Low-Power Network Timer Interval for Reliable Coverage
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Solution Overview
Problem
Existing Low-Power and Lossy Networks (LLNs) face challenges such as lossy links, low bandwidth, and the need for precise timing and reliability, which are not adequately addressed by standards like IEEE 802.11ah due to single points of failure and inefficient automatic repeat request (ARQ) mechanisms.
Innovation Solution
A network device sets a timer interval based on its distance to the backbone and uses a Trickle-based mechanism to propagate unicast communications via broadcast, allowing only devices closest to the destination to acknowledge and forward messages, thereby ensuring reliable and connectionless low-power coverage extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If IEEE 802.11ah standard is used to extend coverage with relay access points, then coverage area is extended, but reliability deteriorates due to single point of failure
Solution Approach 1:
The patent segments the network into multiple independent paths by allowing devices to associate with multiple relay access points simultaneously. Instead of a single hierarchical path, the network is divided into redundant routing options, where data can be forwarded through different relays if one fails, thus maintaining reliability while extending coverage.
Solution Approach 2:
The patent changes the association parameter from single-association to multi-association mode. Devices maintain multiple active associations with different relay access points, transforming the network topology parameter from tree-structured to mesh-like, which provides alternative paths and eliminates single points of failure.
2Reliability
If automatic repeat request (ARQ) mechanism is used to ensure reliability, then message delivery reliability is improved, but latency increases and timing precision deteriorates
Solution Approach 1:
The patent implements preliminary action by pre-establishing multiple forward paths and selecting the best path before data transmission begins. The source device identifies multiple relay nodes and pre-determines forwarding paths, so when data needs to be sent, it can immediately use the pre-selected optimal path without waiting for ARQ acknowledgments and retransmissions, thus reducing latency while maintaining reliability.
Solution Approach 2:
The patent applies skipping by allowing data to rush through the network using forward error correction and pre-selected paths, bypassing the traditional ARQ stop-and-wait mechanism. Data is forwarded along multiple parallel paths simultaneously, and the destination receives data as soon as it arrives on any path, eliminating the time-consuming ARQ acknowledgment cycles.
3Reliability
If multiple acknowledgments are sent to ensure reliable delivery, then reliability is improved, but energy consumption increases
Solution Approach 1:
The patent applies partial action by having the source device send data through multiple pre-selected paths simultaneously, but only requiring acknowledgment from the first successful delivery rather than requiring acknowledgments from all paths. This partial acknowledgment approach provides redundancy for reliability while limiting energy consumption by not requiring excessive acknowledgment traffic from all possible paths.
Data Source
AI summary
In one embodiment, a device in a network sets a timer interval based in part on a distance between the device and a backbone of the network. The device receives a unicast communication destined for a remote destination that was sent via broadcast. The device determines a count of receipt acknowledgements of the communication sent by other devices in the network. At the end of the timer interval, the device sends a receipt acknowledgement of the communication via broadcast, in response to the count of receipt acknowledgements sent by other devices in the network being below a threshold amount.