Extended Range CTS Messages for Wireless Network Collision Avoidance
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Solution Overview
Problem
Wireless networks face challenges in extending communication range due to the 'hidden node problem,' where stations operating in different modes cannot detect each other's transmissions, leading to collisions and reduced network efficiency.
Innovation Solution
Implementing extended range Request-to-Send (XR RTS) and Clear-to-Send (XR CTS) messages with longer preambles and repetitions to enhance detection and coexistence between stations supporting different operating modes, along with energy measurements during backoff procedures to assess channel availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If extended range mode is implemented with longer preambles and repetitions, then communication range is extended by approximately 8 dB, but message collision probability increases and device complexity increases
Solution Approach 1:
The patent segments the CTS message into two distinct types: a first CTS message with a first preamble for legacy stations, and a second CTS message with a second preamble (including repetitions) for extended range stations. This segmentation allows each station type to process only the relevant message, reducing processing complexity while enabling extended range communication.
Solution Approach 2:
Different preamble structures are applied locally to different message types based on the receiving station's capabilities. Legacy stations receive and process only the first CTS message with its appropriate preamble, while extended range stations receive and process the second CTS message with its extended preamble containing repetitions. This local differentiation optimizes performance for each station type without burdening all stations with the more complex processing requirements.
2Adaptability or versatility
If multiple CTS messages are sent for different operating modes, then coexistence between stations is improved, but the time required for communication increases
Solution Approach 1:
The patent segments the response to an RTS message into two separate CTS messages transmitted in sequence. The first CTS message is transmitted immediately for legacy stations, and the second CTS message with extended preamble follows for extended range stations. This segmentation allows both station types to receive appropriate messages without requiring a single complex message that would increase processing time for all stations.
Solution Approach 2:
The patent transmits both the first CTS message (necessary for legacy station operation) and the second CTS message (necessary for extended range operation) as a complete set of actions. While this appears excessive, it ensures that all potential receivers can properly process the message according to their capabilities, and the time penalty is localized only to stations that require the extended range functionality.
3Measurement precision
If energy measurements are made over multiple time slots during backoff procedure, then detection accuracy is improved, but the backoff procedure duration increases
Solution Approach 1:
The patent segments the energy measurement process into multiple discrete time slots during the backoff procedure. Each time slot contains a specific number of OFDM symbols that can be independently measured. This segmentation allows the station to accumulate sufficient energy measurement data across multiple slots to accurately determine channel availability, while maintaining a structured approach that minimizes overall backoff duration.
Data Source
AI summary
Techniques for supporting communication over an extended range in a wireless network are disclosed. In one aspect, a station sends multiple messages of a given type for different operating modes. These messages can be detected by stations with different capabilities, which may avoid collisions between stations. In one design, a first station receives a Request-to-Send (RTS) message from a second station having data to send. The first station sends a first Clear-to-Send (CTS) message and also a second CTS message in response to the RTS message. The second CTS message has an extended range as compared to the first CTS message. The first station thereafter (i) receives data sent by the second station in response to the second CTS message and (ii) sends an acknowledgement having an extended range.