This whitepaper introduces the Theta Network, a new blockchain and token as the incentive mechanism for a decentralized video streaming and delivery network.
The Theta Network and protocol solves various challenges the video streaming industry faces today. First, tokens on the Theta blockchain are used as an incentive to encourage individual users to share their redundant computing and bandwidth resources as caching or relay nodes for video streams. This improves the quality of stream delivery and solves the “last-mile” delivery problem, the main bottleneck for traditional content delivery pipelines, especially for high resolution high bitrate 4k, 8k and next generation streams. Second, with sufficient network density the majority of viewers will pull streams from peering caching nodes, allowing video platforms to significantly reduce content delivery network (CDN) costs. More importantly, by introducing tokens as an end-user incentive mechanism the Theta Network allows video platforms to deepen viewer engagement, drive incremental revenues, and differentiate their content and viewing experience from their competitors.
The Theta blockchain introduces three main novel concepts:
● Multi-Level BFT: A modified BFT consensus mechanism which allows thousands of nodes to participate in the consensus process, while still supporting very high transaction throughput (1,000+ TPS). The core idea is to have a small set of nodes, which form the validator committee, produce a chain of blocks as fast as possible using a PBFT-like process. Then, the thousands of consensus participants, called guardians, finalize the chain generated by the validator committee at regular checkpoint blocks. The name multi-level BFT consensus mechanism reflects the fact that the validator/guardian division provides multiple levels of security guarantee. The validator committee provides the first level of consensus — with 10 to 20 validators, the committee can come to consensus quickly. The guardian pool forms the second line of defense. With thousands of nodes, it is substantially more difficult for attackers to compromise the integrity of the network, and thus provides a much higher level of security. We believe this mechanism achieves a good balance among transaction throughput, consistency, and level of decentralization, the three pillars of the so-called “impossible triangle”.
● Aggregated Signature Gossip Scheme: A basic all-to-all broadcasting of the checkpoint block hash could work between guardian nodes, but it yields quadratic communication overhead, and therefore cannot scale to 1,000+ nodes. Instead, we propose an Aggregated Signature Gossip Scheme which significantly reduces messaging complexity. Each guardian node keeps combining the partially aggregated signatures from all its neighbors, and then gossips out the aggregated signature. This way the signature share of each node can reach other nodes at an exponential rate, 2 leveraging the gossip protocol. In addition, the signature aggregation keeps the size of the node-to-node messages small, and thus further reduces the communication overhead.
● Resource Oriented Micropayment Pool: An off-chain “Resource Oriented Micropayment Pool” that is purpose-built for video streaming. It allows a user to create an off-chain micropayment pool that any other user can withdraw from using off-chain transactions, and is double-spend resistant. It is much more flexible compared to off-chain payment channels.
This white paper will describe these concepts and the Theta blockchain in detail. The Theta Network launched with ERC20-compliant tokens and were integrated into the SLIVER.tv platform in December 2017. The Theta blockchain mainnet code has been released, and the first live mainnet implementation is planned to launch on March 15, 2019, at which time each ERC20 Theta token will be exchanged 1:1 for native Theta tokens.