  For the 5th Generation (5G) networks, Third Generation Partnership Project
(3GPP) is considering standardization of various solutions for traffic
aggregation using licensed and unlicensed spectrum, to meet the rising data
demands. IP Flow Mobility (IFOM) is a multi access connectivity
solution/protocol standardized by the Internet Engineering Task force (IETF)
and 3GPP in Release 10. It enables concurrent access for an User Equipment (UE)
to Heterogeneous Networks (HetNets) such as Long Term Evolution (LTE) and IEEE
802.11 Wireless Local Area Network (WLAN). IFOM enabled UEs have multiple
interfaces to connect to HetNets. They can have concurrent flows with different
traffic types over these networks and can seamlessly switch the flows from one
network to the other. In this paper, we focus on two objectives. First is to
investigate the performance parameters e.g. throughput, latency, tunnelling
overhead, packet loss, energy cost etc. of IFOM enabled UEs (IeUs) in HetNets
of LTE and WLAN. We have proposed a novel mechanism to maximize the throughput
of IeUs achieving a significant throughput gain with low latency for the IeUs.
We have explored further and observed a throughput energy trade off for low
data rate flows. To address this, we also propose a smart energy efficient and
throughput optimization algorithm for the IeUs, resulting in a substantial
reduction in energy cost, while maintaining the high throughput at lower
latency and satisfying the Quality of Service (QoS) requirements of the IeUs.
