OTFS Tone Reservation Layout for High-PAPR Waveforms
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Solution Overview
Problem
Wireless communication systems using orthogonal time-frequency space (OTFS) waveforms face high peak-to-average power ratio (PAPR) issues, leading to power backoff at power amplifiers and affecting transmit power and decoding performance.
Innovation Solution
Implementing a tone reservation signal using a subset of resources within the OTFS frame, such as delay-Doppler locations or out-of-frame subcarriers, to mitigate high PAPR, with the transmitting device indicating the tone reservation pattern and resources to the receiving device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OTFS waveform is used for wireless communication, then communication performance in high mobility scenarios is improved, but peak-to-average power ratio increases causing power amplifier inefficiency
Solution Approach 1:
The patent segments the OTFS frame resources by designating specific resource elements (REs) as tone reservation REs, separating them from data-carrying REs. This segmentation allows dedicated tones to be reserved for PAPR mitigation while other resources maintain normal communication functions, resolving the contradiction between communication performance and power efficiency.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and embedding tone reservation signals into the OTFS frame before transmission. The transmitting device determines optimal tone reservation patterns and inserts them into designated resource elements in advance, enabling PAPR reduction to be built-in rather than requiring post-processing at the receiver.
2Use of energy by moving object
If tone reservation signal is implemented using subset of OTFS frame resources, then PAPR is reduced and power amplifier efficiency is improved, but available resources for information transmission are decreased
Solution Approach 1:
The patent applies partial action by reserving only a subset of resource elements for tone reservation rather than dedicating all resources. The tone reservation REs represent a partial allocation (e.g., certain subcarriers or time-frequency positions) that provides sufficient PAPR mitigation while leaving the majority of resources available for information transmission, balancing efficiency gains with capacity requirements.
3Use of energy by moving object
If tone reservation resources are allocated within OTFS frame, then PAPR mitigation is achieved, but resource allocation complexity increases
Solution Approach 1:
The patent applies local quality by assigning specific, predetermined characteristics to tone reservation resource elements (e.g., specific subcarrier indices, time positions, or delay-Doppler locations). This localized assignment with clear rules simplifies the allocation process compared to global optimization, reducing complexity while maintaining effective PAPR mitigation at the targeted resource locations.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described that provide for application of a tone reservation signal for orthogonal time-frequency space (OTFS) waveform communications. A tone reservation signal may use a first subset of resources of a set of resources associated with an OTFS frame, which may mitigate relatively large PAPR associated with transmission of the OTFS frame. A tone reservation signal may use in-frame resources (e.g., as delay-Doppler locations within a delay-Doppler resource grid) of the OTFS frame, or may use tone reservation resources may correspond subcarriers that are out-of-band with subcarriers of an OTFS frame. Signaling may be provided by a transmitting device that indicates the tone reservation resources, and a receiving device may decode a received communication in accordance with remaining resources other than the tone reservation resources.