O-FRONTHAUL GATEWAY CYCLIC PREFIX DETECTION IN O-RAN
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Solution Overview
Problem
In wireless communications systems, especially in open radio access networks (O-RAN) based on 5G communications, the cyclic prefix (CP) removal from random-access symbols is inaccurate due to the fixed detection window, leading to potential interference and increased access latency when wireless client devices are at the edge of the coverage cell, as the CP duration is standardized and does not account for varying propagation delays.
Innovation Solution
The open fronthaul gateway (OFG) determines the group delay associated with random-access symbols to accurately identify the start of the CP, allowing for its precise removal, thereby reducing access latency and maintaining the integrity of the random-access symbols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed detection window is used for CP removal, then the system is simple to implement, but CP detection becomes inaccurate for devices at the edge of the coverage cell
Solution Approach 1:
The patent implements a dynamic detection window that adapts its position and size based on the detected random access preamble timing. Instead of using a fixed detection window, the system dynamically adjusts the window parameters according to the actual propagation delay experienced by different user devices, thereby achieving accurate CP detection for both edge and center devices while maintaining implementation feasibility through algorithmic adaptation.
Solution Approach 2:
The system changes the detection window parameters (position and size) based on the detected preamble timing information. By adjusting these parameters dynamically according to the measured propagation delay, the system achieves accurate CP removal for devices at various locations within the coverage cell, resolving the contradiction between fixed simplicity and adaptive accuracy.
2Adaptability or versatility
If the CP duration is standardized, then interoperability is ensured, but access latency increases for devices at the edge of the coverage cell
Solution Approach 1:
The patent applies preliminary group delay compensation to the received random access signal before CP removal. By pre-compensating for the propagation delay using the detected group delay value, the system effectively aligns the signal timing, allowing devices at the edge of the coverage cell to experience reduced access latency while maintaining the standardized CP duration for interoperability.
3Device complexity
If CP removal is performed at the antenna port, then processing is simplified, but accuracy is compromised in O-RAN systems with fronthaul delay
Solution Approach 1:
The patent introduces an intermediary group delay compensation step between signal reception and CP removal. The system first measures the group delay, applies compensation to align the signal timing, and then performs CP removal. This intermediary compensation mechanism bridges the gap caused by fronthaul delay in O-RAN systems, enabling accurate CP removal at the antenna port despite the distributed architecture.
Data Source
AI summary
Cyclic prefix (CP) detection and removal in a wireless communications system (WCS) is disclosed. More specifically, embodiments disclosed herein relate to removing a CP(s) from a random-access symbol(s) in an open radio access network (O-RAN) communications system in the WCS. The random-access symbol(s) includes the CP followed by a random-access sequence. As such, the CP must be removed before the random-access sequence can be detected and processed. In this regard, in embodiments disclosed herein, the O-RAN communications system is configured to determine a group delay associated with the random-access symbol(s) to thereby accurately determine a start of the CP in the random-access symbol(s). Accordingly, the O-RAN communications system can detect and remove the CP from the random-access symbol(s) based on the determined start of the CP. As a result, it is possible to preserve integrity of the random-access symbol(s) to thereby reduce random-access latency in the WCS.