Fast handover management in mobile IPv6 environments has been a research subject for a long time. Exploiting the cooperative diversity paradigm in Partner-based Hierarchical MIPv6 (PHMIPv6) promises an acceleration of the handoff management operation by relaying some signaling over a selected partner node prior to the actual handover to the new access point. For this purpose, a suitable partner node, that stays in communication range for sufficient time until the signaling in the pre-handoff phase is finalized, should be selected. PHMIPv6 proposes to select the node with the highest signal strength as the partner node. In this paper, we show that using the Link Expiration Time (LET) metric to select the partner node can significantly improve handovers in Mobile IP (MIP) networks. The basis of this new metric is the relative position and the relative speed of the mobile node to the potential partner nodes. A set of simulations is conducted to evaluate the performance of the proposed scheme and encouraging results are obtained.