How wireless LANs can be integrated with GSM networks

For seasoned road warriors who spend time at airports, hotels or conference centers, the chance to easily obtain secure, high-speed data access for laptops or PDAs is a real business plus. Enterprise solutions already exist that allow those within corporate buildings or even traveling accountants to use wireless local area network (WLAN) technology to gain access to company networks to process data and e-mail.

But from a widespread public access perspective, there are only a few providers who offer wireless Internet access service today, and it is generally on a pay-as-you-go basis. Their networks may differ greatly in terms of access, service availability and, most importantly, customer billing. In the current environment, the customer's perception of a potential business plus can quickly devolve into a frustrating exercise.

There is a concern about security when using a credit card, in understanding the charges, which may vary from site to site , or in having to return some piece of hardware to an attendant. Despite widespread customer interest and industry pronouncements about the potential of this technology, widely available high-speed wireless Internet access has to date been disappointing from the commercial perspective.

There are many who believe the technology is itself mature. What is needed is a business solution to create mass customer appeal and foster widespread use. One way this can be accommodated is through a simplified billing process. Ideally, a customer should be able to easily obtain and use high-speed wireless Internet access without the billing complications — as easily as the enterprise solutions. For example, why not bundle this capability as an added charge to an existing monthly wireless telephone bill, either as a flat rate or a per occurrence fee? With a single service provider, charges can be clearly identified and consistently applied, and customer service personnel can be available, if required, to discuss any discrepancies or service irregularities that the user experiences.

Another solution to ensure widespread customer adoption is to make all parts of the service provisioning solution simple to create, install and integrate into existing data networks. To facilitate the success of this type of solution, service delivery components should be based on common industry standards.

These business requirements may now have been satisfied. Transat Technologies (Southlake, Texas) and Performance Technologies recently introduced an open standard solution for interconnecting WLANs located in high traveler traffic areas, or "hot spots," with GSM cellular networks. This innovative wireless solution enables customers to access the Internet through portable laptops or PDA devices at true broadband speeds, up to 11 Mbits/second, while utilizing authentication and billing procedures related to their regular GSM cellular accounts. The solution uses a secure software feature for terminals and LAN servers that allows for integration between the GSM wireless network infrastructure and the widely available IEEE 802.11b WLAN standard for high-speed data transmission.

This system allows Internet access from a laptop over the wireless telephone network. The end user must support the 802.11b standard protocol. The site owner uses a similar software component loaded onto an application server to ensure that the International Mobile Subscriber Identifiers (IMSI) of the subscriber's portable device can be transported over IP and SS7 networks. Source: Performance Technologies Inc.

This solution makes high-speed data access from a variety of locations as easy as using a cellular phone. The connection is simple, transparent and reliable. First, the end user needs a laptop that supports the 802.11b standard protocol, either built-in or as a separate SIM card, as well as additional, secure client software. The site owner uses a similar software component loaded onto an application server to ensure that the International Mobile Subscriber Identifiers (IMSI) of the subscriber's portable device can be transported over IP and SS7 networks to the appropriate carrier database for authentication and validation. The wireless carrier installs a pair of redundant, carrier-grade signaling gateways in its SS7 network, which will accept IP network originated authentication messages from the server, translate them into SS7 queries, and then route them to validation databases in appropriate carrier designated locations.

Once the subscriber is authenticated, the Internet session begins, and usage is charged to the subscriber's account. Each site owner communicates with the carrier's billing server using a GSM/GPRS standard software solution to ensure billing data is regularly and securely delivered to the carrier. The authentication, authorization, encryption, billing, mobility and management are all GSM-compliant.

Technology now exists that offers an SS7 network solution that represents the next step in the evolution toward an all IP-based integrated solution for wireless service providers. Using SS7 link replacement devices, service providers can significantly reduce the costs of leasing or provisioning dedicated, long haul SS7 links that carry the GSM wireless LAN customer authentication messages to and from carrier databases (HLRs). The entire solution now requires just a very short, dedicated, 64 kbits/s link interface to the carrier's core SS7 network. In the near future, a similar solution using IP STPs or signaling gateways will allow SS7 network entities such as STPs or HLRs to be directly connected over IP networks, without the need for provisioning expensive dedicated circuits. The STPs and signaling gateways in such applications will communicate using the new Internet Engineering Task Force SS7/IP interworking SIGTRAN protocol standards.

This solution offers considerable opportunity for customers, site owners and carriers alike. The key to success will be the efforts of carriers who must establish the infrastructure, perhaps in tandem with third party site owners and operators), take the message to their customers, and make the network and customer service components perform smoothly. Certainly the simplicity of an open standards-based solution and a cost reducing SS7/IP architecture makes the solution attractive to carriers. And the idea of selling high-speed Internet access to cellular customers should not be foreign to these carriers, since they have been touting the benefits of next-generation/3G broadband wireless networks for some time. This solution offers a chance to provide customers with high-speed Internet access now, in advance of the implementation of the next-generation networks, which could still be a number of years off. It also educates the customers on the power of multimedia services now, facilitating quicker adoption to the widespread availability of 3G