# Blockchain Release: HIP 17

The 2020.12.15.2 release was a monumental release adding support for HIP17. Note that we have decided to scrap the 2020.12.09.0, 2020.12.11.0, and 2020.12.15.1 releases because of bugs we identified during ongoing testing. Details about those bug fixes can be found here and here.

#### HIP17: Hex density based reward scaling​

The primary goal of HIP17 is to scale the rewards for challengees (transmitters) and witnesses (receivers) depending on the h3 hexagon they are asserted at. This change to reward distribution is to better incentivize coverage by reducing rewards earned by transmitting/witnessing hotspots in close proximity to each other. The formulae used for the scaling are detailed in the above link.

Essentially we expect an optimum density at every possible h3 resolution, these would be supplied as chain variables when we activate this feature. If the challengee is found to be in a hex where the density is higher than the configured optimum value, they would get scaled rewards. The witnesses for those transmissions would get the scale of the transmitter applied to their rewards as well. It's important to note that the scale of the witness does not matter.

The team has modeled all the Hotspots on the network with their corresponding scale values, below are some examples of scale values from the map.

NOTE: The scale value on the below images does not apply to overall reward scaling, it's only an indicator for PoC transmission reward scaling. A scale of 0.2 does not mean that a Hotspot's overall rewards will go down by 80%.

Sparse Density Scaling

Variable Scaling

Dense Cluster Scaling

Finally, here's San Francisco with Scaling

The team had previously published 2020.11.10.0 which added support for HIP15, this release adds on top of that since HIP17 goes in conjunction with HIP15.

NOTE: This release only adds support for HIP17, please refer to the plan to know the exact activation time.

#### HIP17: Proposed chain variables​

These are the same chain variables as proposed in the HIP17, just written in a way that the chain understands.

Chain VariableProposed ValueReason
hip17_res_0<"2,100000,100000">>Default (unused)
hip17_res_1<"2,100000,100000">>Default (unused)
hip17_res_2<"2,100000,100000">>Default (unused)
hip17_res_3<"2,100000,100000">>Default (unused)
hip17_res_4<<"1,250,800">>Number of siblings: 1, density_tgt: 250, density_max: 800
hip17_res_5<<"1,100,400">>Number of siblings: 1, density_tgt: 100, density_max: 400
hip17_res_6<<"1,25,100">>Number of siblings: 1, density_tgt: 25, density_max: 100
hip17_res_7<<"2,5,20">>Number of siblings: 2, density_tgt: 5, density_max: 20
hip17_res_8<<"2,1,4">>Number of siblings: 2, density_tgt: 1, density_max: 4
hip17_res_9<<"2,1,2">>Number of siblings: 2, density_tgt: 1, density_max: 2
hip17_res_10<<"2,1,1">>Number of siblings: 2, density_tgt: 1, density_max: 1
hip17_res_11<<"2,100000,100000">>Default (unused)
hip17_res_12<<"2,100000,100000">>Default (unused)
density_tgt_res4Resolution to calculate density
hip17_interactivity_blocks3600Number of blocks since last_poc_challenge a Hotspot is considered active

Furthermore, below are the proposed chain variables for HIP15:

Chain VariableProposed ValueReason
witness_redundancy4Optimum desired redundant witnesses for a poc transmission
poc_reward_decay_rate0.8Decay rate for additional poc transmission

In order to have full effect for HIP17 all the above mentioned chain variables (HIP15 + HIP17) are required.

#### Bump snapshot to 624961​

This release also bumps the blessed snapshot to height 624961 which will improve sync times of newly onboarded Hotspots.

### Plan​

We began beta-testing 2020.12.09.0 around 5:00 PM PST, December 8th, 2020 and plan to GA on Thursday, December 10th, 2020 around 2PM PST. We will activate HIP17 and HIP15 chain variables on Monday, December 14th, 2020 and will be announcing this change via push notification and on Discord.

We began beta-testing 2020.12.09.0 around 5:00 PM PT, December 8th, 2020 and deployed the release to GA on Thursday, December 10th, 2020 around 3:00 PM PT. After identifying an issue that required an additional deployment before the chain variable activation, we began beta-testing 2020.12.11.0 around 4:00 PM PT, Friday, December 11, 2020. We plan to GA around 10:00 AM, Sunday, December 13, 2020.

We planned to activate the HIP17 and HIP15 chain variables on Monday, December 14th, 2020 but scrapped the change due to bugs we found in HIP17 implementation. A future blog post will describe our next steps.

We activated the HIP17 and HIP15 chain variables on Wednesday, December 16th, 2020 at 10AM PST. Activation Transaction can be found on Helium Explorer.