Uplink Synchronization via Bandwidth Request Ranging
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Solution Overview
Problem
The existing uplink synchronization methods in wireless portable Internet systems, such as WiBro, face inefficiencies in resource use and delays in data transmission due to the periodic ranging process and bandwidth request ranging, which result in lower power control gains and delayed data transmission timing.
Innovation Solution
A method that calculates uplink synchronization timing by comparing a reference adjustment value with the arrival time of a downlink preamble and requests bandwidth allocation through a bandwidth request ranging process, using a CDMA allocation information element structure that includes transmission and power adjustments to correct synchronization errors and optimize resource allocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If periodic ranging process is used for uplink synchronization, then transmission parameters can be adjusted, but resource use efficiency decreases and data transmission timing is delayed
Solution Approach 1:
The patent changes the synchronization trigger from periodic time-based activation to event-based activation when synchronization error exceeds a threshold. This parameter change in the triggering mechanism allows the system to maintain reliable synchronization only when necessary, thereby improving resource use efficiency by eliminating unnecessary periodic ranging operations.
Solution Approach 2:
The patent replaces continuous periodic ranging with event-driven ranging operations. Instead of performing ranging at fixed periodic intervals regardless of need, the system performs ranging only when synchronization error thresholds are exceeded, converting a periodic action into a conditional event-based action that improves efficiency while maintaining reliability.
2Reliability
If periodic ranging process is used for uplink synchronization, then transmission parameters can be adjusted, but data transmission timing is delayed
Solution Approach 1:
The system performs preliminary synchronization error detection and calculation before triggering ranging operations. By continuously monitoring synchronization error and only initiating ranging when thresholds are exceeded, the system prepares in advance and avoids unnecessary ranging delays, thereby reducing data transmission timing delays while maintaining synchronization reliability.
Solution Approach 2:
The patent introduces dynamic threshold-based triggering for ranging operations instead of static periodic scheduling. The system dynamically determines when ranging is needed based on actual synchronization error conditions, allowing flexible adaptation that prevents unnecessary delays in data transmission while maintaining reliable synchronization.
3Adaptability or versatility
If bandwidth request ranging is used, then bandwidth can be requested, but uplink synchronization errors are not corrected timely
Solution Approach 1:
The patent merges the synchronization error detection function with the bandwidth request ranging process. When uplink traffic is generated and synchronization error exceeds the threshold, the system combines both the synchronization correction and bandwidth request into a single ranging operation, thereby achieving timely synchronization correction while maintaining bandwidth allocation adaptability.
Solution Approach 2:
The patent makes the bandwidth request ranging process universal by enabling it to serve dual purposes: both bandwidth allocation and synchronization error correction. The ranging operation becomes multi-functional, handling both resource allocation and synchronization maintenance, thereby eliminating the limitation of timely synchronization correction while preserving bandwidth adaptability.
4Reliability
If existing ranging methods are used, then transmission parameters can be adjusted, but power control gains are reduced
Solution Approach 1:
The patent changes the triggering parameter for ranging operations from periodic time-based activation to event-based activation using synchronization error thresholds. This parameter change ensures that power control adjustments are performed only when actually needed, maximizing power control gains by eliminating unnecessary transmission parameter adjustments while maintaining reliable transmission control.
Data Source
AI summary
The present invention relates to an uplink synchronization request method in a mobile communication system, a CDMA allocation information element structure thereof, and an apparatus using the same. For this purpose the uplink synchronization request method includes: when uplink traffic is generated, determining whether an uplink synchronization error occurs; when the uplink synchronization error occurs, calculating a timing adjustment value; and transmitting a bandwidth request code including the calculated timing adjustment value to a base station and performing a bandwidth request. According to the present invention, the PSS compares a reference adjustment value and an arrival time of a downlink preamble to calculate uplink synchronization timing and synchronize an uplink of the PSS that requests bandwidth allocation through a bandwidth request ranging process to thereby maximize resource use efficiency in the uplink synchronization.