Orthonormal Time-Frequency Shifting for Wireless Signal Integrity
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Solution Overview
Problem
Existing wireless communication protocols face challenges in transmitting data over limited wireless radio spectrum while maintaining low power consumption, distinguishing signals from background noise, and coping with Doppler shifts and multi-path effects caused by moving devices and environmental reflections.
Innovation Solution
The Orthonormal Time-Frequency Shifting and Spectral Shaping (OTFSSS) method spreads data across a larger range of times, frequencies, and spectral shapes, using novel time-frequency shifting and spectral shaping codes to enhance resistance to interference and noise, and employs convolution and deconvolution schemes to maintain data transmission rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low power transmission is used to extend battery life, then energy consumption is reduced, but signal distinguishability from background noise deteriorates
Solution Approach 1:
The data transmission is segmented into multiple time slots and frequency subcarriers. Each data symbol is transmitted across multiple segments rather than concentrated in a single transmission, allowing the use of lower power per segment while maintaining overall signal integrity through combiner at the receiver
Solution Approach 2:
The invention transitions from traditional time-domain or frequency-domain spreading to a two-dimensional time-frequency grid structure. Data symbols are mapped to specific time-frequency resource elements, creating a structured distribution that improves signal distinguishability through the combined time and frequency diversity without requiring high peak power
2Reliability
If data is spread across broader spectrum to resist noise, then noise resistance is improved, but data transmission rate deteriorates
Solution Approach 1:
The system dynamically allocates time-frequency resources based on channel conditions and data rate requirements. The spreading factor and resource allocation can be adjusted to balance between noise resistance and transmission rate, allowing adaptive optimization rather than fixed trade-off
Solution Approach 2:
The invention changes the fundamental parameter of how spreading is implemented - instead of traditional code-based spreading that uniformly spreads across frequency, it uses time-frequency shifting that distributes symbols across both time and frequency dimensions with controllable density, allowing flexible adjustment of the noise resistance versus rate trade-off
3Reliability
If time-frequency spreading is used to resist Doppler shifts, then reliability under mobility is improved, but device complexity increases
Solution Approach 1:
The invention replaces complex signal processing mechanisms with simpler operations. Instead of requiring complex equalization or synchronization mechanisms to handle Doppler effects, it uses straightforward time-frequency shifting and resource element mapping that are computationally efficient and easier to implement in practical devices
Data Source
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AI summary
A wireless combination time, frequency and spectral shaping communications method that transmits data in convolution unit matrices (data frames) of NxN (N2), where generally either all N2 data symbols are received over N spreading time intervals (each composed of N time slices), or none are. To transmit, the N2 sized data frame matrix is multiplied by a first NxN time-frequency shifting matrix, permuted, and multiplied by a second NxN spectral shaping matrix, thereby mixing each data symbol across the entire resulting N x N matrix (TFSSS data matrix). Columns from this N2 TFSSS data matrix are selected, modulated, and transmitted, on a one element per time slice basis. At the receiver, the replica TFSSS matrix is reconstructed and deconvoluted, revealing the data. The method can accommodate multiple users at once, can adapt to changing channel conditions, and is particularly useful for coping with channel impairments such as Doppler shifts.