UWB Ranging Using Overlapping Orthogonal Responses
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Solution Overview
Problem
Existing UWB ranging methods are inefficient in terms of time and processor resource usage, as they require multiple time slots and significant processing power to determine distance between an initiator and multiple responders, especially in secure access applications like vehicle access systems.
Innovation Solution
The method involves transmitting a polling signal followed by overlapping responses from responders, where each response includes a scrambled time-stamp sequence with unique and common segments, allowing the initiator to decode only the specific segment for each responder, reducing processing load and time slots to two, and using out-of-band communication to pre-share keys and sequence numbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If known UWB ranging methods are used where responders send secure responses one by one, then secure authentication is achieved, but time efficiency deteriorates and processor resource consumption increases
Solution Approach 1:
Multiple responders transmit their secure responses simultaneously in the same time slot by assigning each responder a unique orthogonal code sequence. The initiator receives all responses at once and separates them using correlation processing with the known orthogonal codes, eliminating the need for sequential time slots while maintaining security through code-based separation.
Solution Approach 2:
Orthogonal code sequences are pre-assigned to each responder before the ranging process. This preliminary assignment allows the initiator to efficiently separate and identify individual responses from multiple simultaneous transmissions using correlation processing, enabling parallel response reception without increasing processing complexity during the actual ranging operation.
2Reliability
If known UWB ranging methods are used where responders send secure responses one by one, then secure authentication is achieved, but processor resource consumption in the initiator increases
Solution Approach 1:
Multiple responders transmit their secure responses simultaneously in the same time slot by assigning each responder a unique orthogonal code sequence. The initiator receives all responses at once and separates them using correlation processing with the known orthogonal codes, eliminating the need for sequential time slots while maintaining security through code-based separation.
Solution Approach 2:
The orthogonal code sequences embedded in each responder's transmission enable self-identification and self-separation at the initiator side. By correlating the received signal with each known orthogonal code, the initiator automatically extracts individual responses without requiring complex demultiplexing logic or sequential processing, reducing overall processor resource consumption.
3Productivity
If overlapping responses from multiple responders are received in the same time slot, then time efficiency improves, but response identification and decoding complexity increases
Solution Approach 1:
Orthogonal code sequences are pre-assigned to each responder before the ranging process. This preliminary assignment allows the initiator to efficiently separate and identify individual responses from multiple simultaneous transmissions using correlation processing with the known orthogonal codes, enabling parallel response reception without increasing processing complexity during the actual ranging operation.
Solution Approach 2:
Each responder's signal is distinguished by its unique orthogonal code sequence, analogous to different colors. The initiator uses correlation processing to detect which code sequence is present in the received signal, enabling easy identification of individual responses even when multiple responders transmit simultaneously, as each code acts as a unique identifier.
Data Source
AI summary
UWB ranging methods and apparatus are disclosed. The method comprises a ranging communication with a plurality of responder devices, the ranging communication comprising: transmitting, by an initiator device, a polling signal in a time slot; receiving a respective response from each of the plurality of responder devices, overlapping and in a next time slot, each response comprising: synchronization bits, and a frame comprising Start of Frame Delimiter, and a Scrambled Timestamp Sequence; wherein the STS comprises a sequence of segments each preceded by a respective guard interval, wherein a specific one of the segments comprises data derived from a ranging key and a responder-identifier each unique to the respective responder among the plurality of responders, wherein a sequence-number of the specific segment is unique to the respective response, and wherein a remainder of the segments each comprise the same data derived from a predetermined common key and predetermined common data.