OFDM Slot Control Without MLI for Higher User Data Throughput
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Solution Overview
Problem
In wireless communication systems using OFDM/MTPC, the transmission of unnecessary modulation level information (MLI) reduces efficiency as it occupies time that could be used for user data transmission, as MLI is sent in every slot even after successful demodulation.
Innovation Solution
A modulator that determines successful demodulation of MLI and subsequently generates slots without MLI in the communication frame, allowing the time previously used for MLI to be allocated for user data, thereby improving transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If modulation level information (MLI) is transmitted in every slot to ensure reliable demodulation, then demodulation reliability is improved, but transmission efficiency deteriorates due to redundant information transmission
Solution Approach 1:
The patent applies local quality by differentiating slot types based on local channel conditions and receiver state. Slots are classified as synchronization slots (requiring MLI transmission for reliability) or data slots (where MLI can be omitted to improve efficiency). This localized approach ensures MLI is transmitted only where necessary for demodulation reliability.
Solution Approach 2:
The patent implements dynamics by making the MLI transmission status dynamic rather than static. The base station determines for each slot whether to include MLI based on synchronization status and channel conditions. This dynamic adaptation allows the system to switch between reliable MLI transmission and efficient no-MLI transmission modes, resolving the contradiction between reliability and efficiency.
2Reliability
If MLI is transmitted in all slots, then demodulation can be performed with sufficient information, but time resources are wasted transmitting unnecessary data
Solution Approach 1:
The patent extracts MLI from slots where it is unnecessary. Once the receiver achieves synchronization and obtains MLI from a synchronization slot, subsequent data slots have their MLI component removed. This extraction eliminates redundant information transmission, freeing up time resources while maintaining demodulation capability through the previously obtained MLI.
Solution Approach 2:
The patent applies preliminary action by obtaining MLI in advance during synchronization slots before data transmission begins. The receiver acquires modulation level information early in the synchronization phase, which then enables demodulation of subsequent data slots without requiring MLI to be repeated. This preliminary acquisition eliminates the need for continuous MLI transmission, saving time resources.
3Reliability
If slot length is maintained to include MLI, then demodulation information is complete, but user data transmission capacity is reduced
Solution Approach 1:
The patent segments slots into two distinct types: synchronization slots that contain complete demodulation information including MLI, and data slots that transmit only user data without MLI. This segmentation allows the system to maintain complete demodulation information where needed while maximizing user data capacity in other slots, effectively separating the functions of information provision and data transmission.
Solution Approach 2:
The patent applies partial action by providing MLI only partially - specifically in synchronization slots rather than in every slot. This partial provision of demodulation information is sufficient for the receiver to function, as once obtained, the MLI can be used for multiple subsequent data slots. This approach provides exactly enough MLI transmission to ensure demodulation capability while avoiding excessive transmission that would reduce user data capacity.
Data Source
AI summary
Improvement of transmission efficiency is sought by stopping transmission of unnecessary MLI data.A transmitting circuit 111 in a base station apparatus 110 has an MLI modulation part 248 composed of an MLI generating circuit 238, a symbol modulation circuit 239, and an IFFT circuit 240, a user data modulation part 249 composed of an encoder circuit 234, a symbol modulation circuit 235, a transmission power control circuit 236, and an IFFT circuit 237, and a transmission operation control circuit 113. The transmission operation control circuit 113 controls operation timing of the MLI modulation part 248, the user datamodulationpart 249, and a multiplexer 243 based on a signal to notify that ACK input from a receiving circuit 112 has been received so that slots containing no MLI data are generated.