Cellular Services: Speed, from Wi-Fi

The wireless local area network (WLAN) technology is sweeping the world of wireless data communication and wireless Internet access globally. It is one of the hottest technologies today, gaining worldwide popularity and market acceptance very fast and leaving behind other similar technologies like GPRS (popularly known as 2.5G) and UMTS (popularly known as 3G). 

3G versus Wi-Fi

The traditional GSM technology provides voice communication, SMS and data communication at 9.6 kbps. GPRS uses an upgraded GSM infrastructure and provides data connectivity at up to 64 kbps. Here, since the existing GSM infrastructure is used with some upgrades, it is viewed a cost-effective solution to provide higher data rate in-wireless networks. This technology is regarded as the natural migration of GSM technology and is spreading its wings all over the world. However, with multimedia messaging (MMS), Internet access, and graphics-rich applications gaining popularity and acceptance, the 64 kbps data limit in GPRS will be a limiting factor. The UMTS technology provides long-term solution to the ever-increasing thirst for higher data rate. It uses an entirely different infrastructure and can have data rates up to 2 Mbps. While GPRS is seen as short-term solution, UMTS is a long-term solution and is regarded as the future technology for wireless voice and data communication.

From the deployment perspective, globally, there are an estimated 1.3 billion wireless subscribers and 600 networks, out of which, 785 million subscribers and 500 networks are using GSM; 6 million subscribers and 140 networks have been upgraded to GPRS; and two live networks are providing UMTS services. Because of the global economic slowdown, and due to non-availability of revenue generating applications and higher infrastructure and licensing cost associated with UMTS, the deployment of UMTS networks is progressing at a much slower pace than anticipated three years ago. In India, there are an estimated 15 million wireless subscribers and 22 networks and almost all of them are using the GSM technology. Of late, however, a few CDMA-based networks and GPRS-enabled networks have come up, but with limited subscription.

802.11x–Complementing GSM

While the GPRS-versus-UMTS debate and the dilemma over upgrading the network now or later continues, the wireless technology has further advanced and the WLAN or WiFi 802.11 technology has emerged. It provides a much higher bandwidth of 11 Mbps at much cheaper costs. WLAN operates in the unlicensed Instrumentation, Scientific and Medical (ISM) band at 2.4 GHz unlike GSM and UMTS, which operate in licensed bands. 

WLAN is fast to deploy, much cheaper, and easy to use. It can be deployed independent of other wireless technologies, either as an independent network or as an overlay network with existing GPRS networks. It can also be connected to existing GSM/GPRS networks for seamless roaming. 

WLAN does have a few limitations. One, the coverage is limited to 100 meter as compared to the ubiquitous coverage provided by GPRS/UMTS networks, and therefore, is most suitable for ‘hot-spots’ like airports, coffee shops, hotels, and malls. Then there are security-related issues that restrict its usage in critical data applications. Technologists are devising solutions to sort them out. 

WLAN has given the cellular technologies a good reason to flag an alert. After all, WLAN provides a combo of higher bandwidth, flexibility and cost that cellular networks just can’t match. It looks all set to become tomorrow’s killer network, with deployment and usage taking off at an explosive rate throughout the world. WLAN service revenues are expected to reach $7 billion, with 120,000 hot spots covered.

Carrier-grade WLAN 

By leveraging WLAN, developing countries like India can enjoy clear benefits, as most of the networks here are
GSM-only.

Operators can wait for the business and technology maturity of UMTS and then directly go for it without transiting through GPRS. They can offer WLAN-based wireless data services to fill the time gap and meanwhile judge the business potential of high-speed data application in the Indian market, instead of following the business models of other countries. GPRS operators can also ensure greater business viability by first deploying WLANs before going for
UMTS. 

The Government of India has already announced free (un-licensed) usage of the WLAN spectrum. Clearly, from the Indian wireless business perspective, WLAN can be the first choice as an overlay network to the existing GSM networks, with service level integration that provides existing GSM authentication and billing coverage to WLAN users as well. This will provide high-speed data access at hot spots without roaming. This arrangement should go well with the Indian market, which is very cost-sensitive and doesn’t really need high-speed wireless data roaming services initially. 

The next step can be to go for GPRS or UMTS with full inter-working with WLAN, to provide seamless roaming between WLAN and cellular networks, in addition to integrated authentication and billing. Although this path may be a bit different from those being taken in countries where GPRS or UMTS have already made inroads, but suits India well. After all, different countries do need different business models.

Ajit Jain, AVP (wireless engineering division), Hughes Software Systems