OFDM Transmitter Guard Interval Adaptation for 6 MHz Bandwidth
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Solution Overview
Problem
Optimizing communications parameters, particularly frequency planning and network deployment, for Orthogonal Frequency Division Multiplexing (OFDM) systems is complex, especially in determining suitable guard intervals for efficient data transmission in radio communications systems like DVB standards.
Innovation Solution
A transmitter and receiver system configured to transmit and receive OFDM symbols with a guard interval inserter adding a predetermined guard interval to each OFDM symbol, allowing for efficient use of communications resources by reusing parameters from the DVB-T2 standard adapted for a 6 MHz channel bandwidth, and optimizing sub-carrier configurations for 8K, 16K, or 32K modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DVB-T2 parameters are adapted for 6 MHz bandwidth, then resource utilization efficiency is improved, but device complexity increases due to parameter optimization requirements
Solution Approach 1:
The patent applies parameter changes by adapting DVB-T2 communications parameters for 6 MHz bandwidth operation. Specifically, it modifies the guard interval duration to 1/32 of the useful symbol duration and adjusts the number of sub-carriers to 6817, thereby optimizing resource utilization for the narrower bandwidth while maintaining compatibility with existing OFDM frameworks
Solution Approach 2:
The patent achieves universality by enabling the same transmitter and receiver architectures to operate across different bandwidths (both 6 MHz and 8 MHz) using a unified parameter set. This multi-functionality allows the system to maintain efficient resource utilization across varying channel conditions without requiring separate optimization for each bandwidth
2Reliability
If guard interval duration is extended, then channel impulse response coverage is improved, but data transmission efficiency deteriorates due to increased redundancy
Solution Approach 1:
The patent resolves this contradiction by changing the guard interval parameter to exactly 1/32 of the useful symbol duration. This specific ratio provides sufficient coverage for the channel impulse response in 6 MHz bandwidth scenarios while minimizing the redundancy overhead, thereby maintaining data transmission efficiency
3Measurement precision
If sub-carrier spacing is reduced for 6 MHz bandwidth, then frequency resolution is improved, but synchronization precision deteriorates
Solution Approach 1:
The patent addresses this contradiction by adjusting the total number of sub-carriers to 6817 for 6 MHz bandwidth operation. This specific parameter setting optimizes the balance between frequency resolution and synchronization precision by ensuring that the sub-carrier spacing remains appropriate for the reduced bandwidth while maintaining adequate timing synchronization capabilities
Data Source
AI summary
A transmitter transmits data to a receiver using OFDM symbols including plural sub-carrier symbols, some carrying data symbols and some carrying pilot symbols. A data formatter can form the data for transmission into sets of data symbols for each OFDM symbol, and an OFDM symbol builder can receive each set of data symbols from the data formatter and combine the data symbols with pilot symbols. A modulator can map the data symbols and the pilot symbols onto modulation symbols and modulate the plural sub-carriers to form the OFDM symbols. An inverse Fourier transform can convert the OFDM symbols from the frequency domain to the time domain, and a guard interval inserter can add a guard interval to each of the OFDM symbols by copying a part of the OFDM symbols and appending the copied part sequentially in the time domain to the OFDM symbols.