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Light Hotspots - Beta

This document describes the architecture and technical roadmap planned for converting existing Approved Hotspots to Light Hotspots. As part of this migration, we have introduced a new Hotspot variant onto the network, called a Data Only Hotspot. More details on progress and timeline are listed below.

This project is in progress and subject to change. Last updated Wednesday October 21, 2021.

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For real-time development and community support of Data Only Hotspots and Light Hotspots, please join the #gateway-development channel on Helium Discord

What is a Light Hotspot?

Light Hotspots are the evolution of how LoRaWAN gateways will interact with the Helium blockchain. Since the genesis block, the Helium blockchain has run entirely on the physical Hotspot itself. As the blockchain network grows, each Hotspot running a full node undergoes increasing load and are starting to fall out of sync due to the higher compute requirements.

To mitigate this, the Hotspot's consensus work has been moved off of physical Hotspots and onto Validators as of July 8, 2021. This simplifies the architecture and enables us to grow the Network exponentially while keeping blocktimes and epochs stable.

As all approved Hotspots transition to a Light Hotspot architecture, we also introduce a new type of Hotspot known as Data Only Hotspots, activated as of July 20, 2021, to satisfy the increasing demand and continue to expand network coverage.

As of October 11 2021, Data-Only Hotspots can mine HNT for forwarding data packets on the network.

Rewards TypeData Only HotspotsFull & Light Hotspots
Network Data ForwardingYESYES
Proof of CoverageNOYES

Light Hotspot Properties

When the Light Hotspot Client is fully developed and in production (which will happen with the completion of Milestone 4 detailed below) they will satisfy the following properties:

  • A Hotspot on the Helium network that, via Validators, can participate in PoC beacons and witnesses, and forwards data packets;
  • Does not store a copy of the Blockchain, eliminating synchronization;
  • Does not create challenges (relies on Validators to create challenges on their behalf);
  • Does not participate in Consensus Groups (relies on Validators for block production);
  • Will no longer depend on libp2p or "gossip", and instead use gRPC, a new framework to communicate between distributed systems;
  • Will be eligible to earn $HNT (see table below)

In other words, the client will allow the Hotspot to participate as a Full Hotspot, without the extra overhead of maintaining a local copy of the blockchain.

Architecture

This image shows the progression to Light Hotspots, with the role of Miner being deprecated as we move the blockchain off the Hotspots and into the Validator infrastructure. At the conclusion of Milestone 4, the entire Helium blockchain, and the coordination of Proof of Coverage, will be handled by Validators.

Code and Development

The bulk of the code that enables Light Hotspots on actual LoRaWAN gateways is called gateway-rs. It's easiest to think of this as Helium's next-generation packet forwarder.

Development of this code takes place in the above GitHub repo, as well at the #gateway-developement channel on the Helium Discord Server.

Development Milestones

The development of Light Hotspots will be broken up into the five following milestones.

Milestone 1: Free Packet Forwarding

  • Target Completion Date: March 18
  • Status: COMPLETE

At the completion of Milestone 1, any LoRaWAN gateways running gateway-rs can route packets to and from the Helium Network but not earn HNT. This means an DIY gateway can send and receive data on the Network. These LoRaWAN Gateways running gateway-rs are known as Data Only Hotspots.

Milestone 1.5: Add Hotspot to Blockchain

  • Target Completion: early July
  • Status: COMPLETE

At the completion of Milestone 1.5, Data Only Hotspots can be added to the blockchain, assert its location, and be seen on explorer.helium.com.

Data Only Hotspots are added to the blockchain by paying a $10 Add Gateway transaction fee, and a $5 Assert location transaction fee using the Helium Wallet CLI and will not earn $HNT.

Milestone 2: Earn HNT For Device Packet Transfer

  • Target Completion: Fall 2021
  • Status: Development Complete (Oct 11, 2021)

Data Only Hotspots will earn $HNT for device data transfer. A further breakdown of progress is outlined below:

Path to Milestone 3 and Milestone 4

Work for both Milestone 3 and 4 are under way. The core team is currently focused on transitioning Full Hotspots to Light Hotspots due to the increasing size of the network and the amount of work needed to sustain this large peer-to-peer network.

  • Change how Hotspots route data packets by replacing its state_channel client from erlang to rust, taking advantange of the improvements in gRPC and data streaming (complete)
  • Update how Hotspots receive, emit, and acknowledge proof-of-coverage receipts from erlang to rust (in progress, targets milestone 4)
  • Test PoC in testnet (not started, targets milestone 4)
  • Update how full Hotspots communicate from libp2p to gRPC and follow a Validator for ledger information instead of syncing a local copy of the blockchain (in progress, targets milestone 4)
  • Implement the work to move Challenge creation to Validators from Hotspots, to be gated behind a chain variable (HIP in progress)
  • Activate the chain variable to move Challenge creation to Validators (to be announced)
    • At this point, existing Hotspots no longer need to sync or absorb the blockchain, and will satisfy another property of Light Hotspot
    • Hotspots existing on-chain will be able to participate in Proof-of-Coverage, no longer need to syncronize the blockchain, and will require less computational power (Milestone 4)

Milestone 3: Introduction of Light Hotspots

  • Target Completion: Q1 2022
  • Status: Development in Progress/PoC work started

Approved Hotspots from HIP19-approved manufacturers with lower compute requirements can be added to the network and participate in PoC.

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HIP-19 Makers: Hardware Audit will commence as soon as early November. Milestone 3 completion is not required for Audit. Please contact MOC for more details.

Onboarding for these Light Hotspots will be done via the standard Helium Wallet app onboarding. The fees will be equivalent to other Approved Hotspots ($40 and $10 for add assert, respectively).

At this stage, there will be three types of Hotspots:

  1. Approved Hotspot (HIP-19 approved, earns HNT for PoC and Data Transfer, follows Blockchain)
  2. Light Hotspot (HIP-19 approved, earns HNT for PoC and Data Transfer)
  3. Data Only Hotspot (DIY LoRaWAN Gateway, earns HNT for Data Transfer)

Milestone 4: "Heavy" Hotspots -> Light Hotspots

  • Target Completion: Q4 2021
  • Status: Development in Progress

Approved Hotspots on the Network will be converted to run gateway-rs and will be dependent on Validators to generate challenges and process witness receipts.

Hotspots will not need to follow the Blockchain.

Work on Milestone 4 has already started, please see Path to Milestone 3 and 4 above.