Variable SDMA ACK Timeout Mechanism
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Solution Overview
Problem
In wireless data communications systems, the variable length of data blocks can lead to unnecessary retransmissions and inefficiencies due to the base station's inability to transmit acknowledgments simultaneously with receiving data from multiple devices on the same frequency, causing potential service interruptions.
Innovation Solution
Implementing a sliding timeout period for mobile devices to wait until the base station has finished receiving transmissions from other devices before initiating their own timeout period, and using channel clear detection to ensure acknowledgments are sent only when the channel is clear, preventing premature timeouts and retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the base station waits for all incoming data blocks to be complete before sending acknowledgments, then transmission reliability is improved, but communication efficiency deteriorates due to unnecessary retransmissions
Solution Approach 1:
The patent applies dynamics by making the timeout period variable rather than fixed. Each mobile device's timeout period is dynamically adjusted based on the length of its data block and the current channel conditions. Short data blocks receive shorter timeout periods while long data blocks receive longer timeout periods, allowing the system to adapt to varying transmission conditions and eliminate unnecessary retransmissions.
Solution Approach 2:
The patent changes the parameter of timeout period from a fixed value to a variable value that depends on data block length and channel state. By modifying this temporal parameter dynamically, the system resolves the contradiction between maintaining reliable transmission (avoiding premature timeouts) and improving communication efficiency (avoiding unnecessary waits).
2Device complexity
If a fixed timeout period is used for all mobile devices, then device complexity is reduced, but loss of time increases due to premature timeouts on short data blocks
Solution Approach 1:
The timeout period becomes a dynamic parameter that automatically adjusts based on the mobile device's data block length and the base station's reception schedule. This dynamic adjustment eliminates premature timeouts for short data blocks while maintaining simple device operation, as the timeout calculation is performed automatically based on pre-established rules.
3Device complexity
If the base station transmits and receives on the same frequency, then device complexity is reduced by using a single frequency, but loss of time occurs due to inability to simultaneous transmit and receive
Solution Approach 1:
The patent applies preliminary action by having mobile devices calculate and set their timeout periods in advance, before the actual transmission and acknowledgment exchange occurs. This preliminary timeout configuration allows the system to account for the base station's reception schedule ahead of time, eliminating delays caused by the inability to simultaneously transmit and receive on the same frequency.
Data Source
AI summary
In a spatial division multiple access system that employs acknowledgements to variable length transmissions within a timeout period, a station that has completed its transmission may delay beginning the timeout period until it determines that other stations on the same channel have completed their transmissions.