A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> The Real Time Streaming Protocol, or RTSP, is an application-level protocol for control over the delivery of data with real-time properties. RTSP provides an extensible framework to enable controlled, on-demand delivery of real-time data, such as audio and video. Sources of data can include both live data feeds and stored clips. This protocol is intended to control multiple data delivery sessions, provide a means for choosing delivery channels such as UDP, multicast UDP and TCP, and provide a means for choosing delivery mechanisms based upon RTP (RFC 1889). <s> BIB001 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Real-time multimedia transport has stringent quality of service requirements, which are generally not supported by current network architectures. In emerging mobile ad hoc networks, frequent topology changes and link failures cause severe packet losses, which degrade the quality of received media. However, in such mesh networks, there usually exist multiple paths between any source and destination nodes. Such path diversity has been demonstrated to be effective in combating congestion and link failures for improved media quality. In this paper, we present a new protocol to facilitate multipath transport of real-time multimedia data. The proposed protocol, the multiflow real-time transport protocol (MRTP), provides a convenient vehicle for real-time applications to partition and transmit data using multiple flows. We demonstrate through analysis that data partitioning, which is an essential function of MRTP, can effectively reduce the short-range dependence of multimedia data, thus improving its queueing performance in underlying networks. Furthermore, we show that a few flows are sufficient for MRTP to exploit most of the benefits of multipath transport. Finally, we present a comprehensive simulation study on the performance of MRTP under a mobile ad hoc network. We show that with one additional path, MRTP outperformed single-flow RTP by a significant margin. <s> BIB002 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Video streaming ranks among the most popular services offered through the Internet today. At the same time, accessing the Internet over public WiFi and 3G networks has become part of our everyday lives. However, streaming video in wireless environments is often subject to frequent periods of rebuffering and characterized by low picture quality. In particular, achieving smooth and quality-adaptive streaming of live video poses a big challenge in mobile scenarios. Building on the observation that the subjective video experience on mobile devices decreases when quality changes are more frequent than every 1 to 2 seconds, we present a client-side scheduler that retrieves segments of several video encodings over heterogeneous network interfaces simultaneously. By extending the DAVVI streaming platform with support for multiple interfaces, the proposed scheduler's performance is experimentally evaluated. The results show that our scheduler reduces the video interruptions and achieves a higher and more stable average quality over multiple, truly heterogeneous wireless interfaces. <s> BIB003 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Devices capable of connecting to multiple, overlapping networks simultaneously are becoming increasingly common. For example, most laptops are equipped with LAN- and WLAN-interfaces, and smart phones can typically connect to both WLANs and 3G mobile networks. At the same time, streaming high-quality video is becoming increasingly popular. However, due to bandwidth limitations or the unreliable and unpredictable nature of some types of networks, streaming video can be subject to frequent periods of rebuffering and characterised by a low picture quality. In this paper, we present a client-side request scheduler that distributes requests for the video over multiple heterogeneous interfaces simultaneously. Each video is divided into independent segments with constant duration, enabling segments to be requested over separate links, utilizing all the available bandwidth. To increase performance even further, the segments are divided into smaller subsegments, and the sizes are dynamically calculated on the fly, based on the throughput of the different links. This is an improvement over our earlier subsegment approach, which divided segments into fixed size subsegments. Both subsegment approaches were evaluated with on-demand streaming and quasi-live streaming. The new subsegment approach reduces the number of playback interruptions and improves video quality significantly for all cases where the earlier approach struggled. Otherwise, they show similar performance. <s> BIB004 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Video streaming is gaining popularity among mobile users. The latest mobile devices, such as smart phones and tablets are equipped with multiple wireless network interfaces. How to efficiently and cost-effectively utilize multiple links to improve the video streaming quality needs to be investigated. In order to maintain