Coordinating Simultaneous Wireless Transmissions via RST and CST Frames
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Solution Overview
Problem
Dense Wi-Fi deployments with overlapping coverage areas experience performance degradation due to increased channel contention and collisions, leading to reduced throughput and quality of service, as existing protocols like CSMA/CA fail to efficiently coordinate transmissions between overlapping Basic Service Sets (OBSS).
Innovation Solution
A decentralized signaling mechanism using new management frames, Request-Simultaneous-Transmission (RST) and Clear-to-Simultaneous-Transmission (CST), allows for coordinated simultaneous transmissions between OBSS Wi-Fi nodes by estimating signal strength and determining whether a second transmission can be admitted based on criteria like SINR, thereby protecting initial transmissions from collisions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CSMA/CA protocol is used for channel access coordination, then channel contention is managed, but transmission collisions still occur in dense overlapping deployments leading to performance degradation
Solution Approach 1:
The patent applies preliminary action by having nodes exchange coordination frames (RST/CTS) before actual data transmission. This advance coordination allows nodes to reserve transmission opportunities and avoid collisions, improving reliability while maintaining productivity through efficient pre-planning of transmission schedules
2Reliability
If random backoff is implemented to avoid collisions, then collision probability is reduced, but channel access latency increases
Solution Approach 1:
The coordination frame exchange performs preliminary collision avoidance by establishing transmission rights before data transfer. This eliminates the need for random backoff delays during actual data transmission, reducing latency while maintaining collision avoidance through pre-negotiated access rights
3Device complexity
If decentralized signaling mechanism is used for transmission coordination, then network complexity is reduced, but coordination capability between OBSS nodes must be established
Solution Approach 1:
The patent implements self-service by enabling OBSS nodes to autonomously exchange coordination frames and establish transmission rights without centralized control. Each node independently performs clear channel assessment, sends RST/CTS frames, and coordinates its own transmissions, reducing network complexity while maintaining reliability through distributed intelligence
Data Source
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AI summary
In one aspect the embodiments of the invention provide a method that includes transmitting a first frame comprising a first type of message from a first node for reception by a second node. The first node is associated with a first wireless communication system and the second node is associated with a second wireless communication system. The first type of message includes a first information element for identifying the second node and a second information element for specifying that the first frame is transmitted to initiate a request for simultaneous transmission by the first node and by the second node. The first frame is also received by a third node that is part of the first wireless communication system. The method further includes receiving from the third node a second frame that includes a second type of message. The second type of message identifies the second node and specifies, based on a measurement performed by the third node on the first frame and a measurement performed by the third node on a third frame transmitted by the second node, whether the request for simultaneous transmission is accepted or is not accepted by the third node. The method further includes transmitting a fourth frame that includes the second type of message from the first node for reception by the second node. The second type of message identifies the second node and specifies that the request for simultaneous transmission was accepted by the third node.