Wireless Preamble Long Training Sequence MIMO Channel Estimation
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Solution Overview
Problem
Current wireless communication systems face challenges in supporting multiple wireless communication protocols within a wireless local area network, particularly due to performance losses associated with backward compatibility mechanisms, and the need for efficient channel estimation in MIMO systems.
Innovation Solution
The method involves generating a preamble with an expanded long training sequence and a second training sequence, compatible with specific wireless communication standards, to ensure backward compatibility and improve channel estimation in MIMO systems, allowing for seamless operation of devices compliant with different standards like IEEE 802.11a and 802.11n.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If backward compatibility mechanisms are used to support multiple wireless communication protocols, then legacy devices can operate in the network, but performance loss occurs
Solution Approach 1:
The training sequence is divided into multiple segments including legacy training sequences and new training sequences. Legacy training sequences maintain compatibility with older devices while new training sequences enable advanced MIMO functionality, allowing the system to serve multiple protocol requirements simultaneously without performance degradation
Solution Approach 2:
The preamble structure is designed to serve multiple functions: it provides backward compatibility for legacy devices through included legacy training sequences, while simultaneously enabling MIMO channel estimation and signal transmission for newer devices through additional new training sequences and data fields
2Reliability
If legacy devices are kept off the air to avoid interference, then collision is avoided, but network utilization decreases
Solution Approach 1:
The expanded preamble structure acts as an intermediary mechanism that allows legacy devices to remain active in the network. By including legacy training sequences that legacy devices can recognize, the system enables these devices to coexist with MIMO-capable devices without causing collisions or being forced offline
3Measurement precision
If training sequences are expanded for MIMO channel estimation, then channel estimation accuracy improves, but overhead increases
Solution Approach 1:
The training sequences are segmented into distinct legacy and new portions. The legacy training sequences maintain compatibility and occupy minimal space, while the additional new training sequences provide the necessary information for MIMO channel estimation, achieving accurate measurement without excessive overhead
Solution Approach 2:
The patent implements partial expansion of training sequences by adding only the necessary new training sequences required for MIMO functionality while retaining the essential legacy sequences. This provides sufficient channel estimation capability without adding excessive overhead that would significantly impact network efficiency
Data Source
AI summary
A method and device for transmitting a frame of a wireless communication begins by generating a preamble of the frame that includes a short training sequence and at least one long training sequence. The at least one long training sequence includes non-zero energy on each of a plurality of subcarriers except a DC subcarrier. The at least one long training sequence corresponds to the number of antennas and applicable wireless communication standards. A matrix is defined to represent the at least one long training sequence. The preamble is compatible with legacy and current standards. A channel is defined with a set of sub carriers to transmit the frame.