Frame-based mapping mechanism for energy-efficient MPEG-4 video transmission over IEEE 802.11e networks with better quality of delivery

Recent developments in hardware, software and communication technologies have resulted in increasing interest in the use of wireless local area networks (WLANs). Mobile devices with embedded WLAN functionality are becoming increasingly popular. Such devices must be designed to support applications that require high quality of service (QoS) and have favorable to maximize battery capacity. The resources of queues in IEEE 802.11e networks may be wasted by the transmission of information that is useless to the receiver. This work develops a frame-based mapping mechanism (FBM) that exploits different methods to process I/P/B (Intra/Predictive/Bipredictive) video frame packets. FBM refers to the dropping of arriving packets if the preceding packets in the same video frame have been dropped. When fragmented packets of a single frame are allocated to different access categories (AC) queues, out-of order delivery may occur. Hence, FBM tries to treat all fragmented packets of each video frame equally and allocates them to the same AC queue if possible. The simulation results demonstrate that transmission by the FBM is more efficient than that by other mechanisms, such as EDCA (Enhanced Distributed Channel Access), static mapping and adaptive mapping, suggesting that the energy of a device is not wasted in the transmission of useless video data in WLANs. (C) 2015 Elsevier Ltd. All rights reserved.Foundation item: The National Project of Taiwan (No.: MOST 103-2221-E507-001). Authors are grateful to Ministry of Science and Technology Grant no. (MOST 103-2221-E507-001), Government of Taiwan for financial support to carry out this work.Ke, C.; Yang, C.; Chen, J.; Ghafoor, KZ.; Lloret, J. (2015). Frame-based mapping mechanism for energy-efficient MPEG-4 video transmission over IEEE 802.11e networks with better quality of delivery. Journal of Network and Computer Applications. 58:280-286. https://doi.org/10.1016/j.jnca.2015.08.005S2802865

3D video transmission over LTE

This thesis presents a research work on quality of experience in 3D video transmission over LTE networks. The objective is to study the state-of-art of LTE and 3D video, described in the scientific literature, and to quantify the user quality of experience (QoE) during a simulated LTE transmission. The work will start by a study of the University of Wien “LTE-A System Simulator” and its capabilities. In addition, different scenarios with various users equipment (UEs) and base stations (eNodeBs) densities will be configured and simulated in order to obtain the frame-by-frame Block Error Rate (BLER) values experienced by different UEs. Once obtained, the Block Error Rate frames will be converted to packet level error traces, which will be used to introduce erasures and corruptions into the packetized 3D video bitstream. The corrupted encoded video stream will be decoded using an error-concealment capable video decoder and the decoded/recovered video quality (QoE) will be estimated based on the Structural Similarity Index of the recovered video. Finally, the QoE results for the different system configurations will allow classifying the severity of the QoE degradations due to transmission losses, through inferring the relationship between those system parameters and the achievable QoE.Esta dissertação apresenta um trabalho de investigação sobre a qualidade de experiência numa transmissão de vídeo 3D sobre redes LTE. O objectivo é estudar o estado-da-arte no que respeita a rede LTE e vídeo 3D, descrito na literatura científica, e obter a qualidade de experiência de usuário (QoE) durante uma simulação de transmissão LTE. O trabalho começará por um estudo do University of Wien “LTE-A System Simulator” e as suas capacidades. Para este efeito, vão ser configurados diferentes cenários com distintas densidades de utilizadores (UEs) e estações base (eNodeBs), com o fim de obter a taxa de erros do bloco (BLER) experimentada por diferentes utilizadores. Depois de obter esta taxa, as tramas da taxa de erros do bloco (BLER) serão convertidas em tramas de nível de erro de pacotes, que vão ser usadas para adicionar corrupções de bit em ficheiros de vídeo 3D. O fluxo de vídeo codificado e corrompido será descodificado usando um descodificador de vídeo e a qualidade do vídeo recuperado vai ser calculada com base no Índice de Similitude Estrutural. Finalmente, os resultados de QoE para as diferentes configurações do sistema permitirão classificar o nível das degradações de QoE devido a perdas de transmissão, por meio de inferir a relação entre os parâmetros do sistema e a QoE obtida.Ingeniería de Telecomunicació

