Cyclic Shift Pilot Signals for Multi-Antenna Channel Estimation
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Solution Overview
Problem
Existing cyclic delay diversity (CDD) methods in wireless communication systems require long pilot signal lengths, which reduce data transmission efficiency due to redundant pilot signals, and do not optimize cyclic shift amounts for both pilot and data signals.
Innovation Solution
The system employs cyclically shifted pilot and data signals with different cyclic shift amounts, using constant amplitude zero auto-correlation (CAZAC) sequences to ensure orthogonality and minimize pilot signal length, allowing for efficient data transmission by separating pilot and data signals effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If long pilot signals are used for channel estimation in CDD systems, then channel estimation accuracy is improved, but data transmission efficiency deteriorates due to increased redundancy
Solution Approach 1:
The patent applies parameter changes by using CAZAC sequences with specific properties (constant amplitude and zero auto-correlation) to create pilot signals that maintain estimation accuracy while reducing length. The cyclic shift amounts are optimized parameters that enable shorter pilot signals to achieve the same channel estimation performance, thereby improving data transmission efficiency without sacrificing measurement precision.
2Productivity
If cyclic shift amounts are not optimized for pilot signals, then implementation complexity is reduced, but transmission efficiency deteriorates due to insufficient pilot signal orthogonality
Solution Approach 1:
The patent optimizes cyclic shift amounts as key parameters to achieve orthogonality between pilot signals from different antennas. By carefully selecting cyclic shift values, the system ensures that pilot signals remain orthogonal even when shortened, thereby maintaining transmission efficiency without requiring complex additional processing mechanisms.
Solution Approach 2:
The patent applies preliminary action by pre-defining optimal cyclic shift amounts for CAZAC sequences before transmission. These predetermined shift values are configured to ensure orthogonality is automatically maintained, eliminating the need for real-time optimization calculations and reducing implementation complexity while preserving transmission efficiency.
Data Source
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AI summary
A transmitter for transmitting signals via at least a first antenna and a second antenna, comprising: a first sequence generating unit configured to generate a first sequence for estimating a first channels condition, the first sequence being same as a sequence obtained by performing a first cyclic shift on a CAZAC sequence, the first cyclic shift being a first amount set for the transmitter; a second sequence generating unit configured to generate a second sequence for estimating a second channel condition, the second sequence being same as a sequence obtained by performing a second cyclic shift on the CAZAC sequence, the second cyclic shift being a second amount set for the transmitter and different from the first amount; a first block signal generating unit configured to generate a first block signal, the first block signal being same as a signal obtained by performing a third cyclic shift on a block signal generated from data, the third cyclic shift being a third amount; and a second block signal generating unit configured to generate a second block signal, the second block signal being same as a signal obtained by performing a fourth cyclic shift on the block signal generated from the data, the fourth cyclic shift being a fourth amount different from the third amount; wherein a period In which the first sequence and the second sequence are transmitted differs from a period in which the first block signal and the second block signal are transmitted; a frequency with which the first block signal and the second block signal are transmitted is set to each transmitter; the first amount and the second amount are set to the each transmitter; a gap between the first amount and the second amount differs from a gap between the third amount and the fourth amount; the first sequence and the first block signal are transmitted at least via a first antenna; and the second sequence and the second block signal are transmitter at least via a second antenna.