Zigbee Router Fragment Acknowledgment for Sleepy End Devices
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Solution Overview
Problem
The Zigbee protocol experiences significant communication overhead and power consumption due to redundant data exchanges and unnecessary re-transmissions caused by fragmentation processes, particularly affecting battery-powered 'sleepy' end devices.
Innovation Solution
A Zigbee router device is configured to intercept and manage fragmentation processes, sending acknowledgement messages on behalf of the end device, except for the last block, thereby reducing redundant communications and optimizing the fragmentation window to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ZED sends individual APS acknowledgments for each received data block, then the source device can confirm successful receipt of each block, but the communication overhead and power consumption increase significantly
Solution Approach 1:
The patent combines multiple individual APS acknowledgment transmissions into a single batched acknowledgment message. Instead of sending separate APS ACKs for each data block received, the ZED accumulates acknowledgments and transmits them together in one message, thereby confirming receipt of multiple blocks while significantly reducing the number of radio transmissions and associated power consumption.
Solution Approach 2:
The patent implements preliminary buffering of acknowledgment information before transmission. The ZED prepares and queues acknowledgment data for multiple received blocks in advance, then transmits them together when appropriate, rather than immediately transmitting each acknowledgment as it is generated. This preliminary action reduces the frequency of radio transmissions.
2Reliability
If the fragmentation window is set to '1' data block, then each block can be acknowledged individually, but the number of re-transmissions and communication overhead increases
Solution Approach 1:
The patent merges multiple individual acknowledgment operations into a single batched acknowledgment transmission. By combining acknowledgments for multiple data blocks into one message, the system maintains individual block confirmation capability while reducing the total number of transmission cycles and associated delays from re-transmissions.
3Reliability
If the ZED keeps its radio open to receive fragmented data blocks, then complete data can be received, but power consumption increases due to extended radio activity
Solution Approach 1:
The patent allows the ZED to receive and buffer multiple data blocks in advance while in a low-power state, then process and acknowledge them together in a single radio transmission event. This preliminary reception and buffering action enables complete data acquisition without requiring the radio to remain continuously active, thereby reducing overall power consumption while maintaining reliable data reception.
Data Source
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AI summary
A method for delivering data frames from a source device (702) to a Zigbee end device, ZED, (550) via a Zigbee router, ZR, (510), comprises, at the ZR, receiving individual data blocks with a fragmentation window of '1' data block between the ZR and the source, individually transmitting an APS acknowledgement for received data blocks identified by APS transmission parameters. Data blocks are re-transmitted until an acknowledgement of a successful receipt is transmitted to the source. The data block is transmitted to the ZED until an acknowledgement is received. Following a penultimate data block (720) having been transmitted from the ZR and acknowledged by the ZED, the method further comprises at the ZED: transmitting a second data request (762, 772) to the ZR for a final data block; and transmitting an APS acknowledgement of successfully receiving the final data block to the ZR; and to the source.