Soft Handover Message Format Adaptation for WCDMA Version Compatibility
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Solution Overview
Problem
In WCDMA communication systems, soft handoff fails due to compatibility issues between Node Bs using earlier versions and SRNC/DRNC using later versions, leading to incorrect packet transmission and call drops, as they cannot process the unidirectional DCH indicator correctly.
Innovation Solution
Setting the TFS to zero format and deleting the unidirectional DCH indicator in RL setup request information allows Node Bs using earlier versions to process messages as bidirectional, ensuring correct packet transmission and preventing call drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the unidirectional DCH indicator is included in RL setup request messages, then HSDPA service compatibility in later versions is improved, but compatibility with earlier version Node Bs deteriorates
Solution Approach 1:
The patent changes the format of the transport format combination set indicator parameter to encode unidirectional DCH information. By modifying the existing TFS parameter structure and its mapping relationships, the system conveys directional information without adding separate indicator fields, thus maintaining compatibility with earlier version Node Bs while enabling HSDPA services.
Solution Approach 2:
The patent extracts the unidirectional DCH indicator function from a separate indicator field and integrates it into the existing transport format combination set indication. This extraction and integration approach allows the information to be conveyed through the established message structure that earlier version Node Bs can process, while later version Node Bs can interpret the encoded information correctly.
2Manufacturing precision
If the TFS is configured to indicate unidirectional DCH, then packet transmission accuracy is improved, but compatibility with earlier version Node Bs deteriorates
Solution Approach 1:
The patent modifies the TFS parameter encoding to include unidirectional DCH information. By changing the parameter structure and its interpretation rules, the system achieves accurate packet transmission through proper format configuration while maintaining backward compatibility through the use of existing parameter fields.
Solution Approach 2:
The patent makes the TFS parameter serve multiple functions: it indicates transport format combinations for packet transmission accuracy while also encoding unidirectional DCH information for compatibility. This multi-functionality allows a single parameter to address both requirements without creating version-specific message structures.
3Adaptability or versatility
If the unidirectional DCH indicator is deleted for earlier version Node Bs, then compatibility is improved, but HSDPA service functionality deteriorates
Solution Approach 1:
The patent extracts the unidirectional DCH indicator function from a separate field and embeds it within the existing TFS parameter structure. This allows earlier version Node Bs to process the message without recognizing the encoded indicator, while later version Node Bs can decode and utilize the information for proper HSDPA service functionality.
Solution Approach 2:
The patent changes the encoding of the TFS parameter to incorporate unidirectional DCH information. This parameter change enables HSDPA services to function correctly in later versions while maintaining apparent compatibility with earlier versions that process the parameter according to their existing specifications.
Data Source
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AI summary
A method for soft handoff in a communication system includes: when the version of standard that a Node B which is to receive the RL setup request information follows is earlier than the version of the standard that an equipment which is to send the RL setup request information follows, the TFS indicating the invalid direction of DCH in the RL setup request information is set to zero format and the unidirectional DCH indicator in the message is deleted; the new RL setup request information in which TFS is set to zero format is sent to the Node B; an RL is established between the Node B and the UE, and the active set is updated. This invention also discloses an apparatus for soft handoff in a communication system. With this invention, the DRNC or Node B that uses the standard of an earlier version can process the messages sent by the SRNC and/or DRNC that uses the standard of a later version.