Communication Apparatus Pseudo Back-Off Contention Control
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Solution Overview
Problem
Conventional communication systems using CSMA/CA for contention control face challenges in systems without a central control terminal, where collision detection is difficult, and unequal transmission chances lead to reduced throughput and capture effects, especially in high traffic conditions.
Innovation Solution
A communication apparatus that employs a pseudo back-off process to observe medium occupation states, determining contention window sizes based on statistical information such as trial numbers, contention wins, losses, and collisions, allowing for dynamic adjustment of contention window sizes without a central control terminal, ensuring equal transmission chances among terminals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If each terminal sets its CW size based only on its own trial results, then the back-off process is simple to implement, but collision is not avoided effectively in high traffic conditions leading to reduced throughput
Solution Approach 1:
The patent introduces a pseudo back-off process as an intermediary mechanism that allows terminals to observe medium occupation states without actually transmitting data frames. This mediator process enables terminals to gather statistical information about medium usage patterns and determine appropriate CW sizes based on system-wide conditions rather than just individual trial results, thereby improving throughput while maintaining reasonable implementation complexity
Solution Approach 2:
The patent applies preliminary action by performing pseudo back-off processes before actual data transmission attempts. Terminals use these preliminary pseudo trials to observe medium states and build statistical information about traffic conditions, allowing them to set optimal CW sizes in advance before real transmission occurs, thus avoiding collisions and improving overall system productivity
2Reliability
If the CW size is increased to avoid re-collision, then collision probability is reduced, but waiting time increases rapidly and throughput decreases
Solution Approach 1:
The patent implements dynamics by making the CW size adaptive rather than static. Through the pseudo back-off process, terminals dynamically adjust CW sizes based on observed medium occupation states and statistical information. This dynamic adjustment allows the system to use smaller CW sizes when traffic is light (reducing waiting time) and larger CW sizes when traffic is heavy (improving collision avoidance), thus resolving the contradiction between reliability and time loss
Solution Approach 2:
The patent employs feedback mechanisms where terminals continuously monitor medium occupation states through pseudo back-off processes and use this feedback information to adjust their CW sizes. The statistical information gathered from multiple pseudo trials provides feedback about system conditions, enabling terminals to optimize their transmission timing and balance collision avoidance with waiting time minimization
3Productivity
If the CW size of newly transmitting terminals is small, then they can transmit with higher probability, but inequality occurs with repeatedly retransmitting terminals having larger CW sizes
Solution Approach 1:
The patent applies equipotentiality by creating equal transmission opportunities for all terminals through the pseudo back-off process. All terminals, whether newly transmitting or repeatedly retransmitting, use the same pseudo back-off mechanism to observe medium states and determine their CW sizes. This levels the playing field by removing the advantage that newly transmitting terminals had due to their smaller initial CW sizes, ensuring fair and equal transmission chances for all terminals in the system
Data Source
AI summary
A communication apparatus improves the throughput of a whole communication system while performing contention distributed control which provides equality of a transmission chance by observing a medium occupation state. The communication apparatus includes a back-off process section for performing, using a contention window, a regular back-off process which is performed at transmission of a transmission frame and a pseudo back-off process which is performed in a pseudo manner when the transmission frame is not transmitted. The communication apparatus also includes a medium information obtaining section for obtaining, by the pseudo back-off process, medium information indicative of a state of the transmission line medium when the transmission frame is not transmitted, and a medium state determination section for determining the state of the transmission line medium using the medium information to obtain determination information.