Orthogonal frequency division multiplexing based spread spectrum multiple access
US6711120B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1999 |
| Grant date | Mar 23, 2004 |
| Priority date | — |
| Expiry date | Mar 11, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L5/026
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An orthogonal frequency division multiplexing (OFDM) based spread spectrum multiple access system using offsetting between cells, and in particular, the use of tone offsetting and time offsetting, is disclosed. More specifically, frequencies that define the tone set of one cell is offset from the frequencies that define the tone set of at least one adjacent cell. In other words, if a first base station is using tones F1, F2, . . . , FN within a frequency band, then a second base station adjacent to the first base station uses tones F1+&Dgr;f, F2+&Dgr;f . . . , FN+&Dgr;f within the same frequency band. Furthermore, the symbol timing of the base-station of one cell may be offset from the symbol timing of the base-station of an adjacent cell. Thus, if a first base station starts successive symbols at times T1, T2, and T3, then a second base station adjacent to the first base station starts its respective corresponding successive symbols at times T1+&Dgr;t, T2+&Dgr;t, and T3+&Dgr;t. For example, in a cellular system with hexagonally shaped cells, the tone sets of two adjacent cells are offset by ⅓ of the spacing between adjacent tones, and the symbol timings of two adjacent cell…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.