Wireless multicarrier system with subcarriers reserved for communication between unsynchronized nodes
US7616556B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 1, 2004 |
| Grant date | Nov 10, 2009 |
| Priority date | — |
| Expiry date | Jul 20, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L27/2647
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a system applying orthogonal frequency division multiplexing, OFDM, a number of carriers are reserved for communication between unsynchronized nodes (N1, N2). At least one such reserved carrier is assigned to each base station. A sinusoidal signal is transmitted on this reserved carrier during a time period at least equal to two consecutive OFDM symbols. The unsynchronized receiver detects the sinusoidal signal during one of two consecutive OFDM symbol time periods. The existence, the frequency and the signal power of the signal give information about the existence and identity of the transmitter. Also, estimates of relative velocities and distances can be deduced. In preferred embodiments, the sinusoidal signal can also be used to transmit further information by using signal modulation or coding that is independent of the absolute signal phase.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.