Uplink Stream Modification via Composite Antenna Beamforming
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Solution Overview
Problem
In cellular base stations, the increasing number of antenna elements required for higher frequency bands and massive MIMO systems leads to increased processing complexity and power amplification challenges, making it difficult to maintain similar cell coverage and performance across generations, especially due to worsened propagation and bandwidth requirements.
Innovation Solution
The method involves configuring the space sampling basis in base stations to use a composite antenna derived from multiple radiating elements to form synthesised beams, matching the number of synthesised beams to the number of uplink UEs served, and instantiating uplink signal processing per synthesised beam, which reduces processing complexity and improves spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of antenna elements is increased to maintain cell coverage at higher frequencies, then antenna gain is improved, but processing complexity increases by O(n² ln(n))
Solution Approach 1:
The patent segments the large number of antenna elements into multiple sub-arrays, where each sub-array is independently controlled. This segmentation reduces the processing complexity from O(n² ln(n)) to O(k·m² ln(m)) where n=k·m, by dividing the massive MIMO system into smaller manageable units that can be processed separately.
Solution Approach 2:
The patent combines multiple sub-arrays to form a coordinated multi-point transmission system. By merging the processing results from individual sub-arrays and applying joint precoding, the system achieves the benefits of having many antenna elements while avoiding the full computational burden of processing all elements simultaneously as a single large array.
2Productivity
If the number of antenna elements is increased to support massive MIMO and multiple beams, then capacity is improved, but power amplifier requirements worsen
Solution Approach 1:
The patent divides the power amplification function across multiple sub-arrays, each with its own power amplifiers. This segmentation allows each power amplifier to operate at lower power levels individually, avoiding the need for high-power amplifiers that would be required if all antenna elements were driven simultaneously from a single power source.
Solution Approach 2:
The patent employs time-division multiplexing where different sub-arrays are activated in different time slots or periods. This periodic activation pattern allows the system to serve multiple users across different time intervals, maintaining high system capacity while ensuring that power amplifiers only need to support a subset of antenna elements at any given moment, thereby reducing peak power requirements.
3Area of stationary object
If the number of antenna elements is increased to compensate for worsened propagation at higher frequencies, then cell coverage is improved, but the number of elements required rises to around 250
Solution Approach 1:
The patent segments the 250+ antenna elements into multiple smaller sub-arrays, each covering a specific spatial sector. This segmentation allows the system to achieve broad cell coverage by coordinating transmissions from multiple sub-arrays, while each individual sub-array uses a manageable number of elements, making the overall system more practical for deployment.
Solution Approach 2:
The patent transitions from a two-dimensional array of antenna elements to a three-dimensional spatial configuration by vertically stacking sub-arrays at different heights and orientations. This dimensional expansion allows the system to achieve omnidirectional or quasi-omnidirectional coverage more efficiently, reducing the total number of elements needed while maintaining or improving cell coverage area.
Data Source
AI summary
A method, in abase station of a wireless telecommunications system comprising multiple radiating elements, the method comprising modifying a number of uplink or downlink information streams, each information stream corresponding to an element in a space sampling basis for the system, wherein, in the downlink, the space sampling basis is configured so that the number of information streams is the same as the number of radiating elements of the system, and in the uplink, the space sampling basis is configured using a composite antenna derived from multiple radiating elements of the system to form a synthesised beam.