Wireless Video Communication System Research Articles

Coexistence of light emission and detection in a III-nitride quantum well diode.

The demand for on-chip multifunctional optoelectronic systems is increasing in today's Internet of Things era. III-nitride quantum well diodes (QWDs) can transmit and receive information through visible light and can be used as both light-emitting diodes (LEDs) and photodetectors (PDs). Spectral emission-detection overlap gives the III-nitride QWD an intriguing capability to detect and modulate light emitted by itself. In this paper, the coexistence of light emission and detection in a III-nitride QWD is experimentally demonstrated, and a wireless video communication system through light is established. When approximately biasing and illuminating at the same time, the III-nitride QWD can achieve light emission and detection simultaneously. This work provides a foundation for the development of multifunctional III-nitride QWDs and the realization of device-to-device data communication.

On the Performance of Wireless Video Communication Using Iterative Joint Source Channel Decoding and Transmitter Diversity Gain Technique

In this research work, we have presented an iterative joint source channel decoding- (IJSCD-) based wireless video communication system. The anticipated transmission system is using the sphere packing (SP) modulation assisted differential space-time spreading (DSTS) multiple input-multiple output (MIMO) scheme. SP modulation-aided DSTS transmission mechanism results in achieving high diversity gain by keeping the maximum possible Euclidean distance between the modulated symbols. Furthermore, the proposed DSTS scheme results in a low-complexity MIMO scheme, due to nonemployment of any channel estimation mechanism. Various combinations of source bit coding- (SBC-) aided IJSCD error protection scheme has been used, while considering their identical overall bit rate budget. Artificial redundancy is incorporated in the source-coded stream for the proposed SBC scheme. The motive of adding artificial redundancy is to increase the iterative decoding performance. The performance of diverse SBC schemes is investigated for identical overall code rate. SBC schemes are employed with different combinations of inner recursive systematic convolutional (RSC) codes and outer SBC codes. Furthermore, the convergence behaviour of the employed error protection schemes is investigated using extrinsic information transfer (EXIT) charts. The results of experiments show that our proposed R a t e − 2 / 3 SBC-assisted error protection scheme with high redundancy incorporation and convergence capability gives better performance. The proposed R a t e − 2 / 3 SBC gives about 1.5 dB E b / N 0 gain at the PSNR degradation point of 1 dB as compared to R a t e − 6 / 7 SBC-assisted error protection scheme, while sustaining the overall bit rate budget. Furthermore, it is also concluded that the proposed R a t e − 2 / 3 SBC-assisted scheme results in E b / N 0 gain of 24 dB at the PSNR degradation point of 1 dB with reference to R a t e − 1 SBC benchmarker scheme.

Optimal HEVC Configuration for Wireless Video Communication Under Energy Constraints

High Efficiency Video Coding (HEVC) provides a doubling in coding efficiency compared with the H.264/AVC at the expense of increased computational complexity. However, mobile devices that perform video encoding and communication over wireless networks have limited energy supply. A video encoding system which has the ability to adjust its computational complexity and power consumption could be used to prolong the lifetime of these devices. In this paper, we develop a framework, which selects the optimal HEVC encoding configuration in order to optimize the performance of the wireless video communication system under energy constraints. More specifically, in this paper, we develop an analytic HEVC encoder behavior model based on the extensive analysis of key HEVC encoding tools. We use the developed model for the performance optimization of the HEVC encoder under energy constraints. We propose an adaptive algorithm to estimate the HEVC encoder model parameters and perform online encoder coding configuration optimization. We show that using the proposed framework, the video encoder is able to select appropriate coding tools to automatically adjust its coding efficiency and complexity to match the available power budget with the maximum possible video quality. The proposed HEVC encoder model provides a guideline for optimized tool selection in the energy constrained wireless video communication.

Delay–Rate–Distortion Optimized Rate Control for End-to-End Video Communication Over Wireless Channels

In addition to the rate-distortion (R-D) behavior, in a real-time wireless video communication system, the end-to-end delay would also significantly affect the overall video reception quality. To analyze, control, and optimize the R-D behavior under the end-to-end delay constraint, in this paper we extend the traditional R-D optimization (RDO) for the wireless video communication system and formulate a novel delay-RDO-based rate control problem, by investigating the allocation of end-to-end delay to different delay components. It aims at minimizing the average total end-to-end distortion under the transmission rate and end-to-end delay constraints, by a joint selection of both the source coding and the channel coding parameters. The wireless channel is represented by a finite-state Markov channel model characterizing the time-varying process and predicting the future channel condition. As applicable solutions, a practical algorithm based on the Lagrange multiplier approaches, Karush-Kuhn-Tucker conditions, and sequential quadratic programming methods is developed. The experimental results demonstrate the superiority of the proposed algorithm over the existing schemes.

