Timing Data Packet Transit Delay Calculation
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Solution Overview
Problem
In 3GPP communication systems, particularly in MBMS, determining the transit time for multicast FACH Frame Protocol messages over IP multicast links is challenging, especially in asymmetric links, leading to latency and increased buffer requirements at Node Bs, which does not scale well for large numbers of Node Bs and complicates the synchronization process.
Innovation Solution
A communication network element that transmits timing data packets over both unidirectional and bidirectional links, allowing signal processing logic to calculate transit delays and schedule transmissions accurately, minimizing latency and buffer capacity by determining the worst-case transmit delay and adjusting frame advance accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If timing is determined using only unidirectional multicast links, then bandwidth is minimized, but transit delay cannot be accurately calculated in asymmetric links
Solution Approach 1:
The patent introduces a bidirectional link as an intermediary measurement channel. Timing data packets are sent over the unidirectional multicast link for actual data transmission, while a separate bidirectional link is used solely for measuring transit delay through round-trip time measurements. This mediator approach allows accurate delay calculation without increasing the bandwidth of the data-carrying multicast link.
2Measurement precision
If timing data packets are sent over bidirectional links only, then transit delay can be calculated, but bandwidth efficiency is reduced
Solution Approach 1:
The patent segments the communication function into two separate channels: a unidirectional multicast link for efficient data distribution and a bidirectional link for timing measurement. This segmentation allows each link to be optimized for its specific purpose - the multicast link minimizes bandwidth usage for data, while the bidirectional link provides accurate timing information without competing for data transmission resources.
3Ease of operation
If frame advance is not adjusted for worst-case delay, then transmission scheduling is simpler, but latency increases
Solution Approach 1:
The patent calculates the worst-case transit delay in advance and uses this information to determine an appropriate frame advance value. By performing this calculation beforehand, the system can schedule transmissions optimally without adding complexity to the real-time scheduling operation. The frame advance is set to compensate for the maximum expected delay, ensuring timely delivery while maintaining simple scheduling logic.
Data Source
AI summary
A communication network element (536) comprises a transmitter (535) for transmitting at least one timing data packet to at least one further network element (524) over both a first communication link and a second communication link and a receiver (537) for receiving two timing data packets from the at least one further network element (524) over the second communication link. The communication network element (536) further comprises signal processing logic (538) operably coupled to the transmitter and receiver and arranged to calculate a transit delay of the at least one timing data packet over the first communication link based on the received two timing data packets from the at least one further network element (524) over the second communication link, wherein the signal processing logic (538) is capable of scheduling at least one transmission across the first communication link to the at least one further network element (524) in response thereto.