You can set your smartphone as mobile hotspot, but if you need longer use time or more functions, the following BRCK wireless router with built-in battery may be more suitable for you.
BRCK is an innovative and practical wireless router and mobile hotspot designed to offer you an easy way to access to the Internet on the go. The wireless router measures 5.5 x 2.75 x 1.5 inches, and as we can see from the images, BRCK features portable low-profile design, and features WiFi connectivity that includes bridged, access point, and router capacities in order that you can conveniently access the Internet via local network, your SIM card, or Ethernet in any place. Most importantly, the wireless router has a built-in rechargeable battery, when AC power supply fails it offers you 8-hour battery life. Apart from that, BRCK can hold 16GB of memory in order to sync your data directly to your Dropbox account, other connected devices or applications.
At present the team of BRCK is raising fund at Kickstarter. Pledging $200 will let you own the wireless router with built-in battery. If you’re interested, jump to Kickstarter official site for more details.