Logical RLC and MAC PDU Creation in LTE Protocol Stacks
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Solution Overview
Problem
The existing LTE L-2 protocol stack's efficiency is hindered by repeated data movement across sub-layers, leading to increased CPU effort and limited PDU size, which restricts the system's throughput and feature utilization.
Innovation Solution
A method for creating logical RLC and MAC PDUs that eliminates the need for data copying between sub-layers, using memory addresses to represent PDU structures and attributes, allowing direct transmission without duplicating CPU effort and removing size limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data is copied from transmission buffer of one sub-layer to transmission buffer of another sub-layer, then PDU transmission is enabled across sub-layers, but CPU effort increases and throughput decreases
Solution Approach 1:
The patent applies the copying principle in reverse - instead of physically copying PDU data between transmission buffers of different sub-layers, it creates logical copies through pointer references. The RLC sub-layer creates logical RLC PDU structures that reference PDCP PDU data in its original buffer location, and the MAC sub-layer creates logical MAC PDU structures that reference RLC PDU data. This eliminates repeated physical data copying while maintaining the protocol stack's PDU transmission capability across sub-layers.
2Ease of manufacture
If contiguous buffer allocation is limited in size, then memory management is simplified, but PDU size is restricted and LTE L-2 standard features cannot be fully exploited
Solution Approach 1:
The patent applies segmentation by dividing large PDU data into multiple smaller buffer segments that can be managed within the limited contiguous buffer allocation constraints. The logical PDU structures created by the RLC and MAC sub-layers can reference multiple segmented buffer regions, allowing the system to support large effective PDU sizes while maintaining simple contiguous buffer management for each individual buffer allocation.
3Reliability
If PDU data is physically moved between sub-layer buffers, then data transmission is achieved, but the same CPU effort is duplicated at each subsequent layer
Solution Approach 1:
The patent introduces logical PDU structures as intermediaries between the physical data buffers of different sub-layers. These logical structures act as mediators that reference the actual data locations without requiring physical data movement. The RLC logical PDU structures reference PDCP PDU data, and the MAC logical PDU structures reference RLC PDU data, eliminating the need for repeated physical data movement and reducing CPU cycle consumption.
Data Source
AI summary
A system for creating logical RLC and MAC PDUs in a mobile communication system includes first and second remote network entities that communicate using the LTE link-layer protocol. The first and second remote network entities include first and second layer-2 protocol stacks, respectively. The first layer-2 protocol stack includes first PDCP, RLC and MAC sub-layers and the second layer-2 protocol stack includes second PDCP, RLC and MAC sub-layers. During transmission of data from the first remote network entity to the second remote network entity, the logical RLC and MAC PDUs are created by the first RLC and MAC sub-layers by populating logical RLC and MAC PDU structures.