In this thesis, we take an application of multiple symbol differential detection (MSDD)
technique in direct-sequence code division multiple access (CDMA) system. It is well-
known that MSDD is an effective noncoherent demodulator which outperform the
conventional M-ary differential phase shift keying (MDPSK) in additive white Gaussian
noise (AWGN) channel. Take MPSK demodulator into consideration, the performance
of MSDD based on noncoherent demodulation approaches the performance of coherent
demodulation. However, there is little research about MSDD in frequency-selective
fading channel. We are now combining the MSDD and Rake receiver to be the signal
demodulator. In conventional, there are two kinds of Rake receivers. One is coherent
demodulator. Another is noncoherent demodulator. For coherent demodulation, it needs
to have channel estimation at each path. The advantage is that the performance will be
improved. On the other hand, the disadvantage is complexity and operation will increase.
On the contrast, for noncoherent demodulation, it is the performance degradation and
complexity simplification. In this thesis, We suggest a multiple symbol differential detection
on Rake receiver for CDMA system. From our computer simulation, only for hard decision,
the performance is improved and the improvement is proportional to the number of multipath
and the number of the length of multiple symbol. This will not happen in conventional MDPSK.
However, from our observation, the improvement of performance is degrading as the number
of multipath increase. Thus, we employee the technique of Viterbi decoding differential
detection (VDDD) to demodulate the differential sequence. By the property of decision
interval, the VDDD can obtain additional improvement.
| Identifer | oai:union.ndltd.org:NSYSU/oai:NSYSU:etd-0711101-150734 |
| Date | 11 July 2001 |
| Creators | Chung, Yi-Ping |
| Contributors | Gin-Kou Ma, Min-Chung Hao, Hsin-Hsiung Yang, Shiunn-Jang Chern |
| Publisher | NSYSU |
| Source Sets | NSYSU Electronic Thesis and Dissertation Archive |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.lib.nsysu.edu.tw/ETD-db/ETD-search/view_etd?URN=etd-0711101-150734 |
| Rights | off_campus_withheld, Copyright information available at source archive |
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