Relay Station Delay Diversity for Low-Correlation Multi-Antenna Links
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Solution Overview
Problem
In wireless communications, particularly in 5G systems, achieving sufficient diversity effect is challenging due to high correlation between radio signal propagation characteristics among multiple antennas in relay stations, which limits the diversity gain at terminal stations using non-regenerative relay.
Innovation Solution
A relay station with multiple antennas and FIR filters applies different delay amounts to baseband signals, implementing delay diversity by assigning unique delays to each antenna, thereby enhancing the diversity gain at the reception station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-regenerative relay is used with multiple antennas in relay stations, then communication coverage is expanded and delay is reduced, but diversity effect is insufficient due to high correlation between radio signal propagation characteristics
Solution Approach 1:
The patent applies delay diversity by changing the time parameter of signal transmission. Specifically, it introduces different delay amounts (e.g., 0 μs, 1 μs, 2 μs) for signals transmitted from different antennas, thereby altering the propagation characteristics and reducing correlation between antenna signals. This enables the reception station to obtain preferable diversity effect even with a single antenna.
2Power
If multiple antennas are used in relay stations, then signal transmission capability is improved, but self-interference increases and signal timing alignment becomes complex
Solution Approach 1:
The patent introduces different delay amounts for different antennas to change the timing parameter of transmitted signals. This delay diversity approach transforms the harmful self-interference into useful diversity gain by ensuring that signals from different antennas arrive at the reception station at different times, reducing constructive interference and improving signal reliability.
3Reliability
If delay diversity is implemented with different delay amounts for each antenna, then diversity gain is enhanced, but device complexity increases due to additional FIR filters and delay control
Solution Approach 1:
The patent segments the signal processing function by introducing separate FIR filters for each antenna, where each filter applies a specific delay amount. This segmentation allows independent control of delay parameters for each antenna, simplifying the overall control architecture while achieving delay diversity. The controller configures each FIR filter with predetermined delay values, making the system manageable despite the added components.
Data Source
AI summary
A relay station comprises antennas, wireless devices corresponding to the antennas, and a controller to control an operation of the wireless devices. Each of the wireless devices includes a receiver to convert the first radio signal received by a corresponding antenna into a baseband signal, an FIR filter to assign a delay to the baseband signal; and a transmitter to convert a signal output from the FIR filter into a second radio signal transmitted from the corresponding antenna to the reception station. The controller sets a different delay amount in the FIR filter in each of the wireless devices so that the FIR filter assigns a delay, which is different from among the antennas, to the baseband signal input from the receiver in each of the wireless devices.