HS-DPCCH Feedback Signaling for Multi-Cell Handover Reliability
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Solution Overview
Problem
High-speed downlink packet access (HSDPA) systems face challenges in maintaining continuous cellular communication during handovers due to delays in RRC handover message transmission, leading to increased dropped calls and suboptimal performance from UEs designed to receive data from multiple cells, as existing feedback signaling is limited to a single cell.
Innovation Solution
Implementing feedback signaling using a high-speed dedicated physical control channel (HS-DPCCH) to enable simultaneous transmission of ACK/NACK signals to both the source and target cells, allowing for dual or multi-cell operation and improving handover reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RRC handover message is transmitted via the source Node B over the high speed shared channel, then the handover procedure can be executed, but transmission delay occurs leading to handover failure and increased dropped calls
Solution Approach 1:
The patent introduces a new feedback signaling mechanism as an intermediary channel between the UE and the network during handover. This feedback channel allows the UE to confirm receipt of the handover command and provides acknowledgment information, enabling the network to verify successful handover execution and reduce handover failures without increasing transmission delay.
2Productivity
If feedback signaling is limited to a single cell, then the existing system structure is maintained, but UEs designed for multi-cell reception perform suboptimally and handover reliability decreases
Solution Approach 1:
The patent implements a universal feedback signaling mechanism that can operate in both single-cell and multi-cell scenarios. The feedback channel is designed to be cell-agnostic, allowing UEs to send acknowledgment and channel quality information regardless of whether they are in handover mode or normal operation, thereby enabling multi-cell UEs to perform optimally while maintaining compatibility with existing single-cell systems.
Solution Approach 2:
The feedback signaling mechanism is made dynamic by allowing the UE to adaptively adjust feedback content and timing based on whether it is in a handover scenario or normal operation. During handover, the feedback includes specific handover confirmation information; during normal operation, it includes standard channel quality indicators, enabling optimal performance across different operational states.
3Device complexity
If the UE monitors the high speed shared channel in a single serving cell, then the system operation is simplified, but service interruption occurs during handover transitions
Solution Approach 1:
The patent implements a feedback mechanism where the UE sends acknowledgment information back to the network regarding handover command reception and execution status. This feedback allows the network to detect handover failures early and initiate corrective actions, thereby reducing service interruption time during handover transitions while maintaining relatively simple UE monitoring requirements.
Data Source
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AI summary
A method and apparatus of feedback signaling using a high speed dedicated physical control channel (HS-DPCCH) includes transmitting to a first cell a first uplink feedback signal that includes channel quality information (CQI) associated with the first cell. A second uplink feedback signal that includes CQI information associated with a second cell is transmitted to the second cell.