OFDM Radio Receiver Guard Interval Elimination
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Solution Overview
Problem
In OFDM transmission systems, the energy wasted due to guard intervals (GIs) is significant, especially when transmitting to multiple receiving apparatuses with varying maximum delay times, leading to inefficient use of transmission power and reduced received quality.
Innovation Solution
A radio transmitting apparatus configures data repetition in the time domain, allowing for the extraction and combination of non-interfered leading data parts with adjacent data parts, followed by frequency domain conversion to minimize energy loss and improve signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If guard intervals are attached to transmission data in OFDM systems, then inter-symbol interference is prevented, but transmission power is wasted due to repeated data in GI parts
Solution Approach 1:
The invention extracts and removes the guard interval from the transmission signal structure. Instead of attaching GI to each OFDM symbol, the system transmits only the data part, thereby eliminating the energy waste associated with repeated GI data while maintaining error robustness through other means such as coding and signal processing techniques.
Solution Approach 2:
The invention inverts the conventional approach by not attaching GI to prevent interference, but rather by designing a receiving apparatus that can handle interference through signal processing. The receiving end performs correlation processing and timing synchronization to identify and process valid data portions, effectively solving the interference problem without requiring GI transmission.
2Adaptability or versatility
If guard interval length is increased to accommodate maximum delay time of distant receiving apparatus, then all receiving apparatus can receive signals without interference, but transmission power is wasted on unnecessarily long GI for closer apparatus
Solution Approach 1:
The invention introduces dynamic timing synchronization at the receiving apparatus. Each receiving apparatus independently determines its optimal timing window based on its own delay characteristics. The receiving apparatus identifies the timing of OFDM symbols and extracts valid data portions dynamically, allowing the system to serve multiple apparatus with different delay times without requiring a universally long GI that would waste power for closer apparatus.
3Productivity
If data is transmitted to multiple receiving apparatuses using different subcarriers, then bandwidth utilization is improved, but energy loss of GI part increases due to varying maximum delay times
Solution Approach 1:
The invention segments the reception process into independent timing synchronization operations for each receiving apparatus. Each apparatus performs its own timing identification and data extraction based on its specific delay characteristics. This segmentation allows the system to maintain high bandwidth utilization across multiple apparatus while avoiding the energy waste of transmitting uniformly long GIs, as each apparatus processes only the necessary data portion for its timing window.
Data Source
AI summary
A radio receiver apparatus and a radio transmitter apparatus wherein the energy loss caused by addition of GI is suppressed, while the reception quality is improved. A signal having been subjected to an IFFT process is repetitively transmitted N times with a length of one OFDM symbol interval. At a receiver apparatus receiving the transmitted signals, a leading data extracting part (207) extracts, from the leading data portions of the direct waves of the received signals, portions that are not interfered with by temporally adjacent data. A combing part (209) combines the received signals in such a manner that align the rear end of each repetitively transmitted data portion except the leading data portion with the rear end of the leading data portion extracted by the leading data extracting part (207). The combined signal is then subjected to an FFT process in an FFT part (210).