Frequency-Selective Carrier Sensing for FDMA-CSMA Collision Avoidance
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Solution Overview
Problem
The combination of Frequency Division Multiple Access (FDMA) with Carrier Sense Multiple Access (CSMA) or CSMA/CA is not feasible without full-duplex communication devices, leading to underutilization of wireless communication networks, as existing methods require sensing the entire channel bandwidth and cannot differentiate between transmission and reception on different frequency subcarriers.
Innovation Solution
A method and device that allow communication devices to transmit a control sequence on specific subcarriers, enabling demodulation of radio resources to determine if a device is currently transmitting, thereby refraining from transmission if the control sequence is detected, and allowing data transmission if not, thus enabling FDMA with CSMA/CA without full-duplex capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If frequency-selective sensing is used to enable FDMA with CSMA, then medium utilization improves, but device complexity increases due to full-duplex requirement
Solution Approach 1:
The patent segments the channel sensing process by frequency subcarriers, introducing a control sequence that is transmitted on specific subcarriers to indicate transmission status. This allows receiving devices to sense only relevant subcarriers rather than the entire bandwidth, enabling FDMA with CSMA without full-duplex capability and improving medium utilization while reducing device complexity
Solution Approach 2:
The control sequence acts as an intermediary signal that carries transmission status information on specific subcarriers. This intermediary mechanism allows devices to infer channel availability without requiring full-duplex capability, resolving the contradiction between medium utilization and device complexity
2Reliability
If wide-band sensing across complete channel bandwidth is used, then collision avoidance improves, but energy consumption increases
Solution Approach 1:
The patent divides the channel sensing process into segments based on frequency subcarriers, with devices sensing only the subcarriers relevant to their transmissions. The control sequence is placed on specific subcarriers to indicate transmission status, allowing collision avoidance through targeted sensing rather than exhaustive wide-band sensing, thus reducing energy consumption while maintaining reliability
Solution Approach 2:
The sensing process is optimized by applying different sensing strategies to different frequency subcarriers. The control sequence is transmitted on specific subcarriers with distinct properties, allowing devices to focus sensing efforts locally on relevant subcarriers rather than uniformly across the entire bandwidth, reducing energy consumption while ensuring collision avoidance
Data Source
AI summary
A first communication device and a method performed thereby are provided for communicating with at least a second communication device. The first and the second communication device are operable in a wireless communication network employing contention based access for radio resources comprising a plurality of frequency subcarriers, wherein at least the second communication device transmits a control sequence on at least one subcarrier of a predefined subcarrier pattern when transmitting data. The method comprises: demodulating the radio resources on at least a subset of subcarriers of the predefined subcarrier pattern; and determining whether the demodulated radio resources comprise the control sequence; that being the case: refraining from transmitting data to the second communication device; and otherwise: transmitting data to the second communication device.