Robust addressing schema for spatial awareness via doppler null scanning (DNS)
A node of a multi-node network (e.g., a transmitter (Tx) node or receiver (Rx) node) is disclosed. The node may include a communications interface with antenna elements and a controller. The controller may include one or more processors and have information of own-node velocity and own-node orientation relative to a common reference frame. The node may be time synchronized to apply Doppler corrections associated with the node's own motions relative to the common reference frame. The node may receive an input sequence via a zero or near-zero Doppler path from a source node, the input sequence one of a set possible correlation sequence uniquely identifying the source node. The controller includes a correlator with sub-correlator blocks for breaking the input sequence into a set of N sub-sequences. Based on sequence processing by the sub-correlators, the correlator outputs the decoded input sequence and associated delay metrics.
1 . A receiver (Rx) node comprising:
a communications interface comprising at least one antenna element;
and
a controller operatively coupled to the communications interface, the controller including one or more processors, wherein the controller has information of own-node velocity and own-node orientation of the Rx node relative to a stationary common inertial reference frame;
wherein the Rx node is in motion relative to at least one source node, the common reference frame known to the Rx node and to the source node prior to the Rx node receiving transmissions from the source node;
wherein the Rx node is time synchronized to apply one or more Doppler corrections associated with the Rx node's own motions relative to the common reference frame,
wherein the Rx node is further configured to receive at least one zero or near-zero Doppler pulse along a zero or near-zero Doppler path from the source node to the Rx node within known time intervals, the at least one zero or near-zero Doppler pulse associated with a correlation sequence of S symbols, wherein S is an integer, the correlation sequence uniquely identifying the source node;
wherein the Rx node further includes a correlator comprising a set of N sub-correlators, wherein N is an integer not more than S, wherein the correlation sequence comprises N sub-sequences, each sub-correlator of the set of N sub-correlators configured to:
receive the correlation sequence as a sequence of the N sub-sequences;
and
provide to the correlator, for each of the N sub-sequences, a delay value indicative of the receipt of the corresponding sub-sequence;
and
wherein the correlator is configured to output, based on the received delay values from each sub-correlator:
the decoded correlation sequence;
and
a cumulative delay value corresponding to the decoded correlation sequence, the cumulative delay value associated with a Doppler time error based on the received delay values from each sub-correlator.
2 . The Rx node of claim 1 , wherein the N sub-sequences include at least two sub-sequences having an unequal symbol length.
3 . The Rx node of claim 1 , wherein the correlation sequence is one of a set of N! possible correlation sequences.
4 . The Rx node of claim 1 , wherein the one or more Doppler corrections are in both of the frequency domain and the time domain.
5 . The Rx node of claim 1 , wherein the zero or near-zero Doppler path is unknown to the source node and the Rx node prior to receipt of the at least one zero or near-zero Doppler pulse.
6 . The Rx node of claim 1 , wherein the common reference frame is a two-dimensional (2D) stationary common inertial reference frame.
7 . The Rx node of claim 1 , wherein the common reference frame is a three-dimensional (3D) stationary common inertial reference frame.
8 . The Rx node of claim 1 , wherein the at least one antenna element comprises at least one of a directional antenna element or an omnidirectional antenna element.
9 . A system, comprising:
a transmitter (Tx) node and a receiver (Rx) node, wherein each node of the Tx node and the Rx node comprises:
a communications interface including at least one antenna element;
and
a controller operatively coupled to the communications interface, the controller including one or more processors, wherein the controller has information of own-node velocity and own-node orientation;
wherein each node of the Tx node and the Rx node are in motion relative to each other;
wherein each node of the Tx node and the Rx node are time synchronized to apply one or more Doppler corrections associated with said node's own motions relative to a stationary common reference frame, the common reference frame known to the Tx node and the Rx node prior to the Tx node transmitting signals to the Rx node and prior to the Rx node receiving the signals from the Tx node;
wherein the Tx node is configured to apply the one or more Doppler corrections relative to the common reference frame for a plurality of azimuthal angles across a multi-pulse Doppler group, such that each direction corresponding to an azimuthal angle of the multi-pulse Doppler group is associated with a zero or near-zero Doppler time error known to the Rx node based on the time synchronization;
wherein the Rx node is configured to apply the one or more Doppler corrections in an inverse fashion relative to the Tx node's application of the one or more Doppler corrections;
wherein the Rx node is further configured to receive at least one zero or near-zero Doppler pulse along a zero or near-zero Doppler path from the Tx node to the Rx node within known time intervals, the at least one zero or near-zero Doppler pulse associated with a correlation sequence of S symbols, wherein S is an integer, the correlation sequence uniquely identifying the Tx node;
wherein the Rx node further includes a correlator comprising a set of N sub-correlators, wherein N is an integer not more than S, wherein the correlation sequence comprises N sub-sequences, each sub-correlator of the set of N sub-correlators configured to:
receive the correlation sequence as a sequence of the N sub-sequences;
and
provide to the correlator, for each of the N sub-sequences, a delay value indicative of the receipt of the corresponding sub-sequence;
and
wherein the correlator is configured to output, based on the received delay values from each sub-correlator:
the decoded correlation sequence;
and
a cumulative delay value corresponding to the decoded correlation sequence, the cumulative delay value associated with a Doppler time error based on the received delay values from each sub-correlator.
10 . The system of claim 9 , wherein the N sub-sequences include at least two sub-sequences having an unequal symbol length.
11 . The system of claim 9 , wherein the correlation sequence is one of a set of N! possible correlation sequences.
12 . The system of claim 9 , wherein the one or more Doppler corrections are in both of the frequency domain and the time domain.
13 . The system of claim 9 , wherein:
the one or more Doppler corrections for the plurality of azimuthal angles across the multi-pulse Doppler group are associated with the frequency domain;
and
the one or more Doppler corrections associated with the at least one zero or near-zero Doppler pulse along the zero or near-zero Doppler path are associated with the time domain.
14 . The system of claim 9 , wherein the zero or near-zero Doppler path is unknown to the Tx node and the Rx node prior to transmission of the multi-pulse Doppler group.
15 . The system of claim 9 , wherein the common reference frame is a two-dimensional (2D) stationary common inertial reference frame.
16 . The system of claim 9 , wherein the common reference frame is a three-dimensional (3D) stationary common inertial reference frame.
17 . The system of claim 9 , wherein:
the at least one antenna element of the Tx node comprises at least one of a directional antenna element or an omnidirectional antenna element;
and
wherein the at least one antenna element of the Rx node comprises at least one of a directional antenna element or an omnidirectional antenna element.