Wireless modems are devices that allow computers to connect to a wireless local area network (WLAN) without physical cabling such as ethernet wiring. They use cellular, satellite or WiFi protocols to connect to a WLAN, which can then provide Internet service. This differs from dial-up and DSL modems which use telephone lines to connect to the Internet, while cable modems use cable TV lines for connectivity.
For mobile applications, a PCMCIA wireless modem card in a laptop can provide access to the Internet through public "hotspots." These are geographical areas where WLANs allow public Internet access via these type of modems. In some cases a small membership fee is required, while other hotspots are free.
Various wireless networks use proprietary protocols, and wireless modems are certified as compatible with certain architecture(s). Some protocols, like CDPD (Verizon), GPRS and EDGE (AT&T and Cingular), are even slower than dialup; while Cellular UMTS (AT&T) and 1xRTT (Verizon) wireless networks can operate at about 300 kilobits per second (kbs). A newer cellular flavor offered by Verizon and Sprint, EVDO, advertises speeds of 400-700 kbs, rivaling broadband packages. Future technologies including Cingular's HSDPA and Verizon's EVDV promise even greater speeds.
Another popular network for mobile wireless modems is WiFi (Wireless fidelity), which can operate at a respectable 400 kbps. WiFi is used in many Internet cafés and other hotspots. WiFiMax is a newer standard that offers even faster speeds and more features.
Since wireless modems are certified as being compatible with particular standards and protocols, you should be sure the modem you purchase has the capabilities required for the network(s) you wish to connect to.
General features to look for in wireless modems are:
- Modem speed.
- Protocol(s) supported: Ethernet, CPCD, GPRS, ISDN, EVDO, WiFi, etcetera.
- Frequency band: 900mhz, 2.4 GHz, 5 HHz, 23 GHz, VHF and UHF.
- Radio technique: direct sequence spread spectrum, or frequency hopping.
- Number of channels for transmitting and receiving.
- Maximum Signal Strength.
- Full duplex capability vs. half-duplex (full duplex permits simultaneous transmitting/receiving for faster data transfer).
DSL or cable Internet access in your home or office can also be set up with a wireless broadband modem. In this case all computers in the household can communicate with the broadband modem through wireless network adapter cards, thus eliminating the need for a physical wire between every desktop/laptop and the modem. The wireless network cards, which can be PCMCIA or external adapters using a USB port, should be of the same manufacturer as the wireless modem/router, or clearly state they are compatible with such.