The small extension node (SEN) is part of a US military communication system known as Mobile Subscriber Equipment (MSE).
Prior to the advent of the satellite based Joint Network Node (JNN), the United States Army used a system known as Mobile Subscriber Equipment (MSE) in order to provide tactical battlefield communications.
The MSE SEN primary role is to provide tactical telephone and data network communications to the battlefield.
A single switching shelter is mounted on the back of a HMMWV, powered is provided by a 10 kW diesel generator, and the SEN is operated by up to a six soldier team.
Both versions interface at various levels with the MSE Area Communication Systems through cable, via line of sight or via tactical satellite terminal.