Transmitter Frame Structure With Negative Training Sequences
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Solution Overview
Problem
Existing frame structures for mm-wave communication systems are inefficient in providing training signals for channel estimation and are complex, especially in scenarios with severe hardware impairments and varying channel conditions, as they require excessive overhead and are prone to corruption.
Innovation Solution
A frame structure that inserts two training sequences between signal blocks, with one being the negative of the other, to enable effective channel estimation while maintaining low Peak to Average Power Ratio (PAPR) and reducing inter-channel interference, allowing flexible switching between single carrier and multi-carrier waveforms based on channel conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If a single training sequence is used between signal blocks, then overhead is reduced, but channel estimation reliability deteriorates due to potential corruption by preceding signal blocks
Solution Approach 1:
The patent applies local quality by making the two training sequences have different properties: one is the negative of the other, creating complementary characteristics. This allows the receiver to use one sequence for channel estimation while the other serves as a backup or validation, with each sequence optimized for specific estimation conditions.
Solution Approach 2:
The patent implements beforehand cushioning by inserting two training sequences between signal blocks, providing redundant training signals that protect against corruption. If one training sequence is corrupted by inter-block interference, the other remains available for reliable channel estimation, thus cushioning against estimation failures.
2Measurement precision
If more training sequences are inserted between signal blocks, then channel estimation accuracy improves, but overhead and frame structure complexity increase
Solution Approach 1:
The patent applies asymmetry by making one training sequence the negative of the other, creating an asymmetric relationship between the two sequences. This asymmetric design allows efficient use of training signals while maintaining low overhead, as the two sequences provide complementary information rather than redundant copies.
3Adaptability or versatility
If traditional cyclic prefix based signal structures are used, then flexibility in switching between single carrier and multi-carrier waveforms is achieved, but hardware impairment estimation requires more training signals at mm-wave frequencies
Solution Approach 1:
The patent applies universality by designing a frame structure with two training sequences that can serve multiple functions: channel estimation, hardware impairment estimation, and validation. This multi-functional design reduces the need for separate training signals for different estimation purposes, thereby reducing overall training signal requirements at mm-wave frequencies.
Data Source
AI summary
A transmitter has a transmit chain that is configured to format transmit data into a frame structure that comprises signal blocks interspersed with training sequences for assisting a receive operation. The transmit chain is configured to insert two training sequences between a signal block and its following signal block in the frame structure. The transmitter also comprises a sequence generator configured to form the two training sequences, and in particular to form them such that a first of the training sequences is a negative of the second. Having one training sequence being the negative of the other helps to avoid the Direct Current (DC) subcarrier and provides good properties for channel estimation.