WLAN traffic offload in LTE

Tight LTE-WLAN integration

Mobile operators have now a couple of possibilities for integration of WLAN into the LTE network: LTE-WLAN aggregation (LWA) using dual connectivity and LTE-WLAN radio level integration with IPsec tunnel (LWIP), where the user and control plane are handled by the eNB. For LWA, the WLAN function could be fully eNB integrated or separated using a new Xw interface. RAN assisted interworking (RALWI) and RAN controlled interworking (RCLWI) are both based on the original WLAN offloading schemes, such as RALWI defined in Rel. 8. The eNB has a specific functionality for controlling the WLAN access, but the user planes are separated. Consequently, different functionalities are required on the mobile device for network discovery, network selection, handover, etc.

Comprehensive protocol and end-to-end testing

Testing for smooth LTE-WLAN interworking requires a test setup that allows simultaneous WLAN and LTE access as well as the support for the related interworking functionalities such as ePDG or IMS for VoWLAN services. Ideally, these functions are integrated into a single test instrument with the ability to inspect the protocol layers in detail, but also the possibility to run scenarios such as handovers as well as end-to-end performance and security testing. It is also important to test the very often underestimated impact of in-device interference caused by WLAN and LTE operating simultaneously.