| Author | Piya Patcharamaneepakorn |
| Call Number | AIT Thesis no.TC-01-05 |
| Subject(s) | Wireless communication systems
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of
Engineering, School of Engineering and Technology
|
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-01-05 |
| Abstract | Orthogonal Frequency Division Multiplexing (OFDM) is an efficient multicarrier
modulation scheme used to avoid intersymbol interference (ISi) due to multipath
propagation in mobile radio channel. However, it does not remove errors due to channel
fading and additive white Gaussian noise (A WGN) in the channel. Channel coding
schemes are still required in OFDM system. Antenna diversity is another effective
technique to combat the channel fading in wireless communication system without
bandwidth expansion. Space-time code (STC) is a combined channel coding with antenna
diversity technique to achieve both coding and diversity advantage. In addition,
concatenated coding scheme with sub-optimal iterative decoding is a well-known coding
scheme used to improve the coding gain while decoding complexity is kept comparable to
single coding scheme. It is motivated to consider space-time code with concatenated
coding scheme to provide the antenna diversity and high coding gain in OFDM system.
In the thesis, performance of serial concatenated space-time code (SCSTC) in
OFDM system has been investigated over frequency-selective fading channel. The pairwise error probability (PEP) for coded modulation scheme with antenna diversity in
OFDM system has been derived for both quasi-static and time-varying frequencyselective Rayleigh fading channel. Time variation of the channel leads to interchannel
interference (ICI) which degrades the bit error rate (BER) performance of the system. The
degradation depends on the maximum doppler shift and number of subcarriers. By using
the obtained PEP, an analytical upper bound for bit error probability of serial
concatenated space-time code in OFDM system has been derived based on the union
bound. Some analytical results for both SCSTC over flat fading channel and SCSTC in
OFDM over frequency-selective fading channel have been discussed. From the BER
expression, the guideline to design SCSTC in OFDM system has been presented. It is
similar to the case of serial concatenated convolutional code. In addition, the guideline
holds for both quasi-static and time-varying case. Finally, simulation results have been
evaluated for quasi-static frequency-selective fading channel. The results show that the
guideline can be used to yield a BER improvement. |
| Year | 2001 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-01-05 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Rajatheva, R.M.A.P.; |
| Examination Committee(s) | Ahmed, Kazi M. ; Makelainen, Kimmo |
| Scholarship Donor(s) | Sonera Corporation, Finland |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2001 |