Multi-Channel RTS CTS Exchange for Wireless Interference
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Solution Overview
Problem
In wireless communication networks, the hidden node problem occurs where a device may sense a channel as free but is actually busy for another device due to interference from neighboring networks, leading to incorrect reception of transmissions.
Innovation Solution
Implementing a multi-channel request-to-send (MRTS) and multi-channel clear-to-send (MCTS) exchange to ensure that both devices agree on available channels, avoiding interference by using only channels sensed as free by both devices for communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a device transmits simultaneously over multiple channels to increase data transmission rate, then productivity is improved, but reliability deteriorates due to the hidden node problem causing interference
Solution Approach 1:
The patent performs preliminary channel sensing and RTS/CTS exchange before actual data transmission. The transmitter sends RTS on each channel and receives CTS responses to identify which channels are truly free, establishing a list of available channels before transmitting data. This preliminary action prevents hidden node interference by ensuring both devices agree on channel availability.
Solution Approach 2:
The patent implements feedback through the RTS/CTS exchange mechanism. The transmitter requests channel availability information by sending RTS, and the receiver provides feedback through CTS responses indicating which channels are free. This feedback loop ensures both devices have consistent knowledge of channel status, resolving the hidden node problem while enabling multi-channel transmission.
2Device complexity
If a device senses channels independently without coordination, then device complexity is reduced, but measurement precision deteriorates because the receiver may sense channels as busy due to hidden nodes while the transmitter senses them as free
Solution Approach 1:
The patent merges the channel sensing operations of both transmitter and receiver through the RTS/CTS exchange. Instead of each device independently sensing channels (which leads to discrepancies), the transmitter's RTS and receiver's CTS are combined to establish a mutual agreement on channel availability. This merging ensures both devices use the same channel status information without significantly increasing individual device complexity.
Data Source
AI summary
In various embodiments, a multi-channel request-to-send and a multi-channel clear-to-send may be used in a wireless communications network to assure that a subsequent multi-channel communications exchange between two devices takes place only over channels that are sensed by both devices as being free.