high video streaming quality while reduce the wireless service cost, in this paper, the optimal video streaming process with multiple links is formulated as a Markov Decision Process (MDP). The reward function is designed to consider the quality of experience (QoE) requirements for video traffic, such as the interruption rate, average playback quality, playback smoothness and wireless service cost. Using dynamic programming, the MDP can be solved to obtain the optimal streaming policy. To evaluate the performance of the proposed multi-link rate adaptation (MLRA) algorithm, we implement a testbed using the Android mobile phone and the open-source X264 video codec. Experimental results demonstrate the feasibility and effectiveness of the proposed MLRA algorithm for mobile video streaming applications, which outperforms the existing state-of-the-art one. <s> BIB005 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Devices capable of connecting to multiple, overlapping networks simultaneously is becoming increasingly common. For example, most laptops are equipped with LAN- and WLAN-interface, and smart phones can typically connect to both WLANs and 3G mobile networks. At the same time, streaming high-quality video is becoming increasingly popular. However, due to bandwidth limitations or the unreliable and unpredictable nature of some types of networks, streaming video can be subject to frequent periods of rebuffering and characterized by a low picture quality. In this paper, we present a multilink extension to the data retrieval part of the DAVVI adaptive, segmented video streaming system. DAVVI implements the same core functionality as the MPEG DASH standard. It uses HTTP to retrieve data, segments video, provides clients with a description of the content, and allows clients to switch quality during playback. Any DAVVI-data retrieval extensions can also be implemented in a DASH-solution. The multilink-enabled DAVVI client divides video segments into smaller subsegments, which are requested over multiple interfaces simultaneously. The size of each subsegment is dynamic and calculated on the fly, based on the throughput of the different links. This is an improvement over our earlier subsegment approach, which divided segments into fixed size subsegments. The quality of the video is adapted based on the measured, aggregated throughput. Both the static and the dynamic subsegment approaches were evaluated with on-demand streaming and quasi-live streaming. The new subsegment approach reduces the number of playback interruptions and improves video quality significantly for all cases where the earlier approach struggled. Otherwise, they show similar performance. <s> BIB006 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> The Internet infrastructure often supports multiple routes between two communicating hosts and, today, especially mobile hosts usually offer multiple network interfaces, so that disjoint paths between the hosts can be constructed. Having a number of (partly or fully) disjoint paths available may allow applications to distribute their traffic, aggregate capacity of different paths, choose the most suitable subset of paths, and support failover if a path fails. Exploiting multipath characteristics has been explored for TCP, but the requirements for real-time traffic differs notably. In this paper, we devise a multipath communication model for Real-time Transport Protocol (RTP); present minimal set of required protocol extensions; develop algorithms for scheduling RTP traffic across multiple paths at the sender and a corresponding de-jittering algorithm at the receiver side; and evaluate our proposal in varying scenarios using media traffic across different emulated mobile access network setups. <s> BIB007 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Video streaming is gaining popularity among mobile users. The latest mobile devices, such as smart phones and tablets, are equipped with multiple wireless network interfaces. How to efficiently and cost-effectively utilize multiple links to improve video streaming quality needs investigation. In order to maintain high video streaming quality while reducing the wireless service cost, in this paper, the optimal video streaming process with multiple links is formulated as a Markov Decision Process (MDP). The reward function is designed to consider the quality of service (QoS) requirements for video traffic, such as the startup latency, playback fluency, average playback quality, playback smoothness and wireless service cost. To solve the MDP in real time, we propose an adaptive, best-action search algorithm to obtain a sub-optimal solution. To evaluate the performance of the proposed adaptation algorithm, we implemented a testbed using the Android mobile phone and the Scalable Video Coding (SVC) codec. Experiment results demonstrate the feasibility and effectiveness of the proposed adaptation algorithm for mobile video streaming applications, which outperforms the existing state-of-the-art adaptation algorithms. <s> BIB008 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Utilizing the