Gain Adjustment for Uplink Noise Suppression in Distributed Systems
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Solution Overview
Problem
In indoor distributed UMTS systems, the co-cell solution increases uplink background noise, leading to a reduced signal-to-noise ratio and lower success rates for user terminal access, especially when multiple remote radio units are involved in signal combination.
Innovation Solution
A gain adjustment device determines a carrier-level weighting factor based on the uplink user power of remote coverage units and adjusts the carrier-level uplink receive gain to reduce uplink background noise by decreasing the power of noise signals before combination, thereby improving the signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple remote radio units are cascaded for co-cell coverage, then coverage radius is increased and handover is reduced, but uplink background noise increases greatly after combination
Solution Approach 1:
The patent introduces a new parameter (weighting factor) to control the combination process. Instead of directly adding uplink signals from multiple remote radio units, each unit's signal is weighted according to its uplink user power level. This parameter change transforms the combination operation from simple addition to weighted summation, thereby controlling noise accumulation while maintaining coverage expansion benefits
2Device complexity
If direct addition of carriers is used for combination, then device complexity is reduced, but signal-to-noise ratio deteriorates due to noise accumulation
Solution Approach 1:
The patent performs preliminary measurement of uplink user power at each remote radio unit before the combination process. Based on these pre-measured values, weighting factors are calculated and applied to each unit's signal. This preliminary action ensures that the combination process, while slightly more complex than direct addition, achieves optimal signal-to-noise ratio by preventing noise accumulation from units with low or no active users
3Productivity
If cascading of multiple levels of remote radio units is used, then carrier utilization is improved, but uplink background noise increases severely reducing access success rate
Solution Approach 1:
The patent applies different weighting factors to different remote radio units based on their local conditions (uplink user power). Each unit contributes to the combined signal according to its actual activity level, with units having active users contributing more and units without users contributing minimally. This local quality approach maintains high carrier utilization across the cascaded system while ensuring that noise from inactive units does not severely degrade access success rate
Data Source
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AI summary
Embodiments of the present invention provide a method for suppressing uplink background noise in an indoor distributed system, a device, and a system, including: acquiring, by a gain adjustment device, carrier-level uplink user power of a remote coverage unit in a co-cell and carrier-level uplink user power of the rest of remote coverage units in the co-cell; determining, by the gain adjustment device, a carrier-level weighting factor of the remote coverage unit according to the carrier-level uplink user power of the remote coverage unit and the carrier-level uplink user power of the rest of remote coverage units in the co-cell; and adjusting, by the gain adjustment device, a carrier-level uplink receive gain of the remote coverage unit according to the carrier-level weighting factor of the remote coverage unit, where the carrier-level uplink receive gain of the remote coverage unit is less than 0. Because the carrier-level uplink receive gain is less than 0, power of uplink background noise after combination can be reduced, thereby achieving an objective of reducing uplink background noise that exists after combination.