| 摘要 |
A system to provide narrowcast communications uses adaptive data rate control to individual subscribers such that the effects of precipitation or other link conditions, which are not common to all subscribers, is mitigated. The invention takes advantage of the fact that the narrowcast data consist of packets which are individually addressed to specific subscribers, or groups of subscribers. The narrowcast data is communicated on a plurality of FDM carriers, each of potentially differing data rates. The subscribers are assigned a particular FDM carrier, based upon their link quality, to receive packets addressed to them. The lower data rate FDM carriers will be less affected by adverse link conditions and are hence assigned to subscribers most likely to incur adverse link conditions. |
