ESA: Packet data transmission over a shared transmission channel

Kurzfassung

An international organization has developed a method of packet mode digital communication over a transmission channel shared by a plurality of users. The invention lends itself to varied applications, and it’s especially designed for the digital video broadcasting with a return channel via satellite or for broadband access systems via satellite (for example those conforming to the ETSI DVB-RCS standard or the TIA IPoS standard). Company is looking for a license agreement collaboration.

Details

A first object of the present invention is to provide a method of transmitting data packets based on an improvement to the diversity slotted Aloha protocol that makes it possible, when one of the replicas of a packet is received, to locate in the time and/or the frequency domain the other replica(s) of the same packet, even if corrupted by collisions to the point of no longer being decodable correctly. Such a method can be used with the object of transmission channel diagnosis, but it is above all beneficial in that it enables a transmitted packet recovery method to be implemented at the receiver.
Providing such a packet recovery method is a second object of the invention.
The simultaneous use of such a transmission method and such a packet recovery method in the receiver constitutes a new communications protocol with control of random access to the medium that its inventors call the contention resolution diversity slotted Aloha (CRDSA) protocol.
Another object of the invention is to combine said CRDSA protocol with a conventional DA (demand assignmrnt) protocol to obtain a protocol for efficiently managing very different traffic profiles that vary in time. Such a protocol is referred to below as a CRDSA-DA protocol.
Other objects of the invention are to provide a transmitter equipment ("modulator") and a receiver packet recovery equipment ("demodulator") adapted to implement the CRDSA or CRDSA-DA protocol, in particular in the context of an interactive satellite system.

Innovative Aspects:
In addition to significantly improve the performance of a diversity slotted Aloha (DSA) protocol, this novel method advantageously require only a limited number of modifications at the level of the physical layer of the TDMA-FM systems (time division multiple access multiple frequency) used at present. Such a method should also advantageously be combinable easily with demand assignment (DA) methods in order to be able to manage efficiently a great diversity of traffic profiles.