Precoder Switching Pattern for PRS Interference Mitigation
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Solution Overview
Problem
In LTE positioning systems, existing technologies face challenges in improving the reception of Positioning Reference Signals (PRS) due to static interference from colliding PRS patterns, leading to reduced hearability and positioning accuracy, especially in dense deployments where multiple base stations create interference.
Innovation Solution
A Radio Network Node (RNN) selects and applies different precoders for forming beams to transmit PRS symbols, using a precoding switching pattern to steer energy in multiple directions, thereby reducing static interference and enhancing the Line Of Sight (LOS) path, allowing for improved reception of PRS at communications devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple base stations transmit PRS simultaneously in dense deployments, then positioning coverage is improved, but static interference from colliding PRS patterns increases and hearability deteriorates
Solution Approach 1:
The patent applies dynamics by switching precoders over time according to a precoding switching pattern. Instead of using a static precoder configuration, the system dynamically changes the precoder applied to PRS symbols, which changes the beamforming pattern over time. This allows the system to maintain positioning coverage while reducing static interference through temporal variation of the transmitted signal patterns.
Solution Approach 2:
The patent implements periodic action through the use of a precoding switching pattern that periodically switches between different precoders. The switching occurs at regular intervals defined by the pattern, creating periodic variations in the beamforming patterns. This periodic switching helps to mitigate persistent interference by ensuring that interfering signals vary over time, improving hearability.
2Device complexity
If a single precoder is used for PRS transmission, then device complexity is reduced, but hearability and positioning accuracy deteriorate due to static interference
Solution Approach 1:
The system transitions from a static single precoder configuration to a dynamic multi-precoder configuration with switching. The complexity is managed by using a predefined precoding switching pattern that the UE can track, while the positioning accuracy improves through the reduction of static interference achieved by varying the beamforming patterns over time.
Solution Approach 2:
The patent changes the parameter of precoder selection over time according to the precoding switching pattern. By varying which precoder is applied to different PRS symbols or subframes, the system alters the spatial distribution of transmitted energy, thereby mitigating persistent interference and improving measurement precision without requiring complex real-time adaptation.
3Reliability
If precoding switching is implemented to reduce interference, then hearability improves, but device complexity and processing requirements increase
Solution Approach 1:
The network node provides the precoding switching pattern to the UE in advance, allowing the UE to prepare for the switching without requiring complex real-time decision-making. The UE can track the predetermined switching pattern and accordingly adjust its reception processing, reducing the processing complexity while maintaining improved hearability through interference mitigation.
Solution Approach 2:
The precoding switching pattern acts as an intermediary that coordinates between the network's transmission strategy and the UE's reception processing. By providing this pattern as intermediate information, the system enables the UE to anticipate and adapt to precoder changes without requiring complex real-time analysis, thus improving hearability while managing processing complexity.
Data Source
AI summary
A Radio Network Node (RNN) and a method for enabling an improved reception of Positioning Reference Signals (PRSs) at a communications device. The RNN and the communications device are operable in a wireless communications network. The RNN selects a first precoder and a second precoder for forming a first beam and a second beam, respectively, and obtains a precoding switching pattern relating to when the first precoder is to be applied to one or more first PRS symbols and when the second precoder is to be applied to one or more second PRS symbols. Further, the RNN transmits, to the communications device, the one or more first PRS symbols to which the first precoder is applied; and in accordance with the obtained precoding switching pattern, the RNN transmits, to the communications device, the one or more second PRS symbols to which the second precoder is applied.