Reference Signal Redundancy for Contention-Based Access Collision Reduction
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Solution Overview
Problem
In wireless communication systems, contention-based access procedures often result in collisions of reference signals, leading to decoding or demodulation failures when multiple devices select the same reference signal, which can impair the efficiency of communication protocols like 5G NR.
Innovation Solution
A method where a wireless communications device transmits at least two reference signals during a contention-based access procedure, ensuring that the payload can be decoded using either signal, thereby reducing the likelihood of demodulation failure due to collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single reference signal is used during contention-based access, then the device complexity is reduced, but the reliability of access procedure deteriorates due to collision probability
Solution Approach 1:
The single reference signal is segmented into multiple reference signals (e.g., multiple RACH preambles) that are transmitted simultaneously or sequentially. Each reference signal carries the same payload information, providing redundant transmission paths. This segmentation increases reliability by ensuring that at least one reference signal can be successfully decoded even if others collide, while the complexity increase is managed through standardized processing of multiple signals.
Solution Approach 2:
The system prepares multiple reference signals in advance before the contention-based access procedure occurs. These pre-configured reference signals act as a cushion against potential collisions, ensuring that if one reference signal fails due to collision, other pre-prepared reference signals are already available to carry the payload, thus cushioning against the harmful effect of collision before it impacts the access procedure.
2Reliability
If multiple reference signals are transmitted, then the reliability of payload decoding is improved, but the loss of time increases due to processing multiple signals
Solution Approach 1:
The payload is prepared and associated with multiple reference signals in advance before transmission. The device configures multiple reference signals to carry the same payload information beforehand, so that when transmission occurs, the base station can immediately attempt decoding using multiple pre-configured reference signals without requiring additional processing time for signal configuration or payload preparation after reception.
3Adaptability or versatility
If the number of reference signals is fixed for a coverage area, then the system simplicity is maintained, but the adaptability to varying collision probabilities deteriorates
Solution Approach 1:
The system transitions from a static, fixed number of reference signals to a dynamic configuration where the number of reference signals can be adjusted based on detected collision conditions. When collisions are detected or anticipated (e.g., during high traffic conditions), the system dynamically increases the number of reference signals allocated for contention-based access. This dynamic adaptation allows the system to respond to varying collision probabilities while maintaining manageable complexity through controlled adjustment rather than complete reconfiguration.
Data Source
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AI summary
A wireless communications of a contention-based access procedure that reduces collision of reference signals (e.g., when multiple devices select a same reference signal) may support a relatively high user capacity. For a contention-based access procedure, a user equipment may select at least two reference signals and transmit those at least two reference signals in association with a payload to a base station. The payload may be demodulated using each of the at least two reference signals. Thus, if collision occurs with a first reference signal of the at least two reference signals, the payload may still be demodulated using a second reference signal of the at least two reference signals. A base station may demodulate the payload using either first reference signal or the second reference signal. The base station may transmit, to the wireless communications device, a response based on the demodulated payload.