The Internet Protocol.

Summary form only given. The layered architecture is one of the key reasons behind the explosive and continuing growth of the Internet. There are, however, special networks in which cross-layer design is appropriate and may even be necessary. Two such cases are small wireless LAN and large-scale sensor networks. We consider first the design of medium access control (MAC) for a small wireless LAN based on a multiuser physical layer. We present a complete characterization of the throughput region and present conditions under which ALOHA is optimal. Next we consider the estimation of signal field using data collected from a large scale sensor network. The impact of medium access control on estimation is examined. We show that there exists a threshold on sensor outage probability above which a distributed random access protocol (such as ALOHA) outperforms the centralized deterministic schedulers.

On cross-layer design of wireless networks

In this paper, we introduce distributed caching of videos at the base stations of the Radio Access Network (RAN) to significantly improve the video capacity and user experience of mobile networks. To ensure effectiveness of the massively distributed but relatively small-sized RAN caches, unlike Internet content delivery networks (CDNs) that can store millions of videos in a relatively few large-sized caches, we propose RAN-aware reactive and proactive caching policies that utilize User Preference Profiles (UPPs) of active users in a cell. Furthermore, we propose video-aware backhaul and wireless channel scheduling techniques that, in conjunction with edge caching, ensure maximizing the number of concurrent video sessions that can be supported by the end-to-end network while satisfying their initial delay requirements and minimize stalling. To evaluate our proposed techniques, we developed a statistical simulation framework using MATLAB and performed extensive simulations under various cache sizes, video popularity and UPP distributions, user dynamics, and wireless channel conditions. Our simulation results show that RAN caches using UPP-based caching policies, together with video-aware backhaul scheduling, can improve capacity by 300% compared to having no RAN caches, and by more than 50% compared to RAN caches using conventional caching policies. The results also demonstrate that using UPP-based RAN caches can significantly improve the probability that video requests experience low initial delays. In networks where the wireless channel bandwidth may be constrained, application of our videoaware wireless channel scheduler results in significantly (up to 250%) higher video capacity with very low stalling probability.

Video-aware scheduling and caching in the radio access network

An important issue of supporting multi-user video streaming over wireless networks is how to optimize the systematic scheduling by intelligently utilizing the available network resources while, at the same time, to meet each video's Quality of Service (QoS) requirement. In this work, we study the problem of video streaming over multi-channel multi-radio multihop wireless networks, and develop fully distributed scheduling schemes with the goals of minimizing the video distortion and achieving certain fairness. We first construct a general distortion model according to the network?s transmission mechanism, as well as the rate distortion characteristics of the video. Then, we formulate the scheduling as a convex optimization problem, and propose a distributed solution by jointly considering channel assignment, rate allocation, and routing. Specifically, each stream strikes a balance between the selfish motivation of minimizing video distortion and the global performance of minimizing network congestions. Furthermore, we extend the proposed scheduling scheme by addressing the fairness problem. Unlike prior works that target at users' bandwidth or demand fairness, we propose a media-aware distortion-fairness strategy which is aware of the characteristics of video frames and ensures max-min distortion-fairness sharing among multiple video streams. We provide extensive simulation results which demonstrate the effectiveness of our proposed schemes.

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Distributed scheduling scheme for video streaming over multi-channel multi-radio multi-hop wireless networks

Consumer configurable mobile communications solution enabling policy-enforcement services allowing authorized users to define, manage and enforce restrictions for voice, data, and mobile Web services of a secondary mobile device.

