Recursive deterministic maximum likelihood estimation of direction of arrival in automotive radar sensing

An automotive radar system, comprising:

• at least one transmitter and at least one receiver, wherein the at least one transmitter and the at least one receiver are configured to transmit and receive radar signals, wherein the at least one transmitter and the at least one receiver are coupled to a vehicle;
• and
• an automotive radar processor, configured to:
• transmit, at a first time, a first radar signal,
• receive, using the at least one receiver, a received signal,
• process the received signal to generate a plurality of snapshot signals, wherein each snapshot signal in the plurality of snapshot signals is associated with a range-Doppler bin, and
• execute a direction of arrival analysis of a first snapshot signal of the plurality of snapshot signals, including steps of:
• determining a hierarchical tree structure, wherein each layer in the hierarchical tree structure is associated with a number of candidate objects and each node in the hierarchical tree structure is associated with a set of direction of arrival angles for the number of candidate objects determined by the layer of the hierarchical tree structure in which the node is located,
• selecting a first layer in the hierarchical tree structure,
• calculating, for the first layer in the hierarchical tree structure, a first set of path variables, wherein the first set of path variables includes a residue value and a matched filter response vector based upon the residue value,
• determining a subset of path extensions using the matched filter response vector out of a set of path extensions that connect to nodes within the hierarchical tree structure associated with a second layer in the hierarchical tree structure, wherein the second layer is associated with one more candidate object than the first layer, and
• determine, for a first path extension out of the subset of path extensions, a path metric associated with a first node in the second layer of the hierarchical tree structure, and
• determining a direction of arrival angle for a first candidate object associated with the first node using the path metric.

A method, comprising:

• processing a received radar signal to generate a plurality of snapshot signals, wherein each snapshot signal in the plurality of snapshot signals is associated with a range-Doppler bin,
• determining a hierarchical tree structure, wherein each layer in the hierarchical tree structure is associated with a number of candidate objects and each node in the hierarchical tree structure is associated with a set of direction of arrival angles for the number of candidate objects determined by the layer of the hierarchical tree structure in which the node is located,
• selecting a first layer in the hierarchical tree structure,
• calculating, for the first layer in the hierarchical tree structure, a first set of path variables, wherein the first set of path variables includes a residue value and a matched filter response vector based upon the residue value,
• determining a subset of path extensions using the matched filter response vector out of a set of path extensions that connect to nodes within the hierarchical tree structure associated with a second layer in the hierarchical tree structure, wherein the second layer is associated with one more candidate object than the first layer, and
• determining, for a first path extension out of the subset of path extensions, a path metric associated with a first node in the second layer of the hierarchical tree structure;
• and
• determining a direction of arrival angle for a first candidate object associated with the first node using the path metric.