MP-H2 is a client-only, HTTP-based multipath solution. It enables an HTTP client to fetch content (an HTTP object) over multiple network paths such as WiFi and cellular on smartphones. Compared to MPTCP, MP-H2 offers several key advantages including server transparency, middlebox compatibility, and friendliness to CDN, anycast, and load balancing. MP-H2 strategically splits the file into byte range requests sent over multipath, and dynamically balances the workload across all paths. Furthermore, MP-H2 leverages new features in HTTP/2 including stream multiplexing, flow control, and application-layer PING to boost the performance. MP-H2 also supports multi-homing where each path contacts a different CDN server for enhanced performance. Evaluations show that MP-H2 offers only slightly degraded performance (6% on average) while being much easier to deploy compared to MPTCP. Compared to other state-of-the-art HTTP multipath solutions, MP-H2 reduces the file download time by up to 47%, and increases the DASH video streaming bitrate by up to 44%.

Simultaneously using multiple network paths (e.g., WiFi and cellular) is an attractive feature on mobile devices. A key component in a multipath system such as MPTCP is the scheduler, which determines how to distribute the traffic over multiple paths. In this paper, we propose DEMS, a new multipath scheduler aiming at reducing the data chunk download time. DEMS consists of three key design decisions: (1) being aware of the chunk boundary and strategically decoupling the paths for chunk delivery, (2) ensuring simultaneous subflow completion at the receiver side, and (3) allowing a path to trade a small amount of redundant data for performance. We have implemented DEMS on smartphones and evaluated it over both emulated and real cellular/WiFi networks. DEMS is robust to diverse network conditions and brings significant performance boost compared to the default MPTCP scheduler (e.g., median download time reduction of 33%--48% for fetching files and median loading time reduction of 6%--43% for fetching web pages), and even more benefits compared to other state-of-the-art schedulers.

We present the demonstration of DEMS, a new multipath scheduler aiming at reducing the data chunk download time. DEMS consists of three key design decisions: (1) being aware of the chunk boundary and strategically decoupling the paths for chunk delivery, (2) ensuring simultaneous subflow completion at the receiver side, and (3) allowing a path to trade a small amount of redundant data for performance. We integrate the DEMS components into a holistic system and implement it on commodity mobile devices, where unmodified mobile applications can use DEMS to transmit data over multipath. We demonstrate the simple configuration of using DEMS over multipath, visualization of multipath scheduling, download time reduction of data chunks with DEMS over both emulated and real cellular/WiFi networks compared to default MinRTT scheduler, and application QoE improvement on mobile phones from DEMS.

Today's mobile devices are usually equipped with multiple wireless network interfaces that provide new opportunities for improving application performance. In this paper, we conduct an in-depth study of multipath for mobile settings, focusing on MPTCP, with the goal of developing key insights for evolving the mobile multipath design. First, we conduct to our knowledge the most in-depth and the longest user trial of mobile multipath that focuses not only on MPTCP performance, but also on cross-layer interactions. Second, we identify a new research problem of multipath-aware CDN server selection. We demonstrate its real-world importance and provide recommendations. Third, our measurement findings lead us to design and implement a flexible software architecture for mobile multipath called MPFlex, which strategically employs multiplexing to improve multipath performance (by up to 63% for short-lived flows). MPFlex decouples the high-level scheduling algorithm and the low-level OS protocol implementation, and enables developers to flexibly plug-in new multipath features. MPFlex also provides an ideal vantage point for flexibly realizing user-specified multipath policies and is friendly to middleboxes.

Energy consumption due to network traffic on mobile devices continues to be a significant concern. We examine a range of excessive energy consumption problems caused by background network traffic through a two-year user study, and also validate these findings through in-lab testing of the most recent versions of major mobile apps. We discover a new energy consumption problem where foreground network traffic persists after switching from the foreground to the background, leading to unnecessary energy and data drain. Furthermore, while we find some apps have taken steps to improve the energy impact of periodic background traffic, energy consumption differences of up to an order of magnitude exist between apps with near-identical functionality. Finally, by examining how apps are used in the wild, we find that some apps continue to generate unneeded traffic for days when the app is not being used, and in some cases this wasted traffic is responsible for a majority of the app's network energy overhead. We propose that these persistent, widespread and varied sources of excessive energy consumption in popular apps should be addressed through new app management tools that tailor network activity to user interaction patterns.

Mobile Internet availability, performance and reliability have remained stubbornly opaque since the rise of cellular data access. Conducting network measurements can give us insight into user-perceived network conditions, but doing so requires careful consideration of device state and efficient use of scarce resources. Existing approaches address these concerns in ad-hoc ways.

No abstract available.

While the availability and accessibility of cellular network connectivity have improved in recent years, our ability to diagnose and debug network problems in this environment has not. One key challenge is that many of the network problems occur near the edge of the network where only mobile devices can perceive them, but network and battery resources to conduct measurements from these mobile devices are scarce. Traditional network measurement approaches that use continuous, periodic, or random measurements are either infeasible or ineffective in this environment.

Mobilyzer is an open-source network measurement library that coordinates network measurement tasks among different applications, facilitates measurement task design, and allows for more effective measurement task management than in existing standalone approaches. Unifying various network tasks into one framework greatly simplifies the problem of developing, deploying and managing measurement tasks which may otherwise interfere with one another. An intelligent scheduler, coordinated by a central server, dynamically schedules tasks to run in the background, preserving the user's battery life and respecting limits set by the user on task frequency and data consumption. We will demo MobiPerf, an open-source mobile network measurement tool built using the Mobilyzer library. MobiPerf collects a wide range of network performance data, ranging from the latency and throughput measurements common in existing client-based measurement frameworks, to HTTP loading times for specific URLs, to inferring RRC state configuration parameters and their impact on performance. We will also demo an interface for viewing a large, open dataset of performance data from around the world collected by MobiPerf.