Energy Optimization for Hybrid ARQ

Hybrid automatic repeat request (HARQ) \cite{costello1983error} plays an important role in providing reliable and efficient data transmission. In wireless communications, the wireless channel may vary fast, due to the mobility of the transmitter/receiver and the channel. Forward error correction (FEC) and automatic repeat request (ARQ) are two basic techniques to control errors. FEC employs error correction coding, by adding parity bits to the information bits, to combat channel errors. ARQ allows the receiver to request a retransmission of the packet when an error is detected in the received packet. HARQ gives protection to the wireless transmission by combining FEC and ARQ. In typical HARQ systems, redundancy is added to the information bits, and a retransmission is performed until either the packet is successfully decoded, or a maximum number of transmissions is reached.The motivation to optimize the energy consumption of HARQ is the high energy consumption of wireless communications on mobile devices. Wireless devices usually have a limited battery life, and wireless communications consume the majority of the battery energy of mobile devices. One example is that 3G and Wifi units consume more than 50\% of the energy for some smart phones \cite{tawalbeh2016studying}. Another example is that battery depletion has been identified as one of the primary factors that limit the lifetime of wireless sensor networks \cite{verdone2010wireless}.Previous works on HARQ mainly use information-theoretic approach, which assumes that the number of bits in each transmission round is sufficiently large. This assumption does not necessarily hold for actual codes with finite length. Therefore, in this dissertation, we consider HARQ with actual codes. We use turbo-coded HARQ, since turbo codes are well-known capacity-approaching codes \cite{berrou1993near} and widely used in standards such as 3GPP Long-Term Evolution (LTE) \cite{3gpp2007mulltiplexing}. We study the energy optimization for HARQ in two scenarios: the energy optimization for incremental redundancy (IR) HARQ, and the energy optimization for HARQ in wireless video transmission. For IR HARQ, each retransmission contains additional parity bits beyond those of the previous transmissions. For the first scenario, we consider different cases of channel state information (CSI) at the transmitter: the transmitter has no knowledge of any CSI, or knows the CSI in previous transmission rounds through a perfect feedback channel, or knows both current and previous CSI. The transmitter decides the forward error correction code rate based on the CSI it has. We minimize the energy consumption of turbo-coded HARQ, subject to a packet loss rate constraint. Numerical results show that the energy consumption of HARQ decreases when more CSI information is available at the transmitter. We also compare IR combining with both Chase combining and the system without combining, and IR combining yields the least energy consumption.For the second scenario, we formulate the problem as maximizing the video quality, subject to a constraint on the wireless transmission energy consumption. We consider multiple parameters in multiple layers in a wireless video transmission system: transmit power, alphabet size, FEC code rate, maximum number of transmissions and unequal video data importance. An analytical framework is proposed to include these parameters, which allows us to divide this problem into two sub-problems: data transmission and unequal error protection (UEP) for video content. The problem is tackled by solving the two sub-problems, which are done by exhaustive search and convex optimization, respectively. Simulations of different videos show that the proposed scheme outperforms methods using conventional data transmission and/or unequal error protection. For example, in the low SNR region, there is a total gain of 4.8 to 5.6dB on the peak signal-to-noise ratio of the received video compared to video transmission using conventional HARQ without any video UEP

Content-aware radio resource management for IMT-advanced systems

Radio Resource Management (RRM) is crucial to efficiently and correctly manage the delivery of quality-of-service (QoS) in IMT-Advanced systems. Various methods on radio resource management for LTE/LTE-Advanced traffic have been studied by researchers especially regarding QoS handling of video packet transmissions. Usually, cross-layer optimisation (CLO) involving the PHY and MAC layers, has been used to provide proper resource allocation and distribution to the entire system. Further initiatives to include the APP layer as part of CLO techniques have gained considerable attention by researchers. However, some of these methods did not adequately consider the level of compatibility with legacy systems and standards. Furthermore, the methods did not wholly address User Equipment (UE) mobility or performance metrics for a specific data type or a specified period. Consequently, in this thesis, a content-aware radio RRM model employing a cross-layer optimiser focusing on a video conferencing/streaming application for a single cell long-term evolution (LTE) system has been proposed. Based on two constructed look-up tables, the cross-layer optimiser was found to dynamically adjust the transmitted video data rates depending on the UE or eNodeB SINR performance. The proposed look-up tables were derived from the performance study of the LTE classical (baseline) simulation model for various distances at a certain UE velocity. Two performance parameters, namely the average throughput and measured SINR were matched together to find the most suitable data rates for video delivery in both the uplink and downlink transmissions. The developed content-aware RRM model was then tested against the LTE baseline simulation model, to benchmark its capability to be used as an alternative to existing RRM methods in the present LTE system. Based on the detailed simulations, the output performance demonstrated that for video packet delivery in both uplink and downlink transmissions, the content-aware RRM model vastly outperformed the legacy LTE baseline simulation model with regard to the packet loss ratio and average end-to-end delay for the same amount of throughput. The baseline simulation model and the newly developed cross-layer approach were investigated and compared with practical measurement results in which PodNode technology, besides other components and supporting simulation software, were used to emulate the LTE communication system. The first emulation experiment involving the baseline model was generally in sync with the uplink throughput simulation performance. The second test which implemented the cross-layer approach employing the look-up table derived from the previous emulated results, confirmed the viability of the proposed content-aware RRM model to be used in current LTE or LTE-Advanced systems for improving the performance in the packet loss ratio and average packet delay