High-quality Multimedia Services Research Articles

Signal Properties under Multi-Carrier Chaos–Shift Keying

In recent years, increased demand for high-quality multimedia services requires increasing the wireless communications application data rates and be more reliable and secure. To meet this request, the researches related to Multi-Carrier (MC) transmission technologies have made considerable efforts in recent years because multi-carrier techniques can improve the data transmission rates. In this research, an overall study on performing Multi-Carrier Chaos Shift keying by using a technique Orthogonal Frequency Division Multiplexing (OFDM) is presented. A multi-carrier system simulation is designed because of the limited speed provided by Chaos Shift keying (CSK) due to the spreading factor. To increase security in this system; the chaotic sequence was generated by proposed to modify on one of the well-known chaos generators that is a tent map. The performance test and the security analysis were carried out using the Bit Error Rate (BER), Mean Squared Error (MSE), correlation test; the chaotic characteristics of the chaos generators sequences using are tested the Lyapunov Exponent. Results have showed the proposed tent map the autocorrelation is like a delta function, so that it appears as a noise that is difficult to discern the information carried by signal, it is much more sensitive to change the initial state and control parameters, where the proposed tent map provides better chaotic properties for encryption such as greater Lyapunov exponent, compared with well-known chaos maps (Logistic map1, Tent map, Quadratic map), it provides a lower Bit Error Rate (BER) performance than a tent map. In addition, the proposed method to multi-carrier CSK system with various Spreading Factors (SF) values outperforms the CSK system in improving the data transmission rate.

Attractor selection based limited feedback hybrid precoding for uplink V2I communications.

As an essential part of vehicle networks, the Vehicle to Infrastructure (V2I) needs the support of millimeter wave and massive MIMO technologies to enable high data rate applications, such as automated driving, real-time high-quality multimedia services and so on. As the scale of the antenna array increases, the complexity of the beamforming and channel estimation algorithms under high mobility conditions also increases significantly. In particular, highly robust beamforming methods need to cope with fast changing transmission environments. In this paper, we adopt a biological inspired self-adaptive selection algorithm called attractor selection algorithm (ASA) to support uplink beamforming. The ASA requires only a little feedback information from the Road Side Infrastructure (RSI) to perform fast beam training, hence making the transmission link more stable. The simulation results indicate that the proposed ASA-assisted algorithm can significantly reduce the time required to achieve a timely beam training, which would be essential for V2I high communications under high mobility conditions.

Multi-Point Media Content Sharing Scheme in Internet of Things Networks

Media content sharing scheme among multiple devices is one of the most important service technologies in the Internet of Things (IoT) era. Typically, there are three kinds of schemes adopted for the content sharing among devices: screen mirroring, file casting, and content redirection. Among them, the content redirection in which a sink pulls the content from a cloud server based on universal resource locator information received from a source is a very promising technology in terms of resource usage. However, for the content redirection scheme, the link quality between the access point (AP) and sink must be reliable enough to share the high-quality multimedia services. The link quality problem usually occurs because AP and sink are installed without considering the link quality between the two devices. To solve this problem, in this paper, we introduce a multi-point content delivery scheme, which transfers the media content from both source and AP to sink simultaneously. The proposed scheme can operate in two modes, namely power combining mode that increases the received signal power by combining the transmitted power of both devices and bandwidth aggregation mode that increases the bandwidth of the received signal by aggregating the bandwidth of the transmitted signal of both devices. Numerical results show that using the proposed scheme, with 10 m of AP and sink separation distance, we can get 300% ~ 400% performance improvement; therefore, the proposed scheme can be a core technology for media content sharing in the IoT era.

Implementation of a Regional Spectrum Sensing Based Cognitive Radio System for Digital TV White Space

ABSTRACTIt is well-known that cognitive radio (CR) is a fundamental solution to mitigate the spectrum scarcity of today's wireless communication systems. For the realization of CR, there are many obstacles to resolve, including technical and policy perspectives. Since CR is a very sensitive technology, it is particularly important to test the scheme with appropriate operation in a real environment. In this regard, we have developed a testbed of a regional spectrum sensing based CR system for digital TV (DTV) white space. The developed system has a centralized spectrum sensor, and according to the sensing results, mobile WiMAX system provides high quality multimedia service through the spectrum hole in DTV band. There is also a fast frequency hopping capability depending on the sensing results to minimize interference to the actual licensee, the primary DTV system. The performance analysis shows that the developed CR system has excellent performance satisfying the IEEE 802.22 requirements, and is suitable for use in the real environment.

