  User-generated content can be distributed at a low cost using peer-to-peer
(P2P) networks, but the free-rider problem hinders the utilization of P2P
networks. In order to achieve an efficient use of P2P networks, we investigate
fundamental issues on incentives in content production and sharing using game
theory. We build a basic model to analyze non-cooperative outcomes without an
incentive scheme and then use different game formulations derived from the
basic model to examine five incentive schemes: cooperative, payment, repeated
interaction, intervention, and enforced full sharing. The results of this paper
show that 1) cooperative peers share all produced content while non-cooperative
peers do not share at all without an incentive scheme; 2) a cooperative scheme
allows peers to consume more content than non-cooperative outcomes do; 3) a
cooperative outcome can be achieved among non-cooperative peers by introducing
an incentive scheme based on payment, repeated interaction, or intervention;
and 4) enforced full sharing has ambiguous welfare effects on peers. In
addition to describing the solutions of different formulations, we discuss
enforcement and informational requirements to implement each solution, aiming
to offer a guideline for protocol designers when designing incentive schemes
for P2P networks.
