Frame Synchronization in UWB MB-OFDM Systems
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Solution Overview
Problem
High data rate transmission in Ultra-Wideband (UWB) Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) systems requires improved frame synchronization techniques, especially when symbols are transmitted over time-varying frequencies, making it difficult to determine the location of symbols within a packet.
Innovation Solution
The method involves correlating pairs of symbols to obtain correlation results, performing second-order correlations on the first-order results, and examining these for patterns indicating a known location in the packet preamble, using a frame synchronization unit with first and second-order correlation blocks and a determination block to achieve synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If symbols are transmitted over time-varying frequencies in UWB MB-OFDM systems, then transmission rate increases, but frame synchronization difficulty increases
Solution Approach 1:
The patent segments the frame synchronization process into two distinct stages: first-order correlation (comparing current symbol with previous symbol) and second-order correlation (comparing first-order correlation results). This segmentation allows the system to handle time-varying frequencies systematically by breaking down the complex synchronization task into manageable steps, thereby maintaining high transmission rates while improving synchronization accuracy.
Solution Approach 2:
The patent performs preliminary first-order correlation operations before conducting the final second-order correlation. By pre-processing the symbols through first-order correlation and storing these results, the system prepares data in advance for the more computationally intensive second-order correlation, enabling efficient frame synchronization even at high transmission rates with time-varying frequencies.
2Measurement precision
If second-order correlation is performed to improve synchronization accuracy, then measurement precision increases, but computational complexity increases
Solution Approach 1:
The patent computes first-order correlation results in advance and stores them for later use in second-order correlation. This preliminary computation approach allows the system to perform the computationally intensive second-order correlation only when needed for final synchronization determination, reducing overall computational burden while maintaining high synchronization accuracy.
Solution Approach 2:
The patent performs second-order correlation on selected first-order correlation results rather than all possible pairs. By examining second-order correlations for specific patterns indicating known locations in the packet preamble, the system achieves sufficient synchronization accuracy without the excessive computational cost of examining all possible correlations.
Data Source
AI summary
Frame synchronization methods and systems suited for packet communications systems, and particularly time frequency hopping packet communication systems, are disclosed. Frame synchronization is performed by performing a first correlation on information of received symbols and performing a second correlation on results of the first correlation. In systems with repeating synchronization information modulated by a cover sequence, the results of the second correlation may be used to determine symbol numbering of symbols in a packet.