How Does a USB Broadband Card Work?

Interfacing With the Computer

A USB broadband card interfaces with the connected computer using a Universal Serial Bus (USB) connector. When the device is connected, the computer interprets the device as a network adapter and the machine's operating system begins sending network traffic to the device using standard networking protocols. Depending on the version of USB connector used, the networking speed may be moderate or exceptionally fast.

Conversion of Data to Radio Waves

When the broadband card receives networking data from the computer, it must convert the data into radio waves in order to interface with the wireless broadband carrier's point of presence or hub. Because the process used to modulate data into radio waves varies from vendor to vendor and is highly proprietary, a wireless broadband card must be approved by the carrier and provisioned for use on the wireless network. When the card is provisioned, certain information--including the card's electronic serial number (ESN), modulation formula and frequency--is programmed into the carrier's network to make the card active.

High Frequencies

Depending on the card's vendor and the wireless broadband carrier, the frequency of radio waves may vary considerably. At the low end of the wireless broadband spectrum, some carriers use the 800 megahertz (800MHz) frequency for wireless data communication; at the opposite end of the spectrum, specialized carriers use frequencies reaching up to 38 gigahertz (38GHz). In the United States, the 900 MHz, 2.4 GHz and 5 GHz frequencies may be used without special wireless licenses, though many carriers choose to buy their own frequency range to avoid outside interference.

Wireless Broadband Uses TDM

In addition to the much researched and developed modulation and frequency usage of the wireless broadband card, wireless broadband employs an advanced data encapsulation method known as Time Division Multiplexing, or TDM. This technology, an advanced formula that is widely considered a stable and secure data transfer method, helps the broadband card balance upstream (upload) and downstream (download) data packet transfer for optimum network and frequency utilization. The TDM technology has been adopted by the Universal Wireless Communication Consortium as the standard for wireless broadband communication.