Active Antenna Arrangement Beam Width Control
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Solution Overview
Problem
In three-sector base station antenna configurations, achieving a desired beam width of 65 degrees while maintaining antenna separation of half a wavelength is challenging, leading to grating lobes that increase interference and reduce efficiency.
Innovation Solution
An active antenna arrangement with multiple active antenna devices, splitters, and combiners is used to split and combine precoded signals, allowing for optimal beam width control without grating lobes, by configuring antenna elements to transmit split precoded signals effectively, thereby achieving desired beam width and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If antenna separation is increased to 0.8λ to achieve 65-degree beam width, then beam width requirement is met, but grating lobes occur when pre-coding beams are steered away from broadside
Solution Approach 1:
The precoded signal is segmented into multiple split precoded signals using splitters. Each antenna element transmits a combination of these split signals with different weights and phases, allowing the system to achieve the desired 65-degree beam width while eliminating grating lobes through coordinated signal combination.
Solution Approach 2:
The combiner merges multiple split precoded signals from different splitters into a single composite signal that is transmitted by a single antenna element. This combining process with appropriate weighting and phase adjustment enables beam forming that achieves narrow beam width without generating grating lobes.
2Object-generated harmful factors
If antenna separation is reduced to λ/2 to eliminate grating lobes, then grating lobe issue is resolved, but beam width increases to around 90 degrees
Solution Approach 1:
Different antenna elements are assigned different local signal characteristics through the splitter-combiner architecture. Each antenna transmits a unique combination of split precoded signals with element-specific weights and phases, enabling each antenna to contribute to a narrow overall beam pattern while maintaining λ/2 spacing that prevents grating lobes.
Solution Approach 2:
The system dynamically adjusts the weights and phases of split precoded signals transmitted by each antenna element based on beam steering requirements. This dynamic signal adjustment allows the system to maintain narrow beam width across different steering angles while keeping antenna spacing at λ/2 to avoid grating lobes.
3Device complexity
If multiple antennas spaced λ/2 apart are used, then device complexity is managed, but it is difficult to obtain antenna element patterns with beam widths as small as 65 degrees
Solution Approach 1:
The splitter-combiner structure acts as an intermediary between the simple λ/2 spaced antenna array and the desired narrow beam pattern. The splitters divide precoded signals into multiple paths, and the combiners recombine them with adjusted weights and phases, enabling narrow beam width achievement without increasing physical antenna spacing or overall system complexity.
Data Source
AI summary
The invention relates to an active antenna arrangement for transmitting precoded signals in a communication system supporting multi-stream beam-forming. The active antenna arrangement comprises: three or more active antenna devices each comprising an antenna element and a power amplifier; at least a first and a second splitter, each arranged to split a respective one of the precoded signals into two or more split precoded signals; and at least one combiner arranged to: receive one of the two or more split precoded signals from the first splitter, and one of the two or more split precoded signals from the second splitter, and combine the received split precoded signals for transmission by a single one of the active antenna devices. The invention also relates to a base station, methods and computer programs.