Multi-Carrier F-DPCH Power Control via Flexible TPC Allocation
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Solution Overview
Problem
Conventional multi-carrier HSPA systems face challenges in efficiently and reliably controlling the downlink transmit power of the fractional downlink physical control channel (F-DPCH) due to varying channel conditions across different carriers, especially in soft handover scenarios.
Innovation Solution
Adapting the transmit power control (TPC) command mechanism to support multi-carrier scenarios by defining and transmitting TPC commands on uplink carriers to adjust the downlink power of F-DPCH, with options including separate commands for each downlink carrier or a common command for all, and varying transmission methods based on the number of uplink and downlink carriers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single-carrier TPC command mechanism is used in multi-carrier HSPA systems, then device complexity is reduced and ease of operation is maintained, but downlink power control reliability deteriorates due to varying channel conditions across different carriers
Solution Approach 1:
The patent segments the power control mechanism by introducing separate TPC commands for different downlink carriers. Each TPC command can be independently transmitted on different uplink carriers, allowing carrier-specific power control adjustments that adapt to varying channel conditions on each downlink carrier while maintaining manageable complexity through structured segmentation.
Solution Approach 2:
The patent implements dynamic power control by allowing the number and allocation of TPC commands to be flexible based on the number of uplink and downlink carriers. The system can dynamically adjust whether to use one common TPC command or multiple carrier-specific TPC commands, optimizing reliability according to actual channel conditions and system configuration.
2Measurement precision
If separate TPC commands are defined for each downlink carrier, then downlink power control precision is improved for each carrier, but the number of TPC commands increases beyond the number of uplink carriers available for transmission
Solution Approach 1:
The patent applies universality by allowing a single TPC command to serve multiple downlink carriers when the number of uplink carriers is limited. The same TPC command can be transmitted on multiple uplink carriers and applied to adjust power on multiple downlink carriers, making the power control mechanism universally applicable across different carrier configurations without requiring a separate command for each carrier.
Solution Approach 2:
The patent changes the parameter of TPC command allocation from fixed one-to-one mapping to flexible many-to-many mapping. The system can dynamically adjust the number of TPC commands and their allocation based on the relationship between uplink and downlink carrier counts, transforming the rigid parameter structure into a flexible one that adapts to available resources.
3Reliability
If TPC commands are transmitted on multiple uplink carriers, then power control reliability is improved under frequency selective conditions, but transmission complexity and signaling overhead increase
Solution Approach 1:
The patent uses uplink carriers as intermediaries to transmit TPC commands for downlink power control. By allowing TPC commands to be transmitted on multiple uplink carriers, the system creates redundant transmission paths that improve reliability under frequency selective fading conditions, where the intermediary uplink carriers mediate the control information delivery to ensure successful reception.
Solution Approach 2:
The patent implements beforehand cushioning by transmitting the same or redundant TPC commands on multiple uplink carriers before the actual downlink power control adjustment is needed. This redundant transmission provides a buffer against potential transmission failures on any single uplink carrier, ensuring that power control commands are reliably delivered even when channel conditions are poor.
Data Source
AI summary
A method, User Equipment (UE), and radio base station or NodeB for controlling the downlink transmit power of a Fractional Downlink Physical Control Channel (F-DPCH) in a multi-carrier High-Speed Packet Access (HSPA) system. Single-carrier Transmit Power Control (TPC) commands are modified to support different kinds of multi-carrier scenarios. The UE defines at least one TPC command for adjustment of the transmit power of the F-DPCH of N downlink carriers, the number of TPC commands being equal to or less than N, and transmits the TPC command(s) on at least one of M uplink carriers. The NodeB receives the TPC command(s) and adjusts the transmit power of the F-DPCH of the N downlink carriers based on the received TPC command(s).