OFDM Transmission Apparatus Minimizing Delay via Training Symbol Storage
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Solution Overview
Problem
Existing OFDM transmission systems face challenges in minimizing transmission delay, particularly in voice communication over WLAN technologies, which can lead to echo generation and degraded communication quality due to prolonged transmission delays between transmitting and receiving parties.
Innovation Solution
The implementation of an OFDM transmission apparatus and method that includes a training symbol storage and generation unit, a delay unit, and a controller to output training symbols immediately upon a frame transmission request, while also considering the data processing time of function blocks to ensure timely output of signal and data fields, thereby minimizing overall transmission delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If training symbols are previously stored and output immediately upon data transmission request, then transmission delay is reduced, but device complexity increases due to additional storage and control mechanisms
Solution Approach 1:
Training symbols are pre-calculated and stored in a training symbol storage unit before actual data transmission occurs. When a data transmission request is received, the controller immediately outputs the pre-stored training symbols without requiring real-time generation, thereby reducing transmission delay while managing device complexity through advance preparation
Solution Approach 2:
The transmission system is divided into separate functional blocks: a training symbol storage and generation unit that handles preamble generation independently from the main data transmission path. This segmentation allows the training symbols to be prepared and stored separately, enabling immediate output when needed without blocking the overall transmission process
2Loss of time
If data processing time of function blocks is considered for timing signal and data field output, then transmission delay is minimized, but control complexity increases
Solution Approach 1:
The controller monitors and measures the actual data processing time consumed by each function block (scrambler, convolution encoder, interleaver, constellation mapper, IFFT, guard-interval inserter). Based on this feedback, the controller dynamically adjusts the timing for requesting signal and data fields from the MAC layer, ensuring that data arrives exactly when needed for immediate transmission without unnecessary waiting or premature buffering
Solution Approach 2:
The system employs dynamic timing adjustment where the controller adapts the request timing for signal and data fields based on real-time processing conditions. The transmission apparatus transitions from static predetermined timing to dynamic timing that responds to actual processing speeds, allowing optimal transmission delay minimization under varying operational conditions
Data Source
AI summary
An OFDM transmission apparatus having minimal transmission delay comprises a training symbol storage and generation unit, a delay unit and a controller. The training symbol storage and generation unit stores training symbols for the preamble, and outputs the stored training symbols when a training symbol output request signal is received. The delay unit receives data for the signal field from the MAC layer, delays the received data by the data processing time of the scrambler, and outputs the delayed data to the convolution encoder. The controller outputs the training symbol output request signal, requesting the preamble of the frame, to the training symbol storage and generation unit when a frame transmission request is received from the MAC layer, and outputs a data request signal, requesting the signal field and the data field, to the MAC layer in consideration of total data processing time (TPROCESS).