PDCP Time Field for Accurate Packet Delay Measurement
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Solution Overview
Problem
Current wireless communication systems, such as LTE, face challenges in accurately measuring packet delay in the PDCP entity, particularly in the uplink direction, as the eNB cannot determine when the UE receives a PDCP SDU from an upper layer, leading to inaccurate delay measurements.
Innovation Solution
A method is introduced where the PDCP transmitter includes a time field in the PDCP PDU, allowing the PDCP receiver to calculate the total delay from the time the PDCP SDU is received from the upper layer to the time it is delivered, enabling accurate packet delay calculation across the PDCP entity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the eNB uses conventional delay measurement methods in the downlink, then it can measure packet delay from the network side, but it cannot accurately measure uplink packet delay because it does not know when the UE receives a PDCP SDU from an upper layer
Solution Approach 1:
The PDCP transmitter inserts a time field indicating the time when the PDCP SDU is received from an upper layer into the PDCP PDU before transmission. This preliminary timing record enables the receiver to calculate packet delay without requiring the receiver to track complex timing information, thus improving measurement precision while maintaining system simplicity.
2Measurement precision
If the PDCP transmitter includes a time field in every PDCP PDU, then accurate packet delay calculation is enabled, but the signaling overhead and processing burden increase
Solution Approach 1:
The time field is inserted into PDCP PDUs based on a configured ratio rather than in every PDCP PDU. This partial action approach provides sufficient timing information for delay measurement while reducing the signaling overhead and processing burden compared to inserting the time field in all PDUs.
3Reliability
If the system implements comprehensive packet delay measurement in both downlink and uplink, then QoS verification accuracy improves, but the implementation complexity and resource consumption increase
Solution Approach 1:
The PDCP receiver calculates packet delay using the time field from received PDUs and provides feedback information about delay measurements to the network. This feedback mechanism enables comprehensive QoS verification in both downlink and uplink directions while maintaining manageable implementation complexity through automated delay calculation and reporting.
Data Source
AI summary
A method and device for performing a packet delay calculation in a PDCP entity in a wireless communication system. The method including receiving, by a PDCP transmitter, a PDCP SDU from an upper layer; generating, by the PDCP transmitter, a PDCP data PDU including the PDCP SDU and a time field corresponding to the PDCP SDU, wherein a value of the time field is set to a time when the PDCP SDU received from the upper layer; and transmitting, by the PDCP transmitter, the generated PDCP data PDU to a PDCP receiver.