dormant path diversity through multipath routing in the Internet to reach end users—thereby fulfilling their QoS requirements—is rather logical. While offering better resource utilization, better reliability, and often even much better quality of experience (QoE), multipath routing and provisioning was shown to help network and data center operators achieve traffic engineering in the form of load balancing. In this survey, we first highlight the benefits and basic Internet multipath routing components. We take a top-down approach and review various multipath protocols, from application to link and physical layers, operating at different parts of the Internet. We also describe the mathematical foundations of the multipath operation, as well as highlight the issues and challenges pertaining to reliable data delivery, buffering, and security in deploying multipath provisioning in the Internet. We compare the benefits and drawbacks of these protocols operating at different Internet layers and discuss open issues and challenges. <s> BIB009 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video. <s> BIB010 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> End-users in online video services are sensitive to the overall quality of the video at screen, but also, and more importantly, to other factors, including the latency between the video generation and the playback for live videos. If the improvement of the quality of the perceived video has been well investigated by the multimedia community, the impact of delay, latency, and re-buffering has not received a significant attention. Adaptive streaming technologies, which have been widely adopted in the recent years, contribute to this lack of consideration since vendors usually recommend the introduction of significant extra-latency. In this paper, we address the problem of low-latency live video streaming. We propose an implementation of multi-path video delivery at the applicative level, which exploits the information provided in the latest version of the video delivery standards. We present an implementation of a video player, which takes advantage of multi-path networking to enable video playback using TCP with a latency below 100 ms. By initiating the multi-path delivery from the client side, our mechanism is compatible with current network equipments and does not require any change neither at the server nor in the middleboxes. <s> BIB011 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Currently, most multimedia applications utilize a combination of real- ::: time transport protocol (RTP) and user datagram protocol (UDP). ::: Application programs at the source end format payload data into RTP ::: packets using RTP specifications and dispatch them using unreliable ::: UDP along a single path. Multipath transport is an important way to ::: improve the efficiency of data delivery. In order to apply the ::: framework of multipath transport system based on application-level ::: relay (MPTS-AR) to RTP-based multimedia applications, this document ::: defines a multipath real-time transport protocol based on application- ::: level relay (MPRTP-AR), which is a concrete application-specific ::: multipath transport protocol (MPTP). Packet formats and packet types ::: of MPRTP-AR follow the common rules specified in MPTP profile. Based ::: on MPRTP-AR, RTP-based multimedia applications can make full use of ::: the advantages brought by MPTS-AR. <s> BIB012 </s> A Holistic Survey of Wireless Multipath Video Streaming <s> 1) RTP: <s> Bandwidth constraints and high end-to-end delays are real challenges for achieving and sustaining high quality mobile video streaming services. Diverse multipath transmission techniques are being investigated as possible solutions, since recent developments have enabled mobile devices users to receive video data simultaneously over multiple interfaces (e.g., LTE and WiFi). While some multipath protocols have been recently standardized for this purpose (e.g., MPTCP), being network layer protocols they cannot properly handle challenging transmission scenarios subject to packet losses and congestion, such as lossy wireless channels. In this work, we adopt the MPEG Media Transport (MMT) protocol to propose an improvement for mobile multipath video streaming solutions. MMT is an application layer protocol with inherent hybrid media delivery properties. We propose a novel path-and-content-aware scheduling strategy for MMT by means of full cooperation between network metrics and video content features. Our strategy provides better models to adaptively cope with unstable communication channel conditions and to improve the final user quality of experience (QoE). For the experimental evaluation, we used NS3-DCE to simulate a realistic multipath network scenario which includes channel error models and background traffic. Results for two video sequences are presented in terms of PSNR, SSIM, goodput, delay and packet loss rates. When compared with a simple scheduling strategy for the traditional multipath MMT, our approach yields significant packet loss rate reductions (~90%) and video quality improvements of around 12 dB for PSNR and 0.15 for SSIM. <s> BIB013
