Method and apparatus for frame synchronization in mobile OFDM data communication
US5444697A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 11, 1993 |
| Grant date | Aug 22, 1995 |
| Priority date | — |
| Expiry date | Aug 11, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L7/10
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are disclosed for achieving symbol (frame) synchronization of digital data in an OFDM channel such as an OFDM/FM radio link. The method and apparatus are suitable for use in a pure ALOHA environment because synchronization is achieved on a frame-by-frame basis. The required bandwidth overhead is less than 10%. The bit-error-rate performance achievable with this technique is within 1.5 dB of the performance assuming ideal synchronization. The method and apparatus provide a three-stage synchronization process. First the onset of an ODFM frame is detected. Second, coarse synchronization is achieved by sampling the received signal, and measuring the correlation between the received signal and a reference signal. Coarse synchronization provides synchronization to within .+-.1/2 sample period. The correlation is preferably carried out in the frequency domain after carrying out a Fast Fourier Transform on the sampled signal data. Third, synchronization is achieved by calculating the time-shift between the coarse synchronization point and the actual synchronization point and using the calculated time shift to determine the phase correction to apply to each data carry…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.