This draft presents the investigation of 4via6 in the scenario where IPv6 prefix delegation is deployed. A practicable application scenarios with IPv6 prefix delegation have been introduced in the mobile network environments. The applicability of 4via6 mechnism has been analyzed in term of mapping rules and 4via6 address structure. Targeting to alignment with existing 4via6 mapping algorithm and RFC6052 recommendation, an alternative 4via6 address structure have been proposed to be capable of assigning flexible address/port set to 4via6 domains.