Reciprocity-Based Beamforming Antenna Array Balancing Link Budgets
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Solution Overview
Problem
Traditional mobile communication systems face challenges in achieving reciprocity-based transmission due to the imbalance between uplink (UL) and downlink (DL) link budgets, particularly with legacy frequency division duplex (FDD) systems, where the number of receive (Rx) antennas is higher than transmit (Tx) antennas, leading to inefficient resource utilization.
Innovation Solution
The method involves obtaining channel estimations of both Rx and Tx distribution networks, with more Rx antennas being utilized for reciprocity-based transmission, including reciprocity-based beamforming, and interlacing Rx-only antenna elements with Rx/Tx antenna elements to improve beamforming and channel estimation, thereby balancing UL and DL link budgets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of Rx antennas is increased to balance UL link budget, then UL performance is improved, but the system cannot achieve reciprocity-based transmission efficiently
Solution Approach 1:
The patent combines channel estimation from both Rx/Tx distribution networks and Rx-only distribution networks to create a unified channel estimate for reciprocity-based transmission. This merging allows the system to utilize all available antenna elements (both Rx and Tx) for channel estimation, resolving the contradiction by enabling reciprocity-based transmission while maintaining UL link budget balance through proper weighting of the combined estimates.
2Measurement precision
If more Rx distribution networks are used for channel estimation, then channel estimation accuracy is improved, but system complexity increases
Solution Approach 1:
The patent changes the weighting parameter of channel estimates from different distribution networks to optimize the balance between estimation accuracy and system complexity. By assigning larger weights to Rx-only distribution network estimates and smaller weights to Rx/Tx distribution network estimates, the system achieves improved channel estimation accuracy while managing complexity through parameter optimization rather than structural complexity.
3Measurement precision
If Rx-only antenna elements are added to improve beamforming, then spatial resolution is improved, but array structure complexity increases
Solution Approach 1:
The patent segments the antenna array into two distinct parts: Rx/Tx antenna elements and Rx-only antenna elements. This segmentation allows the system to improve spatial resolution through the additional Rx-only elements while managing array structure complexity by treating them as separate functional groups that can be configured and processed independently in the beamforming algorithm.
4Shape
If interlaced antenna structure is used, then beam narrowing is achieved, but grating lobes may be introduced
Solution Approach 1:
The patent applies local quality by differentiating the treatment of interlaced antenna elements based on their specific positions and functions. By carefully designing the weighting and phase compensation for each Rx-only element relative to its corresponding Tx element, the system achieves beam narrowing in the main lobe direction while suppressing grating lobes through localized parameter optimization rather than uniform treatment of all elements.
Data Source
AI summary
Embodiments presented herein relate to a method for reciprocity-based transmission in a radio communication network. The method is performed in a base station and may include obtaining a channel estimation of Rx quantities of a set of receive, Rx, and transmit, Tx, distribution networks, obtaining a channel estimation of Rx quantities of a set of Rx distribution networks, and performing reciprocity-based transmission with utilization of the obtained channel estimation of Rx quantities of both the set of Rx and Tx distribution network and the set of Rx distribution network, whereby channel estimation of Rx quantities of more Rx distribution networks than Tx distribution networks are utilized for the reciprocity-based transmission. A method, a base station, a wireless device, a computer programs and a computer program product for reciprocity-based beamforming in a radio communication network are also presented.