Comparison

Problem

"How to transfer the sensors readings (quality of the opinion) into a secure dissemination strategy that is similar to the existing approach?"

Comparison

Dissemination

Feature	Classical approach	Blockchain approach
Number of used opinions for voting strategy	Last 2 opinions in robot's memory	Last 2 opinions in robot's blockchain
Time	proportional to sensor readings p, using a sample from an exponential distribution with pg, g = 10	see strategies below
Broadcasting	During the entire phase	During the entire phase
Listening	Only in the last 3s of the phase [1]	Only in the last 3s of the phase
Peers	Send opinions to peers if distance is below 50 cm	Connect to peers (i.e., to their Ethereum process) if distance is below 50 cm (only in the last 3 s)
Mining	Not applicable	In the last 3s of the dissemination state
Decision-making strategies:	DC, DMMD, DMVD	see strategies below

[1] This is done, such that on average the robot has the same number of neighbors and no time effects are introduced into the system.

Exploration

Feature	Classical approach	Blockchain approach
Time	Sample from an exponential distribution with σ = 10	Sample from an exponential distribution with σ = 10
Peers	Do not send/receive messages	Not connected to any peers
Mining	Not applicable	No

Strategies

Strategy 1: Amount of transactions

• Send a transaction with 1 ether in each timestep of the dissemination state
• Expected behavior: The stronger the opinion, the more transactions will be sent; therefore it is more likely that one of these transactions belong to the last two in the blockchain
• Disadvantage: Is this strategy close enough (amount of votes vs. time of dissemination) to the other approach?

Strategy 2: Direct modulation

• Send one transaction each time a robot enters the dissemination state, include amount of ether that is proportional to the quality of the opinion
• Expected behavior: Should be very similar to the non-secure version; the last two votes in the blockchain
• Disadvantage: None. Should be directly comparable to the DC strategy.

Strategy 3: Dissemination time

• Make dissemination time proportional to the quality of the opinion (i.e., exactly the same as in the non-secure approach)
• Expected behavior: The longer a robot disseminates its opinion, the more likely it is that the transaction gets included in the blockchain (more robots receive the transaction -> more hash power).
• Only listen to other opinions in the last 3s, only mine in the last 3s
• Send voting transaction in the dissemination state using the JSON-RPC interface
• Open questions: When to start the mining process? Does it make sense? Is it a secure approach (i.e., how robust is it to attacks)?

Strategy 4: Hash-puzzle

• Robots have to solve a (hash-based) puzzle, whose difficulty is proportional to the quality of the opinion they want to send
• Expected behavior:

Strategy 5: Most similar

• Only connect to neighbors in the dissemination state
• The longer a robot is in the state, the more other robots will receive its opinion
• Problem: When do robots mine? Only in the last x seconds (fixed)? Or for a time proportional to their opinion?
• Expected behavior:

Alternative

• Use an alternative approach that is not similar to Gabri's approach
• Expected behavior:
• Advantages: Can tailor approach to the blockchain
• Disadvantages: Might be harder to compare the approach and show its advantages