Indoor RF Distribution Emulating Multi-Path Propagation
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Solution Overview
Problem
Indoor communication systems in buildings and tunnels often fail to benefit from the technical advantages of rake receivers due to insufficient multi-path time delays, resulting in suboptimal signal quality.
Innovation Solution
A method and system that emulate outdoor multi-path propagation effects by generating signals with time delays of at least one chip length through combining substantially identical RF sub-signals with varying time delays, improving signal quality for both downlink and uplink transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional RF distribution is used in indoor environments, then system simplicity is maintained, but signal quality deteriorates due to insufficient multi-path time delays
Solution Approach 1:
The patent segments the RF signal into multiple sub-signals with different time delays. The signal is divided into at least two sub-signals, each experiencing different propagation paths, creating artificial multi-path effects that enable rake receivers to function properly in indoor environments.
Solution Approach 2:
The patent introduces an intermediary device (the RF distribution system with multiple antennas) that mediates between the outdoor signal source and the indoor receiver. This intermediary creates the necessary time delays and multi-path effects without requiring the mobile station to generate them.
2Reliability
If rake receivers are used in indoor environments without multi-path effects, then device capability is maintained, but performance deteriorates due to lack of time delay diversity
Solution Approach 1:
The patent changes the temporal parameters of the RF signal by introducing controlled time delays between multiple sub-signals. By adjusting the time delay parameters to be at least one chip length apart, the system creates conditions suitable for rake receiver operation, transforming the signal characteristics to match outdoor multi-path propagation.
3Reliability
If outdoor multi-path propagation effects are emulated in indoor environments, then signal quality improves, but system complexity increases
Solution Approach 1:
The patent employs periodic action by continuously generating multiple sub-signals with different time delays and combining them to create sustained multi-path effects. This periodic creation of time-delayed signal copies maintains the simulated outdoor propagation environment throughout the communication process.
Data Source
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AI summary
The invention relates to a method for indoor communications, the method comprising receiving a signal (Ws) for/from a mobile station (Ms) located inside a confined environment (B), converting the received signal into an RF signal for transmission through an RF connection (C2), splitting the RF signal into at least two substantially identical RF sub-signals, applying a different time delay to each individual RF sub-signal so that the time delay difference between the RF sub-signals is at least one chip length, combining the at least two RF sub-signals with different time delays and adapting said combined signal for reception by a rake receiver of a mobile station (Ms) or a rake receiver of a base station (Bs).