| Author | Doan Ngoc Dung |
| Call Number | AIT Thesis no.TC-99-5 |
| Subject(s) | Wireless communication systems
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering. School of Advanced Technologies |
| Publisher | Asian Institute of Technology |
| Abstract | Two main contributions of the thesis are: 1) development of a new receiver for trellis
and turbo coded modulation schemes over frequency selective Rayleigh fading channels; 2)
theoretical performance analysis of trellis and turbo coded modulation schemes.
The combined receiver doing equalization and decoding of coded signals which
considerably removes the detrimental effect of intersymbol interference (ISI) is developed.
The proposed receiver is applied to trellis coded modulation (TCM) and turbo trellis coded
modulation (TTCM) schemes to verify its performance. The performance of the new receiver
is compared with the conventional approach (i.e. separate equalizer and decoder) through
computer simulation on independent and correlated frequency selective Rayleigh fading
channels. It is shown that the new receiver significantly improves the error performance with
only a small number of iterations.
Some analytical results for coded modulation schemes using multilevel signal
mappings are presented in the thesis. Performance analysis of TCM working over frequency
selective Rayleigh fading channels is first discussed. A method to find the exact pairwise error
probability (PEP) is provided. Some simplified versions of the upper bound on the PEP are
also given with small loss of tightness. It is shown that those bounds are better than bounds
derived by using the Chernoff technique.
The error performance of turbo coded modulation schemes over additive white
Gaussian noise (A WGN) channels is analyzed by the Spherical bounding technique. In the
derivation, Euclidean geometry is used as a tool to get the bound. The bound accounts for all
kinds of modulation schemes as well as for the specific distance spectra of underlying turbo
codes.
One question that needs an answer is "does a receiver for turbo coded modulation
designed for flat fading channels work well over frequency selective Rayleigh fading
channels?" This problem is equivalent to the performance investigation of turbo coded
modulation over the frequency selective Rayleigh fading channels for the worst case when the
receiver only operates on the code states. In the thesis, a solution to this problem is found. An
approximate upper bound for the performance of mismatched decoding of turbo coded
modulation that the decoder only operates on the code states is analyzed by using an
approximation to the an ISI pdf. It is applicable to a raw ISL The bound can be easily
evaluated and gives us a good approximation of error performance. It is shown that when
applied to TCM schemes, the bound is especially tight. |
| Year | 1999 |
| Type | Thesis |
| School | School of Advanced Technologies |
| 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, Kirnrno; |
| Scholarship Donor(s) | Government of Finland; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1999 |