PRACH Frequency Offset Adjustment for Interference Avoidance
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Solution Overview
Problem
The channel frequency domain position of the Physical Random Access Channel (PRACH) in LTE systems cannot be adaptively adjusted to the current communication environment, leading to reduced access success rates due to noise and interference.
Innovation Solution
A method and device that determine the current frequency domain position of the PRACH, obtain Interference Over Thermal (IOT) values of Physical Resource Blocks, compare these values with a detection threshold, and adjust the channel frequency domain offset if overlapping interference is detected, using a preset adjustment rule to determine an adjusted offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the channel frequency domain offset of PRACH is configured manually or by importing an initialization file before cell deployment, then the configuration is simple and quick, but the channel frequency domain position cannot be adaptively adjusted to the current communication environment, leading to reduced access success rates when noise or interference is high
Solution Approach 1:
The patent implements dynamic adjustment of the PRACH channel frequency domain offset by continuously monitoring the Interference Over Thermal (IOT) values and adaptively changing the offset parameter. The base station dynamically selects from multiple pre-configured offset values based on current interference conditions, transforming a static configuration into a dynamic adaptive system that responds to changing communication environments.
Solution Approach 2:
The system performs self-configuration by automatically monitoring IOT values and adjusting the PRACH frequency domain offset without requiring manual intervention. The base station autonomously determines when adjustment is needed by comparing IOT values against thresholds and automatically selects appropriate offset values, enabling the system to self-optimize for current interference conditions.
2Reliability
If the power of interference or noise is higher than the power of useful signal in the frequency band, then the base station cannot detect and decrypt the preamble, but increasing transmission power to overcome interference may cause more interference to other channels
Solution Approach 1:
The patent extracts the PRACH channel from the interfered frequency domain position and relocates it to a cleaner frequency position by adjusting the frequency domain offset. Instead of trying to overcome interference through power increase, the solution separates the PRACH channel from the harmful interference environment by selecting an alternative frequency resource where IOT values are acceptable.
Solution Approach 2:
The frequency domain offset acts as an intermediary parameter that mediates between the PRACH channel and the interference environment. By adjusting this offset parameter, the system indirectly relocates the PRACH channel to avoid high interference areas, providing a controlled mechanism to navigate around interference without direct confrontation through power increase.
3Adaptability or versatility
If the channel frequency domain position of PRACH is fixed before cell deployment, then the configuration process is simple, but the position cannot be adjusted to avoid frequency bands with high noise floor or strong interference busting
Solution Approach 1:
The patent prepares multiple pre-configured frequency domain offset values in advance during cell setup. These pre-configured offsets are stored and ready for immediate selection based on current interference conditions. This preliminary preparation enables rapid adaptation without requiring complex real-time calculations or lengthy reconfiguration processes.
Data Source
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AI summary
Provided is a method for adjusting channel frequency domain offset of a physical random access channel (PRACH), comprising: determining the current frequency domain location of a PRACH; obtaining interference over thermal (IOT) values of physical resource blocks (PRB) of all uplink subframes; comparing the IOT values of all the PRBs of the uplink subframes with an IOT detection threshold to determine from all the PRBs of the uplink subframes a plurality of PRBs with the IOT values above the IOT detection threshold; judging whether the plurality of PRBs with IOT values above the IOT detection threshold overlap with the current frequency domain location of the PRACH; if yes, then adjusting the channel frequency domain offset of the current frequency domain location of the PRACH based on a predetermined adjustment rule to determine the adjusted channel frequency domain offset. If the system has strong IOT or strong burst interference, then the channel location of the PRACH can be adjusted automatically to ensure that a base station can correctly detect and parse a preamble carried by the PRACH, thus ensuring successful access of a UE.