MIMO-OFDM Preamble Sequence Segmentation for PAPR Reduction
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Solution Overview
Problem
In orthogonal frequency division multiplexing (OFDM) communication systems using a multiple input multiple output (MIMO) scheme, the increase in the number of preamble sequences leads to higher Peak to Average Power Ratio (PAPR) and increased hardware load, making it challenging to distinguish between base stations and acquire synchronization efficiently.
Innovation Solution
The method involves segmenting base sequences into subsequences with different time offsets and transmitting them through multiple transmit antennas, optimizing preamble sequence design to minimize PAPR and cross-correlation, while maintaining orthogonality and auto-correlation characteristics, allowing for efficient channel estimation and BS identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of preamble sequences is increased to distinguish multiple base stations in MIMO-OFDM system, then base station identification capability is improved, but Peak to Average Power Ratio (PAPR) increases and hardware load increases
Solution Approach 1:
The patent segments a single base sequence into multiple preamble sequences by applying different time offsets (cyclic shifts) to create distinct sequences for different base stations. This segmentation allows multiple base stations to be distinguished using a limited set of underlying sequences, reducing the total number of unique sequences needed and thereby reducing hardware complexity while maintaining base station identification capability.
Solution Approach 2:
The patent introduces time offset as an additional dimension to differentiate preamble sequences. Instead of creating entirely new sequences for each base station, the invention varies the time offset parameter across existing sequences. This dimensional approach enables multiple base station identifiers to be generated from a smaller set of base sequences, reducing the overall sequence space required and lowering hardware requirements.
2Adaptability or versatility
If the number of preamble sequences is increased to distinguish multiple base stations, then base station identification capability is improved, but PAPR increases making synchronization difficult
Solution Approach 1:
By segmenting a single base sequence into multiple time-offset variants, the patent reduces the need to create entirely new high-PAPR sequences for each base station. The segmented approach allows reuse of the same base sequence structure across multiple base stations, maintaining lower PAPR characteristics while enabling multiple base station identification.
Solution Approach 2:
The patent changes the time offset parameter of existing base sequences to create different preamble sequences for different base stations. This parameter-based differentiation avoids the need to design new sequences with potentially high PAPR, as the time offset modification preserves the underlying sequence's power characteristics while providing base station discrimination capability.
3Measurement precision
If more preamble sequences are used for synchronization and channel estimation, then synchronization accuracy is improved, but computational load increases
Solution Approach 1:
The patent segments the correlation computation task by organizing preamble sequences into groups based on time offsets. This segmentation allows the receiver to efficiently identify which sequence variants are needed for synchronization and channel estimation, reducing the computational search space while maintaining synchronization accuracy through structured sequence design.
Solution Approach 2:
By introducing time offset as a structured parameter dimension, the patent enables more efficient correlation processing. The receiver can leverage the known time offset structure to guide the synchronization search process, reducing computational complexity compared to searching through entirely different sequences, while still achieving accurate synchronization.
Data Source
AI summary
In an orthogonal frequency division multiplexing (OFDM) communication system using multiple transmit antennas, a first base sequence with a first length is segmented into a first number of second sequences to which different time offsets are applied. Subsequences of a first preamble sequence corresponding to the number of second sequences are generated. A second base sequence with a second length is segmented into a second number of third sequences to which different time offsets are applied. Subsequences of a second preamble sequence corresponding to the number of third sequences are generated. A subsequence is selected from the subsequences of the first preamble sequence and is transmitted through a transmit antenna in a first time interval. A third preset number of subsequences are selected from the subsequences of the second preamble sequence, and are mapped and transmitted to the transmit antennas in a second time interval.