Ilias Politis

Energy efficient and perceived QoS aware video routing over Wireless Multimedia Sensor Networks

Wireless Sensor Networks (WSNs) have an ever increasing variety of multimedia based applications. In these types of applications, network nodes should ideally maximize QoS and minimize energy expenditures in video communication. This article presents PEMuR, a novel dual scheme for efficient video communication, which aims at both energy saving and high QoS attainment. To achieve its objectives, PEMuR proposes the combined use of an energy aware hierarchical routing protocol with an intelligent video packet scheduling algorithm. The adopted routing protocol enables the selection of the most energy efficient routing paths, manages the network load according to the energy residues of the nodes and prevents useless data transmissions through the proposed use of an energy threshold. In this way, an outstanding level of energy efficiency is achieved. Additionally, the proposed packet scheduling algorithm enables the reduction of the video transmission rate with the minimum possible increase of distortion. In order to do so, it makes use of an analytical distortion prediction model that can accurately predict the resulted video distortion due to any error pattern. Thus, the algorithm may cope with limited available channel bandwidth by selectively dropping less significant packets prior to their transmission. Simulation results demonstrate the effectiveness of the proposed scheme.

Power efficient video multipath transmission over wireless multimedia sensor networks

This paper proposes a power efficient multipath video packet scheduling scheme for minimum video distortion transmission (optimised Video QoS) over wireless multimedia sensor networks. The transmission of video packets over multiple paths in a wireless sensor network improves the aggregate data rate of the network and minimizes the traffic load handled by each node. However, due to the lossy behavior of the wireless channel the aggregate transmission rate cannot always support the requested video source data rate. In such cases a packet scheduling algorithm is applied that can selectively drop combinations of video packets prior to transmission to adapt the source requirements to the channel capacity. The scheduling algorithm selects the less important video packets to drop using a recursive distortion prediction model. This model predicts accurately the resulting video distortion in case of isolated errors, burst of errors and errors separated by a lag. Two scheduling algorithms are proposed in this paper. The Baseline scheme is a simplified scheduler that can only decide upon which packet can be dropped prior to transmission based on the packet’s impact on the video distortion. This algorithm is compared against the Power aware packet scheduling that is an extension of the Baseline capable of estimating the power that will be consumed by each node in every available path depending on its traffic load, during the transmission. The proposed Power aware packet scheduling is able to identify the available paths connecting the video source to the receiver and schedule the packet transmission among the selected paths according to the perceived video QoS (Peak Signal to Noise Ratio—PSNR) and the energy efficiency of the participating wireless video sensor nodes, by dropping packets if necessary based on the distortion prediction model. The simulation results indicate that the proposed Power aware video packet scheduling can achieve energy efficiency in the wireless multimedia sensor network by minimizing the power dissipation across all nodes, while the perceived video quality is kept to very high levels even at extreme network conditions (many sensor nodes dropped due to power consumption and high background noise in the channel).

A middleware architecture supporting seamless and secure multimedia services across an intertechnology radio access network

This article presents a middleware architecture to support multimedia services across intertechnology radio access networks in a secure and seamless manner. The proposed architecture uses the media-independent handover framework, where the handover decision function is based on triggering/collecting statistics from the physical, network, and application layers so that an ongoing multimedia session (video) can be transferred seamlessly and securely (using context transfer) across intertechnology radio access networks. Simulation results show that when a vertical handover is based on the proposed MIH framework (including the context transfer of AAA information), handover latency is reduced by 38 percent during WiFi to UMTS handover and 20 percent during UMTS to WiFi handover compared to a non-MIH-based handover scheme.

Optimizing Video Transmission over Wireless Multimedia Sensor Networks

This paper proposes an efficient packet scheduling scheme for minimizing perceived video distortion and power consumption over multipath wireless multimedia sensor networks. The proposed scheduling algorithm is responsible for transmitting the video packets over selected multipaths according to their importance (high priority packets over high bandwidth paths). Moreover, whenever the aggregate transmission rate available at the network cannot support the required transmission rate due to high packet loss probability, the scheduling algorithm can selectively drop combinations of video packets prior to transmission to adapt the rate of the sender to the limitations of the wireless channel capacity. The video packets that will be dropped prior to transmission are selected based on a recursive distortion prediction model that has been customized for H.264/AVC coding scheme and counts for isolated losses, burst of losses and losses separated with small lag. Two scheduling algorithms are proposed. The baseline scheme utilizes a novel distortion prediction model and decides upon which packet can be dropped prior to transmission based on the packets impact on the video distortion. Moreover, the power aware packet scheduling is an extension of the baseline capable of estimating the power that will be consumed by each node during the transmission; hence it can control the power consumption by selectively drop the least significant video packets prior to transmission. Simulation results indicate the efficiency of the proposed scheduling scheme in terms of received video distortion (PSNR) and power consumption.

