Northrop Grumman Systems Corporation

Trw Limited

Jason R Kincaid

Jaime L Prieto, Jr

A downlink scheduler ( ) is provided for scheduling the downlink transmission of data cells in a spot beam processing satellite ( ). The downlink scheduler ( ) includes a beam selector ( ) for selecting one of the spot beams associated with the satellite ( ), a plurality of wholesale selectors ( ) for selecting one of a plurality of wholesalers, such that each of the wholesale selectors ( ) is associated with one of the spot beams, and a plurality of retail selectors ( ) for selecting one of a plurality of retail connections, such that each of the retail selectors ( ) is associated with one of the wholesalers. Each of the selectors may use a packet fair queuing (PFQ) method to make its selection. The downlink scheduler ( ) then passes at least one data cell from a selected retail connection to a downlink modulator ( ), thereby scheduling the downlink transmission of data cells in the satellite.

Hierarchical downlink scheduler for a processed satellite payload

An onboard DAMA protocol for use in connection with a processing satellite communications network, where multiple users are assigned to a common transmission resource as part of a sharing set. A media access controller ( ) on the satellite maintains a reservation log which identifies the frequencies and number of uplink time slots in the resource that are currently reserved by one or more members of the sharing set. To reserve a time-frequency slot on the transmission resource for a non-contentious transmission of data, a user of the sharing set will transmit a reservation request to the satellite on a contentious uplink resource. If a return message is not received, the user knows that the reservation request collided with another reservation request, and a retransmission strategy of the reservation request is employed. When the media access controller ( ) receives the reservation request, it decides whether to grant, deny or delay the request based on the service and price class of the user, the amount of data already sent by the user, the number and type of other users with reservation requests in the queue, and the congestion state of the destination downlink port and subsequent nodes in the network. When the user receives a reservation grant message from the media access controller ( ) on the satellite in the downlink, it will then wait for its reservation time frequency slot, and transmit its data in a non-contentious basis on the transmission resource at that time. If the user needs additional bandwidth to transmit more data, it may piggyback a reservation request on the data transfer.

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Redondo Beach, CA, United States of America

Jason R Kincaid