[Show abstract][Hide abstract] ABSTRACT: By adding a subsystem that provides continuous network service to a host system such as a PC (Personal Computer), even while the host system is sleeping, it is possible to achieve efficient use of the system and energy reduction. Remote management is a typical example. Recently, to maintain network service anytime and anywhere, WWAN (Wireless Wide Area Network) technology such as 3G (3rd generation mobile telecommunications) has been employed. The design of the subsystem should be independent of the network device in terms of development cost because once modifications are made, they are dependent on a network device, this would lead to extra work being required to use the new network devices and retain the modification. Furthermore, modification to the logic or firmware of a wireless network device may make re-certification necessary owing to rules and regulations for radio devices. Therefore, realization of a method that does not require any modification to wireless network devices, network drivers, and connection software is considered ideal, however, it has not been achieved thus far. In this paper, we propose a unique architecture for a subsystem that overcomes this design issue by introducing two elements to achieve host unaware network service: pseudoresponse and bridge functionality for communicating through the subsystem. In general, a highly independent design contributes to processing overhead and tends to degrade performance. Hence, we prototype the subsystem on an ARM7 board and evaluate it using actual 3G network and cloud services. The results show that the proposed technique works transparently, even when the host system uses the network, and the required CPU (Central Processing Unit) frequency is more than 70 MHz. Furthermore, it is confirmed that power reduction of around 60% can be achieved while downloading.