Design of Optimized Multimedia Data Streaming Management Using OMDSM over Mobile Networks

Mobility management is an essential challenge for supporting reliable multimedia data streaming over wireless and mobile networks in the Internet of Things (IoT) for location-based mobile marketing applications. The communications among mobile nodes for IoT need to have a seamless handover for delivering high quality multimedia services. The Internet Engineering Task Force (IETF) mobility management schemes are the proposals for handling the routing of IPv6 packets to mobile nodes that have moved away from their home network. However, the standard mobility management scheme cannot prevent packet losses due to longer handover latency. In this article, a new enhanced data streaming route optimization scheme is introduced that uses an optimized Transmission Control Protocol (TCP) realignment algorithm in order to prevent the packet disordering problem whenever the nodes in the IoT environment are communicating with each other. With the proposed scheme, data packets sequence realignment can be prevented, the packet traffic speed can be controlled, and the TCP performance can be improved. The experimental results show that managing the packet order in proposed new scheme remarkably increases the overall TCP performance over mobile networks within the IoT environment thus ensuring the high quality of service (QoS) for multimedia data streaming in location-based mobile marketing applications.

Information-centric cost-efficient optimization for multimedia content delivery in mobile vehicular networks

Providing high-quality multimedia services is a challenging and high-cost task in mobile vehicular networks due to intermittent connectivity, highly dynamic capacity, mostly associated to heterogeneous hosts distribution and their high mobility. Information-centric networking (ICN), which adopts novel content-based dissemination instead of the traditional host-based one, has great potential to accomplish cost-efficient quality-oriented multimedia delivery. This paper proposes a novel cost-Efficient Multimedia content Delivery approach (EcoMD) in vehicular networks leveraging the ICN features. In EcoMD, two essential factors are first analyzed and modeled: content mobility and supply-demand balance, and then, a mixed integer programming (MIP) optimization is formulated to minimize the economic cost associated to guaranteed the quality level of multimedia services. To resolve this NP-hard problem, heuristic mechanisms are proposed covering three aspects: priority-based path selection, least-required source maintaining and on-demand caching enhancement. By comparison with existing state-of-the-art solutions, simulation results demonstrate how EcoMD provides an improved performance in terms of start-up delay, jitter, playback continuity, and Quality of Experience (QoE) while particularly reduces the economic cost.

Guest Editorial: Multimedia Services Provision over Future Mobile Computing Systems

Motivated by research in the area of multimedia services over future computing systems, the articles in this special issue aim to present recent advances in multimedia services provided over energy-efficient mobile computing environments toward alleviating associated problems and addressing related challenges. More specifically, the target of this special issue is to foster the dissemination of high-quality research in the interrelated scientific fields and present future directions in terms of energy-efficient high quality multimedia services provision over mobile computing systems, as well as novel multimedia processing technologies with emphasis on mobile applications.

CHANNEL ESTIMATION IN LTE DOWNLINK

3GPP LTE is the evolution of the UMTS in response to ever-increasing demands for high quality multimedia services according to users’ expectations. Since downlink is always an important factor in coverage and capacity aspects, special attention has been given in selecting technologies for LTE downlink. Novel technologies such as orthogonal frequency division multiplexing (OFDM) and multiple input, multiple output (MIMO), can enhance the performance of the current wireless communication systems. The high data rates and the high capacity can be attained by using the advantages of the two technologies. These technologies have been selected for LTE downlink. Pilot-assisted channel estimation is a method in which known signals, called pilots, are transmitted along with data to obtain channel knowledge for proper decoding of received signals. This thesis aims at channel estimation for LTE downlink. Channel estimation algorithms such as Least Squares (LS), Minimum Mean Square Error (MMSE) haven been evaluated for different channel models in LTE downlink. Performance of these algorithms has been measured in terms of Bit Error Rate (BER) and Symbol Error Rate (SER).

