Efficient Transmission of H.264 Video over Multirate IEEE 802.11e WLANs

The H.264 video encoding technology, which has emerged as one of the most promising compression standards, offers many new delivery-aware features such as data partitioning. Efficient transmission of H.264 video over any communication medium requires a great deal of coordination between different communication network layers. This paper considers the increasingly popular and widespread 802.11 Wireless Local Area Networks (WLANs) and studies different schemes for the delivery of the baseline and extended profiles of H.264 video over such networks. While the baseline profile produces data similar to conventional video technologies, the extended profile offers a partitioning feature that divides video data into three sets with different levels of importance. This allows for the use of service differentiation provided in the WLAN. This paper examines the video transmission performance of the existing contention-based solutions for 802.11e, and compares it to our proposed scheduled access mechanism. It is demonstrated that the scheduled access scheme outperforms contention-based prioritized services of the 802.11e standard. For partitioned video, it is shown that the overhead of partitioning is too high, and better results are achieved if some partitions are aggregated. The effect of link adaptation and multirate operation of the physical layer (PHY) is also investigated in this paper

Intergrating DMIF and internet standard protocols for QoS-aware delivery of MPEG-4

Delivering high quality multimedia presentations over the Internet spurred the development of numerous encoding and delivery standards. MPEG-4 is the first true object-based multimedia standard that seeks to address the issues concerning the delivery of multimedia content over the Internet, in particular QoS-Internet. MPEG-4 defines a generic framework, Delivery Multimedia Integration Framework (DMIF), for this purpose. The DMIF standard, however, only describes the semantics of the delivery platform. Incorporation of the tools and protocols provided by the QoS-Internet into this framework remains an issue to be solved by system developers. This thesis presents a QoS-aware system architecture for MPEG-4 streaming over the QoSInternet. This novel architecture benefits from an object-based design that very well fits the requirements of MPEG-4 standard. This design addresses the shortcomings of the DMIF framework in providing a complete solution for the delivery of MPEG-4. Defining a practical syntax for DMIF semantics is one of the aspects of the presented design. Integrating the services that are available through existing transport protocols such as TCP, UDP and RTP forms another part of the presented design. MPEG-4 uses a very generic approach toward specifying QoS constraints and does not specify how QoS signalling methods are exploited in DMIF. Tackling QoS issues of MPEG-4 delivery forms an important part of this thesis. This part presents a method for integrating RSVP into DMIF, and proposes a QoS-aware streaming system design. To verify the validity of the proposed architecture and as a proof of concept for the DMIF standard, a version of the presented design has been implemented for the best-effort Internet. The implementation provides a complete realization of the proposed streaming system for best-effort Internet as well as a partial but functional realization for QoS-Internet. In addition to standard conformity, the implementation features a novel fast-start rate controller and multi-client support. This implementation of the DMIF instance for remote retrieval and MPEG-4 Streaming Server (also considered as the first open source code of this part of the DMIF standard) have become part of the IM1 software, the reference implementation of MPEG-4. This research work has also resulted in the publication of three papers in various prestigious conferences.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat

Per-session weighted fair scheduling for real time multimedia in multi-rate wireless local area networks

Supporting real time multimedia applications is of utmost importance for future wireless data networks. In particular, it is crucial to support such applications in widely deployed and fast growing wireless local area networks (WLAN) that are based on IEEE 802.11 standard. However, achieving this goal requires features and mechanisms that have not been offered by the original IEEE 802.11 standard. To address this issue, several Quality of Service (QoS) enabling features have been added to the Medium Access Control (MAC) layer in the new IEEE 802.11e standard. Nevertheless, the new standard does not mandate a specific QoS solution, and intentionally leaves such task to developers and equipment vendors. Devising mechanisms that can efficiently provide the required QoS in WLANs has proved to be a challenging task. This is mainly due to the fact that WLANs such as 802.11e are based on the CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance) access method, which is inherently a distributed mechanism with random uplink or downlink access. Moreover, the physical layer of a WLAN allows each station to use a different transmission rate. The transmission rate could also dynamically change from one packet to the next, for the same station. The general problem of packet loss in wireless networks is also present in WLANs. The existing solutions and the prioritized contention based mechanism provided by the standard are found to be inadequate for providing the required services, especially in heavily loaded networks. Considering the issues mentioned above, we present a solution in this thesis that employs the controlled access mechanisms of the 802.11e standard to provide per-session guaranteed QoS to multimedia sessions. We introduce a framework that centralizes the task of scheduling uplink and downlink flows in the access point through the concept of virtual packets. We propose a new queuing structure that works with a fair generalized processor sharing based scheduler, integrated with a traffic shaper, for scheduling controlled (polling) and contention access durations. To address the issues of physical channel impairment and variable rate operation of a WLAN, we extend our scheduling framework to provide throughput or temporal fairness in multirate WLANs. Through analysis and experiments, we demonstrate that our solution provides guaranteed fair access for multimedia sessions over WLANs.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat

Enhanced Controlled-Access and Contention-Based Algorithms for IEEE 802.11e Wireless LANs

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High-Definition Map Representation Techniques for Automated Vehicles

Many studies in the field of robot navigation have focused on environment representation and localization. The goal of map representation is to summarize spatial information in topological and geometrical abstracts. By providing strong priors, maps improve the performance and reliability of automated robots. Due to the transition to fully automated driving in recent years, there has been a constant effort to design methods and technologies to improve the precision of road participants and the environment’s information. Among these efforts is the high-definition (HD) map concept. Making HD maps requires accuracy, completeness, verifiability, and extensibility. Because of the complexity of HD mapping, it is currently expensive and difficult to implement, particularly in an urban environment. In an urban traffic system, the road model is at least a map with sets of roads, lanes, and lane markers. While more research is being dedicated to mapping and localization, a comprehensive review of the various types of map representation is still required. This paper presents a brief overview of map representation, followed by a detailed literature review of HD maps for automated vehicles. The current state of autonomous vehicle (AV) mapping is encouraging, the field has matured to a point where detailed maps of complex environments are built in real time and have been proved useful. Many existing techniques are robust to noise and can cope with a large range of environments. Nevertheless, there are still open problems for future research. AV mapping will continue to be a highly active research area essential to the goal of achieving full autonomy