  Multi-Path TCP (MPTCP) is a new transport protocol that enables systems to
exploit available paths through multiple network interfaces. MPTCP is
particularly useful for mobile devices, which usually have multiple wireless
interfaces. However, these devices have limited power capacity and thus
judicious use of these interfaces is required. In this work, we develop a model
for MPTCP energy consumption derived from experimental measurements using MPTCP
on a mobile device with both cellular and WiFi interfaces. Using our energy
model, we identify an operating region where there is scope to improve power
efficiency compared to both standard TCP and MPTCP. We design and implement an
improved energy-efficient MPTCP, called eMPTCP. We evaluate eMPTCP on a mobile
device across several scenarios, including varying bandwidth, background
traffic, and user mobility. Our results show that eMPTCP can reduce the power
consumption by up to 15% compared with MPTCP, while preserving the availability
and robustness benefits of MPTCP. Furthermore, we show that when compared with
TCP over WiFi, which is more energy efficient than TCP over LTE, eMPTCP obtains
significantly better performance with relatively little additional energy
overhead.
