OFDM Channel Estimation Memory Reduction via Time-Division Multiplexing
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Solution Overview
Problem
Conventional DVB-T/H receivers require large memory storage for channel estimation due to two-dimensional interpolation, especially in severe fading environments, and duplicating receive channel hardware for frequency-domain combining diversity processing is burdensome, especially with a large number of carriers.
Innovation Solution
Implementing time-sharing of a single digital chain between two diversity signals and sharing a single frequency-domain sample buffer memory, along with reducing memory requirements through selective interpolation and extrapolation in the time domain and non-uniform interpolation in the frequency domain, allowing for reduced gate count and chip cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-dimensional interpolation is used for channel estimation in severe fading environments, then channel estimation accuracy is improved, but memory storage requirements increase significantly
Solution Approach 1:
The patent segments the channel estimation process into two separate one-dimensional interpolation steps: first in the time domain, then in the frequency domain. This segmentation avoids the need for storing large two-dimensional interpolation tables, reducing memory requirements while maintaining estimation accuracy in severe fading environments.
Solution Approach 2:
The patent transforms the two-dimensional interpolation problem into a sequential process involving time-domain interpolation followed by frequency-domain interpolation. By changing the dimensional approach from simultaneous 2-D to sequential 1-D operations, the memory storage burden is significantly reduced while preserving channel estimation precision.
2Reliability
If receive channel hardware is duplicated for frequency-domain combining diversity processing, then diversity processing capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the processing of multiple diversity signals into a single receive channel by time-multiplexing the FFT processor and frequency-domain sample buffer. The system alternates processing between different antenna ports and combines results in the frequency domain, eliminating the need for duplicate hardware while maintaining diversity processing capability.
Solution Approach 2:
The patent introduces dynamic time-multiplexing operation where a single receive channel dynamically switches between processing different diversity signals. The FFT processor and buffer memory are dynamically allocated to different antenna ports in time sequence, enabling flexible resource sharing and reducing static hardware requirements.
3Device complexity
If a single digital chain is time-shared between diversity signals, then device complexity is reduced, but processing speed may be affected
Solution Approach 1:
The patent employs periodic time-multiplexed operation where the single digital chain processes diversity signals in alternating time slots. The system periodically switches between different antenna ports, with each signal receiving complete processing attention in its designated time window, maintaining processing quality while reducing hardware complexity.
Data Source
AI summary
A frequency domain diversity DVB receiver device includes multiple antenna ports for receiving radio signals, and radio signal processing circuits connected to the antenna ports that convert the received radio signals into digital samples. The digital samples from the different antenna ports time-share a front-end processor which processes the digital samples to provide time-domain symbols. The time-domain symbols are stored in time-domain symbol buffers according to which of the antenna ports the time-domain symbols are received. A fast fourier transform circuit then retrieves the time-domain symbols and converts them frequency-domain symbols, which are then stored one or more frequency-domain symbol buffers according to the antenna ports the corresponding radio signals are received. A diversity processor which combines the frequency-domain symbols from the frequency-domain symbol buffers.