US-12621054-B2 - Adaptive coding such as for free-space optical communication systems

US12621054B2US 12621054 B2US12621054 B2US 12621054B2US-12621054-B2

Abstract

Aspects of the present disclosure relate to adaptive coding of digital communications, such as for a free-space optical channel. Some implementations can transmit, via a first transceiver over a communications channel, a first series of data packets to a second transceiver. The first transceiver can receive a second series of data packets from the second transceiver, and an adaptive coder can analyze the second series of data packets to detect transmission conditions of the communications channel. The adaptive coder can execute one or more proactive actions based on the detected transmission conditions, such as sending error correction information for the first series of data packets and/or modifying one or more future transmission characteristics, and can do so before information regarding the reception of the first series of data packets is received from the second transceiver.

Inventors

Paul Daniel Heninwolf

Assignees

AALYRIA TECHNOLOGIES, INC.

Dates

Publication Date: 20260505
Application Date: 20240415

Claims (20)

1 . A method for providing adaptive coding for transmitted data packets, the method comprising: transmitting, by a first optical transceiver via an optical channel, a first series of data packets to a second optical transceiver, the first series of data packets having a code rate corresponding to a proportion of i) one or more bits that carry source data to ii) total bits in respective data packets of the first series of data packets; receiving, by the first optical transceiver via the optical channel, a signal corresponding to a second series of data packets from the second optical transceiver; estimating, based at least partially on one or more characteristics of the received signal corresponding to the second series of data packets, one or more transmission conditions of the optical channel; and performing, based on the estimated one or more transmission conditions of the optical channel, at least one of: A) retransmitting at least one first data packet, of the first series of data packets, to the second optical transceiver; B) transmitting repair data relevant to at least one particular data packet of the first series of data packets, to the second optical transceiver; C) adapting the code rate, for a third series of data packets to be transmitted to the second optical transceiver, by modifying the proportion of one or more bits that carry source data to total bits in respective data packets of the third series of data packets, wherein the respective data packets of the third series of data packets each include at least one error correction bit in the total bits; or D) any combination thereof.
2 . The method of claim 1 , wherein, based on the estimated one or more transmission conditions of the optical channel, at least A), B), or both is performed, wherein the one or more characteristics of the received second series of data packets includes at least one data packet, of the second series of data packets, being corrupted, wherein the at least one corrupted data packet has at least one associated time of transmission and/or reception, and wherein the method further comprises: identifying the at least one first data packet and/or the at least one particular data packet based on a time of transmission, of the at least one first data packet and/or the at least one particular data packet, being within a threshold time period of the at least one time of transmission and/or reception associated with the at least one corrupted data packet.
3 . The method of claim 1 , wherein at least one of A), B), C), or D) is performed prior to receiving, from the second optical transceiver, any information derived by the second optical transceiver from its reception of attempted reception of the first series of data packets.
4 . The method of claim 1 , wherein at least C) is performed and wherein, further based on the estimated one or more transmission conditions of the optical channel, the method further comprises performing at least one of: E) modifying code type for the third series of data packets to be transmitted to the second optical transceiver; F) modifying modulation for the third series of data packets to be transmitted to the second optical transceiver; G) modifying transmit power for the third series of data packets to be transmitted to the second optical transceiver; H) modifying baud rate for the third series of data packets to be transmitted to the second optical transceiver; I) modifying interleaving type or characteristics for the third series of data packets to be transmitted to the second optical transceiver; or J) any combination thereof.
5 . The method of claim 1 , wherein the at least one error correction bit is redundant with at least one bit of source data.
6 . The method of claim 1 , wherein the optical channel is a free-space optical channel.
7 . The method of claim 1 , wherein the first optical transceiver is included in an optical ground station, and wherein the second optical transceiver is included in a satellite terminal.
8 . The method of claim 1 , wherein the one or more characteristics includes corruption of at least one data packet of the second series of data packets.
9 . The method of claim 1 , wherein performance of the optical channel is asymmetrical.
10 . The method of claim 1 , further comprising: causing the second optical transceiver to throttle its data transmissions while at least one of A), B), C), or D) is performed.
11 . The method of claim 1 , wherein at least one of A), B), or both is repeated until an acknowledgment, of receipt of the first series of data packets from the second optical transceiver, is received by the first optical transceiver.
12 . The method of claim 1 , wherein, based on the estimated one or more transmission conditions of the optical channel, at least C) is performed, and wherein utilized forward error correction of the third series of data packets is rateless, windowless, or both.
13 . An optical system comprising: a first optical transceiver configured to: transmit, via an optical channel, a first series of data packets to a second optical transceiver, the first series of data packets having a code rate corresponding to a proportion of i) one or more bits that carry source data to ii) total bits in respective data packets of the first series of data packets; and receive, via the optical channel, a signal corresponding to a second series of data packets from the second optical transceiver; and an adaptive coder configured to: estimate, based at least partially on one or more characteristics of the received signal corresponding to the second series of data packets, one or more transmission conditions of the optical channel; and based on the detected change in the one or more conditions of the optical channel, adapt the code rate, for a third series of data packets to be transmitted to the second optical transceiver, by modifying the proportion of one or more bits that carry source data to total bits in respective ones of the third series of data packets.
14 . The optical system of claim 13 , wherein the first optical transceiver is further configured to: based on the estimated one or more transmission conditions of the optical channel, perform at least one of: A) retransmitting at least one first data packet, of the first series of data packets, to the second optical transceiver; B) transmitting one or more repair packets, relevant to at least one particular data packet of the first series of data packets, to the second optical transceiver; or C) both.
15 . The optical system of claim 14 , wherein the estimated one or more transmission conditions indicate deterioration of the optical channel at an associated time, and wherein the adaptive coder is further configured to: identify the at least one first data packet and/or the at least one particular data packet based on a time, of the at least one first data packet and/or the at least one particular data packet, being within a threshold time period of the time associated with the indicated deterioration of the optical channel.
16 . The optical system of claim 14 , wherein at least one of A), B), or C) is performed prior to receiving any signal or information derived from reception or attempted reception of the first series of data packets from the second optical transceiver.
17 . A computer-readable storage medium storing instructions that, when executed by a computing system, cause the computing system to perform a process for providing adaptive coding for transmitted data packets, the process comprising: transmitting, via a communications channel, a first series of data packets to a transceiver, the first series of data packets having a code rate corresponding to a proportion of i) one or more bits that carry source data to ii) total bits in respective data packets of the first series of data packets; receiving, via the communications channel, a signal corresponding to a second series of data packets from the transceiver; estimating, based at least partially on one or more characteristics of the received signal corresponding to the second series of data packets, one or more transmission conditions of the communications channel; and based on the detected one or more transmission conditions of the communications channel, performing at least one of A) sending correction information relevant to one or more first data packets of the first series of data packets, B) modifying one or more future transmission characteristics, or C) both.
18 . The computer-readable storage medium of claim 17 , wherein the communications channel is an optical channel.
19 . The computer-readable storage medium of claim 17 , wherein the process comprises sending the correction information for the one or more first data packets, and wherein the sending the correction information includes at least one of retransmitting the one or more first data packets, transmitting one or more repair packets corresponding to the one or more first data packets, or both.
20 . The computer-readable storage medium of claim 17 , wherein the process comprises modifying the one or more future transmission characteristics, and wherein the modifying the one or more future transmission characteristics includes adapting at least one of C) the code rate, D) code type, E) modulation, F) transmit power, G) baud rate, or H) any combination thereof, for a third series of data packets to be transmitted to the transceiver.

