A portable Wi-Fi access point or router meet the requirements you have mentioned. Consider…
If you want to use your mobile service provider’s data plan, then you should opt for a 3G USB dongle/data card. It comes with a sim slot and can be connected to a plug point (via an adapter), or even a PC or laptop. Here, you can look at the D-Link DWR-710 Le Petit HSPA+ (Rs 1,999) or the Huawei E8231 (Rs 1,980).
The former allows you to share your broadband connection with eight devices wirelessly, while the latter lets you connect up to ten Wi-Fi-enabled gadgets. The D-Link also has provision for a microSD card (up to 32GB), allowing you to share its contents wirelessly with devices connected to the network.
In case you already own a 3G USB dongle that’s locked to a service provider (Reliance, Tata Photon etc), you need to get a portable Wi-Fi router that comes with a USB port and support for your mobile broadband service. For such a set up, go with the TP-Link TLMR3020 (Rs 1,290). This little router also has an Ethernet (RJ45) port for a wired connection. It does not include a memory card slot and needs to be powered via its microUSB port.
If you need to stay connected while on the road, then you can choose between the D-Link DWR 730 HSPA+ (Rs 3,800) and the Huawei E5730s-2 3G (Rs 5,400). Both have a sim card slot, built-in Li-ion battery and LED connection status indicators. The D-Link model houses a 2,000mAh battery and a microSD slot for data storage. The Huawei does not include the latter function, but has a larger 5,200mAh battery and an Ethernet port for a wired connections.
Source: How to set up a portable ‘Wi-Fi zone’, Ashutosh Desai,TNN ( http://timesofindia.indiatimes.com/tech/how-to/How-to-set-up-a-portable-Wi-Fi-zone/articleshow/46002632.cms )