METHODS, APPARATUSES AND SYSTEM FOR ASYNCHRONOUS SPREAD-SPECTRUM COMMUNICATION
First Claim
1. A method of receiving data packets asynchronously transmitted by a plurality of user terminals using an unslotted spread-spectrum medium access protocol, each data packet being constituted by a contiguous sequence of bits comprising at least a preamble and a payload, the method including a step of successive interference cancellation comprising:
- f) storing received signal samples in a processing memory;
g) performing packet identification on all the signals stored in said processing memory within a sliding processing window;
h) selecting one among the identified packets, decoding it and, if decoding is successful, cancelling the interferences of said packet with the other received data inside the sliding processing window;
i) repeating step c) for all or part of the packets identified at step b); and
j) shifting the processing window by a shifting step which is shorter than the overall length of said processing window.
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Accused Products
Abstract
A method of receiving data packets asynchronously transmitted by a plurality of user terminals using a spread-spectrum medium access protocol, comprises a step of cancelling interferences between colliding packets according to an innovative “sliding window” processing algorithm. A gateway receiver is adapted for carrying out interference cancellation using this algorithm. Asynchronous packet transmission from a user terminal is controlled by estimating a parameter indicative of the quality of information transmission through a communication channel; and inhibiting or allowing data transmission depending on a comparison between said estimated parameter and an adaptively varying threshold. A user terminal comprises transmission control means adapted for carrying out such a method. A communication system comprises a plurality of mobile user terminal communicating with a gateway through a satellite channel using an asynchronous spread-spectrum medium access protocol without closed-loop power control, wherein the user terminals and said gateway are of the kind described above.
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Citations
22 Claims
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1. A method of receiving data packets asynchronously transmitted by a plurality of user terminals using an unslotted spread-spectrum medium access protocol, each data packet being constituted by a contiguous sequence of bits comprising at least a preamble and a payload, the method including a step of successive interference cancellation comprising:
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f) storing received signal samples in a processing memory; g) performing packet identification on all the signals stored in said processing memory within a sliding processing window; h) selecting one among the identified packets, decoding it and, if decoding is successful, cancelling the interferences of said packet with the other received data inside the sliding processing window; i) repeating step c) for all or part of the packets identified at step b); and j) shifting the processing window by a shifting step which is shorter than the overall length of said processing window. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification