Chirp Receiver Synchronization Using Gradient Sequences
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Solution Overview
Problem
In multi-user systems, chirp communication systems face challenges in distinguishing synchronization signals from different transmitters, leading to high likelihoods of incorrect synchronization or failure, due to the similarity of synchronization signals and the overhead required for exchanging additional header information, which increases latency and spectral pollution.
Innovation Solution
A method and apparatus for synchronizing a receiver with a transmitter using a synchronization chirp signal comprising symbols with different gradients, allowing for correlation and determination of timing and frequency offsets, and adjusting the receiver's timing and frequency accordingly, while reducing the need for additional information exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If synchronization signals with identical gradients are used, then the correlation process is simple, but the receiver cannot distinguish between signals from different transmitters in multi-user systems
Solution Approach 1:
The patent applies local quality by assigning different gradient characteristics to different portions of the synchronization signal. Specifically, the signal contains a first portion with gradient g1 and a second portion with gradient g2, where the gradients differ. This allows the receiver to distinguish between signals from different transmitters while maintaining a relatively simple correlation process, as the gradient differences create distinct correlation peaks for each transmitter.
2Reliability
If additional header information is exchanged to resolve incorrect synchronization, then synchronization reliability improves, but latency increases and spectral pollution worsens
Solution Approach 1:
The patent implements preliminary action by embedding gradient information directly in the synchronization signal itself, before any data transmission occurs. The different gradients in the first and second portions of the signal allow the receiver to identify the correct transmitter and establish synchronization without needing to exchange additional header information or perform subsequent negotiation protocols, thereby reducing latency.
3Productivity
If multiple transmitters send synchronization signals simultaneously, then system productivity is high, but the likelihood of incorrect synchronization increases
Solution Approach 1:
The patent applies parameter changes by varying the gradient parameter of the chirp signal across different portions of the synchronization signal. Each transmitter uses a unique gradient sequence (different g1 and g2 values), which allows the receiver to distinguish between simultaneous signals from multiple transmitters through correlation processing, maintaining both high productivity and synchronization accuracy.
Data Source
AI summary
A method of synchronizing the frequency and timing of a receiver with a synchronization chirp signal from a transmitter, comprising: receiving the synchronization chirp signal, the synchronization chirp signal comprising a sequence of symbols, the sequence of symbols including at least a first symbol having a first gradient g1 and a second symbol having a second gradient g2, wherein the magnitudes of the first gradient and the second gradient are both greater than one, and the magnitude of the first gradient is different to the magnitude of the second gradient; correlating the sequence of received symbols with expected symbols to form a correlator output; determining timing and frequency offsets between the transmitter and the receiver from the correlator output; and adjusting the timing and frequency of the receiver by the determined timing and frequency offsets.