Portable Terminal OFDM Guard Time Adjustment for Handover
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Solution Overview
Problem
Conventional OFDM communication systems face issues with transient deterioration of signals during handover between base stations, requiring stringent timing synchronization and leading to decreased channel throughput when guard time lengths change.
Innovation Solution
A portable terminal equipped with a switching timing detector and an OFDM signal controller that adjusts the guard time length of OFDM signals during handover, synchronized with base stations to prevent inter-symbol interference and maintain communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the guard time length is extended to prevent inter-symbol interference during handover, then signal reliability is improved, but channel throughput decreases
Solution Approach 1:
The guard time length is made dynamically adjustable based on the communication state. During handover, the guard time is extended to prevent inter-symbol interference, while during normal operation, the guard time is reduced to maintain high throughput. This dynamic adjustment resolves the contradiction between reliability and productivity.
Solution Approach 2:
The system changes the guard time parameter according to the operational state (handover vs. normal operation). By varying this critical parameter based on contextual conditions, the system optimizes both signal reliability during transitions and channel throughput during stable operation.
2Reliability
If the guard time length is changed to accommodate handover, then handover reliability is improved, but timing synchronization requirements become more stringent
Solution Approach 1:
The system prepares for handover by detecting the handover state in advance and proactively adjusting the guard time before actual signal transmission begins. This preliminary action ensures that the guard time is already optimized for handover conditions, reducing the complexity of real-time synchronization adjustments.
Solution Approach 2:
The system continuously monitors the communication state to detect handover conditions and uses this feedback to dynamically adjust the guard time. This closed-loop control ensures that the guard time is always appropriate for the current operational state, simplifying synchronization requirements.
3Reliability
If the guard time length is extended during handover, then inter-symbol interference is reduced, but system overhead increases
Solution Approach 1:
The guard time is dynamically adjusted based on the operational state. During handover, it is extended to suppress inter-symbol interference, while during normal operation, it is reduced to minimize system overhead. This dynamic behavior ensures that time overhead is only incurred when necessary.
Solution Approach 2:
The system periodically monitors the communication state and adjusts the guard time accordingly. By making periodic adjustments rather than maintaining a constantly extended guard time, the system minimizes the accumulation of system overhead while ensuring interference suppression during critical handover periods.
Data Source
AI summary
A portable terminal communicates with a plurality of base stations by use of an OFDM signal. The portable terminal includes a communication unit sending and receiving the OFDM signal to and from the base stations, a switching timing detector, and an OFDM signal controller. The switching timing detector detects switching timing at which handover and a normal state are switched therebetween. The OFDM signal controller changes a guard time length of the OFDM signal upon detecting the timing by the switching timing detector.