Mobile printing & presenting solutions - wireless protocol basics

Three protocols govern today's wireless communications:

• IR (Infrared) communication allows you to connect two devices that have built-in IR ports and are located in the same room. Simply line up the devices' IR ports and beam (or send) data. IR technology is by far the simplest way to connect PDAs and laptops with an IR-enabled printer such as the HP Color LaserJet 4100mfp printer. However, for an IR solution to work, the computer or PDA must have a clear line of sight to the printer, which can make for a crowded three-foot space around a shared printer.
  
  
• Bluetooth (also known as the IEEE 802.15 standard) is ideally suited for connecting up to eight devices within a single room. Bluetooth operates in the 2.4 GHz radio band (part of the "Unlicensed Spectrum" that does not require the user to obtain a license to operate the equipment). To minimize potential interference from other devices that might transmit in the same band, Bluetooth uses a technique called FHSS (Frequency Hopping Spread Spectrum) to ensure that each device transmits only briefly on a given radio channel and then moves (hops) to another channel.
  
  Many printers, like the HP DeskJet 995c, have built-in Bluetooth technology, which allows you to extend wireless printing to all members of a workgroup who have Bluetooth-enabled PDAs or notebooks and are within 30 feet of the printer. This approach to wireless printing is perfect for training rooms, ad hoc project rooms, small task centers, and other small and medium-sized areas that you regularly need to reconfigure or adapt to different uses. However, the transmission rate for Bluetooth is a maximum of 1 Mbps and the range is somewhat limited at 30 feet.
  
  
• The IEEE 802.11 family of standards known collectively as Wi-Fi was introduced to establish a common, secure set of standards for device-to-device data communication over wireless in much the same way that Ethernet (IEEE 802.3) connects computers on a wired LAN. On a wired network, computers are connected to the network by cables plugged into Ethernet hubs and switches. In a wireless LAN, computers connect to the network by sending radio signals to an access point. Each access point is connected to a wired network and it relays traffic between wireless devices and the wired network. Today, most wireless LAN products support 802.11b (also called Wi-Fi), a standard that operates in the 2.4 GHz band at speeds up to 11 Mbps. However, a growing number of products are beginning to support two newer standards: 802.11a (operating in the 5 GHz band at speeds up to 54 Mbps) and 802.11g (sharing the same 2.4 GHz band at speeds up to 54 Mbps). Because its range is greater than either IR or Bluetooth, Wi-Fi is the more practical choice for wireless LAN printing. You can use it to not only extend printing services to users in a small work center, but to serve telecommuters or other laptop users.