The Real-time Transport Protocol (RTP) was first published in 1992  and then updated in RFC 1889  , later obsoleted by RFC 3550  . The newest protocol specification is RFC 8108  published in 2017. RTP is an application layer transport protocol that provides end-to-end network transport functions to supports live, on-demand, and interactive multimedia applications. Next, we highlight more properties of the protocol, and then we survey multipath works based on RTP. RTP Properties. Although RTP is designed to run over UDP, it could also carry data over other transport protocols such as TCP or SCTP. Another property of RTP is that it can be used in conjunction with the RTP Control Protocol (RTCP) to send monitored information and QoS parameters periodically. RTP also can be used in conjunction with other protocols, such as Real-time Streaming Protocol (RTSP) BIB001 , which is used to control multimedia playback. A big problem of RTP, running over UDP, is that it lacks congestion control and it is unfair to give room to other flows. There is also no guarantee of reliable delivery and it needs a method to protect high priority frames (I-frames). Furthermore, a challenge to improve RTP to support multipath streaming is that RTP establishes at the media session level and receiver reports per media (video or audio) flow BIB007 . Multipath support. Multiflow Real-Time Transport Protocol (MRTP) BIB002 , Multipath RTP (MPRTP) BIB007 and Multipath RealTime Transport Protocol Based on Application-Level Relay (MPRTP-AR) BIB012 improved RTP to support multipath video streaming. The works MRTP and MPRTP are Constant Bit Rate (CBR) approaches. Since RTP lacks congestion control, a considerable receiver buffer is required to compensate the different path latencies of RTP streams when playing a CBR video BIB009 . Both MRTP and MPRTP use QoS reports (e.g., sender report and receiver report), similar to RTCP reporting in RTP, to carry periodic per flow and session statistics. The time interval between reports is set by the application in MRTP, and can be adapted based on network conditions by the receiver. The goal of Multiflow Real-time Transport Protocol (MRTP) BIB002 is to remedy the failure and congestion in mobile wireless ad hoc networks. It is claimed by its authors that the approach is also applicable to the Internet. MRTP is used in conjunction with the Multi-flow Realtime Transport Control Protocol (MRTCP). Inherently, MRTP/MRTCP is an extension of the RTP/RTCP to support media delivery over multiple wireless networks. Unlike RTP, MRTP is a sessionoriented protocol. Therefore, MRTCP establishes the session in a three handshake to exchange information (e.g., available paths). Data transmission could be over UDP/TCP/SCTP and during transmission, it is possible to add or remove paths based on the QoS reports. In particular, media divides into flows, and each flow is for one path (in MRTP, the concept of flow is used for series of video packets which are transmitted through an individual path). MRTCP manages flows by utilizing ADD/DELETE acknowledgments (ACKs) for flows. QoS reports are transferred through the best path or multiple paths to guarantee reliable delivery. These reports are useful for the sender to adapt to transmission errors. For example, by adding redundancy to increase error resilience and by assigning data to more proper paths. There is a reassembly buffer at the receiver side to compensate jitter, reorder and reassemble packets by utilizing session ID, flow ID and flow sequence number. MRTP uses a retransmission mechanism to retransmit packets to cope with unreliable UDP/IP. The timeout value for retransmission is set by RTT and the maximum number of retransmissions is set by the application. Different error control schemes, including Forward Error Correction (FEC), Multiple Description Coding (MDC) or Automatic Repeat reQuest (ARQ) could incorporate with MRTP. Finally, the results of the surveyed work show that MRTP outperforms single path RTP on received video quality. In MRTP, it is possible to choose the data distribution method. For example, it could be just a simple Round Robin, striping (over multiple servers), layered coding, multiple description coding or object-oriented coding (video or audio objects encode individually). Multipath RTP (MPRTP) protocol BIB007 is a RTP extension with multipath transmission for real-time media. The target of MPRTP is minimizing latency. Initially, the scheduler distributes equal traffic rate to each path and then after gathering information about the path characteristics, it recalculates the data distribution for each path. It uses RTCP to monitor and BIB002 Server and Client RTP MPRTP BIB007 Server and Client MRTP-AR BIB012 Server and Client Xing et al. BIB005 Client Chowrikoppalu et al.  Client DASH RTRA BIB008 Client Houzé et al. BIB011 Client MMT Kolan et al.  Server and Client Afzal et al. BIB013 Server and Client Sohn et al. BIB010 Server and Client Evensen et al. BIB003 Client Evensen et al. BIB004 Client Evensen et al. BIB006 Client