This paper proposes a heterogeneous wireless communication network with soft handover in the application layer. The proposed network requires no upgrades of wireless infrastructure and mobile terminals to evolve the present homogeneous networks to the proposed heterogeneous network. Only installing application programs on the content server side and the mobile terminal side is required. The performance of the proposed network has been evaluated in a field trial using a mobile broadband wireless access (MBWA) air interface with wide coverage and a wireless local area network (WLAN) air interface with high throughput. The field trial results show that the maximum value of the handover outage time is only 170 ms. The proposed heterogeneous wireless communication network is promising since both high throughput and wide coverage area are attained by a combination of the proposed handover scheme with the present homogeneous wireless networks.