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Wireless video transmission through multiple-input multiple-output (MIMO) channels has become more and more popular recently. In the superposition MIMO system which non-orthogonally multiplexes several signals in the power domain, the receiver performs non-linear detection to estimate the transmitted signals, which is called postcoding. This paper proposes a multistage postcoder which combines maximum likelihood detection (MLD) with codeword-level interference cancellation (CWIC) to balance the accuracy and complexity. It is shown from simulations that the proposed postcoder outperforms the conventional minimum mean square error-based detection with CWIC, where its improvement in peak signal-to-noise ratio comes up to 11 dB.

The demand for high-resolution wireless video transmission technology is expected to increase greatly as the video resolution increases, and as the Wi-Fi devices spread. Wireless transmission of high-resolution video requires high throughput, therefore it is necessary to use a multiple-input multiple-output (MIMO) system. In this paper, we propose an evaluation platform for video transmission method based on joint source-channel coding (JSCC) that suppresses the degradation of received video by combining source coding and precoding, and efficient hardware software co-design for implementing it on hardware such as field-programmable gate array (FPGA) board. As a result of simulation, beamforming based on eigenbeam-space division multiplexing (E-SDM), one of the precoding method, is performed and the effectiveness of the proposed method has been confirmed.

With the spread of mobile devices, image and video transmission is in great demand. The use of multiuser multiple-input multiple-output (MU-MIMO) systems, where multiple data can be sent to multiple users, is highly expected. This paper proposes a novel power allocation scheme for MU-MIMO systems, which minimizes the variance of channel capacities of each spatial stream of all users to achieve user fairness in terms of video quality. In addition to the user fairness, we make the spatial streams which convey visually more important information be high-quality for achieving high video quality. Simulation results show that the proposed power allocation enables to equalize video quality even if the distances between a transmitter and users are different.

Recently, video distribution over wireless networks has become more common due to the spread of smart devices. This paper proposes an optimal power allocation algorithm for the transmission of layered video streams over point-to-point multiple-input multiple-output (MIMO) systems combined with superposition coding. The proposed power allocation scheme is derived from the maximization of the weighted sum-rate, where two-step optimization leads to a closed-form solution. First, the power distribution between eigen-channels is optimized, and then the optimal power allocation to quality layers is obtained. Results demonstrate that the proposed scheme attains higher peak signalto-noise ratio on average in a wide range of signal-to-noise ratio than conventional fixed power allocation schemes.

In recent years, wireless video streaming has become very popular due to the widespread of Wi-Fi terminals supporting multiple-input multiple-output (MIMO) techniques. High-quality video streaming in wireless networks is a challenging topic. This paper proposes a greedy power allocation algorithm (GPA) for video streaming by overloaded MIMO systems. The proposed GPA adaptively controls power distribution based on received signal-to-noise ratio (SNR) so that the required bit error rate can be achieved. Simulation results demonstrate that GPA shows better performance than a conventional equal power allocation (EPA) scheme in terms of peak-signal-to-noise ratio (PSNR). The minimum SNR for achieving 35 dB in PSNR is 6 dB with GPA while EPA requires 10 dB in SNR to achieve 35 dB in PSNR.

Wireless video transmission over multiple-input multiple-output (MIMO) systems is a challenging theme. Eigen beam-space division multiplexing (E-SDM) is an optimal beamforming technique in terms of channel capacity when the transmitter and receiver can share channel state information. E-SDM sorts the channel quality from the highest signal-to-noise ratio (SNR) to the lowest one. This paper presents the video transmission scheme for H.264 scalable video streams over MIMO E-SDM with optimized packetization. The proposed method controls the ratio of a base layer and enhancement layers contained in a packet. The result shows that the optimized ratio is obtained when a packet consists of the lowest base layer ratio. This ratio provides the 39.9 dB of peak-signal-to-noise ratio after decoding while no frame can be decoded with the other ratio at SNR of 10 dB.

High efficiency video coding (HEVC) is the newest video coding standard of the ITU-T Video Coding Experts Group and the ISO/IEC Moving Picture Experts Group. The introduction of multiple-input multiple-output (MIMO) eigenbeam-space division multiplexing (E-SDM) systems makes it possible to increase data rate by multiplexing different data streams on multiple parallel eigen-channels. In this paper, we propose a MIMO video transmission scheme for scalable high efficiency video coding (SHVC), which is the scalable extension of H.265/HEVC. Simulation results show that our video transmission scheme has more potential to broadcast video streams efficiently than conventional MIMO systems.

