OAM Multiplexing Channel Estimation Overhead Reduction
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Solution Overview
Problem
In OAM multiplexing communication systems, the overhead of channel estimation signals increases with the multiplex number, leading to deteriorated transmission capacity and increased calculation amounts for channel estimation, especially when performing broadband communication or dividing the band into multiple bands.
Innovation Solution
A method where a single channel estimation signal sequence is time-shifted and transmitted across all streams, using a Golay code with a cyclic prefix longer than the channel response, allowing for batch channel estimation using circulant matrices and reducing the overhead and calculation load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple channel estimation signals are transmitted for each stream in OAM multiplexing communication, then channel estimation accuracy is improved, but the overhead of channel estimation signals increases and transmission capacity deteriorates
Solution Approach 1:
The patent merges the channel estimation signals of all streams into a single shared signal. Instead of transmitting separate channel estimation signals for each stream, a single channel estimation signal is transmitted and reused by all streams, thereby eliminating redundant overhead while maintaining channel estimation capability for all streams.
Solution Approach 2:
The patent makes the channel estimation signal universal across all streams. A single channel estimation signal serves multiple functions by being used for channel estimation of all streams simultaneously, rather than having dedicated channel estimation signals for each individual stream.
2Measurement precision
If multiple channel estimation signals are transmitted for each stream in OAM multiplexing communication, then channel estimation accuracy is improved, but calculation amount for channel estimation increases
Solution Approach 1:
The patent combines the channel estimation process for all streams into a single unified calculation. By using a single shared channel estimation signal, the system performs one channel estimation calculation that can be applied to all streams, rather than performing separate calculations for each stream.
Solution Approach 2:
The patent creates a universal channel estimation approach where a single channel estimation result derived from one signal can be universally applied to all streams, reducing the computational burden of performing separate channel estimations for each stream.
3Productivity
If the multiplex number increases in OAM multiplexing communication, then transmission capacity is improved, but the overhead of channel estimation signals and calculation amounts increase
Solution Approach 1:
The patent merges the channel estimation overhead across all multiplexed streams by using a single shared channel estimation signal. This approach ensures that the overhead does not scale with the multiplex number, allowing transmission capacity to increase without proportionally increasing channel estimation overhead.
4Productivity
If the multiplex number increases in OAM multiplexing communication, then transmission capacity is improved, but calculation amount for channel estimation increases
Solution Approach 1:
The patent combines the channel estimation calculations for all streams into a single unified process. By using one shared channel estimation signal, the calculation amount remains constant regardless of the multiplex number, enabling transmission capacity to scale without increasing computational complexity.
Data Source
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AI summary
An OAM multiplexing transmission device includes a unit generating each of the transmission streams in a baseband (BB), in which a channel estimation signal sequence is disposed before a transmission target data signal sequence, and a CP having a predetermined length is disposed in the first half of the channel estimation signal sequence, the channel estimation signal sequence is time-shifted with a channel estimation signal sequence (a basic channel estimation signal sequence) having a predetermined length and a zero correlation, by a predetermined shift value for each of the transmission streams; a unit converting a baseband signal sequence of the generated transmission streams to frequency conversion into RF band, or converting into IF band and then converting into the RF band; and a unit converting a plurality of the frequency-converted transmission streams into a plurality of OAM mode signals having different orders, and multiplexing spatially by using the UCA.