrestricted, Copyright information available at source archive |
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