Several options are available to mobile workers requiring wireless data communications. Here's a quick scorecard you can use to keep popular wireless technologies straight:
2.5G cellular networks typically enable data communications between 20Kbps and 80Kbps. The bandwidth limitations make 2.5G network data communications often slower than traditional dial-up networks.
3G cellular networks typically power data communications between 144Kbps for mobile applications and 2Mbps for fixed indoor environments. While the mobile application speeds aren't blazing by most broadband standards, 3G enables mobile workers to at least check and send e-mail and run regular applications using common remote access protocols over cellular networks, as opposed to Wi-Fi hotspots. 3G network communications can be secured using traditional remote access security methods, such as encryption, VPNs and password challenges. Handheld devices and laptop computers with the proper hardware can make use of 3G communications.
The 802.11a standard broadcasts data at 5GHz. 802.11a equipment transfers data up to 54Mbps, but most transmissions occur between 20Mbps and 25Mbps. Since 802.11a signals are broadcast at 5GHz, fewer interference issues exist with 802.11a systems than with 802.11b networks. According to the IEEE, 802.11a networks typically have an indoor range less than 150 feet at low speeds and only a range of 75 feet at higher speeds. The 802.11a standard supports as many as eight channels.
The 802.11b standard broadcasts data at 2.4GHz. 802.11b equipment offers the ability to transfer data up to 11Mbps, but typical transmissions occur in the range of 4Mbps to 6Mbps. Maximum indoor range is typically 250 feet for low speed transmissions and 100 feet for high-speed transmissions. Interference issues can arise, though, as microwave ovens and cordless telephones, among other electronic devices, share the same radio spectrum. The 802.11b standard supports use of MAC filtering and Wired Equivalent Privacy (WEP), which supports up to 128-bit encryption. The 802.11b standard supports the use of only three radio channels, so overlapping signals can become problematic.
The 802.11g standard broadcasts at 2.4GHz and boasts throughput up to 54Mbps, although transmission speeds beginning at 6 Mbps are more common. 802.11g networks tend to possess broadcast ranges similar to 802.11b networks. In addition to supporting Wired Equivalent Privacy (WEP) and MAC filtering, the 802.11g standard also boasts improved security (versus 802.11b networks) via support for the Wi-Fi Protected Access (WPA) standard and the Extensible Authentication Protocol (EAP). The 802.11g standard supports three radio channels.
The Bluetooth standard offers transmission speeds up to 1Mbps. However, Bluetooth's effective communication range is typically limited to less than 100 fee, thus the technology is largely utilized to replace cable and infrared connections between PCs and such devices as handheld computers and printers.
Code Division Multiple Access is a digital wireless technology used to send digital transmissions from a mobile phone to a fixed radio base station. CDMA's big advantage over traditional analog cellular networks is its ability to enable multiple simultaneous transmissions to be carried via a single wireless channel thereby increasing its throughput substantially.
Cellular Digital Packed Data technology enables telecommunications companies to transfer data over traditional analog cellular networks. However, transmission speeds are very slow, with a maximum throughput of only 19.2 Kbps. CDPD data throughput typically occurs at speeds of only 2.4 Kbps during peak periods.
Enhanced Data for GSM Evolution offers faster data transmission speeds (up to 384 Kbps) over GSM and TDMA networks.
Evolution, Data Only (or Optimized) technology offers an always-on connection boasting data transfers up to 2.4Mbps on 3G CDMA networks.
General Packet Radio Service enables an always-on network and data transmission rates up to 114Kbps on GSM networks. GPRS transmits radio signals at 2.5GHz.
Global Systems for Mobile Communication is a CDMA alternative used as the 2G wireless standard worldwide, except in the US. Depending upon the specific device, GSM equipment can transmit at several different frequencies, including 450MHz, 900MHz, 1,800MHz and 1,900MHz. GSM equipment typically requires a Subscriber Identity Module (SIM) card, which includes identification and authentication information about the user. Original GSM technology enabled data transmission speeds of only 9.6 Kbps.
High-Speed Downlink Packet Access technology permits data transmission rates of 8Mbps to 14Mbps over GSM networks. HSDPA's channel-sharing technology enables several users to share channels and substantially improve throughput. HSDPA is a key technology enabling fast data transmissions on 3G networks.
Time Division Multiple Access enables digital signal transmission from a mobile device to a station. By allocating specific time slots for broadcasts on GSM digital cellular networks, TDMA enables increased data throughput.
Universal Mobile Telecommunications System enables higher-speed data transmission on 3G networks. Based on the GSM standard, UMTS is capable of offering data throughput of up to 2 Mbps.