Mitigation of co-channel interference in synchronization bursts in a multi-beam communication system
US6452962B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 11, 1999 |
| Grant date | Sep 17, 2002 |
| Priority date | — |
| Expiry date | Jun 11, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04B7/18513
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
In a cellular satellite system such as Astrolink, where same frequency, same polarization (same “color”) signals are used in multiple ground cells, there exists the possibility of interference and false reception of uplink Synchronization Bursts (SB) in systems employing TDMA access of the frequency in question. In such systems, a SB transmitted from one terminal may be received in more than one satellite beam. The reception of the signal from a terminal in an undesired beam (330) is erroneous and may adversely impact the time synchronization (360) of the desired terminal. For example, a system may employ Maximal Length (ML) Pseudo-Noise (PN) sequences (410) for its SBs wherein every beam may use the same sequence. To minimize false reception, the ML PN sequences (410) of each SB may be cyclicly shifted a different amount for each beam to generate sequences (410, 420) having low corsscorrelation with each other. By choosing ML PN codes having low crosscorrelation (410, 420) for the different beams, the interference from undesired beams may be minimized (530).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.