UWB Wireless Communication Preamble Collision Avoidance
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Solution Overview
Problem
In ultra-wide band wireless communication systems, existing access control methods struggle to prevent collisions and efficiently manage retransmissions, particularly in Ad Hoc networks without a base station, leading to decreased communication quality and increased complexity due to the difficulty in detecting transmission path usage and coordinating retransmissions.
Innovation Solution
The system employs a preamble signal to indicate transmission path usage, with communication apparatuses detecting and responding with ACK or NACK packets to manage data retransmissions and access control, allowing non-communicating devices to recognize path availability and avoid collisions by using beacon signals and integrating RTS/CTS procedures within data packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CSMA/CA access control is used in ultra-wide band wireless communication, then communication terminals can share the frequency channel, but collisions of communication occur between terminals
Solution Approach 1:
The patent applies preliminary action by having communication terminals transmit a preamble signal before actual data transmission. This preamble serves as a reservation signal that reserves the transmission path for the upcoming data packet, allowing terminals to prepare and announce their transmission intentions in advance, thereby preventing collisions before they occur.
Solution Approach 2:
The patent implements feedback mechanisms through ACK (acknowledgement) and NACK (negative acknowledgement) signals that the receiving terminal sends back to the transmitting terminal. This feedback loop allows the transmitting terminal to know whether its data was successfully received and whether retransmission is needed, improving communication reliability while maintaining channel sharing efficiency.
2Reliability
If retransmission control is implemented to avoid collisions, then communication quality improves, but communication intervals increase
Solution Approach 1:
The preamble signal serves as a preliminary reservation that announces the intended transmission duration and timing. By reserving the path in advance and providing timing information through the preamble, the system can efficiently manage retransmissions without unnecessary delays, as the reservation already accounts for the transmission time needed.
Solution Approach 2:
The ACK/NACK feedback mechanism enables rapid detection of transmission success or failure. When a collision or error occurs, the receiving terminal immediately sends back a NACK signal, allowing the transmitting terminal to quickly initiate retransmission without waiting for the entire communication interval to elapse, thus minimizing time loss.
3Device complexity
If transmission path usage is not properly detected, then access control becomes simpler, but collisions occur more frequently
Solution Approach 1:
The patent extracts the essential function of path usage detection into a separate, dedicated preamble signal component. By separating the reservation function from the data transmission itself, the system achieves reliable path detection without complicating the overall access control mechanism. The preamble acts as a standalone reservation signal that can be detected independently.
Solution Approach 2:
The preamble signal serves as an intermediary between the transmission terminal and other listening terminals. It mediates the communication by providing a clear, detectable signal that announces the upcoming data transmission, allowing other terminals to understand the transmission path usage status without requiring complex detection mechanisms.
4Adaptability or versatility
If Ad Hoc communication without base station is used, then network construction flexibility improves, but coordination of retransmissions becomes more complex
Solution Approach 1:
In the Ad Hoc network configuration, each communication terminal autonomously manages its own transmissions and retransmissions using the preamble reservation and ACK/NACK feedback mechanisms. The terminals self-coordinate without requiring a base station or central controller, with each terminal independently detecting path usage and managing its retransmission timing based on the preamble signals it receives.
Data Source
AI summary
An information transmission source forms a transmission packet at a predetermined time unit into which a preamble is inserted and transmits it. The information reception target returns an acknowledge (ACK) packet or a not acknowledge (NACK) packet into which a preamble is inserted. A hidden terminal recognizes that the transmission path is used for data retransmission from when the NACK is received to when the next ACK is received to avoid collisions. Further, when there is transmission data at the information transmission source specified by a beacon signal, it is recognized that the transmission path is used until the next ACK is received. For example, in an ultra wide band communication method, access control is executed while avoiding collisions of communications and a retransmission control is executed.