| Seminarsonly.com |
|
| >>
| |
Abstract of Cellular Communications
Roke Manor Research is a leading provider of mobile telecommunications technology for both terminals and base stations. We add value to our clients' projects by reducing time-to-market and lowering production costs, and provide lasting benefits through building long-term relationships and working in partnership with our customers. We have played an active role in cellular communications technology since the
1980's, working initially in GSM and more recently in the definition and development
of 3G (UMTS). Roke Manor Research has over 200 engineers with experience in designing
hardware and software for 3G terminals and base stations and is currently developing
technology for 4G and beyond. We are uniquely positioned to provide 2G, 3G and
4G expertise to our customers. Before we peek into the future, let's quickly look at where we are today. In 1999, the primary cellular-based data services are Cellular Digital Packet Data (CDPD), circuit-switched data services for GSM networks, and circuit-switched data service for CDMA networks. Some brave souls connect their PC Card modems to their analog cellphones, but this approach is not very popular because it is tricky to configure. All of these services offer speeds in the 9.6 Kbps to 14.4 Kbps range. Why such low speeds? The basic reason is that in today's cellular systems, data is allocated to the same radio bandwidth as a voice call. Since voice encoders (vocoders) in current cellular networks digitize voice in the range of 8 to 13 Kbps, that's about the amount available for data. Remember, too, that today's digital and PCS technology designs started over five years ago. Back then, 9.6 Kbps was considered more than adequate. Today, it can seem slow with graphical or multimedia content, though it is more than adequate for text-based applications and carefully configured applications. There are two basic ways that the cellular industry is currently delivering data services. One approach is with smart phones, which are cellular phones that include a microbrowser. With these, you can view specially formatted Internet information. The other approach is through wireless modems, supplied either in PC Card format or by using a cellphone with a cable connection to a computer. See Figure 1.
Figure 1: Smart phone versus phone connected to laptop Both approaches can give you access to Internet sites and corporate systems, including e-mail, databases, or host-based systems. But both approaches also require that the user take throughput and latency of the network into account. In contrast, next generation networks promise throughput, global coverage, and ease-of-use that will greatly expand your mobile computing options. CDMA
CDMA network deployment and subscriber growth have developed considerable momentum, and data services are now available from a number of carriers. Currently, these carriers use circuit-switched technology operating at 14.4 Kbps. As with GSM, CDMA requires a handset that specifically supports data. Connect the phone to a laptop, and the phone operates just like a modem, enabling you to establish dial-up connections to the Internet, your corporate remote access server (RAS), and so on. WAP-based microbrowser applications are also being made available. Another service for CDMA networks is called QuickNet Connect. By eliminating conventional modem connections, this service allows fast connections (of approximately five seconds) to the Internet. See Figure 3. To the user, the carrier appears like an ISP offering dial-up Internet service
|
copyright © 2006 V2 Computers E-mail :- contactv2@gmail.com
