Realtime Streaming with Guaranteed QoS over Wireless D2D Networks ∗ Navid Abedini Qualcomm Flarion Technologies Bridgewater, NJ navida@qti.qualcomm.com Swetha Sampath IBM Systems & Technology Group Houston, TX swesam@gmail.com Rajarshi Bhattacharyya Dept. of ECE Texas A&M University College Station, TX rajarshibh@tamu.edu Suman Paul Dept. of ECE Texas A&M University College Station, TX sumanpaul@tamu.edu Srinivas Shakkottai Dept. of ECE Texas A&M University College Station, TX sshakkot@tamu.edu ABSTRACT We consider a group of co-located wireless peer devices that desire to synchronously receive a live content stream. The devices are each equipped with an expensive unicast base- station-to-device (B2D) interface, as well as a broadcast device-to-device (D2D) interface over a shared medium. The stream is divided into blocks, which must be played out soon after their initial creation. If a block is not received within a specific time after its creation, it is rendered useless and dropped. The blocks in turn are divided into random linear coded chunks to facilitate sharing across the devices. We transform the problem into the two questions of (i) deciding which peer should broadcast a chunk on the D2D channel at each time, and (ii) how long B2D transmissions should take place for each block. We analytically develop a provably- minimum-cost algorithm that can ensure that QoS targets can be met for each device. We study its performance via simulations, and present an overview of our implementation on Android phones using the algorithm as a basis. Categories and Subject Descriptors C.2.1 [Computer-Communication Networks]: Network Architecture and Design—wireless communication General Terms Theory and Algorithms ∗ Research was funded in part by NSF grants CNS-0904520, CNS-0963818, CNS-1149458, DTRA grant HDTRA1-13-1- 0030, AFOSR grant FA9550-13-1-0008 and the Google Fac- ulty Research Awards program. The first two authors are former students of Texas A&M University Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full cita- tion on the first page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or re- publish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from permissions@acm.org. MobiHoc’13, July 29–August 1, 2013, Bangalore, India. Copyright 2013 ACM 978-1-4503-2193-8/13/07 ...$15.00. Keywords Live streaming, quality of service, linear network coding, multiple wireless interfaces, queueing 1. INTRODUCTION There has recently been a sharp increase in the use of smart, handheld devices for content consumption. These devices, such as smart phones and tablets, are equipped with multiple orthogonal wireless communication interfaces. Interfaces include expensive (both dollar-cost and energy) long-range base-station-to-device (B2D) interfaces (e.g. 3G or 4G), as well as low-cost short-range interfaces like WiFi. More recently, the use of short-range interfaces such as WiFi- Direct and FlashLinQ for device-to-device (D2D) communi- cation is starting to make an appearance. Simultaneously, there has been an explosion in available content, and it is expected that streaming of live events will play a big part in future demand [3]. Figure 1: Each device can simultaneously utilize uni- cast base-station-to-device (B2D) as well as broad- cast device-to-device (D2D) communication. In this paper, we focus on live-streaming of content to mul- tiple co-located devices, as shown in Figure 1. Here, data is generated in realtime by a server, and must be delivered to all the devices quickly in order to maintain the “live” as- pect of the event. Each device is simultaneously capable of