NR Open Loop Uplink Power Control via Cell-Specific Reference Signals
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Solution Overview
Problem
The challenge in wireless communication systems is setting the initial uplink transmission power for devices operating in multiple frequency bands, particularly when the uplink and downlink channels are on vastly different frequency bands, as legacy power control methods assume similar power-loss in both channels, which is not valid for LTE-NR coexistence.
Innovation Solution
The method involves estimating the pathloss of the downlink channel in the first frequency band by measuring reference signals, such as CRS, and using this information to set the initial uplink transmission power for the uplink channel, rather than relying on pathloss estimates from the downlink channel of a different frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If legacy power control methods are used to estimate pathloss from downlink channel, then the method is simple and widely applicable, but the power-loss estimation becomes inaccurate when uplink and downlink channels are on vastly different frequency bands
Solution Approach 1:
The patent applies local quality by frequency band-specific pathloss estimation. Instead of using a universal pathloss estimation method, the system estimates pathloss separately for the uplink frequency band and downlink frequency band, recognizing that propagation characteristics differ by frequency. This allows accurate power control for each band while maintaining overall system simplicity.
Solution Approach 2:
The patent segments the power control process into separate components: one for uplink power control and one for downlink power control. Each component operates independently with its own pathloss estimation, allowing legacy methods to be used for downlink while new methods are applied for uplink, thus managing complexity through modular design.
2Reliability
If pathloss estimation is performed for both uplink and downlink channels, then accurate power control is achieved, but the measurement and processing time increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the UE with reference signal information for the uplink frequency band before actual power control is needed. The network node provides necessary parameters in advance, allowing the UE to perform pathloss estimation more efficiently without requiring real-time measurements for both bands, thus reducing processing time while maintaining reliability.
Solution Approach 2:
The patent uses reference signals as an intermediary mechanism. Instead of directly measuring pathloss for both uplink and downlink, the system uses reference signals transmitted in the uplink frequency band as intermediaries to enable indirect pathloss estimation, reducing the time required for accurate power control.
3Measurement precision
If reference signals are transmitted in the uplink frequency band for pathloss estimation, then accurate uplink power control is enabled, but the network node must provide additional information and configuration
Solution Approach 1:
The patent applies universality by making reference signals serve multiple functions: they are used both for downlink power control and as a basis for uplink power control. The same reference signal transmission infrastructure is leveraged to provide pathloss estimation information for uplink, eliminating the need for separate dedicated uplink reference signals and reducing network configuration complexity.
Solution Approach 2:
The patent uses copying by having the network node provide copied or replicated reference signal information to the UE. Instead of requiring the UE to perform complex measurements, the network provides pre-processed pathloss estimation information derived from reference signals, simplifying the UE's task and reducing network configuration requirements.
Data Source
AI summary
The present disclosure relates power control in wireless communications, to methods for open loop power control for setting the initial uplink transmission power for a wireless device capable of operating in multiple frequency bands. The disclosure includes methods for transmitting an uplink signal in an uplink channel of a first frequency band using an initial transmission power based on measurements of reference signals in the first frequency band when the received downlink channel is in a second frequency band not overlapping with the first frequency band. The disclosure also relates to corresponding devices and to a computer program for executing the proposed methods. Further, embodiments relating to a host computer and activities therein, are also provided.