PDCP Transparent Mode for NB-IoT Control Plane Efficiency
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Solution Overview
Problem
In 3GPP LTE systems, the PDCP layer adds unnecessary overhead for small data transfers over the control plane in NB-IoT and eMTC, which can be redundant due to NAS security, leading to inefficiencies in data transmission.
Innovation Solution
Implementing a PDCP transparent mode (PDCP-TM) that bypasses the PDCP layer for signaling radio bearers, using a logical channel identifier to indicate the mode and allowing data to be transmitted without the 5-byte overhead, enabling efficient data transfer over the control plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the PDCP layer is used for small data transfers over the control plane, then security protection is provided, but overhead increases by 5 bytes
Solution Approach 1:
The patent extracts the PDCP layer processing for specific bearers (SRB0 and SRB1) when data is carried over the control plane, removing the 5-byte overhead while maintaining security through NAS security. The PDCP layer is completely bypassed for these bearers, taking out the unnecessary processing step.
Solution Approach 2:
The patent introduces dynamic configuration of PDCP transparent mode through RRC connection setup complete message, allowing the system to adaptively switch between PDCP processing and transparent mode based on whether data is carried over control plane or user plane, optimizing the balance between security and overhead.
2Reliability
If the PDCP layer processes all data, then security and reliability are maintained, but data transmission efficiency decreases
Solution Approach 1:
The patent applies different quality of processing to different bearers: PDCP processing is applied only when necessary (user plane data), while control plane data on SRB0 and SRB1 uses transparent mode without PDCP processing. This local differentiation optimizes overall system efficiency while maintaining security where needed.
Solution Approach 2:
The patent changes the operational parameter of the PDCP layer from always-processing to conditionally-processing based on the bearer type and data plane configuration. The logical channel ID parameter is used to indicate whether PDCP transparent mode should be applied, dynamically adjusting the processing behavior.
3Quantity of substance
If PDCP transparent mode is implemented, then overhead is reduced, but compatibility with existing protocols must be maintained
Solution Approach 1:
The patent introduces the logical channel ID as an intermediary indicator in the RRC connection setup complete message to signal to the network whether PDCP transparent mode is being used. This intermediary mechanism enables the new transparent mode to coexist with existing protocols without breaking compatibility, as the network can properly interpret and handle the different modes.
Data Source
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AI summary
Technology for a narrowband Internet of Things (NB-IoT) user equipment (UE) operable to establish a radio resource control (RRC) connection with an eNodeB is disclosed. The NB-IoT UE can select a logical channel identifier (ID) for inclusion in an RRC connection setup complete message. The logical channel ID can indicate no packet data convergence protocol (PDCP) layer is used at the NB-IoT UE for a signaling radio bearer 1 bis (SRB1bis) that carries the RRC connection setup complete message. The NB-IoT UE can process the RRC connection setup complete message for transmission on the SRB1bis to the eNodeB. The RRC connection setup complete message can include the logical channel ID.