Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, an optical communication system includes a primary transceiver, a component, and secondary transceivers. The primary transceiver is operable to supply first optical subcarriers to an optical communication path, the first optical subcarriers being amplitude modulated at a first frequency to carry first control information and amplitude modulated at a second frequency to carry second control information. The component is operable to be coupled to the optical communication path and includes circuitry operable to detect the first control information. The secondary transceivers are coupled to a terminal end of the optical communication path. At least one of the secondary transceivers is operable to detect the second control information and block the first control information.

Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, an optical communication system includes a primary transceiver, a component, and secondary transceivers. The primary transceiver is operable to supply first optical subcarriers to an optical communication path, the first optical subcarriers being amplitude modulated at a first frequency to carry first control information and amplitude modulated at a second frequency to carry second control information. The component is operable to be coupled to the optical communication path and includes circuitry operable to detect the first control information. The secondary transceivers are coupled to a terminal end of the optical communication path. At least one of the secondary transceivers is operable to detect the second control information and block the first control information.

Disclosed herein is a method of encoding and/or decoding data for optical data transmission along a transmission link, as well as corresponding transmitters and receivers. The data is encoded based on an adaptive constellation diagram in a 2-D plane, said constellation diagram including a first and a second pair of symbols, wherein the symbols of the first pair of symbols are located at opposite sides of the origin of the 2-D plane at a first distance di from each other, and wherein the symbols of the second pair of symbols are located at opposite sides of the origin of the 2-D plane at a second distance d2 from each other. The method comprises a step of adapting the constellation diagram by varying the ratio of the first and second distances d.sub.1, d.sub.2 such as to minimize or nearly minimize a bit error rate in the transmitted data.

Disclosed herein is a method of encoding and/or decoding data for optical data transmission along a transmission link, as well as corresponding transmitters and receivers. The data is encoded based on an adaptive constellation diagram in a 2-D plane, said constellation diagram including a first and a second pair of symbols, wherein the symbols of the first pair of symbols are located at opposite sides of the origin of the 2-D plane at a first distance di from each other, and wherein the symbols of the second pair of symbols are located at opposite sides of the origin of the 2-D plane at a second distance d2 from each other. The method comprises a step of adapting the constellation diagram by varying the ratio of the first and second distances d.sub.1, d.sub.2 such as to minimize or nearly minimize a bit error rate in the transmitted data.

A transmitter can include a laser operable to output an optical signal; a digital signal processor operable to receive user data and provide electrical signals based on the data; and a modulator operable to modulate the optical signal to provide optical subcarriers based on the electrical signals. A first one of the subcarriers carriers carries first TDMA encoded information and second TDMA encoded information, such that the first TDMA encoded information is indicative of a first portion of the data and is carried by the first one of the subcarriers during a first time slot, and the second TDMA encoded information is indicative of a second portion of the data and is carried by the first one of the subcarriers during a second time slot. The first TDMA encoded information is associated with a first node remote from the transmitter and the second TDMA encoded information is associated with a second node remote from the transmitter. A second one of the subcarriers carries third information that is not TDMA encoded, the third information being associated with a third node remote from the transmitter. A receiver and system also are described.

A transmitter can include a laser operable to output an optical signal; a digital signal processor operable to receive user data and provide electrical signals based on the data; and a modulator operable to modulate the optical signal to provide optical subcarriers based on the electrical signals. A first one of the subcarriers carriers carries first TDMA encoded information and second TDMA encoded information, such that the first TDMA encoded information is indicative of a first portion of the data and is carried by the first one of the subcarriers during a first time slot, and the second TDMA encoded information is indicative of a second portion of the data and is carried by the first one of the subcarriers during a second time slot. The first TDMA encoded information is associated with a first node remote from the transmitter and the second TDMA encoded information is associated with a second node remote from the transmitter. A second one of the subcarriers carries third information that is not TDMA encoded, the third information being associated with a third node remote from the transmitter. A receiver and system also are described.

An OFDM (orthogonal frequency division multiplexing) transmitter includes an inverse fast Fourier transform circuit, which, in operation, generates, based on digital input data, a complex time-varying digital signal having real and imaginary components; and a multiplexer adapted to generate a time-multiplexed digital signal by time-multiplexing one or more of the real components with one or more of the imaginary components.

An OFDM (orthogonal frequency division multiplexing) transmitter includes an inverse fast Fourier transform circuit, which, in operation, generates, based on digital input data, a complex time-varying digital signal having real and imaginary components; and a multiplexer adapted to generate a time-multiplexed digital signal by time-multiplexing one or more of the real components with one or more of the imaginary components.

Techniques for optimizing a scan pattern of a LIDAR system including a bistatic transceiver include receiving first SNR values based on values of a range of the target, where the first SNR values are for a respective scan rate. Techniques further include receiving second SNR values based on values of the range of the target, where the second SNR values are for a respective integration time. Techniques further include receiving a maximum design range of the target at each angle in the angle range. Techniques further include determining, for each angle in the angle range, a maximum scan rate and a minimum integration time. Techniques further include defining a scan pattern of the LIDAR system based on the maximum scan rate and the minimum integration time at each angle and operating the LIDAR system according to the scan pattern.

Techniques for optimizing a scan pattern of a LIDAR system including a bistatic transceiver include receiving first SNR values based on values of a range of the target, where the first SNR values are for a respective scan rate. Techniques further include receiving second SNR values based on values of the range of the target, where the second SNR values are for a respective integration time. Techniques further include receiving a maximum design range of the target at each angle in the angle range. Techniques further include determining, for each angle in the angle range, a maximum scan rate and a minimum integration time. Techniques further include defining a scan pattern of the LIDAR system based on the maximum scan rate and the minimum integration time at each angle and operating the LIDAR system according to the scan pattern.