Antenna Switching Control for Wireless LAN Reception
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Solution Overview
Problem
Conventional wireless LAN devices face challenges in efficiently controlling diversity antennas, particularly in high-speed switching and maintaining optimal signal reception, leading to increased load on control devices and potential packet errors due to high reception levels.
Innovation Solution
A receiving apparatus and method that include an obtaining unit for measuring reception levels and transmission rates, a storing unit for packet error rate ranges, and a controlling unit to switch antennas based on these conditions, optimizing antenna selection to prevent packet errors and reduce control device load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wireless LAN device checks the signal strengths of each packet received by the two antennas to determine which antenna has higher IF level, then the antenna selection accuracy is improved, but the control device load increases and high-speed switching is required
Solution Approach 1:
The patent applies preliminary action by measuring the signal strength of the preamble signal once at the beginning of packet reception and using this measurement for the entire packet reception process. This eliminates the need for continuous signal strength checks during packet reception, significantly reducing control device load while maintaining accurate antenna selection based on the preliminary preamble measurement
Solution Approach 2:
The patent extracts the signal strength measurement function to only the preamble signal period, separating it from the ongoing packet reception process. By taking out the measurement action from continuous operation and limiting it to the preliminary preamble phase, the system achieves accurate antenna selection without the burden of continuous monitoring
2Reliability
If the wireless LAN device selects the antenna with higher reception level at all times, then the signal reception quality is improved, but packet errors occur due to distortion in receiving circuit when reception level becomes too high
Solution Approach 1:
The patent applies parameter changes by introducing a threshold value for reception level and changing the antenna selection criterion from 'always select higher level' to 'select based on whether level exceeds threshold'. When the reception level exceeds the threshold, the system switches to the other antenna or lowers reception level, preventing circuit distortion while maintaining optimal signal quality within the safe range
Solution Approach 2:
The patent applies preliminary anti-action by proactively preventing reception level from becoming too high through threshold-based control. Before distortion can occur in the receiving circuit, the system anticipates the problem by monitoring reception levels against predefined thresholds and taking corrective action by switching antennas or adjusting reception parameters
3Speed
If the wireless LAN device uses high-speed switching between antennas, then the antenna selection responsiveness is improved, but the control device load increases heavily
Solution Approach 1:
The patent applies preliminary action by completing antenna selection during the preamble signal period before actual packet reception begins. The high-speed switching decision is made once based on preamble measurement, and then the selected antenna is used for the entire packet reception without further switching decisions, eliminating the need for continuous high-speed switching control during data reception
Data Source
AI summary
A receiving apparatus according to the present invention includes an obtaining unit operable to obtain the reception level of a first radio wave received via one antenna of first and second antennas, and a transmission rate representing the transmission speed of the first radio wave, the transmission rate being included in the first radio wave and being set by a transmitting apparatus transmitting the first radio wave; a storing unit operable to store, for each of a plurality of transmission rates, a range of signal reception levels in which a packet error rate is substantially 0%; a determining unit operable to determine whether to switch from the one antenna to another antenna based on the reception level of the first radio wave and a first range of reception levels stored in the storing unit which correspond to the transmission rate of the first radio wave; and a controlling unit operable to control switching of the antennas when the determining unit determines to switch from the one antenna to the another antenna so as to receive via the another antenna a second radio wave of a packet different from the packet of the first radio wave.