Array-to-array beamforming and iterative time reversal techniques

Apparatus comprising:

• a first array comprising a plurality of first ad hoc radio frequency (RF) nodes;
• and
• a second array comprising a plurality of second ad hoc RF nodes;
• wherein the first array and the second array are configured to:
• align/synchronize the plurality of first ad hoc RF nodes in time and frequency;
• align/synchronize the plurality of second ad hoc RF nodes in time and frequency;
• transmit an initial sounding signal from the plurality of first ad hoc RF nodes of the first array to the plurality of second ad hoc radio frequency (RF) nodes of the second to array;
• and
• successively send sounding signals from the plurality of first ad hoc RF nodes of the first array to the plurality of second ad hoc RF nodes of the second array and from the plurality of second ad hoc RF nodes of the second array to the plurality of first ad hoc RF nodes of the first array, wherein each sounding signal sent by the second array is beamformed through time reversal of an immediately preceding sounding signal received by the second array from the first array, and each sounding signal except the initial sounding signal sent by the first array is beamformed through time reversal of an immediately preceding sounding signal received by the first array from the second array.

An article of manufacture comprising at least one non-volatile machine-readable storage medium with program code stored in the at least one non-volatile machine-readable storage medium, the program code, when executed by processors of nodes of a first array and of nodes of a second array, each node of the first array and each node of the second array comprising an antenna, a radio frequency transceiver coupled to the antenna, a local oscillator, and a processor coupled to the radio frequency transceiver to control operation of the transceiver, configures the nodes of the first array and the nodes of the second array to:

• align/synchronize the nodes of the first array in time and frequency;
• align/synchronize the nodes of the second array in time and frequency;
• transmit an initial sounding signal from the first array to the second array;
• and
• successively send sounding signals from the first array to the second array and from the second array to the first array, wherein each sounding signal sent by the second array is beamformed through time reversal of an immediately preceding sounding signal received by the second array from the first array, and each sounding signal except the initial sounding signal sent by the first array is beamformed through time reversal of an immediately preceding sounding signal received by the first array from the second array.

A method of radio frequency (RF) communication between arrays of nodes, the method comprising steps of:

• aligning/synchronizing a plurality of ad hoc nodes of a first array in time and frequency;
• aligning/synchronizing a plurality of ad hoc nodes of a second array in time and frequency;
• step for Reciprocal Convergence process between the first array and the second array to enable beamformed transmissions from the first array to the second array and from the second array to the first array;
• and
• sending RF data communications from the first array to the second array and/or from the second array to the first array, the step of sending being performed after the step for Reciprocal Convergence process.

A method of radio frequency (RF) communication, the method comprising steps of:

• aligning/synchronizing a plurality of ad hoc nodes of a first array in time and frequency;
• transmitting an initial sounding signal from the first array to a second array of nodes;
• successively sending sounding signals from the first array to the second array, wherein each sounding signal except the initial sounding signal is beamformed through time reversal of an immediately preceding sounding signal received by the first array from the second array;
• determining whether sufficient focusing between the first array and the second array has been achieved, thereby obtaining a determination;
• terminating the step of successively sending in response to the determination indicating that sufficient focusing has been achieved;
• and
• sending RF data communications from the first array to the second array in response to the determination indicating sufficient focusing.