Software Defined Radio Implementation of an enhanced LTE-WiFi Aggregation System

To reduce the transmission load of cellular network and to enhance the user experience of wireless service, WiFi-offloading is regarded as one of the most important technologies nowadays. The framework of enhanced long term evolution (LTE)-WiFi aggregation (eLWA) system is determined by 3rd Generation Partnership Project (3GPP) Release 14 version, and in this paper, we design and implement the testbed based on an open-source software defined radio (SDR) platform named as OpenAirInterface (OAI) to test and verify the system performance. In the eLWA system, the wireless local area network (WLAN) access points (APs) connect to the eNodeBs (eNBs) directly, and the uplink cellular data can be offloaded to the WLAN link in Packet Data Convergence Protocol (PDCP) layer. This architecture makes full use of existed WLAN APs to improve the performance of cellular network, especially for the indoor scenarios. Furthermore, the eNB scheduler can be more flexible and efficient for operators benefiting from the flow control between LTE and WLAN. Based on the OAI-SDR testbed, a practical reordering function is proposed and implemented. Experimental results demonstrate that the eLWA system can obtain significant performance enhancement compared with the LTE-only system. This architecture can be updated smoothly to be an aggregation system of 5G new radio and WLAN.