OFDMA Wireless Mesh Access Control for Collision Avoidance
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Solution Overview
Problem
Existing access control methods for wireless mesh networks, particularly those based on OFDM, face inefficiencies in resource allocation due to increased transmission power requirements and degradation in resource utilization for small bursts, especially with the need for guard symbols in OFDMA-based systems.
Innovation Solution
A method and apparatus for access control in an OFDMA-based wireless mesh network that involves calculating and transmitting next transmission intervals and subframes between communication nodes, using parameters like Exp, Mx, and RxFwdTimeDiff to determine optimal subframe and subchannel allocation, thereby preventing collisions and improving resource utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OFDM-based time division multiple access is used for access control in wireless mesh networks, then transmission can be performed with guard symbols allocated for each transmission, but resource transmission efficiency for small bursts is severely deteriorated and transmission power requirements increase
Solution Approach 1:
The patent transitions from OFDM-based time division multiple access to OFDMA-based access control, fundamentally changing the access mechanism parameters. This allows multiple users to transmit simultaneously on different subcarriers, eliminating the need for guard symbols for each transmission and significantly improving resource transmission efficiency for small bursts while maintaining transmission reliability through orthogonal frequency division multiplexing
2Ease of operation
If guard symbols are allocated for each transmission in wireless mesh networks, then transmission/reception conversion can be performed, but resource transmission efficiency for small bursts is severely deteriorated
Solution Approach 1:
The patent extracts and eliminates the guard symbol requirement from each transmission by implementing OFDMA-based access control. The orthogonal frequency division multiplexing structure inherently handles transmission/reception conversion without requiring additional guard symbols, thereby removing the source of resource inefficiency while preserving the necessary transmission/reception conversion functionality
3Power
If longer OFDM FFT length is used, then transmission power can be distributed, but the amount of transmission power required increases and resource allocation efficiency for small bursts degrades
Solution Approach 1:
The patent segments the frequency spectrum into multiple orthogonal subcarriers through OFDMA, allowing transmission power to be distributed across these segmented frequency resources. This segmentation enables efficient power utilization for small bursts by allocating power only to the necessary subcarriers and time slots, rather than requiring longer FFT lengths that consume more total power
Data Source
AI summary
In an orthogonal frequency division multiple access (OFDMA)-based wireless mesh network, a communication node receives information regarding a next transmission time of a 1-hop node and a 2-hop node through the 1-hop node, calculates next transmission intervals of the 1-hop node and the 2-hop node, determines a next transmission time of the communication node by using the next transmission intervals of the 1-hop node and the 2-hop node, and then transmits, to an 1-hop node of the communication node, the information of the next transmission time together with the information of the transmission time of the 1-hop node, received from the 1-hop node.