Search

Image processing and communications networking technologies are evolving at a rapid pace. Users are demanding high-quality and realistic services to enjoy cultural contents such as sports and concerts. Free-viewpoint video (FVV) streaming is an active field of research that enables realistic services. FVV streaming service augments the user experience by providing different viewpoints of the same scene. The user can navigate freely and continuously to any viewpoint. In order to provide FVV streaming services, the transmission method of various on-demand user viewpoints is important. In this paper, we propose and implement a DASH-based FVV streaming client to reduce the view switching latency by receiving a number of adjacent images. We verify the performance of the proposed client and analyze the switching time and transmission data rate depending on the number of simultaneously received videos.

Recent advances in video processing and transmitting technologies have increased user interest and demand for realistic services. Among realistic services, the free-viewpoint video (FVV) streaming service has been studied. In order to provide the FVV streaming service, it is necessary to distinguish the number of videos and provide adjacent views for view switching. In this paper, we design and propose a structure that enables the client to know the relationship between views in free-viewpoint relationship description (FRD) architecture. The proposed FRD is used to implement the FVV streaming system, and the possibility of rapid new switching is verified.

In this paper, we designed an embedded audio video bridging (AVB) platform based on IEEE 802.1BA for real-time multimedia transmission in smart-car, smart-home, smart-theater, and then evaluated a performance of the implemented platform by analysis of IEEE 802.1AS (time synchronization protocol) and IEEE 802.1Qat (stream reservation protocol). Especially, the AVB Layer-2 protocol of MRP(Multiple Registration Protocol), MMAP(Multicast Address Acquisition Protocol), IEEE 1722, 1722.1 etc. was and implemented by linux based operating system. It is shown by interoperability tests with commercial products that the implemented platform transmits real-time multichannel AV data over AVB networks for Multichannel Multimedia Transmission. ☞ keyword : AVB, Mutlichannel HD-platform, QoS(Quality of Service), Inter-operability, Realtime Transmission, endpoint

In this paper, we propose a detection method for Digital Radio Mondiale (DRM) Plus suitable for hybrid mode broadcasting which services both DRM Plus and analog FM within the same frequency band. The guard-interval correlation method of Orthogonal Frequency Division Multiplexing (OFDM) is good for DRM Plus signal detection, but the possibility for false alarm increases when FM signal is received. The proposed method includes a reference block in the guard-interval correlation which increases the identification rate of weak DRM Plus signals and decreases the possibility of false alarm when analog FM is received. The performance of the proposed method is verified through simulations.

The performance of pilot-symbol-assisted channel estimation widely used for OFDM systems is degraded due to the small number of pilot symbols used for higher transmission efficiency. In this paper, we propose a pilot symbol based channel estimation using cross-correlation to improve the estimation performance of the OFDM system with small number of pilot symbols. The proposed technique detects a data symbol using the channel estimated by the pilot symbol and estimates the channel using the estimated data symbol and the pilot symbol. It is shown by computer simulations that the proposed technique outperforms the conventional pilot symbol assisted estimation technique.

In this paper, a dual combining based decoding scheme is proposed to enhance the detection performance of space-time block coding with two transmit antennas in a highly time-varying mobile channel. The proposed scheme analyzes the signal-to-noise ratio and signal-to interference plus noise ratio of decision variables for a zero-forcing combiner (ZFC) and a matched filter combiner (MFC), respectively. Based on the analysis, we derive a sophisticated decoding scheme which utilizes tentative detection symbols of the ZFC based decoder to cancel inter-symbol interference from the decision variables of the MFC. Computer simulations show that the proposed scheme outperforms the conventional decoding scheme with the ZFC or the MFC.

We present a multi-band orthogonal frequency division multiplexing (MB-OFDM) ultra-wideband (UWB) technology for a wireless speaker system which offers superior high-fidelity audio quality. The proposed scheme applies the Reed-Solomon code and the puncturer to payload data to improve the receiver sensitivity while maintaining the same data rate. Simulation result shows that the proposed scheme improves the signal-to-noise ratio of 0.8 dB at bit error rate of 10-6 when compared to the conventional scheme.

In this paper, we propose an efficient estimation technique for time-varying multipath channels by exploiting two dimensional delay-time nature in pilot inserted orthogonal frequency division multiplexing (OFDM) systems. The proposed technique consists of multipath snapshot estimation at periodic channel observation instances over an OFDM block and the linear interpolation of two consecutive multipath snapshots. Two decision-directed data utilizing schemes, data removed and data added correlation schemes, are proposed to enhance the performance of the multipath snapshot estimation.

This paper proposes an improved discrete Fourier transform-based and pilot-symbol-aided channel estimation (DFT-based PSA CE) for coherent orthogonal frequency division multiplexing (OFDM) systems. Conventional DFT-based PSA CE suffers from the dispersive distortion of an estimated channel impulse response (CIR) caused by virtual carriers. The proposed method estimates an equal-spaced channel frequency response (CFR) in a virtual carrier region by using forward and backward linear prediction (FBLP). Simulation results show that the proposed method outperforms the conventional one with slightly increased complexity and provides a performance similar to the frequency domain linear minimum mean square error (LMMSE) channel estimation with significantly reduced complexity.

A time-varying multipath channel causes co-channel interference (CCI) as well as inter-carrier interference (ICI) in a space-time block coded orthogonal frequency-division multiplexing (STBC-OFDM) system using two transmit antennas and an conventional simplified decoding scheme (SDS). In this paper, we derive the power of the CCI as a function of normalized channel variation rate. Also, we propose a successive interference cancellation (SIC) technique to improve the performance of the STBC-OFDM by considering the CCI mechanism. The proposed SIC technique can compensate the CCI to some extend with slightly increased complexity compared to the SDS.