Aggregating LTE and Wi-Fi: Fairness and split-scheduling

People are seeking solutions in diverse directions to cope with mobile data explosion and resource scarcity in mobile cellular networks. Of many candidate approaches, smart aggregation of LTE and Wi-Fi radios is a promising solution that bonds heterogeneous links to meet a mobile terminal's available bandwidth need. Motivated by the existence of a significant number of carrier-operated Wi-Fi APs, we propose a mechanism, called LTE-W, of efficiently utilizing LTE and Wi-Fi links only with the minimum changes of eNodeBs, LTE backhaul networks, and mobile terminals. Our mechanism has the following two key components: (i) mode selection and (ii) bearer-split scheduling. In the mode selection, LTE-W internally decides who should be served by either of LTE or LTE-Wi-Fi aggregation considering intra-cell fairness rather than just following users' intention of aggregation. For the users decided to be offered the aggregation service, we choose a bearer (roughly defined a set of flows with a similar QoS in LTE) as a basic unit of aggregation and propose a smart intra-bearer scheduling algorithm that splits a bearer's traffic into LTE and Wi-Fi links, considering the tuning of TCP flows that take two heterogeneous wireless links. We evaluate our mechanism using the NS-3 with LENA, and compare it to a transport-level aggregation mechanism, MPTCP, demonstrating that LTE-W significantly improves MPTCP, e.g., up to 75% in terms of Jain's fairness index.