Multi-Carrier Power Control via Code Division Multiplexing
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Solution Overview
Problem
In multi-carrier HSPA systems, existing methods for conveying transmit power control (TPC) commands on the uplink face challenges such as high power consumption and increased peak to average power ratio, leading to coverage loss and inefficient use of hardware resources due to the need for multiple dedicated physical control channels (DPCCHs).
Innovation Solution
The method involves using different pre-determined slot formats and code words to integrate transmit power control commands based on the number of downlink and uplink carriers, allowing for flexible trading of uplink signaling cost with downlink F-DPCH performance, and transmitting TPC commands for multiple downlink F-DPCHs on the same uplink DPCCH, reducing the need for excessive power and hardware resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple DPCCHs are used on the uplink to convey TPC commands for multiple downlink F-DPCHs, then reliable power control for each carrier is achieved, but power consumption increases and uplink peak to average power ratio increases
Solution Approach 1:
The patent combines multiple TPC commands for different downlink carriers into a single uplink DPCCH by using code division multiplexing. Different TPC commands are mapped to different code words that are transmitted on one uplink carrier, thereby merging multiple control channels into one and reducing the number of simultaneous uplink transmissions, which directly reduces power consumption and peak power ratio.
Solution Approach 2:
The single uplink DPCCH is designed to serve multiple downlink carriers simultaneously by carrying multiple TPC commands through code division. This makes the uplink control channel universal, capable of controlling power for multiple carriers without requiring separate dedicated channels for each carrier, thus reducing overall system power consumption.
2Reliability
If multiple DPCCHs are used on the uplink for power control, then complete TPC command transmission is achieved, but uplink peak to average power ratio increases causing coverage loss
Solution Approach 1:
Multiple TPC commands that would normally require separate DPCCHs are merged into a single DPCCH transmission using code division multiplexing. This consolidation reduces the number of simultaneous high-power uplink transmissions, thereby reducing the peak to average power ratio and preventing coverage loss while still maintaining complete TPC command transmission for all downlink carriers.
3Adaptability or versatility
If multiple DPCCHs are deployed for multi-carrier operation, then all carriers can be controlled independently, but hardware resources and channel setup complexity increase
Solution Approach 1:
The patent merges the functionality of multiple DPCCHs into a single DPCCH by using code division multiplexing to carry multiple TPC commands. This reduces the number of physical channels that need to be set up and managed, simplifying hardware resources and channel configuration while maintaining the ability to independently control power for multiple downlink carriers through code word mapping.
Solution Approach 2:
The single uplink DPCCH is designed with multi-functionality to handle power control for multiple downlink carriers simultaneously. By implementing code division multiplexing and defining specific code word mappings for different carrier combinations, the system achieves versatile multi-carrier power control without requiring separate dedicated channels for each carrier, thereby reducing device complexity.
Data Source
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AI summary
The present invention relates to a method and an arrangement for controlling downlink power in a multi-carrier communication network system. The communication network system comprises communication network nodes (15) communicating with a plurality of user equipments (18) on uplink (17) and downlink (16) carriers over a radio interface. Downlink transmit power control commands are sent on at least one uplink control channel to support power control for a multiple of downlink carriers. Each transmit power control command is assigned a pre-determined code word known by said user equipment (18) and said communication network node (15) and/or different pre-determined slot formats, known by said user equipment (18) and said communication network node (15), are used to integrate different number of transmit power control command based on the number of used downlink and uplink carriers.