Coherent Data Communication via Segmented Incoherent Channels
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Solution Overview
Problem
In digital modulation, achieving a low bit error rate (BER) is crucial, especially in ultra-reliability low-latency communications, but increasing the signal-to-noise ratio (SNR) is not always feasible, and implementing a coherent channel is complex and power-consuming, particularly for devices like narrowband Internet-of-Things devices and base stations with incoherent links.
Innovation Solution
The technique involves splitting a coherent modulation symbol into incoherent modulation symbols, which are transmitted on different physical channels, allowing for simpler modulation and detection without a Costas loop, thereby reducing the symbol error rate (SER) and improving BER by using independent noise channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coherent channel is implemented using a Costas loop for synchronization, then the bit error rate is reduced, but the device complexity and power consumption increase
Solution Approach 1:
The coherent modulation symbol is segmented into multiple incoherent modulation symbols that are transmitted on different physical channels. Each channel uses a simpler single PLL instead of a complex Costas loop, reducing device complexity while maintaining reliability through diversity combining at the receiver
Solution Approach 2:
Multiple independent physical channels act as intermediaries to transmit segmented symbols. These channels use simpler synchronization (single PLL) but collectively provide the reliability of coherent transmission through their independence from phase noise and frequency drift
2Reliability
If the signal-to-noise ratio is increased to reduce the bit error rate, then the reliability improves, but the energy consumption increases
Solution Approach 1:
The transmission is segmented across multiple independent physical channels, each carrying a portion of the modulated symbol. This segmentation allows the system to achieve diversity gain, improving reliability without requiring excessive SNR on any single channel, thus reducing overall energy consumption
Solution Approach 2:
The system changes the parameter of transmission from a single high-SNR coherent channel to multiple lower-SNR incoherent channels. By adjusting the number of channels and their individual power levels, the system achieves the same BER performance with optimized energy distribution
3Device complexity
If orthogonal polarization is used to separate in-phase and quadrature components, then the channel synchronization is simplified, but the signal-to-noise ratio deteriorates due to correlated noise
Solution Approach 1:
Instead of using orthogonal polarization for I/Q separation, the system segments the modulation symbol into multiple independent incoherent symbols transmitted on different physical channels. This avoids the correlated noise problem of polarization division while maintaining synchronization simplicity
Solution Approach 2:
The system transitions from separating I/Q components in the polarization domain to separating them across multiple independent physical channels. This dimensional change from spatial polarization to channel diversity eliminates the correlated noise issue while achieving the same goal of simplified synchronization
Data Source
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AI summary
A technique for transmitting data is described. The data is represented by a modulation symbol comprising an in-phase component and a quadrature component. Considering a method aspect of the technique, the modulation symbol (510) is split into at least two different baseband signals (522, 524), which are in phase with each other and jointly representative of the modulation symbol (510). The at least two baseband signals (522, 524) are up-converted from a baseband frequency to a transmission frequency. Each of the at least two up-converted signals (532, 534) is transmitted on a different physical channel (536, 538).