Many carriers will take an interim step to third generation (3G), referred to as 2.5G, that uses the Internet Protocol (IP) to provide fast access to data networks via General Packet Radio Service (GPRS) technology. Compared to circuit-switched data (CSD), which operates at up to 14.4 kbps and high-speed circuit- switched data (HSCSD), which operates at up to 43.2 kbps, GPRS uses packet-switching technology to transmit short bursts of data over an IP-based network to deliver speeds of up to 144 kbps over an “always on” wireless connection.
True 3G networks based on enhanced data rates for GSM evolution (EDGE) technology deliver data at speeds of up to 384 kbps. EDGE is a step beyond GPRS that will allow up to three times higher throughput compared to GSM/GPRS using the same bandwidth. Carriers in the United States have been moving toward 3G for several years by overlaying various technologies onto their existing networks to enhance their data-handling capabilities.
For carriers with TDMA-based networks, the first step to offering true 3G services is to deploy Global Systems for Mobile communications (GSM) and then GPRS. The GPRS enhancement to GSM can support peak network speeds of wireless data transmissions between 64 and 170 kbps depending on the various claims of hardware vendors.
The new GSM/GPRS network does not replace existing TDMAnetworks; carriers will continue supporting these networks long into the future to service their voice customers. Eventually, all TDMAcustomers will be migrated to GSM/GPRS. Once the GSM/GPRS overlay is in place in a market, the carriers can upgrade their networks with EDGE-compliant software to boost data transmission rates to as much as 384 kbps and begin the availability of true 3G services.
Carriers whose wireless networks are based on CDMA will take a different technology path to 3G, going through CDMA2000, before eventually arriving at Wideband Code Division Multiple Access (W-CDMA). Both EDGE and WCDMAoffer a migration path to the global standard Universal Mobile Telecommunications System (UMTS).
Coverage for 2.5/3G services is still ramping up, despite the impressive figures thrown out by individual carriers. The next step is for service providers to engage in more roaming arrangements, which is a way to save costs, reduce time to market, and add value to attract more customers. The data speed of 2.5/3G services is determined by many factors, including the equipment and software in the wireless network, the distance of the user from the nearest base station, and how fast the user may be moving.
The claimed speed of the service is rarely, if ever, achieved in the realworld operating environment. The pricing plans and price points differ by carrier, from a simple add-on to existing digital voice plans for a basic data service, to tiered pricing plans based on actual data usage. Depending on the applications, users can opt for 2.5/3G cell phones with multimedia messaging capabilities.
Alternatively, users with heavy messaging and file transfer requirements may opt for PC cards for notebooks and personal digital assistants (PDAs). The choice of 2.5G platform depends on whether the carrier has a TDMA- or CDMA-based network. Both technologies are capable of eventual migration to full 3G and at a higher level will be able to interoperate in compliance with the global IMT-2000 initiative.
Some service providers intend to support Wireless Fidelity (Wi-Fi), as well as GPRS. Wi-Fi networks are based on the IEEE 802.11b Standard for Ethernet, which operates in the unlicensed 2.4-GHz band to provide a maximum stated speed of 11 Mbps. In actual operation, however, Wi-Fi offers between 5 and 6 Mbps. Some carriers are looking at ways to offer both Wi-Fi and 3G from the same device to meet the diverse needs of customers.
The existing GPRS and upcoming EDGE networks provide wide area coverage for applications where customers want constant access to such as e-mail and calendar, whereas Wi-Fi networks will be available in convenient locations where customers are likely to spend time accessing larger data files.
The United States lags behind the rest of the world when it comes to wireless technologies for a number of reasons. The telecommunications infrastructure in the United States is more developed than in many European and Asian countries. As a result, the demand for wireless devices has been lower in the United States because consumers have other low-cost options.
Also, the United States has a number of competing technical standards for digital services, while European and Asian countries are predominately centered on GSM. In the United States, carriers have only recently adopted GSM.
Now that carriers in the United States have mapped out their migration strategies, they have been busy positioning their networks to 2.5G, investing billions of dollars for infrastructure upgrades, with billions more committed to go the rest of the way to 3G. In the process, they are betting they can attract millions of new customers who will want high-speed wireless data on their mobile phones, notebooks, and PDAs.