Ad Hoc Network Node Grouping for Collision Reduction
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Solution Overview
Problem
Ad hoc networks experience significant delays due to collisions during message transmission, particularly when using random access time slots, which can lead to lengthy waiting times for retransmissions.
Innovation Solution
A method is introduced where each node estimates the number of neighboring nodes, calculates the probability of collision, and imposes constraints on itself and its neighbors to reduce collisions by dividing nodes into groups that transmit in specific frames, thereby minimizing the risk of simultaneous transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nodes transmit information in organized random access time slots, then the network can organize itself without central management, but collisions occur when multiple nodes transmit simultaneously causing delays
Solution Approach 1:
The patent segments the ad hoc network into virtual clusters based on geographic proximity and transmission interference patterns. Nodes are grouped such that nodes within the same cluster can transmit simultaneously without causing harmful interference to each other, while nodes in different clusters coordinate their transmissions to avoid collisions. This segmentation resolves the contradiction by enabling self-organization through distributed clustering while reducing collisions through spatial separation of simultaneous transmissions.
Solution Approach 2:
The patent introduces a spatial dimension to the transmission coordination problem by using geographic location and interference patterns as additional dimensions for organizing transmissions. Instead of purely temporal coordination (time slots), the system adds spatial coordination through virtual clusters defined by geographic proximity and interference relationships. This dimensional extension allows multiple non-interfering transmissions to occur simultaneously, reducing waiting time while maintaining self-organization.
2Reliability
If exponential backoff algorithm is used to calculate waiting time before retransmission, then collision probability is reduced, but transmission delays increase significantly
Solution Approach 1:
The patent applies local quality by having nodes adjust their transmission parameters based on local conditions within their virtual cluster rather than using a uniform global backoff mechanism. Each node calculates its waiting time and transmission probability based on local factors such as the number of active nodes in its cluster, observed collision rates in the local area, and its position within the cluster hierarchy. This localized adaptation reduces waiting times compared to conservative global exponential backoff while maintaining collision avoidance through context-aware transmission decisions.
Solution Approach 2:
The patent implements dynamic transmission parameters that adapt in real-time based on network conditions. Instead of fixed exponential backoff intervals, nodes dynamically adjust their waiting times and transmission probabilities based on current cluster activity, observed collision patterns, and changing network topology. This dynamic approach allows the system to maintain high reliability by adapting to actual collision risks while minimizing unnecessary waiting periods when collision probability is low, thereby resolving the contradiction between reliability and time loss.
3Loss of information
If nodes transmit signaling data to all neighboring nodes, then information reaches the destination, but collision probability increases with more simultaneous transmissions
Solution Approach 1:
The patent segments the broadcast domain into virtual clusters, where signaling data is transmitted within confined geographic and interference-based boundaries. Instead of every node transmitting to all neighbors simultaneously across the entire network, nodes transmit signaling data primarily to nodes within their own virtual cluster. This segmentation reduces the number of simultaneous transmissions in any given area, thereby reducing collision probability while maintaining information delivery reliability through hierarchical routing between clusters.
Solution Approach 2:
The patent introduces virtual cluster heads or intermediary nodes that coordinate signaling data transmission within clusters. Instead of all nodes transmitting simultaneously to all neighbors, the intermediary nodes manage the transmission schedule and relay information within the cluster and to other clusters. This intermediary mechanism reduces collision probability by coordinating transmissions while ensuring complete information delivery through the intermediary relay system.
Data Source
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AI summary
The information transmission process in an ad hoc network comprises at least two transmitting and receiving nodes, each capable of receiving and transmitting information and communicating with each other by sending information in randomly accessed time slots organized into frames. The network nodes are divided into groups according to a distribution rule, with nodes in each group only authorized to transmit information within a predefined subset of frames specific to that group.