EGPRS Training Sequence Rotation for PAPR Reduction
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Solution Overview
Problem
Precoded EGPRS/EGPRS2 systems face high Peak to Average Power Ratio (PAPR) issues, requiring significant computational and memory resources to generate multiple transmit signals for PAPR reduction, which is a challenge for backwards compatibility with legacy base stations.
Innovation Solution
Combining modulation type signaling through rotation of training sequences with PAPR reduction into a single step, using a set of unique rotation angles to generate new training sequences, allowing for minimal memory and computational complexity, with only one Inverse Discrete Fourier Transformation (IDFT) computation required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transmit signals are generated for PAPR reduction, then PAPR is reduced, but memory usage and computational complexity increase significantly
Solution Approach 1:
The patent combines PAPR reduction with modulation type signaling by merging the training sequence rotation operation with the modulation signaling function. This allows simultaneous achievement of PAPR reduction and modulation signaling without requiring separate operations, thereby reducing overall computational complexity while maintaining PAPR benefits
Solution Approach 2:
The training sequence rotation operation serves multiple functions: it signals the modulation type and simultaneously reduces PAPR. This multi-functionality eliminates the need for separate PAPR reduction operations, reducing computational complexity and memory requirements while maintaining signal quality
2Reliability
If multiple transmit signals are generated for PAPR reduction, then PAPR is reduced, but memory usage increases
Solution Approach 1:
The patent merges the PAPR reduction operation with the training sequence rotation operation used for modulation signaling. This combination allows the system to achieve PAPR reduction without storing multiple complete transmit signals in memory, as only the rotated training sequences need to be stored and processed
Solution Approach 2:
Instead of storing multiple complete transmit signals, the patent uses copies of the training sequence that have been rotated by different angles. These rotated training sequences are much smaller in size and require significantly less memory, while still enabling PAPR reduction through the same computational process
3Adaptability or versatility
If legacy base stations are supported, then backwards compatibility is maintained, but computational resources are limited
Solution Approach 1:
The patent changes the parameter of training sequence rotation angles to encode modulation type information. This allows legacy base stations to support precoded EGPRS without requiring complex new operations, as the rotated training sequences can be processed using standard computational resources while maintaining backwards compatibility with existing GSM infrastructure
Data Source
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AI summary
Methods and arrangements are provided where signalling of the modulation type by means of rotation of the training sequence is provided. For each modulation type, a set of rotation angles is chosen. These sets have no element in common. New training sequences are generated by rotating one original training sequence. The rotation angle that minimizes the PAPR of the transmit signal can be chosen. At the receiver side, knowing the original training sequence, the receiver estimates blindly the rotation angle among the known possible rotation angles. The estimated rotation angle in the receiver maps to a unique modulation type.