User Terminal BSR Table Extension for Carrier Aggregation

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Solution Overview

Problem

In LTE Rel. 10 to 12, the number of component carriers (CCs) that can be configured per user terminal is limited to five, making it difficult for radio base stations to adequately control uplink radio resource allocation, which hinders the achievement of optimal throughput enhancement in carrier aggregation scenarios with six or more CCs.

Innovation Solution

A user terminal is equipped with a data buffering section that generates and transmits Buffer Status Reports (BSRs) using new BSR tables, allowing for adequate communication when more than five CCs are configured, by increasing the buffer size representation and granularity, enabling better resource allocation by radio base stations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the number of component carriers is increased to six or more, then the throughput and bandwidth are improved, but the existing BSR tables cannot adequately represent the buffer size

Engineering Contradiction:
ImprovethroughputVSAvoidbuffer size representation
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent changes the parameters of the BSR table by extending the buffer size values to support larger capacities. Specifically, it introduces a new BSR table with extended buffer size values (e.g., 0x00 to 0x3F range) that can accommodate the increased buffer requirements when six or more component carriers are configured, thereby resolving the information representation limitation.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If the number of component carriers is increased to six or more, then the bandwidth is expanded, but the radio base station cannot adequately control uplink radio resource allocation

Engineering Contradiction:
ImprovebandwidthVSAvoidresource allocation control
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The patent implements feedback mechanism through enhanced BSR reporting. The user terminal continuously reports buffer status using the extended BSR table format to the radio base station, providing accurate feedback about the buffer state across multiple component carriers. This enables the base station to make informed resource allocation decisions and maintain adequate control even when managing six or more component carriers.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3297355B1User terminal and method
Publication Date: 2023.07.05 NTT DOCOMO INC
  • EP3297355B1 patent drawingFigure 1A~1B
  • EP3297355B1 patent drawingFigure 2
  • EP3297355B1 patent drawingFigure 3

AI summary

The present invention is designed so that communication can be carries out adequately even when the number of component carriers that can be configured in a user terminal is expanded from that in existing systems. According to one aspect of the present invention, a user terminal communicates by using a plurality of component carriers (CCs), and has a data buffering section that stores uplink data, a generating section that generates a BSR MAC CE (Medium Access Control Control Element), in which a given index corresponding to a buffer size is included, based on BSR (Buffer Status Report) tables, in which amounts of uplink data that is stored (buffer sizes) and indices are associated, and a transmission section that transmits the BSR MAC CE, and one of the BSR tables is a first BSR table for use when more than five CCs are configured in the user terminal.