Adaptive data rate control for narrowcast networks

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 channels, each of potentially differing data rates. The subscribers are assigned a particular channel, based upon their link quality, to receive packets addressed to them. The lower data rate channel will be less affected by adverse link conditions and are hence assigned to subscribers most likely to incur adverse link conditions.

主权项

1. A satellite communication network system comprising:
a user terminal for receiving a downlink signal from a gateway via a satellite comprising: a demodulator unit configured to:
receive a first data packet contained within the downlink signal having an address for the user terminal;demodulate the first data packet using a first modulation and coding for the first data packet; andderive signal information associated with the downlink signal; a frame decoder unit communicatively coupled to the demodulator unit and configured to decode the first data packet received from the demodulator unit; and a signal quality calculation unit communicatively coupled to the demodulator unit and configured to:
receive the signal information associated with the downlink signal from the demodulator unit;determine a carrier-to-noise ratio using the signal information;determine an at least one signal quality-of-reception parameter using the carrier-to-noise ratio; andtransmit the at least one signal quality-of-reception parameter to the gateway using a return-channel for at least adjusting a modulation and coding used by the gateway for a plurality of consecutive data packets destined for the user terminal; and the gateway for communicating with the user terminal from a plurality of user terminals via the satellite, the gateway comprising: a control unit configured to:
receive the at least one signal quality-of-reception parameter for the downlink signal from the user terminal over the return-channel;determine downlink signal attributes for the user terminal based on the at least one signal quality-of-reception parameter for the downlink signal received from the user terminal; andgenerate a control signal for assignment of a second data packet destined for the user terminal from the plurality of user terminals to at least one attribute from the downlink signal attributes for the user terminal; a router communicatively coupled to the control unit and configured to:
receive the second data packet destined for the user terminal, the second data packet having the address of the user terminal;receive the control signal from the control unit for assignment of the second data packet to the at least one attribute from the downlink signal attributes; androute the second data packet for assignment to the at least one attribute based on the destination user terminal for the second data packet and the control signal received from the control unit; and a modulator communicatively coupled to the router and the control unit and configured to: receive the second data packet from the router destined for the user terminal; determine a second modulation and coding for the second data packet based on the control signal generated by the control unit for the user terminal using the downlink signal attributes, wherein the at least one attribute of the downlink signal attributes is a modulation and coding attribute; and apply the second modulation and coding to the second data packet for the user terminal.