In: Categories » Electronics and communication » Wireless and mobile computing » PDA and Pocket PC Technologies
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Wireless devices are not always cellular phones. In fact, they do not even need voice capabilities. Does you home PC have a telephone receiver hanging on it? Of course not: The computer’s primary function is to do meaningful data crunching! Personal digital assistants and pocket PCs were created to provide a certain level of support for the mobile user, which could only previously be available on a laptop PC, but smaller and lighter. They are not primarily voice communications devices—they are for storage, retrieval, and manipulation of data. Some PDAs and pocket PCs may attach to a cellular phone or other type of wireless modem, but only for the wireless connectivity of data communications. At least one manufacturer’s cellular phone has a PDA built-in. It is immaterial whether we choose to call it a phone with PDA or a PDA with a phone built into it. There is an entire class of devices devoted to wireless mobile data. Some PDAs are primarily email devices. Others are more generic and can run many different applications, such as the Palm Pilot or Visor. All, however, fall into two categories: They either use public cellular for communications or they use other public or private networks. They all share the same limitations for data transmission, and they are limited to the current state of the art of the physical access channel. Except for Ricochet, this means 19.2 Kbps or less. When they are upgraded to next-generation cellular, data rates will increase. One very interesting thing to watch will be the migration or upgrade paths for the noncellular networks when competition for higher data rates begins. Most are using 19.2 Kbps for wireless PDA and Pocket PC communications. RIM AND BLACKBERRY Research in Motion makes RIM and Blackberry wireless handheld models for a variety of applications and personal preferences, including an OEM version. Some models are primarily for Internet email, whereas other models include the functionality to run application software such as calendars, address books, and much more. The devices fit in the palm of a user’s hand and are lightweight. Wireless communications is through one of two different networks, Mobitex or DataTAC (Ardis Network). Both Mobitex and DataTAC are packet-switched, narrowband PCS networks designed for wide-area wireless data communication at a data rate of 19.2 Kbps. They provide always-on connections with extensive coverage and in-building penetration, seamless roaming, fast messaging, high reliability, and advanced messaging services. Dialing up to retrieve emails is unnecessary. PALM Palm offers several Wireless Internet options. Their integrated wireless solution is the Palm VIIx with service provided by Mobitex. Other Palm products can add a modem or connect to a cellular phone. One wireless service used by Palm is OmniSky, which offers CDPD at 19.2 Kbps. This, of course, operates over an analog cellular network. Because analog cellular coverage is very ubiquitous in North America, this provides broad user coverage when traveling. It also carries all of the advantages of CDPD, like packet data transmission and always-on mode. Downloading Web pages with Palm products involves a little trick called Web clipping. The user requests a particular piece of information in a query, and the page is returned minus a lot of the extraneous details. A server gateway is used to optimize the content for displaying on the handheld PDA. HANDSPRING Handspring products also use CDPD modems, just like Palm, for wireless communications. In addition to CDPD modems, Handspring offers an IEEE 802.11b wireless LAN option, which offers connection speeds up to 11 Mbps in a WLAN environment. A third wireless option for Handspring products is a wireless modem connecting to the Glenayre messaging network through SkyTel service. This is basically email service through two-way paging and not suitable for Wireless Internet. HP Wireless Internet solutions for HP products, PDAs, and Pocket PCs are CDPD modems sold by third parties. COMPAQ Compaq Pocket PC products have the greatest number of options for Wireless Internet of all PDAs and Pocket PCs. Through third-party suppliers, a user may select PCMCIA modems using CDPD, Ricochet, or CDMA networks.
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