Image and video transmission is highly expected to proliferate with the wide spread of Wi-Fi devices and the introduction of multiple-input multiple-output (MIMO) systems. This paper proposes a novel precoder for video transmission in overloaded MIMO systems, which is based on an eigenbeam space division multiplexing (E-SDM) technique. This paper also proposes a low complexity postcoder, which detects some of data symbols by a linear approach and the others by a prevoting vector cancellation (PVC) approach. It is shown from simulation results that the proposed precoder and postcoder achieve 40 dB in peak signal-to-noise ratio while reducing the computational complexity by over 61 compared to the conventional PVC-based detection when received signal-to-noise ratio is higher than 10 dB.

Based on the investigation of mechanism for large dielectric losses in relaxor fluorinated polymers, polyvinylidene fluoride (PVDF) derivatives, a new nanostructure-controlled PVDF based polymer films with low dielectric loss, tanδ < 1% (0.6%), and high dielectric constant, εr = 13 at frequency of 1 kHz, was proposed for electrical energy storage applications. The high dielectric loss was mainly due to the electric-field induced α-β phase transition, and one dimensional extension of P(VDF-TrFE)-g-PEMA films was found to reduce the α phase component resulting in reduction of the dielectric loss while keeping the high dielectric constant. In-situ FTIR measurements suggested a possibility of further reducing the dielectric-loss.

The phase separation of ultrahigh molecular weight isotactic polypropylene (it-UHMWPP) solution in the gelation process was investigated by quenching the solutions to the desired temperature. When an incident beam of an He−Ne gas laser was directed to the gel, the logarithm of scattered intensity increased linearly with time in the initial stage and tend to deviate from this linear relationship in the later stage. The melting endotherm of the differential scanning calorimetry curve showed a clear peak in the later stage, but no peak could be observed in the initial stage, indicating poor ordering of molecules in polymer-rich phase. The scattered intensity of laser beam from the gel showed a peak in the scattering angle direction. The peak became more intense with increasing time, but the peak position did not change. Accordingly, the phase separation of UHMWPP solution in the initial stage was analyzed within the framework of the linear theory of spinodal decomposition. In parallel to this small-angle lig...

In this paper, we propose a joint source-channel coding (JSCC) scheme for wireless image transmission over IEEE 802.11ac system. JSCC is a coding technique where both source and channel characteristics are considered. In a multiple-input multiple-output (MIMO) system based on an eigenbeam-space division multiplexing (E-SDM) technique, signal-to-noise ratio (SNR) of each spatial stream varies because it depends on the corresponding singular value of the MIMO channel matrix. Then, we propose the JSCC method which utilizes both the characteristics of the E-SDM and scalable image coding. The proposed algorithm adaptively allocates bit strings of a scalable image to both subcarriers and spatial streams on the physical (PHY) layer. High performance in image quality is attained since the proposed method improves peak signal-to-noise ratio (PSNR) of the image by around 10dB in average. In addition, it also achieves low latency due to no retransmission on medium access control (MAC) layer. The maximum improvement in average PSNR is approximately 15dB compared to a conventional method. The average PSNR performance reaches 40dB when SNR is higher than 17.5dB. The proposed method is capable of stable real-time transmission of high-resolution images even in a bad channel state.

Vier verschiedenartige supramolekulare Anordnungen konnen in einer Eintopfsynthese – je nach Art der vorhandenen Gegenionen – durch intermolekulare Vernetzung eines neuen anionischen Tris(biimidazolato)nickel(II)-Komplexes uber Wasserstoffbruckenbindungen entstehen. Die Verknupfung erfolgt uber die Biimidazolatliganden, die sowohl als H-Bruckendonor wie auch als -acceptor fungieren (siehe Schema).

Four different types of molecular arrangements can be formed by one-pot synthesis, depending on the type of counter cation used, when a new anionic tris(biimidazolato)nickel(II) complex is used to form a network held together by hydrogen bonds. The connections occur through biimidazolate ligands, which can act as hydrogen bond donor as well as acceptor (see scheme).