Unlicensed Spectrum MBMS Synchronization via LBT
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Solution Overview
Problem
Current technologies do not support efficient multi-cast transmissions, such as Physical Multi-cast Channel (PMCH) transmissions, on unlicensed carriers, which limits the utilization of unlicensed spectrum for Multimedia Broadcast/Multi-cast Services (MBMS) and affects coexistence with other wireless technologies like WiFi.
Innovation Solution
Implementing a Listen-Before-Talk (LBT) procedure for radio access nodes to synchronize multi-cast transmissions by performing LBT on unlicensed carriers and either deferring transmission until other nodes have completed their LBT procedures or broadcasting a preamble signal with cell identity and PMCH transmission parameters to ensure synchronized transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If LBT procedure is performed before each multi-cast transmission, then coexistence with other wireless technologies is improved, but transmission synchronization and reliability deteriorate
Solution Approach 1:
The patent applies preliminary action by having all radio access nodes perform LBT procedure before the scheduled transmission time. This advance preparation allows nodes to assess channel availability in advance, and nodes that complete LBT early can wait for synchronization without needing to perform LBT again at the moment of transmission, thus maintaining synchronization while ensuring coexistence.
Solution Approach 2:
The patent introduces a synchronization mechanism as an intermediary that coordinates between individual LBT completions and the actual transmission. This intermediary ensures that even though nodes complete LBT at different times, all transmissions occur at a synchronized moment, resolving the contradiction between individual channel access and collective synchronization.
2Adaptability or versatility
If LBT procedure is performed by all radio access nodes before transmission, then spectrum sharing fairness is improved, but transmission time and productivity worsen
Solution Approach 1:
By performing LBT procedure in advance before the scheduled transmission time, nodes can complete their channel assessment earlier rather than at the moment of transmission. This preliminary action allows for better time management and reduces the overall transmission time while ensuring fair spectrum sharing through proper LBT execution.
3Productivity
If unlicensed spectrum is used for MBMS transmissions, then spectrum utilization is improved, but transmission reliability and coexistence requirements worsen
Solution Approach 1:
The patent introduces a synchronization mechanism as an intermediary that coordinates between individual LBT completions and the actual transmission. This intermediary ensures that even though nodes complete LBT at different times, all transmissions occur at a synchronized moment, resolving the contradiction between individual channel access and collective synchronization.
Data Source
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AI summary
Systems and methods are disclosed that enable multi-cast transmissions (e.g., Physical Multi-cast Channel (PMCH) transmissions) on carriers in unlicensed spectrum. In some embodiments, a method of operation of a radio access node to enable multi-cast transmissions on a carrier in an unlicensed spectrum comprises performing a Listen-Before-Talk (LBT) procedure on a carrier in an unlicensed spectrum based on random backoff and a contention window size prior to a multi-cast transmission. The method further comprises transmitting the multi-cast transmission if the LBT procedure determines that the carrier in the unlicensed spectrum is Idle. In this manner, multi-cast transmissions on the carrier in the unlicensed spectrum are enabled.