Description

TECHNICAL FIELD Aspects of the present disclosure relate to adaptive coding of digital communications, such as across a free-space optical channel. BACKGROUND Free-space optical communication (FSOC), due to its high data rate, high capacity, free license spectrum, and excellent security, offers an alternative to Radio Frequency (RF) or microwave communication in modern wireless communication. In a free-space optical communication system, a transmitter may transmit data at a high speed (e.g., 1 Gbps, 10 Gbps, 100 Gbps, 1 Tbps, or higher) using a narrow laser beam (e.g., in infrared wavelengths) that passes through the atmosphere to a line of-sight receiver. Free-space optical communication can offer point-to-point data communication at rates faster than other solutions available today, cover greater distances, offer connectivity where no supporting infrastructure exists, and is not susceptible to RF-based jamming techniques intended to interfere and disrupt the operation of RF communication systems. For example, free-space optical communication systems may be used to provide links to, from, or between aircrafts, spacecrafts, balloons, satellites, ground vehicles and stations, and water-based vehicles and stations, and can deliver data services at high speed to sites that may otherwise have no access to high speed networks such as fiber optical networks. Free-space optical communication can radically improve satellite communications, connectivity on planes and ships, cellular connectivity, etc. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a communication network that may be implemented using free-space optical communication. FIG. 2 is an example of a point-to-point free-space optical communication system. FIG. 3A is an example of a bistatic free-space optical communication system. FIG. 3B is an example of a monostatic free-space optical communication system. FIG. 4 includes simplified block diagrams of examples of terminals in a free-space optical communication system according to some implementations. FIG. 5 illustrates a block diagram of an example of a free-space optical communication terminal according to some implementations. FIG. 6 is a block diagram illustrating an overview of devices on which some implementations can operate. FIG. 7 is a block diagram illustrating components which, in some implementations, can be used in a system employing the disclosed technology. FIG. 8 is a flow diagram illustrating a process used in some implementations for providing adaptive coding for transmitted data packets, such as in a free-space optical communication system. FIG. 9 is an example of an optical terminal that includes an adaptive encoder for adaptively encoding data packets for transmission based on characteristics of received data packets. FIG. 10A illustrates an example of a ground-to-space and/or space-to-ground free-space optical channel through which data blocks are transmitted and received. FIG. 10B illustrates an example of a ground-to-space and/or space-to-ground free-space optical channel through which data blocks are retransmitted, before an acknowledgement of the data blocks is received, based on a received corrupted data block. FIG. 10C illustrates an example of a ground-to-space and/or space-to-ground free-space optical channel through which repair blocks are sent for data blocks, before an acknowledgment of the data blocks is received, based on received corrupted data blocks. FIG. 10D illustrates an example of a ground-to-space and/or space-to-ground free-space optical channel through which future data blocks are adaptively encoded with error correction blocks based on the reception of corrupted data blocks. FIG. 11 is a simplified block diagram of a point-to-point free space optical communication system. The techniques introduced here may be better understood by referring to the following Detailed Description in conjunction with the accompanying drawings, in which like reference numerals indicate identical or functionally similar elements. DETAILED DESCRIPTION Free-space optical communication can offer high data rate, high capacity, cost effectiveness, free license spectrum, security, and rapid deployment. However, optical signals transmitted through the air and/or atmosphere may be affected by environmental conditions, such as poor weather, air particulates, and other atmospheric conditions, before arriving at a receiver. For example, weather and/or other atmospheric effects can deteriorate the transmission by reducing the signal's optical power level due to attenuation, by causing interference, and/or by causing random optical power and phase fluctuations in the received signal results from, for example, beam spread, scintillation effects, and/or beam wander. Variations in air density, temperature, humidity, pressure, wind speed, and the like in the atmosphere may lead to atmospheric turbulence, which can cause small scale, localized random pockets of varying indices of refraction