Most engineering and scientific phenomena, such as the surface of a landscape or the continuously changing temperature at a location are inherently infinite in space or time or both. We cannot measure all the data. Generally it is possible to record surface elevation values or the temperature only at some specific locations and times.

Interpolation and Approximation

The focus of this demonstration is the performance of streaming video over the mobile wireless channel. We compare two schemes: the standard approach to video which transmits H.264/AVC-encoded stream over 802.11-like PHY, and SoftCast -- a clean-slate design for wireless video where the source transmits one video stream that each receiver decodes to a video quality commensurate with its specific instantaneous channel quality.

/pdf/softcast-one-size-fits-all-wireless-video-3vmoew0u0e.pdf

SoftCast: one-size-fits-all wireless video

Reliability modeling and analysis of communication networks

Current WiFi Access Points (APs) choose transmission parameters when emitting wireless packets based solely on channel conditions. In this work we explore the benefits of deciding packet transmission parameters in a content-dependent manner. We demonstrate the benefits specifically for media delivery applications in WiFi environments by designing, implementing and evaluating a system, called Medusa. In order to keep the APs relatively simple, we implement the Medusa functions in a media-aware proxy. More specifically, when forwarding our media traffic, Medusa requires that APs simply use the WiFi broadcast feature, and that they refrain from making decisions on which wireless packets to retransmit, or what PHY rates such packets should be transmitted at. Instead we combine these typical link layer functions with a few other content-specific choices, in the proxy. Through detailed experiments across diverse mobility and interference conditions we demonstrate the advantages of this scheme for both unicast and multicast media delivery applications. The advantages are particularly substantial in multicast scenarios, where Medusa was able to deliver a 20 Mbps HD video stream simultaneously to 25 clients, using a single 802.11 AP, with good to excellent PSNR.

/pdf/scalable-wifi-media-delivery-through-adaptive-broadcasts-2qqwaup91o.pdf

Scalable WiFi media delivery through adaptive broadcasts

Motivated by recent emerging systems that can leverage partially correct packets in wireless networks, this paper investigates the novel concept of error estimating codes (EEC). Without correcting the errors in the packet, EEC enables the receiver of the packet to estimate the packet's bit error rate, which is perhaps the most important meta-information of a partially correct packet. Our EEC algorithm provides provable estimation quality, with rather low redundancy and computational overhead. To demonstrate the utility of EEC, we exploit and implement EEC in two wireless network applications, Wi-Fi rate adaptation and real-time video streaming. Our real-world experiments show that these applications can significantly benefit from EEC.

/pdf/efficient-error-estimating-coding-feasibility-and-13m1vv6nt1.pdf

Efficient error estimating coding: feasibility and applications

Nowadays, more and more vehicles are equipped with communication capabilities, not only providing connectivity with onboard devices, but also with off-board communication infrastructures. From road safety (i.e., multimedia e-call) to infotainment (i.e., video on demand services), there are a lot of applications and services that may be deployed in vehicular networks, where video streaming is the key factor. As it is well known, these networks suffer from high interference levels and low available network resources, and it is a great challenge to deploy video delivery applications which provide good quality video services. We focus our work on supplying error resilience capabilities to video streams in order to fight against the high packet loss rates found in vehicular networks. So, we propose the combination of source coding and channel coding techniques. The former ones are applied in the video encoding process by means of intra-refresh coding modes and tile-based frame partitioning techniques. The latter one is based on the use of forward error correction mechanisms in order to recover as many lost packets as possible. We have carried out an extensive evaluation process to measure the error resilience capabilities of both approaches in both (a) a simple packet error probabilistic model, and (b) a realistic vehicular network simulation framework. Results show that forward error correction mechanisms are mandatory to guarantee video delivery with an acceptable quality level , and we highly recommend the use of the proposed mechanisms to increase even more the final video quality.

https://www.mdpi.com/1424-8220/18/10/3495/pdf

Error Resilient Coding Techniques for Video Delivery over Vehicular Networks.

With future vehicles equipped with processing capability, storage, and communications, vehicular networks will become a reality. A vast number of applications will arise that will make use of this connectivity. Some of them will be based on video streaming. In this paper we focus on HEVC video coding standard streaming in vehicular networks and how it deals with packet losses with the aid of RaptorQ, a Forward Error Correction scheme. As vehicular networks are packet loss prone networks, protection mechanisms are necessary if we want to guarantee a minimum level of quality of experience to the final user. We have run simulations to evaluate which configurations fit better in this type of scenarios.

/pdf/protection-of-hevc-video-delivery-in-vehicular-networks-with-elwuilqf1o.pdf

Protection of HEVC video delivery in vehicular networks with RaptorQ codes.

The 3D-DWT is a mathematical tool of increasing importance in those applications that require an efficient processing of volumetric info However, the huge memory requirement of the algorithms that compute it is one of the main drawbacks in practical implementations In this paper, we introduce a fast frame-based 3D-DWT video encoder with low memory usage, based on lower-trees In this scheme, there is no need to divide the input video sequence into group of pictures (GOP), and it can be applied in a continuous manner, so that no boundary effects between GOPs appear.

Low bit-rate video coding with 3d lower trees (3D-LTW)

Delivery of video encoded bitstreams in wireless networks is a challenging task due to different factors (node mobility, time-varying wireless channel, etc.) that put in evidence the lack of QoS support for this kind of applications. In particular, we are working with teleoperated mobile robot systems. Our purpose is to perform a study about the behavior of IEEE 802.11 technology to evaluate if it would be able to comply with the requirements of this application. So, we have developed a prototype that consists of one mobile robot with an onboard webcam and an IEEE 802.11 network adapter. The control station sends navigation commands to the robot and, at the same time, receives a video stream that shows to the user a frontal view of actual robot location. We will analyze the different components of the overall system, making special emphasis in video coding engines and network response.

Analyzing the Impact of Commercial Video Encoders in Remotely Teleoperated Mobile Robots through IEEE 802.11 Wireless Network Technologies

In this paper, we present the methodology developed in a course of Artificial Intelligence and Pattern Recognition. The methodology is focused on building a face recognition system. For this purpose, we developed an own face recognition database named “Medfaces”. This database contains controlled and wild images for the same subjects, and it also contains infrared images and facial expression labels. This methodology has been applied for teaching telecommunications engineering course at Miguel Hernández University of Elche (Spain). We also present the results of our teaching experience in terms of student satisfaction.

Miguel O. Martínez-Rach

Papers

Error Resilient Coding Techniques for Video Delivery over Vehicular Networks.

Protection of HEVC video delivery in vehicular networks with RaptorQ codes.

Low bit-rate video coding with 3d lower trees (3D-LTW)

Analyzing the Impact of Commercial Video Encoders in Remotely Teleoperated Mobile Robots through IEEE 802.11 Wireless Network Technologies

Implementation of a face recognition system as experimental practices in an artificial intelligence and pattern recognition course