The nature of mobile ad-hoc networks does not permit a member of the group or a central authority to determine a single key to be used among the group members. Group key agreement offers a solution to this problem by allowing the group members to collaboratively determine the common key for the group. Additionally, authenticated group key agreement (AGKA) is an important issue in many modern collaborative and distributed applications. During the last few years, a number of authenticated group key agreement protocols have been proposed in the literature. In this paper, we present a secure ID-based AGKA protocol which only requires one round by using pairing-based cryptography. We prove that the scheme is secure against an active adversary under the decisional bilinear Diffie-Hellman assumption in the Random Oracle Model. We then extend our scheme to a two-round AGKA protocol which is more efficient in communication costs, and this scheme outperforms any existing AGKA protocols in the literature.