Radar Reference Signal Timing Pattern for Joint Communication Radar
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Solution Overview
Problem
Joint communication radars (JCRs) face challenges in selecting signaling parameters that achieve desirable performance for both communication and radar signaling, particularly due to issues with inter-symbol interference (ISI) and inter-carrier interference (ICI) caused by long path lengths and delay spreads, which affect data rate and radar estimation accuracy.
Innovation Solution
A radar reference signal (RRS) timing pattern is configured based on control messages from network entities, incorporating multiple repetitions of cyclic prefixes (CPs) and RRS symbols, allowing for effective radar and communication signaling without compromising data rate, and using Fast Fourier Transforms (FFTs) to sample received signals with the same quantity of sampling windows as CP repetitions, reducing or eliminating ISI and ICI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a JCR transmits radar signaling with long path lengths to increase detection range, then the radar range is improved, but inter-symbol interference (ISI) and inter-carrier interference (ICI) increase, degrading signal quality
Solution Approach 1:
The transmitted signal is segmented into multiple orthogonal frequency-division multiplexing (OFDM) symbols, each with its own cyclic prefix. This segmentation allows the long radar signal to be divided into manageable segments that can be processed independently, reducing the impact of ISI and ICI while maintaining long detection range capability
Solution Approach 2:
A cyclic prefix acts as an intermediary element inserted between OFDM symbols. This intermediary component absorbs the delay spread effects and prevents inter-symbol interference, enabling long-range radar detection without signal degradation from ISI and ICI
2Object-affected harmful factors
If a JCR increases cyclic prefix duration to reduce inter-symbol interference, then signal quality is improved, but data rate decreases due to reduced useful signal time
Solution Approach 1:
The system dynamically adjusts the cyclic prefix duration and OFDM symbol parameters based on the detected channel conditions and radar requirements. This dynamic adaptation allows the system to use longer cyclic prefixes only when necessary for long-range detection, maintaining high data rates for shorter-range communications
Solution Approach 2:
The system changes key parameters including subcarrier spacing, cyclic prefix length, and OFDM symbol duration to optimize the balance between reducing ISI and maintaining data rate. By adjusting these parameters adaptively, the system achieves both goals of signal quality improvement and productivity maintenance
3Measurement precision
If a JCR uses multiple repetitions of radar signals to improve detection accuracy, then measurement precision is improved, but time consumption increases
Solution Approach 1:
Multiple radar signal repetitions are merged and processed using coherent integration techniques. This merging approach accumulates signal energy from multiple transmissions while suppressing noise, improving detection accuracy without requiring proportionally longer transmission times
Solution Approach 2:
The system employs periodic transmission of radar probe signals with optimized timing intervals. This periodic action allows for efficient use of time by transmitting signals only when needed for detection updates, maintaining high measurement precision while minimizing time loss through structured repetition patterns
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables JCRs to maintain desired data rates while reducing interference, thereby improving radar performance and range without decreasing data rate or introducing additional interference.
Implementation Method 1
The wireless device may sample (e.g., using Fast Fourier Transforms (FFTs)) the received signals using a same quantity of sampling windows as the quantity of CP repetitions, which may enable the wireless device to reduce or eliminate ISI and ICI
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A wireless device may receive, from a network entity, a control message for a radar reference signal (RRS) configuration associated with the wireless device. The wireless device may set a timing pattern for the RRS based on the control message and one or more timing parameters for the RRS configuration. The wireless device may transmit the RRS according to the timing pattern. The RRS may include one or more cyclic prefix (CP) sub-symbols and one or more RRS sub-symbols. The wireless device may receive one or more reflections of the RRS and may perform one or more processing operations on the one or more reflections of the RRS using a plurality of sampling windows. A quantity of sampling windows may be equal to a quantity of CP sub-symbols.