Study of coexistence between indoor LTE femtocell and outdoor-to-indoor DVB-T2-Lite reception in a shared frequency band

Nowadays, the demand for high-quality multimedia services (video, audio, image, and data) is rapidly increasing. The Digital Video Broadcasting - terrestrial (DVB-T) standard, its second-generation version (DVB-T2), and the Long-Term Evolution (LTE) standard are the most promising systems to fulfill the demand for advanced multimedia services (e.g., high-definition image and video quality), especially in Europe. However, LTE mobile services can operate in a part of the UHF band allocated to DVB-T/T2 TV services previously. The main purpose of this work is to explore the possible coexistences of DVB-T2-Lite and LTE systems in the same shared frequency band (co-channel coexistence) under outdoor-to-indoor and indoor reception conditions. Furthermore, an applicable method for evaluating coexistence scenarios between both systems is shown with a particular example. These coexistence scenarios can be noncritical and critical. In the first case, both systems can coexist without significant performance degradation. In the second one, a partial or full loss of DVB-T2-Lite and/or LTE signals can occur. We consider an indoor LTE femtocell and outdoor-to-indoor DVB-T2-Lite signal reception in a frequency band from 791 up to 821 MHz. Simulations of combined indoor and outdoor signal propagation are performed in MATLAB using 3rd Generation Partnership Project (3GPP) channel models, separately for both DVB-T2-Lite and LTE systems. Correctness of path loss simulation results is verified by measurements. Afterwards, an appropriate linear model is proposed which enables to evaluate the impact of coexistence on performance of both systems in outdoor-to-indoor and indoor-to-indoor reception scenarios. The results are related to an actual location in the building and are presented in floor plans. The floor plans include different coexistence conditions (different power imbalance and different amount of overlay of the radio channels). Service availability of both systems is verified again by measurements. The resulting maps help better understand the effect of coexistence on achievable system performance under different indoor/outdoor reception situations considering real transmission conditions.

Fast encoding algorithm for high-efficiency video coding (HEVC) system based on spatio-temporal correlation

Video compression technology is an importa nt research part to the intelligent user interface for interactive multimedia system using technologies and services such as image processing, pattern recognition, computer vision and cloud computing service. Recently, high-efficiency video coding (HEVC) has been established as the demand of very high-quality multimedia service like ultrahigh definition video service. High-efficiency video coding (HEVC) standard has three units such as coding unit (CU), prediction unit (PU) and transform unit. It has too many complexities to improve coding performance. We propose a fast algorithm which can be possible to apply for both CU and PU parts. To reduce the computational complexity, we propose CU splitting algorithm based on rate---distortion cost of CU about the parent and current levels to terminate the CU decision early. In terms of PU, we develop fast PU decision based on spatio-temporal and depth correlation for PU level. Finally, experimental results show that our algorithm provides a significant time reduction for encoding with a small loss in video quality, compared to the original HEVC Test Model (HM) version 10.0 software and the previous algorithm.

Transmitting scalable video coding using VLC with color and dimming control to assure QoS

Recently, light emitting diode (LED) technology has been the focus of the information technology and green technology industries.The visible light communication (VLC) system uses LED technology for simultaneous illumination and data transmission. Therefore, the VLC system provides illumination to the user, which can provide both high quality multimedia services and various application services. The main concerns of VLC systems are illumination and bit error rate (BER) performance. Consequently, it is necessary to analyze the illumination control and method of transmitting multimedia data in the VLC system. In this paper, we propose a method to effectively transmit and Red, Green, Blue (RGB) three-color LED to video signal while providing dimming and color control from the VLC system. In the VLC system, LEDs can generate various colors of light by controlling the mixing ratio of each individual RGB color element. Thus, each RGB channel will have a different signal power, and each channel will have different performance. Therefore, we present a novel resource allocation using the RGB channel state information to allocate the multi-layers of video in the VLC system. The conventional system allocates the fixed channel to a scalable video coding (SVC) signal. However, the proposed system allocates a high priority to the SVC signal channel.As a result of computer simulation tests, the proposed system can improve the BER performance compared to the conventional system.

