Variable Length Sub-Frame Structure for OFDM Bandwidth Efficiency
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Solution Overview
Problem
Existing OFDM/OFDMA systems face challenges in efficiently utilizing bandwidth due to fixed cyclic prefix configurations, which limit adaptability to varying multipath conditions, leading to suboptimal performance in both severe and less severe multipath environments.
Innovation Solution
A variable length sub-frame structure with efficiently sized cyclic prefixes and flexible radio frame structures that allow dynamic adjustment of cyclic prefix durations based on cell coverage area and channel conditions, enabling better bandwidth utilization and interference mitigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed cyclic prefix configuration is used in OFDM/OFDMA systems, then the system structure is simple and easy to implement, but the bandwidth efficiency deteriorates and adaptability to varying multipath conditions is limited
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed cyclic prefix configuration to a variable length cyclic prefix structure. The system dynamically adjusts the cyclic prefix duration based on detected multipath conditions, allowing the prefix length to vary between different transmission scenarios. This enables optimal adaptation to both severe and less severe multipath environments while maintaining manageable system complexity through automated detection and configuration mechanisms.
2Reliability
If a longer cyclic prefix duration is used to mitigate inter-symbol interference in severe multipath conditions, then interference resistance is improved, but bandwidth efficiency deteriorates due to increased overhead
Solution Approach 1:
The patent applies parameter changes by varying the cyclic prefix duration parameter based on channel conditions. In severe multipath environments, the system extends the cyclic prefix length to adequately cover the delay spread and mitigate inter-symbol interference. Conversely, in less severe conditions, the system uses shorter cyclic prefixes to minimize overhead and maximize bandwidth efficiency. This dynamic parameter adjustment optimizes the trade-off between interference resistance and spectral efficiency.
3Productivity
If a fixed cyclic prefix configuration is used, then the system implementation is simple, but performance in diverse operating conditions deteriorates
Solution Approach 1:
The patent applies segmentation by dividing the transmission frame into multiple sub-frames, each capable of having different cyclic prefix durations. This segmentation allows the system to optimize performance in diverse operating conditions without requiring complete redesign of the entire frame structure. Each sub-frame can be independently configured with appropriate cyclic prefix length based on local channel conditions, maintaining overall system simplicity while enhancing performance adaptability.
Data Source
AI summary
An OFDM/OFDMA frame structure technology for communication systems is disclosed. The OFDM/OFDMA frame structure technology comprises a variable length sub-frame structure with efficiently sized cyclic prefixes and efficient transition gap durations operable to effectively utilize OFDM/OFDMA bandwidth. Furthermore, the frame structure provides compatibility with multiple wireless communication systems. An uplink frame structure and a downlink frame structure are provided.