Backscatter Signal Scrambling for Multi-Tag Collision Avoidance
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Solution Overview
Problem
Backscatter communication systems face challenges in demodulating superposed signals from multiple tags due to interference, as existing modulation schemes are limited to single-user scenarios, leading to collisions and demodulation failures.
Innovation Solution
A communication method that involves determining scrambling code sequences and resource blocks based on a mapping relationship to scramble information bits, ensuring codeword weights are within a preset range, and using bit cyclic shifts to avoid collisions among users, allowing for demodulation of superposed signals from multiple devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If backscatter communication uses reflection mode for low power consumption, then energy efficiency is improved, but signal demodulation capability deteriorates due to inability to handle superposed signals from multiple tags
Solution Approach 1:
The patent segments the reflected signal processing by introducing different scrambling code sequences for different tags. Each tag's reflected signal is scrambled with a unique sequence, allowing the receiver to separate and demodulate multiple superposed signals through code division multiplexing, thus maintaining low power consumption while improving demodulation capability.
Solution Approach 2:
The patent dynamically adjusts the scrambling code sequences based on resource block assignments. The scrambling codes are not fixed but are dynamically selected and assigned to different tags based on their resource allocations, enabling flexible handling of multiple users while maintaining the energy-efficient backscatter mode.
2Device complexity
If fixed scrambling code sequences are used for simplicity, then device complexity is reduced, but user collision probability increases leading to demodulation failures
Solution Approach 1:
The patent makes the scrambling code sequences universal by using them for both single-user and multi-user scenarios. The same scrambling code mechanism serves different purposes: avoiding collisions in multi-user backscatter communication while maintaining compatibility with existing single-user systems, thus not increasing device complexity significantly.
Solution Approach 2:
The patent changes the parameters of scrambling code sequences by introducing different initialization values and sequences based on resource block assignments. This parameter variation allows the system to distinguish between multiple tags using the same basic scrambling mechanism, avoiding collisions without requiring fundamentally new code structures.
Data Source
AI summary
This application provides a communication method and a communication apparatus. In the method, a first device determines a scrambling code sequence and a resource block in current transmission based on a mapping relationship between a scrambling code sequence set and a resource block set in the current transmission and a to-be-transmitted information bit. This helps avoid collisions among users by preventing them from using same scrambling code sequences and resource blocks in every transmission. The first device scrambles the information bit based on the scrambling code sequence, to obtain scrambled data in the current transmission, and sends the scrambled data on the resource block. Codeword weight of the scrambled data is within a preset range, allowing the first device to adjust the codeword weight of the scrambled data, thereby enhancing a check capability of a receive end.