RLC Status Reporting for Light Connections in V2X
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Solution Overview
Problem
Next generation mobile communication systems face challenges in supporting multiple access with a single sequence number (SN) and efficiently processing expired packets, particularly in identifying light connections and ensuring successful handovers without random access procedures, especially for LTE terminals supporting vehicle-to-everything (V2X) communications.
Innovation Solution
A gap encoding method and radio link control (RLC) status reporting mechanism are introduced to support multiple accesses with one SN, process expired packets differently based on their extent of expiration, and enable terminals to identify and establish light connections by broadcasting system information, as well as determine successful handovers without random access procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If only one sequence number (SN) is used, then overhead is reduced, but it becomes impossible to support multiple access
Solution Approach 1:
The patent segments the handling of multiple accesses by introducing a distinction between light connection and normal connection modes. Each mode uses its own SN space, allowing one SN to be used per connection type without conflict. This segmentation enables multiple access support while keeping each SN space simple and overhead low.
Solution Approach 2:
The patent introduces an intermediary mechanism (the light connection mode with its own SN) that mediates between the need for low overhead (single SN) and the need for multiple access support. The light connection acts as an intermediary layer that handles simple access scenarios with minimal overhead while normal connections handle complex scenarios.
2Reliability
If a terminal reconnects to a base station that does not support light connection, then connection establishment fails, but identifying supporting base stations increases system complexity
Solution Approach 1:
The patent enables terminals to self-identify suitable base stations for light connection by broadcasting system information that indicates light connection support capability. Terminals can autonomously select base stations that support light connection based on this information, eliminating the need for complex centralized identification mechanisms.
Solution Approach 2:
The patent implements preliminary action by having base stations broadcast their light connection support capability in system information before terminals attempt connection. This allows terminals to pre-screen and select compatible base stations, preventing connection establishment failures before they occur.
3Loss of substance
If light connection is used, then overhead is reduced and connection establishment is simplified, but packet loss handling becomes more challenging
Solution Approach 1:
The patent segments packet loss handling into two distinct paths: light connection mode with simplified handling for basic scenarios, and normal connection mode with comprehensive RLC status reporting for scenarios requiring robust packet loss handling. This segmentation allows the system to use simple overhead-efficient methods when sufficient while maintaining reliability options when needed.
Data Source
AI summary
Methods and apparatuses are provided in a wireless communication system. A radio link control (RLC) protocol data unit (PDU) is obtained from a lower layer. A status PDU is generated based on the RLC PDU. The status PDU includes a first field indicating a sequence number (SN) of an RLC data unit identified as lost, a second field indicating a number of consecutively lost RLC data units starting from and including the SN, and a third field indicating whether the second field follows the first first field. The status PDU is delivered to the lower layer.