A Power Saving Mechanism for Multimedia Streaming Services in Cloud Computing

This paper proposes a power saving mechanism for embedded system and multimedia streaming service design based on digital signal processor. It simultaneously achieves two main functions: a high-quality multimedia service in cloud computing, and a power saving control mechanism for extending the lifetime of hand-held devices used on multimedia streaming server applications. This paper enables dynamic voltage and frequency scaling power control mechanisms to enable frequency and voltage adjustment according to the system state of a device. The proposed mechanism increases the frame rate of multimedia services to 16.66%/s and mitigates power consumption by 1.5%.

Dispersion Managed Optical Links with Optical Phase Conjugator Placed at the Various Positions

The needs of ultra-high optical backbone systems are currently increased to transmit the high-quality multimedia services. For transmitting the ultra-high speed optical signals with better performance, the techniques to suppress or mitigate the optical signal distortion due to group velocity dispersion and optical Kerr effects are required. Dispersion management (DM), optical phase conjugation, and the combination of these two are promising techniques to compensate for the signal distortion. The goal of this paper is to investigate the possibility of the flexible configurations of the ultra-high and long-haul optical backbone systems using optical links with the random distribution of residual dispersion per span (RDPS) and optical phase conjugator (OPC) placed at the various positions. We confirm that the proposed link configurations should be one of the methods suitable for implementing the flexible optical backbone systems, also, the possibility is more available to longer backbone.

Design of Multi-hop Qos Scheduling for IEEE 802.16 Networks

Broadband wireless networks are increasing in popularity owing to current advances in technology. For large area network deployment, IEEE 802.16 mesh networks can provide a wide coverage, high speed and high quality multimedia service. IEEE 802.16 mesh configuration eliminates the need to have direct links between subscriber stations (SSs) and the base station (BS); a node can choose the links and path of the highest quality to transmit data and avoid the congested areas. To provide better Quality of Service (QoS) over the 802.16 network, the network layer 3 (L3) and layer 2 (L2) QoS must be integrated. Hence, cross-layer mechanisms were designed and incorporated into our previously proposed IEEE 802.16 QoS frameworks. Taking into consideration resource utilization and QoS requirements, we devised various scheduling schemes to determine their effects on the IEEE 802.16 mesh network. Our performance evaluation demonstrates that the proposed framework with enhancement scheduling has higher throughput, lower delay and signal cost than comparable systems. In this paper, we provide an appraisal of our proposed scheme.

An Efficient Transmission Scheme of MPEG2-TS over RTP for a Hybrid DMB System

Hybrid digital multimedia broadcasting (DMB) is a next-generation mobile TV system that combines broadcasting and wireless communication networks and can provide various high-quality multimedia services. However, if a system adheres to the current standard of transmitting the DMB content in the form of MPEG2-TS through wireless networks, it results in a burden on the network due to low transmission efficiency. The reasons for the low transmission efficiency are as follows. First, due to its constant bitrate characteristic, DMB MPEG2-TS includes a considerable amount of needless information, such as NULL packets and stuffing bytes. Second, due to the inflexibility of the Real-time Transport Protocol (RTP) standard, one cannot fully utilize the maximum transmission unit of the network when converting MPEG2-TS to RTP stream for transmission. This paper proposes a new transmission scheme that resolves these problems. Experiment results show that the proposed scheme improves data bitrate transmission efficiency by 8% to 36%, compared to the standard scheme, in the streaming of various real-DMB contents.

