LTE, LTE-Advanced and WiMAX: Towards IMT-Advanced Networks

Inter-Technology Access

Inter-radio access technology is the ability to support the mobility of a user device between differing radio access network types, also known as vertical handovers. Inter-radio access between heterogeneous networks is important to be executed properly for seamless communication with minimum delay and packet loss to disassociate from the current serving BS to associate to the new BS. LTE defines two types of inter-radio technologies: inter- technology access between LTE to legacy 3GPP systems, also known as inter-radio access technology (inter-RAT) and inter- technology access between LTE and other non-3GPP systems.

Inter-technology access can be supported using different techniques. The most primitive one is the mobility from one technology to another without the intervention of the network. In this case the device is equipped with different technology interfaces. The user or the device selects which technology to access and associate to the corresponding network. Once this network becomes unavailable, the user or the device selects another technology and associate with. This type of inter-technology handover is acceptable for delay-tolerant and low QoS requirement applications such as http and e-mail. However, delay-intolerant or session based applications cannot tolerate the service interruption and may require re-initiation of the session including the re-authentication process. A more efficient inter-technology mobility for session based applications ...