5.2.3. Data Throughput

In order to evaluate overhead of running EconLedger on communication channel, we considered volumes of message propagation and data throughput during key steps of the PoENF consensus protocol. Figure 6 demonstrates data transmission for different stages of PoENF consensus with varying committee size. In our EconLedger prototype, each ENF transaction has fixed size *dtx* = 430 Bytes, and a vote has fixed size *dvt* = 589 Bytes. Given the total communication complexity of O(*K*<sup>2</sup>) in both ENF collection and chain finality, data transmission of ENF collection is D*ec* = *dtx* × *K*2, and the data transmission of chain finality is D*c f* = *dvt* × *K*2. Thus, communication overheads incurred by ENF collection and chain finality are linearly scaled to *K*2.

**Figure 6.** Communication overhead of running an epoch round of PoENF consensus. Comparative evaluations on different committee size.

Each block has a fixed header *dhead* = 613 Bytes along with a transactions list with size *dtxs* = *dtx* × *K*, and we can obtain block size *dB* = *dhead* + *dtxsK*. Therefore, the block size *dB* is linearly scaled to *K*. Assuming an ideal case that only one valid block is proposed during each epoch cycle, data transmission of block proposal is <sup>D</sup>*bp* = *dB* × *K* = *dheadK* + *dtxsK*<sup>2</sup> such that communication overhead is almost scaled to *K*2. On the other hand, for the worst case that every validator proposed a candidate block such that <sup>D</sup>*bp* = *dB* × *K*2, huge communication cost scaling up *K* can be introduced.

The data throughput could be specified as *Th* = <sup>D</sup>*ec*+D*bp*+D*c f* <sup>T</sup>*ec*+T*bp*+T*c f* (KB/s), where KB/s means KBytes per second. With variant committee sizes, the corresponding block size and data throughput are calculated as shown in Table 3. Given a fixed ENF transaction size, increasing the committee size allows committing more ENF proofs and, therefore, reach a higher data throughput at the cost of latency. In the test case of *K* = 20, EconLedger implies a theoretical maximum data rate of 283 KB/s, which can meet bandwidth conditions in a majority of LAN-based IoVT systems.

**Table 3.** Data throughputs vs. committee sizes.

