Distributed Antenna System Delay Measurement with Switch Compensation
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Solution Overview
Problem
The existing eCPRI measurement procedure in Open Radio Access Network (O-RAN) based fronthaul networks does not account for the transport delays introduced by switches when remote radio units (RRUs) are connected to a remote radio head (RRH) in distributed antenna systems (DAS), making it difficult to accurately measure delays in DAS environments.
Innovation Solution
The method involves transmitting dummy packets of variable size from a distributed unit (DU) to RRUs, determining transport and antenna delays based on delay samples, and adjusting transmission and reception windows using adaptive delay parameters, extending the eCPRI measurement procedure to include these delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the existing eCPRI measurement procedure is used in O-RAN based fronthaul networks, then the measurement process is simple, but it does not account for transport delays introduced by switches when RRUs are connected to RRH in DAS environments
Solution Approach 1:
The patent introduces dummy packets as intermediary elements to measure transport delays through switches in DAS networks. These dummy packets traverse the same path as actual data, allowing the system to measure and compensate for switch-induced delays without modifying the core eCPRI measurement procedure. The dummy packets act as mediators that carry timing information through the complex DAS architecture involving multiple switches and RRUs.
Solution Approach 2:
The patent modifies the existing eCPRI measurement procedure by adding delay measurement parameters specific to DAS configurations. It introduces new parameters such as transport delay measurements for different paths (T12max/T12min for downlink, T34max/T34min for uplink) and integrates these into the existing timing advance calculations, allowing the system to adapt to varying delay conditions in DAS environments.
2Measurement precision
If delay measurements are extended to include all RRUs in DAS simulcast zones, then measurement accuracy improves, but processing time and system overhead increase
Solution Approach 1:
The patent extracts and measures only the critical delay components in DAS networks by using dummy packets to isolate transport delays from other timing variables. It separates the measurement of switch-induced delays from the overall timing advance calculations, allowing the system to process only the essential delay parameters needed for synchronization without analyzing every aspect of the complex DAS signal paths.
Solution Approach 2:
The patent implements partial measurement by focusing on measuring delays to representative RRUs (such as the furthest and nearest RRUs in a simulcast zone) rather than every single RRU. This partial action approach provides sufficient measurement accuracy for DAS synchronization while significantly reducing the processing time and system overhead that would result from measuring all RRUs individually.
Data Source
AI summary
The present disclosure describes techniques for delay measurement in Distributed Antenna Systems (DASs). In an aspect, a method comprises transmitting, by a distributed unit (DU), a plurality of delay measurement requests to a remote radio head (RRH) for uplink delay measurement and downlink delay measurement, receiving, from the RRH, a plurality of delay samples in response to the plurality of dummy packets being transmitted, determining, by the DU, downlink transport delays at least based on the plurality of delay samples and DU timing parameters, determining, by the DU, uplink transport delays at least based on the plurality of delay samples, and transmitting a DU delay profile to the RRH for adjustment a RRH transmission window and a RRH reception window, the DU delay profile comprising the downlink transport delays and the uplink transport delays.