PRACH Configuration Parameter Indication in LTE TDD Systems
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Solution Overview
Problem
In the LTE TDD system, efficiently indicating physical random access channel (PRACH) configuration parameters to terminals with minimal air interface resources is a challenge, as existing methods do not effectively manage system loads and reduce inter-cell interference.
Innovation Solution
A method for configuring and indicating PRACH parameters in a TDD system, where the same PRACH configuration set is stored in both the base station and terminal, allowing the terminal to compute or inquire configuration parameters, including density, format, and version number, to optimize resource usage and distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional PRACH configuration indication methods are used in LTE TDD system, then the base station can provide PRACH configuration parameters to terminals, but the air interface resources are wasted and the processing load on base station is high
Solution Approach 1:
The patent pre-calculates and pre-configures multiple PRACH configuration sets (including density, format, and version number parameters) at the base station before actual random access occurs. These configuration sets are stored in advance and selected based on system load conditions, avoiding the need for complex real-time calculations and reducing air interface signaling overhead.
Solution Approach 2:
The patent introduces version numbers as an additional parameter to differentiate PRACH configurations with the same format and density but different time-frequency locations. By changing the version number parameter, the system can indicate different PRACH configurations efficiently, reducing the information bits required for indication while providing sufficient configuration options for multiple terminals.
2Object-affected harmful factors
If multiple PRACH configurations with same format and density but different versions are used, then inter-cell interference is reduced through time domain scattering, but the configuration management becomes more complex
Solution Approach 1:
The patent segments the PRACH configuration space by introducing version numbers that differentiate configurations with the same format and density. Each version corresponds to a specific time-frequency location pattern, allowing the system to scatter PRACH transmissions across different time resources for different cells, thereby reducing inter-cell interference while maintaining manageable configuration structures.
Solution Approach 2:
The patent adds the version number dimension to the PRACH configuration parameters (format, density, version). This additional dimension allows the system to differentiate configurations that would otherwise be identical, enabling time domain scattering of PRACHs across different cells without increasing the complexity of the base configuration parameters themselves.
3Measurement precision
If PRACH configuration parameters are indicated with detailed information, then terminals can accurately identify PRACH resources, but more air interface resources are consumed
Solution Approach 1:
The patent changes the indication approach by using version numbers instead of directly indicating full PRACH configuration parameters. The version number serves as a compact identifier that terminals can use to look up complete configuration information from pre-stored configuration sets, thereby maintaining accurate PRACH resource identification while minimizing air interface resource consumption.
Solution Approach 2:
The patent creates pre-configured PRACH configuration sets that are stored in both the base station and terminals. Instead of transmitting complete configuration parameters over the air interface, the system transmits compact version numbers that act as references to these pre-stored configuration copies, significantly reducing air interface resource consumption while maintaining full configuration accuracy.
Data Source
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Figure 3
AI summary
The present invention discloses a method for configuring and indicating physical random access channel parameter in a time division duplex system, suitable for the long term evolution, system, including: the same PRACH configuration set is stored in a base station and a terminal respectively; when performing a PRACH configuration, the terminal inquires the PRACH configuration set according to configuration information to obtain a configuration parameter, and/or the terminal computes to obtain the configuration parameter according to a system parameter. Set by using the method provided by the present invention, the PRACH configuration set can provide enough density types for various PRACH formats in order to meet the requirements of different system loads, and meanwhile can provide enough version types for each combination of format and density, decrease the processing load of the base station, and reduce the inter-cell interference.