Downlink Data Of Small Data Transmission Procedure

What is this patent about?

’109 is related to the field of mobile communication networks , specifically addressing scenarios involving small data transmissions (SDT) and mobility management in 5G New Radio (NR) systems. The background involves User Equipments (UEs) transitioning between base stations while attempting to transmit small amounts of data, leading to inefficiencies in context transfer and data routing.

The underlying idea behind ’109 is to optimize the handling of small data transmissions when a UE moves from one base station (first base station) to another (second base station) without fully relocating the UE's context. The key inventive insight is to allow the second base station to indicate to the first base station that it should *not* relocate the UE's context, but instead provide information about the data radio bearer (DRB) configured for the SDT procedure. This enables the first base station to forward downlink data directly to the second base station for delivery to the UE.

The claims of ’109 focus on a method performed by the second base station, which involves sending an indication of a DRB configured for SDT to the UE, receiving a context request from the first base station, and responding with a message indicating *not* to relocate the context, but including the DRB information. The claims further cover receiving downlink data forwarding information from the first base station and, based on this information, sending the downlink data to the first base station.

In practice, the second base station acts as a temporary conduit for downlink data, leveraging the existing DRB configuration at the first base station. The first base station, upon receiving the downlink data forwarding information (e.g., a tunnel endpoint), forwards the downlink data directly to the second base station, which then transmits it to the UE. This avoids the overhead of a full context transfer and path switch, which is particularly beneficial for small data transmissions where the signaling overhead can outweigh the data itself.

This approach differs from prior solutions that typically involve either a full context transfer or a complete RRC connection release and re-establishment. By maintaining the UE's context at the first base station and utilizing data forwarding, ’109 provides a more efficient mechanism for handling small data transmissions during mobility, reducing latency and signaling overhead, and improving the overall network performance. The use of the DRB indication allows the second base station to correctly map the forwarded downlink data to the appropriate radio resources for the UE.