Backscatter Timing Allocation for Multi-Device Ambient IoT Access
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Solution Overview
Problem
Low power backscatter devices, such as ambient IoT devices, face challenges in simultaneous communication due to congestion and interference when multiple devices are in close proximity, limiting their usability in applications like inventory tracking and card scanning.
Innovation Solution
Implementing a timing adjustment mechanism for backscatter devices to modulate carrier signals based on unique timing adjustments, allowing them to communicate without interference by assigning specific periods for modulation and non-modulation, distinct from other devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple backscatter devices are used in close proximity, then device coverage and usability are improved, but congestion and interference increase
Solution Approach 1:
The patent segments the communication resource by introducing a cyclic shift parameter that divides the signal space into distinct, non-overlapping segments for different devices. Each backscatter device is assigned a unique cyclic shift value, which segments the overall signal into device-specific portions that can be independently decoded, thereby allowing multiple devices to operate simultaneously without interference.
Solution Approach 2:
The patent introduces a new dimension (cyclic shift in the time-frequency domain) to resolve the interference problem. Instead of only using spatial separation (distance), the system adds a temporal-frequency dimension through cyclic shifting, allowing devices to be separated in this additional dimension even when physically close, thus expanding coverage without increasing interference.
2Reliability
If distance limitations are imposed to prevent interference, then signal quality is improved, but device usability and coverage are reduced
Solution Approach 1:
The patent changes the signal parameter by applying a cyclic shift to the backscatter signal in the time domain. This parameter change allows the receiver to distinguish between signals from different devices through correlation processing, maintaining signal quality even when devices are at larger distances or in closer proximity, thereby improving usability without sacrificing reliability.
3Productivity
If simultaneous communication by multiple devices is enabled, then productivity is improved, but interference and congestion increase
Solution Approach 1:
The patent segments the communication resource by introducing a cyclic shift parameter that divides the signal space into distinct, non-overlapping segments for different devices. Each backscatter device is assigned a unique cyclic shift value, which segments the overall signal into device-specific portions that can be independently decoded, thereby allowing multiple devices to operate simultaneously without interference.
Solution Approach 2:
The patent employs periodic action through the cyclic nature of the shift operation. The cyclic shift creates periodic patterns in the time domain that allow the receiver to identify and separate signals from different devices through correlation detection, enabling simultaneous communication without congestion while maintaining high productivity.
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
Enables simultaneous communication of multiple backscatter devices by reducing interference, enhancing the usability of ambient IoT devices in crowded environments.
Implementation Method 1
a backscatter device may receive a radiofrequency (RF) signal from a sending device and may reflect the signal, after modulating it with its own data to be transmitted
Data Source
AI summary
Systems and methods for multiple access for ambient IoT devices or other backscatter communication based devices. A backscatter device may receive configuration information from a reader device including information indicating an identification of a timing adjustment for communicating with the reader device. The backscatter device may modulate a carrier signal transmitted by the reader device with a data signal, a timing of the modulation of the carrier signal being based on the indicated timing adjustment. The timing adjustment may include a delay of less than a period of the data signal, and may be different from a delay assigned to another backscatter device configured to modulate the carrier signal; and/or may indicate periods during which to modulate or not modulate the carrier signal, distinct from those assigned to another backscatter device.