Delay Compensation for Base Station and Remote RF Units
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Solution Overview
Problem
Current methods for delay time computation and compensation between a Base Station (BS) and remote Radio Frequency (RF) units in broadband wireless access systems are theoretical and difficult to implement practically, especially in determining the cable delay time, which varies with installation environments and cable types, affecting communication quality.
Innovation Solution
A method and apparatus for determining process and cable delay times using a reference cable with negligible delay, allowing for synchronization between BS and remote RF units, including a signal delay computation unit and pulse difference counters to calculate delay times for accurate traffic data output timing and internal buffer synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a theoretical delay time computation method is used as defined in CPRI specification, then delay time can be computed in principle, but it is very difficult to select and determine a point of computation in the practical system and requires multiple computation blocks
Solution Approach 1:
The patent extracts the delay time measurement function from complex theoretical computation and implements it through a dedicated measurement module that directly measures delay time using synchronization signals, eliminating the need for multiple computation blocks while maintaining measurement precision
Solution Approach 2:
The patent introduces a measurement module as an intermediary component that uses synchronization signals as a mediator to indirectly determine delay time, avoiding direct complex computation and reducing the number of computation blocks required
2Reliability
If cable delay time is not correctly compensated, then system implementation is simpler, but communication quality deteriorates due to timing synchronization issues between BS and remote RF units
Solution Approach 1:
The system performs self-measurement of cable delay time using the measurement module and synchronization signals, automatically determining the delay without external intervention or complex compensation mechanisms, thereby maintaining communication quality while avoiding excessive system complexity
Solution Approach 2:
The patent implements a feedback mechanism where the measurement module continuously monitors delay time using synchronization signals and adjusts timing compensation accordingly, ensuring communication quality is maintained while keeping the compensation mechanism relatively simple
3Adaptability or versatility
If multiple remote RF units are cascaded, then system coverage is extended, but delay time synchronization becomes more difficult to manage
Solution Approach 1:
The measurement module is designed with universal functionality that can measure delay time for any number of cascaded remote RF units using the same synchronization signal-based approach, allowing system coverage extension without proportionally increasing synchronization management complexity
Solution Approach 2:
The patent segments the delay measurement function into individual measurement modules that can be independently applied to each remote RF unit in the cascade, allowing each unit to be managed separately while maintaining overall system synchronization
Data Source
AI summary
An apparatus and method for delay time computation and delay compensation between a Base Station (BS) and a remote Radio Frequency (RF) unit in a broadband wireless access system are provided. In a method of operating an apparatus for determining a delay time to compensate for delay between a BS modem card and a remote RF unit in a wireless access system, the method includes determining a process delay time required when traffic data is output from the BS modem card to an antenna of the remote RF unit in a state where a reference cable having a length short enough to neglect a cable delay time is connected between the BS modem card and the remote RF unit, determining a cable delay time required when a sync pulse signal is transmitted through a cable used in actual system operation between the BS modem card and the remote RF unit, and determining a time for outputting traffic data at an earlier time from a modem included in the BS modem card by using the determined process delay time and cable delay time.