Lens Antenna MIMO Precoding With Fewer RF Chains
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Solution Overview
Problem
Millimeter-wave (mmWave) MIMO systems face high hardware costs and power consumption due to the need for a dedicated RF chain for each antenna, especially with large antenna arrays required to compensate for high path loss.
Innovation Solution
A MIMO transmitter and receiver system that uses a lens antenna array with a selecting unit to couple RF chains to selective sub-arrays of antenna elements, reducing the number of RF chains through digital and analog precoding, and phase shifter modules to optimize data rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full digital precoding with dedicated RF chains for each antenna is implemented, then high data rates and low interference between data streams are achieved, but hardware costs and power consumption become excessively high
Solution Approach 1:
The patent segments the large antenna array into multiple sub-arrays, with each sub-array served by a separate RF chain. This allows the system to handle a large total number of antenna elements without requiring a dedicated RF chain for each antenna, thus reducing hardware complexity while maintaining the ability to process multiple data streams through digital precoding across the segmented structures.
Solution Approach 2:
The patent introduces an additional dimension of processing by implementing two-stage precoding: first across sub-arrays and then across the full antenna array. This dimensional approach allows the system to achieve high data rates through coordinated processing in multiple stages rather than requiring a single complex RF chain per antenna configuration.
2Productivity
If full digital precoding with dedicated RF chains for each antenna is implemented, then high data rates and low interference between data streams are achieved, but power consumption becomes excessively high
Solution Approach 1:
By segmenting the antenna array into sub-arrays and assigning one RF chain per sub-array rather than per antenna, the patent significantly reduces the number of RF chains required. Since RF chains are major power consumers, this segmentation directly reduces overall system power consumption while maintaining high data rates through coordinated digital precoding across the segmented sub-arrays.
Solution Approach 2:
The patent merges multiple antenna elements within sub-arrays to be served by a single RF chain, combining their processing functions. This merging reduces the total number of power-hungry RF chains while the digital precoding mechanism ensures that the combined antennas still achieve the necessary data rate performance through coordinated signal processing.
3Reliability
If a large antenna array is used to compensate for high path loss in mmWave communications, then path loss compensation is achieved, but hardware costs increase
Solution Approach 1:
The patent segments the large antenna array into multiple sub-arrays that can be managed by fewer RF chains. This segmentation allows the system to utilize the path loss compensation benefits of large antenna arrays while reducing hardware costs by sharing RF chains across multiple sub-arrays, rather than requiring dedicated RF chains for each antenna element.
Solution Approach 2:
Each RF chain is designed to serve multiple sub-arrays, giving it universal functionality. This multi-functionality allows the system to achieve path loss compensation with large antenna arrays while reducing hardware costs, as each RF chain can be configured to work with different sub-arrays through the selecting unit and digital precoding mechanisms.
4Device complexity
If the number of RF chains is reduced through sub-array selection, then hardware costs and power consumption are reduced, but data rate performance may deteriorate
Solution Approach 1:
The patent performs preliminary selection of dominant beams and optimal sub-arrays before data transmission. By pre-identifying the most effective sub-arrays and beam directions based on channel conditions, the system ensures that the reduced number of RF chains are allocated to the most productive sub-arrays, thereby maintaining high data rate performance despite having fewer RF chains than total antenna elements.
Solution Approach 2:
The system implements feedback mechanisms to continuously monitor channel conditions and adjust sub-array selections and beamforming parameters. This feedback allows the system to dynamically optimize the use of the reduced number of RF chains, ensuring that data rate performance is maintained by adapting to changing channel conditions and selecting the most effective sub-arrays for current transmission requirements.
Data Source
AI summary
According to the present disclosure there is provided a multiple-input-multiple-output (MIMO) transmitter for transmitting wireless communication signals over a communication channel to a receiver, the transmitter including a digital signal processor configured to perform pre-coding on a plurality Ns of data streams; a plurality NRF of radio-frequency (RF) chains each configured to pass a pre-coded data stream from the digital signal processor to generate a signal representing that data stream; a lens antenna array comprising an array of NT antenna elements; and a selecting unit coupled between the plurality NRF of RF chains and the lens antenna array, the selecting unit including a plurality of separate coupling units each configured to couple a respective RF chain to a selective sub-array of NTB<sub2>RF </sub2>antenna elements concurrently for transmitting the signal representing the data stream passed through that RF chain.