A model of network related QoE for 3D video

Three Dimensional video quality comprises a variety of perceptual attributes, including overall image quality, naturalness, presence, perceived depth, comfort, immersiveness, etc. This paper proposes a novel objective QoE model for 3D video streaming that takes into account network parameters (i.e. packet losses)and is based on the relationship between objective and subjective video quality measures. The investigation is concerned with stereoscopic video (left-and-right views). The analysis of the results indicate that the proposed QoE model has a strong correlation with MOS scores, hence can be effectively used in predicting the overall image quality of 3D videos transmitted over lossy networks.

Hybrid broadcast and broadband networks convergence for immersive TV applications

This article proposes a converged broadcast and broadband platform in order to deliver 3D media to both mobile and fixed users with guaranteed minimum quality of experience (QoE). The work presented offers an ideal business model for operators having both digital video broadcast and Internet Protocol (IP)-based media services. To that end, the DVB and peer-to-peer Internet technologies will be combined to provide sufficient resources for supporting high-bandwidth high-quality 3D multiview video. The motivations behind combining these technologies are outlined with an emphasis on their complementary characteristics. In addition, the overall design of the proposed architecture is presented focusing on the protocols that are exploited to achieve the interworking of the underlying technologies. Moreover, innovative key techniques for supporting both fixed and mobile users in an efficient manner are introduced.

A hybrid scheme for video transmission over wireless multimedia sensor networks

The introduction of multimedia capable sensors has posed new challeges for classic Wireless Sensor Networks that are henceforth required to provide both power and quality efficent routing. This paper proposes an innovative protocol for power and perceived QoS aware routing of multimedia content over Wireless Multimedia Sensor Networks. The proposed scheme comprises the advantages of both energy efficient hierarchical routing and video packet schedulling according to the packets importance. The hierarchical routing algorithms are often utilized for bandwidth efficiency and power control over Wireless Sensor Networks. In addition, packet scheduling is widely adopted as an effective rate adaptation technique in wireless multimedia communications. Both these techniques are combined in a proposed scheme which firstly, utilizes nodes with the highest residual energy and low power-cost paths, in order to perform the routing and secondly, predicts the distortion of video packets and selects to either drop them or transmit them according to the current channel bandwidth limitations. The simulation results prove the efficiency of the proposed combined scheme in terms of power consumption and received video distortion (PSNR).

A quality of service negotiation-based admission control scheme for WCDMA mobile wireless multiclass services

This paper introduces a new call admission control scheme. Quality of service (QoS) parameters are negotiated during the admission procedure at heavy loaded cells and maximum capacity is achieved. Blocking and dropping are used to prevent the system from an outage situation but their probability of occurrence is greatly reduced. Reservation bandwidth is used thoroughly as a means of improving overall QoS. Furthermore, the greatest common divisor of all the application load factors is considered as the resource unit, the resulting resource pool is identified and the performance of the above algorithms is analyzed using a novel multistep Markov analysis. The analysis takes account of classes without time restrictions, which are served with a pre-emptive system. Although the increased channel utilization of our proposed scheme reduces the available bandwidth for calls with pre-emption, we compensate for this loss using an extra reservation bandwidth. Blocking probability, dropping probability, average time delay in the queue, and channel utilization factor are used as benchmarks for the proposed schemes.

Cloud for multimedia applications and services over heterogeneous networks ensuring QoE

This paper aims to identify open challenges and propose the future steps towards establishing QoE driven media aware clouds. Cloud computing emerges as technology that allows access to resources over the Internet, transparently and independently of the underlying infrastructure. This study identifies the research challenges that future media-aware cloud computing will need to address. This is important in order to support multimedia services and applications exchange with efficiency, seamlessness and with guaranteed perceived quality across heterogeneous networking technologies, user devices and preferences.

Intelligence packet scheduling for optimized video transmission over wireless networks

This paper presents an intelligent packet scheduling scheme based on an analytical distortion model for Multi-Referenced H.264 video over 802.11 wireless networks. This model considers that video distortion in H.264 video codecs is based on multi-reference video frames, as opposed to previous video standards. The model has been verified with actual video distortion measurements and it has been compared with a simple additive model that omits the correlation between the frames. The packet dropping that is required in the case of the available transmission rate is limited, takes into consideration the impact of the loss of the frame on the resulting video distortion that depends not only on the distortion of the particular frame but on the distortion effect that propagates to the correlated frames. Furthermore, simulation results show that the proposed model accurately captures the distortion effect for reference based H.264 coding and the improves the reconstructed video quality when is implemented in rate adaptation via packet scheduling.