Carrier Selection in LTE-A Carrier Aggregation
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Solution Overview
Problem
In LTE-A systems, the peak rates exceed the 20 MHz bandwidth limit, leading to congestion in the primary serving cell, which affects the performance of CA UE in terms of access success rate, call drop rate, and user rate due to heavy load.
Innovation Solution
A carrier selection method where the base station obtains radio channel information from CA UE, comparing the PCC and SCC, and sends an RRC reconfiguration message to switch to the SCC as the new PCC when its channel information is greater, thereby improving performance by selecting a better carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the primary serving cell carries all control information for both PCC and SCC, then the CA UE can be served, but the primary serving cell becomes congested and performance deteriorates
Solution Approach 1:
The patent introduces a secondary serving cell as an intermediary to handle control information transmission. Instead of the primary serving cell carrying all control information alone, the secondary serving cell assists by carrying some control information (such as uplink ACK/NACK, CSI, and SR), thereby distributing the load and reducing congestion on the primary serving cell while maintaining service capability.
2Reliability
If the primary serving cell carries all control information, then service can be maintained, but congestion occurs and user rate decreases
Solution Approach 1:
The patent segments the control information transmission function between two serving cells. The primary serving cell continues to carry essential control information, while the secondary serving cell is assigned to carry specific control information (uplink ACK/NACK, CSI, SR). This segmentation distributes the transmission load, reducing congestion on the primary cell and improving overall user rate while maintaining service continuity.
3Productivity
If multiple carriers are aggregated to increase bandwidth, then peak rate improves, but the primary serving cell load increases and causes congestion
Solution Approach 1:
The patent introduces the secondary serving cell as a mediator to handle specific control information tasks. This allows the system to aggregate multiple carriers to increase peak rate while the secondary serving cell absorbs part of the control information handling complexity, preventing the primary serving cell from becoming overloaded and congested.
Data Source
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AI summary
A carrier selection method and device in a carrier aggregation technology are disclosed, so as to improve performance of CA UE. In embodiments of the present invention, a base station obtains radio channel information of a PCC and radio channel information of an SCC that are reported by CA UE; and when the radio channel information of the SCC is greater than the radio channel information of the PCC, the base station sends, to the CA UE, an RRC reconfiguration message including information about the SCC, so that the CA UE uses the SCC as a new PCC.