Self-supporting simplex packets
AssigneeComtech Mobile Datacom Corporation
InventorLuis G. Jordan
Life of this patent
Estimating the term…
Abstract
Existing message fields and/or message parameters are configured to facilitate the packet and message synchronization and decoding tasks that conventionally rely upon a known bit sequence in each packet, thereby eliminating the need for a predefined message preamble in each packet. In example embodiments, the unique identifier of each transmitter is structured to facilitate determination of bit polarity and the start of each packet; packet sequence numbers use an unconventional counting sequence to assure synchronizing bit transitions; and so on. Other techniques, such as the use of run-length limited (RLL) message encoding, or 8b/10b encoding, to assure within-packet bit transitions, are also used to enhance clock synchronization and proper header location determination.
Claims8
A method of decoding a packet that does not include a preamble of known bit values, comprising:
- at a device configured to decode the packet:
- despreading the packet using a spreading code,
- identifying a header of the packet that includes a sequence of bit transitions,
- identifying a body of the packet that includes information that has been transmitted by a transmitter, wherein identifying the header includes identifying a start of the packet based on the sequence of bit transitions,
- determining a first bit transition rate based on transitions in the header,
- identifying an end of packet sequence,
- determining a second bit transition rate based on transitions in the end of packet sequence, and
- estimating a bit transition rate for decoding bits in the body of the packet based on the first and second bit transition rates.
A receiver comprising:
- a receive buffer that is configured to receive a composite signal,
- a phase detector that is configured to detect a code-phase of a message that does not include a sequence of known bit values,
- a demodulator that is configured to:
- identify a header of the packet that includes a sequence of bit transitions,
- identify a start of the packet based on the sequence of bit transitions,
- identify a body of the packet that includes information that has been transmitted
- by a transmitter,
- determine a first bit transition rate based on the bit transitions in the header,
- identify an end of packet sequence,
- determine a second bit transition rate based on transitions in the end of packet sequence, and
- determine a bit transition rate for decoding bits in the body of the packet based on the first and second bit transition rates.
Dependencies are inferred from the claim text.