# US 11,309,996 B2 · Low-latency, low-overhead data framing method for capacity-limited delay-sensitive long distance communication

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- Number: US 11,309,996 B2
- Document ID: US11309996B2
- Status: Granted
- Kind: B2
- Application number: 15/929,164
- Filed: 2019-11-14
- Published: 2020-10-15
- Granted: 2022-04-19
- Earliest claimed: 2018-11-14
- Assignees: Skywave Networks LLC
- Applicants: Skywave Networks LLC
- Inventors: Kevin J. Babich; Terry Lee Vishloff; Danie van Wyk
- Web page: https://patentgrep.com/patent/US11309996B2

## CPC

- H04L 1/0041: {Arrangements at the transmitter end}
- H04L 1/0063: {Single parity check}
- H04L 1/0046: {Code rate detection or code type detection (H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091)}
- H04L 1/0047: {Decoding adapted to other signal detection operation (in conjunction with sequence estimation or equalization H04L25/03286)}
- H04L 1/0057: {Block codes (H04L1/0061, H04L1/0064 take precedence)}
- H04L 1/0059: {Convolutional codes}
- H04L 1/0061: {Error detection codes}
- H04L 1/0064: {Concatenated codes}
- H04L 43/0847: {Transmission error}
- G06Q 20/16: Payments settled via telecommunication systems
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- G06Q: INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR

## Abstract

A communication method is configured to increase speed of messages reception over a bandwidth limited channel such as high frequency (HF) radio. User data arriving from a high-speed network is transformed into a format suitable for transmission over the radio channel. Message packets that will take longer to reach a destination via the radio channel as compared to alternative channels, such as a fiber optic network, are rejected for radio transmission. When the packet is received, the receiver deduces message length by using information from various error handling techniques, such as forward error correction (FEC) and cyclic redundancy check (CRC) techniques. Fill data is transmitted between message packets when no data is available. The FEC and CRC information for the fill data is modified so that the fill data will fail FEC and CRC checks at the receiving station.

## Claims

### Claim 1

A method, comprising:
receiving a message from a primary communication channel at a receiving station;
wherein said receiving the message includes receiving the message through a message data stream;
wherein the message data stream includes user data and fill data;
wherein the user data has been encoded in accordance with a parity check code and an error correction scheme;
wherein the fill data has been encoded in accordance with the parity check code and the error correction scheme;
wherein the till data has been modified to fail a parity check code test;
maintaining a signal lock on the message data stream through the fill data;
detecting a message boundary of the message through the parity check code in combination with the error correction scheme;
wherein said detecting the message boundary includes determining with the receiving station that the fill data has failed the parity check code test; and
wherein said detecting the message boundary includes decoding with the receiving station the user data successfully through the parity check code and the error correction scheme.

### Claim 2 (depends on 1)

The method of claim 1, wherein the primary communication channel includes a low bandwidth, low latency communication link.

### Claim 3 (depends on 2)

The method of claim 2, wherein the primary communication channel includes a high frequency radio channel.

### Claim 4 (depends on 1)

The method of claim 1, wherein the user data is encoded in an asynchronous manner in the message data stream.

### Claim 5 (depends on 1)

The method of claim 1, wherein the fill data includes a pseudorandom binary sequence (PRBS).

### Claim 6 (depends on 5)

The method of claim 5, wherein the fill data includes a version of the PRBS modified by the parity check code and the error correction scheme.

### Claim 7 (depends on 6)

The method of claim 6, further comprising:
detecting a false message with the version of the PRBS.

### Claim 8 (depends on 7)

The method of claim 7, wherein the version of the PRBS has been modified to fail a parity check code test.

### Claim 9 (depends on 7)

The method of claim 7, wherein the version of the PRBS has been modified to fail an error correction scheme test.

### Claim 10 (depends on 1)

The method of claim 1, wherein the parity check code includes a checksum.

### Claim 11 (depends on 1)

The method of claim 1, wherein the parity check code includes a cyclic redundancy check (CRC).

### Claim 12 (depends on 1)

The method of claim 1, wherein the error correction scheme includes forward error correction (FEC).

### Claim 13 (depends on 1)

The method of claim 1, wherein the error correction scheme includes a convolution code scheme.

### Claim 14 (depends on 13)

The method of claim 13, wherein the error correction scheme includes a tail-biting Viterbi decoding algorithm.

### Claim 15 (depends on 1)

The method of claim 1, wherein the error correction scheme includes a block code scheme.

### Claim 16 (depends on 15)

The method of claim 15, wherein the error correction scheme includes a turbo block code scheme.

### Claim 17

A method, comprising:
encoding a message data stream with user data and fill data;
modifying the fill data to reduce a chance of false message detection;
encoding the message data stream with a parity check code in combination with an error correction scheme;
creating a modified version of the fill data in which the modified version fails a test for the parity check code;
wherein the user data is unmodified to pass a parity test and error correction test; and
transmitting the message data stream from a transmission station.

### Claim 18 (depends on 17)

The method of claim 17, further comprising:
creating a modified version of the fill data in which the modified version fails a test for the error correction scheme.

### Claim 19 (depends on 17)

The method of claim 17, wherein the fill data includes a pseudorandom binary sequence (PRBS).

### Claim 20 (depends on 19)

The method of claim 19, wherein the fill data includes a version of the PRBS modified by the parity check code and the error correction scheme.

### Claim 21 (depends on 19)

The method of claim 19, wherein the parity check code includes a checksum.

### Claim 22 (depends on 19)

The method of claim 19, wherein the parity check code includes a cyclic redundancy check (CRC).

### Claim 23 (depends on 19)

The method of claim 19, wherein the error correction scheme includes forward error correction (FEC).

### Claim 24 (depends on 17)

The method of claim 17, further comprising:
maintaining a signal lock on the message data stream through the fill data.

### Claim 25

A method, comprising:
receiving a user data packet from a high speed network at a transmission station;
calculating a message transmission time for the user data packet across a primary communication channel;
wherein the primary communication channel has lower bandwidth than the high speed network;
wherein the transmission time across the primary communication channel is longer than across the high speed data network;
calculating an inter-message transmission time between user data packets from the high speed network;
determining whether to transmit the user data packet over the primary communication channel at least based on message transmission time and inter-message transmission time;
accepting the user data packet for transmission over a primary communication channel when the message transmission time across the primary communication channel is more than an inter-message transmission time between user data packets; and
transmitting a message including the user data across the primary communication channel.

### Claim 26 (depends on 25)

The method of claim 25, further comprising:
rejecting the user data packet for transmission over a primary communication channel when a message transmission time is more than an inter-message transmission time.

### Claim 27 (depends on 26)

The method of claim 26, further comprising:
transmitting a message including the user data across a backend communication channel.

### Claim 28 (depends on 25)

The method of claim 25, wherein the user data packet concerns a transaction for a financial instrument.

### Claim 29 (depends on 1)

The method of claim 1, wherein the message has an integer number of modulated symbols.