Multi-Antenna Preamble Circular Shifting for Wireless Signal Detection
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Solution Overview
Problem
Conventional wireless communication systems with multiple antennas face errors in power estimates and limited tone sets for signal detection, especially in channels with long delay-spreads, and require complex circuitry and multiple carriers, which increases costs.
Innovation Solution
The method involves circularly shifting a legacy preamble to generate multiple preambles, which can be transmitted via multiple antennas, adding a phase roll to ensure compatibility with legacy standards like 802.11a/g and enabling carrier detection and power estimation across multiple antennas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple signal carriers are used for operation in conventional frequency-sparse packet preamble systems, then signal detection capability is improved, but circuitry complexity and implementation cost increase
Solution Approach 1:
The patent combines multiple preambles into a single composite preamble structure that can be transmitted over multiple antennas using a single carrier. The composite preamble includes multiple short training sequences (STS) and long training sequences (LTS) that are multiplexed in time, allowing the system to achieve multi-antenna signal detection capability without requiring multiple simultaneous carriers, thus reducing circuitry complexity while maintaining detection capability
Solution Approach 2:
The patent segments the preamble into multiple distinct parts (short training sequences and long training sequences) that can be independently processed and combined. Each STS is associated with a specific antenna, and the segmentation allows the receiver to process signals from multiple antennas through a unified single-carrier framework, avoiding the need for complex multi-carrier circuitry
2Ease of manufacture
If conventional frequency-sparse packet preamble systems are used, then implementation is simpler, but power estimation errors increase especially in channels with long delay-spreads
Solution Approach 1:
The patent incorporates multiple short training sequences (STS) at the beginning of the preamble, each transmitted from a different antenna. These preliminary training sequences allow the receiver to perform channel estimation and power measurement before the actual data transmission begins. By having multiple STS sequences available in advance, the system can accurately estimate power levels even in channels with long delay-spreads, improving measurement precision while keeping the overall structure relatively simple
3Adaptability or versatility
If legacy preambles are used for multi-antenna transmission, then backward compatibility is maintained, but the number of available tone sets is limited
Solution Approach 1:
The patent extends the legacy preamble structure by adding a time dimension through multiple short training sequences. Instead of relying solely on frequency-domain tone sets, the invention creates multiple antenna-specific training sequences in the time domain, each with its own set of active subcarriers. This dimensional extension allows the system to maintain compatibility with legacy single-antenna receivers while providing sufficient tone sets for multi-antenna operations through temporal multiplexing
Data Source
AI summary
Methods and systems for processing multiple preambles for a wireless signal are disclosed herein. Aspects of the method may comprise selecting a portion of a preamble, and shifting the selected portion of the preamble to generate a plurality of subsequent preambles. The preamble may comprise a legacy preamble and/or an 802.11(n) preamble. The selected portion of the preamble may comprise a short training sequence. The shifting may comprise circular shifting. The circular shifting may comprise forward circular shifting and/or backwards circular shifting. The generated plurality of subsequent preambles may be transmitted via a plurality of antennas. A phase roll may be added to the selected portion of the preamble to generate the plurality of subsequent preambles.