Ultra-wideband (UWB) system is an indoor communication system, high data rate transmission within 5-10m transmitted range. This system suffers from high dense multipath channels impairment. If the spreading code is not orthogonal in dense multipath channels, severe inter-symbol interference (ISI) will degrade the system performance. In this thesis, we will discuss the performance of various receivers in ultra-wideband channels.
Rake receiver can collect signal energy from different multipath. However, the imperfect orthogonal property of spreading code will cause severe ISI and degrade the performance of Rake receiver. Least mean square (LMS) chip equalizer not only combines the energy from different multipath, but also suppresses ISI. But, the complexity is too high to realize.
In this thesis, we combine Rake receiver with ISI canceller to enhance system performance. If the canceller is before Rake receiver, we define it as ISIC RAKE. If the canceller is behind Rake receiver, we define it as RAKE ISIC. In the ISI canceller, not only ISI caused by preceding bits is cancelled, but also the ISI caused by following bit is cancelled. In multiuser cases, we are also canceling multi-access interference (MAI). From simulation results, the proposed method outperforms conventional Rake receiver, Rake receiver combined with LMS symbol equalizer, and LMS chip equalizer. The complexity of proposed method is lower than LMS chip equalizer.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0912108-020611 |
| Date | 12 September 2008 |
| Creators | Chiu, Chih-hsien |
| Contributors | Szu-lin Su, Ju-ya Chen, Cing-piao Hung, Chin-der Wann |
| 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-0912108-020611 |
| Rights | not_available, Copyright information available at source archive |
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