RACH Preamble Detection via Energy Combining
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Solution Overview
Problem
The existing random access channel (RACH) procedure in cellular networks faces challenges in detecting RACH preamble signals, particularly due to high channel attenuation and collisions, which can lead to low signal-to-noise ratio and increased delay in handover processes.
Innovation Solution
Combining the energy of a current RACH preamble with a previously received preamble having the same signature to enhance detection probability, eliminating the need for frequency hopping and simplifying handover procedures by using a network entity with a transceiver and processor to determine successful detection and retransmit with identical signatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequency hopping is used to improve RACH preamble detection, then detection probability increases, but device complexity and signaling overhead increase
Solution Approach 1:
The patent combines multiple RACH preamble transmissions with identical signatures at the network side, accumulating their energy to improve detection probability. This merging approach replaces the complex frequency hopping mechanism at the UE side with a simpler combining operation at the network side, reducing overall system complexity while maintaining or improving detection reliability.
Solution Approach 2:
The network side performs preliminary combining of RACH preamble transmissions before final detection. By accumulating energy from multiple transmissions in advance, the system improves detection probability without requiring complex real-time frequency hopping operations during the detection process.
2Reliability
If frequency hopping is implemented to enhance detection, then signal detection improves, but handover procedure complexity increases
Solution Approach 1:
The patent merges multiple RACH preamble transmissions with identical signatures at the network side through energy combining. This simplifies the handover procedure by eliminating the need for frequency hopping operations, making the process easier to implement while maintaining improved signal detection capability through the combining of multiple transmissions.
3Reliability
If multiple frequency changes are used for retransmission, then detection robustness improves, but signaling overhead increases
Solution Approach 1:
The patent combines multiple RACH preamble transmissions with identical signatures at the network side, accumulating their energy to improve detection robustness. This approach reduces signaling overhead compared to frequency hopping methods, as it requires less frequent signaling to coordinate multiple frequency changes and reduces the complexity of managing multiple frequency resources.
Solution Approach 2:
The network side recovers useful signal energy from multiple RACH preamble transmissions by combining them, rather than discarding failed detection attempts. This recovering approach improves detection robustness while minimizing additional signaling overhead, as the combining operation efficiently utilizes existing transmission resources.
Data Source
AI summary
The present invention provides a method of and a network entity for processing a random access preamble. The network entity comprises a transceiver for receiving an random access preamble; and a processor for determining if the random access preamble is successfully detected, and for determining, in the case where the random access preamble is not successfully detected, if a combined preamble resulting from a combination of the random access preamble with a previous random access preamble received at the network entity prior to reception of the random access preamble and having an identical signature to the signature of the random access preamble, is successfully detected.