Primary Carrier Handover in Multi-Carrier Wireless Systems
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Solution Overview
Problem
In wireless communication systems using multiple carriers, handover processes often fail due to varying cell coverage and frequency characteristics, leading to communication interruptions between adjacent cells.
Innovation Solution
A method is introduced that involves switching to a primary carrier for handover between cells, with a base station determining the best carrier based on received signal strength, accessibility, resource availability, and unit cost, and performing intra- and inter-frequency handovers to ensure continuous coverage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple carriers are used in a cell, then data transfer rate and integrated services are improved, but handover between cells fails due to different cell coverage and frequency characteristics
Solution Approach 1:
The patent segments the multi-carrier system into a primary carrier and multiple secondary carriers. The primary carrier is specifically designated for handover operations between cells, while secondary carriers handle data transmission within cells. This segmentation ensures that handover reliability is not compromised by the varying coverage characteristics of multiple carriers.
Solution Approach 2:
The primary carrier acts as an intermediary for handover operations. When a terminal moves between cells, the handover signaling and data forwarding are performed through the primary carrier, which has consistent coverage across cell boundaries. This intermediary role resolves the conflict between using multiple carriers for high data rate and maintaining reliable handover.
2Adaptability or versatility
If each carrier has different cell coverage according to frequency characteristics, then carrier-specific optimization is improved, but contiguous connection between adjacent cells is interrupted
Solution Approach 1:
The primary carrier is designed with multi-functionality, serving both as a data transmission carrier within cells and as a universal handover carrier between cells. This universal role ensures contiguous connection is maintained across cell boundaries while secondary carriers provide carrier-specific optimization for data transmission.
3Speed
If handover is performed without switching to primary carrier, then handover speed is improved, but data forwarding between carriers of serving cell and target cell cannot be performed
Solution Approach 1:
The patent performs preliminary switching to the primary carrier before executing the handover procedure. By pre-establishing the primary carrier as the active carrier, the system ensures that data forwarding paths are already prepared in both the serving and target cells, enabling seamless data forwarding during handover without additional delays.
Data Source
AI summary
When a terminal moves from a serving cell to a target cell, the carrier in use is switched to the primary carrier of the serving cell and then handed over to the target cell. Hereupon, handover is performed by switching the carrier used by the terminal operating with the primary carrier of the serving cell to the primary carrier of the target cell to perform handover. When the terminal has fully entered the target cell, the best carrier is selected from among the carriers available to the target cell, thus allowing the terminal to perform frequency conversion to the best carrier.