Dynamic Active Carrier Mapping in OFDM Transmitters
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Solution Overview
Problem
The existing DVB-T2 broadcasting communication standard is inefficient in utilizing active carriers due to the fixed determination of carrier numbers based on FFT size, leading to suboptimal bandwidth usage and potential interference with adjacent channels.
Innovation Solution
A transmitting apparatus and method that dynamically determines the number of active carriers by adjusting the frequency spectrum and using pilot patterns, allowing for flexible mapping of OFDM symbols onto active carriers within a preset spectrum mask, thereby optimizing bandwidth utilization and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of active carriers is increased in proportion to FFT size, then bandwidth efficiency is improved, but spectrum mask compliance deteriorates causing adjacent channel interference
Solution Approach 1:
The patent makes the number of active carriers dynamic by determining it based on the actual spectrum mask compliance status rather than using a fixed proportional relationship with FFT size. The system dynamically adjusts the number of active carriers to match the maximum compliant carriers identified through spectrum analysis, allowing optimal bandwidth utilization while preventing adjacent channel interference.
Solution Approach 2:
The patent changes the parameter determination method from a fixed proportional relationship (number of active carriers ∝ FFT size) to a dynamic determination based on spectrum mask compliance. The system identifies the maximum number of compliant carriers through spectrum analysis and uses this as the basis for active carrier allocation, thereby optimizing the parameter setting for each specific transmission condition.
2Reliability
If the number of active carriers is determined based on the smallest FFT size, then spectrum mask compliance is maintained, but bandwidth efficiency deteriorates due to underutilization
Solution Approach 1:
The system dynamically determines the number of active carriers based on the actual spectrum mask compliance status for each FFT size configuration. Rather than fixing the number based on the smallest FFT size, the system performs spectrum analysis to identify the maximum number of compliant carriers for the current FFT size, thereby maintaining reliability while optimizing bandwidth efficiency.
Solution Approach 2:
The patent performs preliminary spectrum analysis to identify the maximum number of spectrum mask compliant carriers before determining the actual number of active carriers to be used. This preliminary identification of compliant carrier positions allows the system to maximize bandwidth utilization while ensuring spectrum mask compliance is maintained.
Data Source
AI summary
Provided are a transmitting apparatus, a receiving apparatus and methods of controlling these apparatuses. The transmitting apparatus includes: a structurer configured to generate a transmission stream comprising an orthogonal frequency division multiplexing (OFDM) symbol and add signaling data to the transmission stream; and a transmitter configured to insert at least one pilot into the OFDM symbol, determine a number of active carriers to be included in a frequency spectrum, corresponding to the OFDM symbol into which the pilot is inserted, which exists in a preset spectrum mask, and map the OFDM symbol, into which the pilot is inserted, onto the active carriers of the determined number, and transmit the mapped OFDM symbol.