Impact of multiple doppler shifts on symbol and carrier synchronization in narrowband and wideband radio channels | |
| Author | Enriquez, Anna Marie C. |
| Call Number | AIT Thesis no.TC-97-11 |
| Subject(s) | Digital communications Cellular radio |
| Note | A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering. |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. TC-97-11 |
| Abstract | This study presents results of the estimated carrier frequency offset and symbol timing offset for GMSK signals in frequency-flat and frequency-selective fading channels that undergo multiple Doppler frequency shifts. The burst-mode transmission format follows GSM Recommendations for the pan-European digital mobile radio. The results are taken from computer simulations in the MATLAB environment wherein discrete-time signals were processed in their complex-envelope (baseband) notations. The received sequence is correlated with a locally modulated known 16-bit training sequence and the maximum point of the correlation is used to estimate the symbol timing offset. We then make use of this estimated symbol timing offset to synchronize and extract the distorted 16-bit training sequence which is the midamble portion of the received signal and divide this with the locally modulated known training sequence. The result is applied to the frequency offset estimator where the algorithm is derived by Luise and Regiannini (1995). The results of the estimated time and frequency offsets are shown as a function of Eb/No for multiple Doppler shifts. Doppler shifts are implemented both as fixed and as random parameters. The error of our estimated frequency offset is also shown as a function of Eb/No. Our results show very large errors of the estimated frequency offset after averaging over 50 data frames for both frequency-flat and frequency-selective fading channels. This indicates that our estimation showed poor performance for both narrowband and wideband channels. The frequency-selective fading contributes to a wider deviation of the frequency offset than the frequency-flat fading. For the symbol timing offset, the major factor is the delay spread introduced by the channel which is more evident for frequency-selective fading channels. |
| Year | 1997 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. TC-97-11 |
| Type | Thesis |
| School | School of Engineering and Technology (SET) |
| Department | Department of Information and Communications Technologies (DICT) |
| Academic Program/FoS | Telecommunications (TC) |
| Chairperson(s) | Makelainen, Kimmo |
| Examination Committee(s) | Ahmed, Kazi Mohiuddin;Zhang, Jian-Guo |
| Scholarship Donor(s) | The Royal Government of Netherlands. |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 1997 |