An Efficient Transmission Scheme of MPEG2-TS over RTP for a Hybrid DMB System

Hybrid digital multimedia broadcasting (DMB) is a next-generation mobile TV system that combines broadcasting and wireless communication networks and can provide various high-quality multimedia services. However, if a system adheres to the current standard of transmitting the DMB content in the form of MPEG2-TS through wireless networks, it results in a burden on the network due to low transmission efficiency. The reasons for the low transmission efficiency are as follows. First, due to its constant bitrate characteristic, DMB MPEG2-TS includes a considerable amount of needless information, such as NULL packets and stuffing bytes. Second, due to the inflexibility of the Real-time Transport Protocol (RTP) standard, one cannot fully utilize the maximum transmission unit of the network when converting MPEG2-TS to RTP stream for transmission. This paper proposes a new transmission scheme that resolves these problems. Experiment results show that the proposed scheme improves data bitrate transmission efficiency by 8% to 36%, compared to the standard scheme, in the streaming of various real-DMB contents.

System design for broadband digital radio broadcasting

In this article, we present an in-band onchannel (IBOC) broadcasting system suitable for digital audio and data broadcasting in FM and AM channels. The new design synergistically integrates frequency hopping, LDPC coding, hierarchical modulation, and band aggregation techniques to increase the data rate, improve spectrum efficiency, and at the same time provide the spectrum flexibility necessary in highquality audio and multimedia services. A prototype has been developed on a personal computer-based software defined radio platform. Numerical results and initial laboratory tests demonstrate the significant performance advantages of the new system design.

Data reorganization for scalable video service with embedded mobile devices

Recent development of high-speed wireless networks and embedded systems has enabled the recording and delivery of high-performance multimedia to heterogeneous mobile users. To support heterogeneous mobile users with high-quality multimedia services, scalable video coding was introduced. In the scalable video coding (SVC), through multidimensional scalability, all types of these scalability can be exploited at the same time. However, the generated video sequences of scalable video coding are not adequate for mobile multimedia service systems since its flexibility makes non contiguous storing and retrieval of partial stream data. In this article, we propose efficient scalable video data reorganization for video servicing systems, which consist of video server and mobile clients. For video server, we reorganize scalable video streams taking into account both of decoding dependency and location in disk array storage, where disk array is widely used for storage systems of video server. In the mobile devices, we place substreams with the consideration of NAND flash memory page and block boundaries, which is storage for mobile devices. The experimental results show that the proposed reorganization of scalable video can improve the performance of mobile multimedia service systems.

Design of an Integrated Internet Data and Digital-Television Receiving System

Abstract Internet Data is hugely increased for high quality multimedia services and the related techniques is also developed rapidly. This paper is aimed to develop integrated internet data and Digital-Television receiving system with high performance and optimization, which is obtained by one-board integration with load control. It is applicable to various devices like computer, set-top box, home multimedia gateway etc. The performance is proved by evaluation test. It shows that the developed device can be TV tuner and internet AP for more robust multimedia services. Key Words : IPTV, Internet data, TV, Home Gateway, Set-Top Box Received 9 April 2013, Revised 29 April 2013Accepted 20 May 2013Corresponding Author: Eui-Seok Nahm(Dept. Ubiquitous IT, Far East Univ.) Email: nahmes@kdu.ac.krⒸ The Society of Digital Policy & Management. All rights reserved. This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.otg/licenses/by-nc/3.0), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.ISSN: 1738-1916

OFDMA with variable tone spaces

Next generation wireless networks such as 3GPP LTE-A demand enhanced system capacity for high-quality multimedia services. Carrier aggregation based on OFDMA has been introduced to achieve this. In CA, each component carrier can be located on a different frequency band, and each user utilizing it moves at a different speed. This results in different channel characteristics for each user. Enhancing the system capacity in this environment requires a multiple access scheme that considers different channel characteristics among users. However, conventional OFDMA using fixed tone space (called OFDMA-FTS) does not consider user-specific channel characteristics, resulting in capacity degradation. In this article, we propose a new OFDMA system with variable tone spaces (OFDMA-VTS) as an approach to enhance system capacity. OFDMA-VTS selects the tone space suitable for each user by considering userspecific channel characteristics in CA. When intersymbol interference is dominant due to a long delay spread, the small tone space is selected to eliminate severe ISI. Conversely, when intercarrier interference due to a large Doppler spread severely degrades the system performance, the large tone space is selected to compensate ICI. In the proposed OFDMA-VTS, each user adaptively selects the optimal tone space needed to minimize the total interference of ISI and ICI, therefore enhancing system capacity.