RTP Packet Synchronization for LTE Group Communications
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Solution Overview
Problem
In LTE group communications systems, the transition between unicast and multicast transmission modes leads to discontinuous reception of RTP packets due to mismatched synchronization source information, causing invalid packet identification and discard by user equipment.
Innovation Solution
The GCS AS or BM-SC provides synchronization source information of both entities to the UE, using RTP packet sequence number and timestamp references, ensuring the UE saves both sets of information in its trust list for continuous packet reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the transmission mode is switched between unicast and multicast, then the system can adapt to different coverage conditions, but the UE may discard RTP packets due to mismatched synchronization source information
Solution Approach 1:
The patent applies preliminary action by having the UE acquire and store synchronization source information from both unicast (GCS AS) and multicast (BM-SC) sources before mode switching occurs. The UE proactively builds a trust list containing multiple synchronization source identifiers, so when transmission mode switches, the UE already has the necessary synchronization information ready, preventing packet discard and ensuring continuous reception.
2Device complexity
If the UE stores only the current transmission mode's synchronization source information, then the trust list remains simple, but packet reception becomes discontinuous during mode switching
Solution Approach 1:
The patent applies universality by designing the trust list to serve multiple functions: it stores synchronization source information for both unicast and multicast modes, allowing the same data structure to support both transmission modes. The UE maintains a unified trust list that can validate packets from either GCS AS or BM-SC, eliminating the need for separate trust lists for each mode and ensuring continuous reception regardless of mode transitions.
3Productivity
If the GCS AS sends RTP packets in multicast mode with BM-SC synchronization source information, then multicast efficiency is achieved, but UE in unicast mode cannot validate these packets
Solution Approach 1:
The patent applies the intermediary principle by introducing the trust list as a mediator between the transmission system and packet validation. The trust list acts as a reference database that contains synchronization source information from both unicast and multicast sources. When the UE receives packets from either mode, it validates them against this intermediary trust list, allowing efficient multicast transmission while ensuring reliable packet validation for both unicast and multicast modes.
Data Source
AI summary
Embodiments of the present disclosure provide an RTP packet transmission method and apparatus. A GCS AS or a BM-SC provides synchronization source information of the GCS AS and synchronization source information of the BM-SC for UE, so that the UE can continuously receive RTP packets. On one hand, the GCS AS (or the BM-SC) may provide the synchronization source information of the GCS AS (or the synchronization source information of the BM-SC) for the UE by sending an RTP packet. On the other hand, the GCS AS (or the BM-SC) further provides the synchronization source information of the BM-SC (or the synchronization source information of the GCS AS) for the UE. Therefore, when being in a unicast (multicast) transmission mode, the UE can obtain both of the synchronization source information of the GCS AS and the synchronization source information of the BM-SC.