Consumer configurable mobile communication solution

This paper proposes a Quality of Experience (QoE) based cross-layer design (CLD) framework for High Speed Downlink Packet Access (HSDPA). The proposed scheme aims at maximizing the user satisfaction by taking advantage of the link adaptation mechanism of HSDPA and the rate adaptation capability of multimedia applications. The main contributions of the paper are as follows. First, we describe the multiuser rate region of HSDPA by constructing a long-term radio link layer model. Next, we formulate multimedia QoE by constructing long-term utility functions, describe the multiuser utility space and derive its properties. We show analytically that the maximization of the sum of utility (max-MOS) can be efficiently solved by a fast greedy algorithm which searches only through the boundary of the utility space. We investigate two alternatives to the max-MOS approach, which introduce additional fairness in the system. We compare our proposed QoE-based cross layer optimization schemes to a system that is configured to maximize the overall throughput. For the sake of completeness, we also compare our approaches to a non-optimized HSDPA system. The performance comparison is made by simulation using a software implementation of an actually deployed HSDPA system. Results show that our QoE-based approach leads to significantly improved user perceived quality compared to the other approaches.

QoE-Driven Cross-Layer Optimization for High Speed Downlink Packet Access

Session mobility is the transfer of media of an ongoing communication
session from one device to another. This document describes the
general methods and specifies the signaling and media flows for
providing this service using the Session Initiation Protocol (SIP).
Service discovery is essential to locate targets for session transfer
and is discussed using the Service Location Protocol (SLP) as an
example.

Session Initiation Protocol (SIP) Session Mobility

This paper proposes a novel approach for Quality of Experience (QoE) driven cross-layer optimization for wireless video transmission. We formulate the cross-layer optimization problem with a constraint on the temporal fluctuation of the video quality. Our objective is to minimize the temporal change of the video quality as perceivable quality fluctuations negatively affect the overall quality of experience. The proposed QoE scheme jointly optimizes the application layer and the lower layers of a wireless protocol stack. It allocates network resources and performs rate adaptation such that the fluctuations lie within the range of unperceivable changes. We determine corresponding perception thresholds via extensive subjective tests and evaluate the proposed scheme using an OPNET High Speed Downlink Packet Access (HSDPA) emulator. Our simulation results show that the proposed approach leads to a noticeable improvement of overall user satisfaction for the provided video delivery service when compared to state-of-the-art approaches.

QoE-Based Cross-Layer Optimization of Wireless Video with Unperceivable Temporal Video Quality Fluctuation

This paper describes the H.264 Scalable Video coding streaming Evaluation Framework (SVEF). This is the first open-source framework for experimental assessment of H.264 Scalable Video Coding (SVC) delivery over real networks. Effectively adapting of the transport of an H.264 SVC stream to time-varying, bandwidth constrained, and loss prone networks is an important research area. However, very little experimental work has been performed due to the unavailability of real-time H.264 SVC players, the limitations of existing decoding software libraries when challenged with network-imparied received SVC streams (e.g., affected by random loss of Network Abstraction Layer Units - NALUs), and the lack of solutions for SVC streaming support. SVEF overcomes these issues by developing missing components and by integrating them in a hybrid online/offline experimental framework. We believe SVEF will be of significant help to the research community interested in experimentally benchmarking their own proposed SVC adaptation approaches and delivery mechanisms. As a proof-of-concept of SVEF, we provide the experimental performance evaluation of an SVC cross-layer in-network scheduler in a Wireless LAN hot spot scenario.

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SVEF: an open-source experimental evaluation framework for H.264 scalable video streaming

Service usage in emerging ubiquitous environments includes seamless and personalized usage of public and private devices discovered in the vicinity of a user. In our work, we describe an architecture for device discovery, device configuration, and the transfer of active sessions between devices. The presented architecture uses the Session Initiation Protocol (SIP) as a standardized, widely used signaling protocol for IP-based multimedia services. Our solution includes support of simple existing devices, split of sessions between devices, user-control of location-based behavior, and handling of security and privacy concerns. We present the implementation and show the feasibility of our work with analytical evaluation and measurements.

Srisakul Thakolsri

Papers

QoE-Driven Cross-Layer Optimization for High Speed Downlink Packet Access

Session Initiation Protocol (SIP) Session Mobility

QoE-Based Cross-Layer Optimization of Wireless Video with Unperceivable Temporal Video Quality Fluctuation

SVEF: an open-source experimental evaluation framework for H.264 scalable video streaming

Ubiquitous device personalization and use: The next generation of IP multimedia communications