WLAN-GPRS interworking (2001)

During the last years it has been experienced a huge growth in Internet users. Nearly\neach household in Norway got a computer attached to the Internet. The trend for\nfurther growth seems to be within the concept of mobile Internet, which means that the\nuser can be attached anywhere at any time. The sales of mobile equipments like\npersonal digital assistants (PDAs) and laptops are currently experiencing a great\ngrowth. This indicates a need for greater flexibility and mobility and gives therefore a\ndemand for mobile Internet.\nThe motive for this thesis was to investigate the opportunities to offer mobile Internet\non the basis of wireless technologies. The two largest telecom operators in Norway,\nNetcom and Telenor Mobile, started offer GPRS early year 2001. GPRS is a\nsupplement to GSM, which offers packet switched data traffic. Wireless LAN (WLAN) is\nanother access technology that can be used for wireless access to the Internet. The\nmost used WLAN standard today are 802.11b. This standard is inexpensive and offers\nrelatively high data rata, up to 11Mbps.\nGPRS offers a large coverage area and WLAN offers relatively high data rate. Building\na bridge between these two access technologies can have the potential of offering the\nusers both large coverage area through GPRS and high data rates through WLAN.\nAdequate solutions for this needs to fulfill the requirement of not demanding the user to\nactively change access technology. Neither should the user applications be affected of\nthe change.\nImplementation of the bridging technology between WLAN and GPRS can be done at\ndifferent levels. This thesis discusses solutions based on integration at IP level and\nintegration with the GPRS network at a lower level.\nThe latter, also called the telecom-integrated solution, investigates the opportunities for\nconnecting a WLAN segment to the GPRS network without affecting existing network\nnodes. The physical connection of the WLAN segment requires a bridge connected at\none of the interfaces specified for the GPRS user plane. Two different solutions are\ndescribed, one with the bridge connected at the Gn interface and one at the Gi\ninterface. The bridge must include both user plane and the signaling plane for the\nGPRS network. The user equipment must be modified to handle location management\nin GPRS, when connected to the WLAN segment.\nThe IP level solutions, described herein, are based on mobile IPv4 with home agent\nand foreign agents. The main difference between these solutions is the location of\nhome agent and foreign agents. The home agent can be located at a corporate\nnetwork, an ISP or on the border of the GPRS network. Foreign agents can be located\nat any network for the provisioning of connectivity to the mobile nodes.\nThe solutions based on physical connection of WLAN to the GPRS network are\ncomplex and require great adjustments on the user equipment. The mobile IP solutions\nrequire less of an effort to implement. The recommended implementation will be to use\nthe solution where the home agent is located at a corporate network or an ISP and\nforeign agents at WLAN segments. When the user equipment is attached to GPRS or\na WLAN network without foreign agent a co-located care-of address will be used. If a\nforeign agent is implemented into the GGSN node it will be preferred to take use a\ncare-of address belonging to the foreign agent.