Packet Segmentation for Hidden Node Collision Avoidance
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Solution Overview
Problem
Communication networks face inefficiencies due to hidden node collisions, where nodes outside the sensing range of a transmitter can collide with ongoing transmissions, leading to packet loss and retransmissions, especially in networks with small maximum transmission units (MTU) sizes like power line communication networks (PLC) compliant with G3 standards.
Innovation Solution
The solution involves subdividing packets into segments and transmitting them sequentially, with acknowledgement packets indicating whether additional segments are to be sent, allowing nodes to refrain from transmission and reducing collisions without using additional RTS and CTS frames, thereby minimizing network overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packets are transmitted without segmentation in networks with small MTU sizes, then transmission simplicity is maintained, but hidden node collisions occur more frequently causing packet loss and retransmissions
Solution Approach 1:
The patent divides large packets into multiple smaller segments before transmission. Each segment is transmitted separately with its own acknowledgment mechanism. This segmentation allows hidden node collissions to affect only individual segments rather than entire packets, reducing retransmission overhead and improving overall network reliability and efficiency.
2Reliability
If reservation time intervals are extended to prevent hidden node collisions, then collision avoidance is improved, but network bandwidth is wasted due to prolonged reservations
Solution Approach 1:
By segmenting packets and creating separate reservation intervals for each segment, the patent reduces the duration of each reservation compared to reserving for the entire packet. This allows other nodes to utilize the network during gaps between segment transmissions, reducing bandwidth waste while maintaining collision avoidance.
Solution Approach 2:
The patent implements periodic transmission of segments with intermittent reservation intervals rather than continuous reservation. Each segment triggers a new reservation period, creating a rhythmic pattern of transmission and network availability that reduces overall bandwidth waste while preventing collisions.
3Reliability
If additional RTS and CTS frames are used to prevent hidden node collisions, then collision prevention is improved, but network overhead increases
Solution Approach 1:
The patent combines the acknowledgment function with the collision prevention mechanism by embedding collision avoidance information within existing acknowledgment packets. This merging eliminates the need for separate RTS and CTS frames, reducing network overhead while maintaining collision prevention capabilities.
Solution Approach 2:
The acknowledgment packet serves multiple functions: it confirms receipt of a segment, triggers the next segment transmission, and simultaneously prevents hidden node collisions by reserving the network. This multi-functionality reduces the number of separate control frames needed, lowering overall network overhead.
Data Source
AI summary
Method and apparatus for avoiding hidden node collisions in a communication network. A network communication device includes a packet transmitter. The packet transmitter is configured to subdivide a packet to be transmitted via a communication network into a plurality of segments based on the packet exceeding a predetermined maximum size, and to sequentially transmit the segments via the communication network. The packet transmitter is also configured to construct an acknowledgement packet responsive to reception of each segment of a packet received via the communication network. The acknowledgement packet includes a field indicating whether an additional segment of the packet is to be transmitted via the communication network. The packet transmitter is further configured to transmit the acknowledgement packet via the communication network.