Communication System Antenna Selection Signal Strength Threshold
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Solution Overview
Problem
As the number of registered portable devices increases, the time required to determine the non-existence state of a device near an antenna becomes longer, leading to delayed vehicle control operations, such as unlocking, due to overlapping RF signals and inefficient signal reception processing.
Innovation Solution
A communication system where a control device transmits a request signal and compares the received signal strength indication to a threshold value, suspending reception processing if it's below the threshold, and switching antennas if necessary, allowing for rapid antenna selection and reducing processing delays by ensuring only one device responds during a common period, and allowing multiple devices to respond during individual periods to avoid collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transmission periods of RF signals for multiple portable devices are assigned in advance so as not to overlap, then signal reception reliability is improved, but the time required to determine the non-existence state of portable devices becomes longer
Solution Approach 1:
The patent applies periodic action by dividing the communication process into distinct periods: a common period where all portable devices may transmit RF signals simultaneously, and individual periods where specific devices transmit. This periodic structure allows the control device to efficiently detect signal presence during the common period and only proceed to individual periods if needed, thereby reducing the time to determine the non-existence state while maintaining reliable signal reception.
2Productivity
If multiple portable devices transmit RF signals simultaneously during a common period, then communication efficiency is improved, but signal collision may occur
Solution Approach 1:
The patent segments the communication process into a common period for simultaneous transmissions and individual periods for dedicated transmissions. During the common period, multiple portable devices can transmit RF signals at the same time, improving communication efficiency. The control device monitors this period and only proceeds to individual periods if signal collisions or failures occur, thus balancing efficiency and reliability through temporal segmentation of the communication protocol.
Data Source
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AI summary
If a portable device (3) receives a request signal from a control device (2) that requires a response from the portable device (3), a first response signal is transmitted from the portable device (3) during a common period (Tc) defined in all portable devices (3). Thus, in a case where there is no portable device (3) which enables wireless communication with the control device (2), a value of received signal strength indication of a wireless signal which is received from the portable device (3) by the control device (2) is very small and becomes smaller than the threshold value during a period (Ts) in the common period (Tc). In this case, the control device (2) suspends reception processing of causing a signal to be transmitted from the plurality of portable devices (3) subsequently to the first response signal.