Wireless LAN Interference Control via CTS-to-Self Channel Reservation
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Solution Overview
Problem
Wireless LAN systems experience deteriorating communication quality due to increased terminal numbers and interference, leading to higher delays and jitters, particularly in applications requiring real-time characteristics like VoIP and streaming video, where conventional technologies fail to provide sufficient low delay and low jitter.
Innovation Solution
A wireless LAN system with an interference control method that uses interference control signal transmitters and management devices to collect environmental information, transmit interference control signals to set transmission waiting periods, and prioritize communication between wireless LAN base stations and terminals, thereby reducing interference from co-channel devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of wireless LAN terminals increases, then network coverage and accessibility are improved, but communication quality deteriorates due to collisions and interference
Solution Approach 1:
The system performs preliminary actions by transmitting CTS-to-self signals before actual data transmission to reserve the channel and prevent collisions. The base station and terminals exchange CTS signals in advance to set NAV values, ensuring that the channel is reserved before data transmission occurs, thus maintaining communication quality even with increased terminal numbers.
Solution Approach 2:
The CTS-to-self signal acts as an intermediary mechanism that mediates between multiple terminals competing for channel access. By using CTS signals as intermediaries to reserve channels and set NAV values, the system coordinates transmissions without direct collision, allowing more terminals to access the network reliably.
2Reliability
If conventional CSMA/CA with RTS/CTS is used, then collision avoidance is improved, but delay and jitter increase in real-time applications
Solution Approach 1:
The system performs preliminary channel reservation using CTS-to-self signals before data transmission. By setting NAV values in advance through CTS exchange, the channel is reserved without requiring the full RTS/CTS handshake, reducing the number of control frames and minimizing delay and jitter for real-time applications.
Solution Approach 2:
The system changes the parameter of channel reservation by using CTS-to-self signals instead of the traditional RTS/CTS exchange. This parameter change reduces the control overhead and transmission time while maintaining collision avoidance, thus reducing delay and jitter for real-time traffic.
3Object-affected harmful factors
If CTS-to-self is transmitted frequently to suppress interference, then interference reduction is improved, but channel utilization decreases
Solution Approach 1:
The system applies partial action by transmitting CTS-to-self signals selectively rather than continuously. CTS-to-self is transmitted only when necessary to suppress interference from specific terminals, rather than being sent on every transmission opportunity. This partial application reduces interference while minimizing the impact on channel utilization.
Solution Approach 2:
The system dynamically adjusts the transmission of CTS-to-self signals based on the interference conditions and channel state. The base station and terminals transmit CTS-to-self signals adaptively, increasing transmission frequency when interference is detected and reducing it when the channel is clear, thus balancing interference suppression with channel utilization.
Data Source
AI summary
Provided is a wireless LAN system in which an interference control signal transmitter that is provided in the surroundings of the wireless LAN base station and the wireless LAN terminal, and is configured to collect wireless environment information regarding the interfering AP/STA, and transmit, to the interfering AP/STA, an interference control signal that is to be used to set a transmission waiting period; and an interference control signal management device configured to collect the wireless environment information from the interference control signal transmitter, determine the interference control signal transmitter whose communication area includes the interfering AP/STA based on the wireless environment information, and control the determined interference control signal transmitter to transmit the interference control signal to be used to set the transmission waiting period that corresponds to a length of time of the communication between the wireless LAN base station and the wireless LAN terminal, wherein while the interfering AP/STA that has received the interference control signal sets the transmission waiting period, the wireless LAN base station and the wireless LAN terminal preferentially perform communication.