Optimal Foresighted Multi-User Wireless Video

Recent years have seen an explosion in wireless video communication systems. Optimization in such systems is crucial – but most existing methods intended to optimize the performance of multi-user wireless video transmission are inefficient. Some works (e.g., Network Utility Maximization (NUM)) are myopic: they choose actions to maximize instantaneous video quality while ignoring the future impact of these actions. Such myopic solutions are known to be inferior to foresighted solutions that optimize the long-term video quality. Alternatively, foresighted solutions such as rate-distortion optimized packet scheduling focus on single-user wireless video transmission, while ignoring the resource allocation among the users. In this paper, we propose a general framework of foresighted resource allocation among multiple video users sharing a wireless network. Our framework allows each user to flexibly choose individual cross-layer strategies. Our proposed resource allocation is optimal in terms of the total payoff (e.g., video quality) of the users. A key challenge in developing foresighted solutions for multiple video users is that the users' decisions are coupled. To decouple the users' decisions, we adopt a novel dual decomposition approach, which differs from the conventional optimization solutions such as NUM, and determines foresighted policies. Specifically, we propose an informationally-decentralized algorithm in which the network manager updates state- and user-dependent resource “prices” (i.e., the dual variables associated with the resource constraints), and the users make individual packet scheduling decisions based on these prices. Because a priori knowledge of the system dynamics is almost never available at run-time, the proposed solution can learn online while performing the foresighted optimization. Simulation results show 7 dB and 3 dB improvements in Peak Signal-to-Noise Ratio (PSNR) over myopic solutions and existing foresighted solutions, respectively.

Rate-Distortion Optimized Cross-Layer Rate Control in Wireless Video Communication

A wireless video communication system can be designed based on the rate-distortion (R-D) criterion, i.e., minimizing the end-to-end distortion (which includes quantization distortion and transmission distortion) subject to the transmission bit-rate constraint. The minimization can be achieved by adjusting the source encoding parameters and channel encoding parameters. This rate-distortion optimization (RDO) is usually done for each video frame individually in a real-time video communication system, e.g., video calls or videoconferencing. To achieve this, an accurate bit-rate model and distortion model for each frame can be used to reduce the RDO complexity. In this paper, we derive a source bit-rate model and quantization distortion model; we also improve the performance bound for channel coding under a convolutional code and a Viterbi decoder, and derive its performance bound under a Rayleigh block fading channel. Given the instantaneous channel condition, e.g., signal-to-noise ratio and transmission bit-rate constraint, we design an R-D optimized cross-layer rate control (CLRC) algorithm by jointly choosing quantization step size in source coding and code rate in channel coding. Experimental results show that our proposed R-D models are more accurate than the existing R-D models. Experimental results also showed that the rate control under our models has more stable R-D performance than the existing rate control algorithms; using the channel estimation, CLRC can further achieve remarkable R-D performance gain over that without channel estimation. Another important result is that the subjective quality of our CLRC algorithm is much better than the existing algorithms due to its intelligent reference frame selection.

Prediction of transmission distortion for wireless video communication: Algorithm and application

In this paper, we develop algorithms for estimating transmission distortion in wireless video communication systems. By leveraging the analytical results obtained in our previous works, we design low complexity algorithms that are capable of estimating transmission distortion accurately. We also extend our algorithm for pixel-level transmission distortion estimation to pixel-level end-to-end distortion estimation. Furthermore, we apply our pixel-level end-to-end distortion estimation algorithm to prediction mode decision in H.264 encoder. Experimental results show that (1) our transmission distortion estimation algorithm is more accurate and more robust against inaccurate channel estimation than existing distortion estimation algorithms; (2) our mode decision algorithm achieves remarkable PSNR gain over the existing algorithms for prediction mode decision in H.264 encoder, e.g., an average PSNR gain of 1.44 dB for ‘foreman’ sequence when Packet Error Probability (PEP) equals 5%.

Rate control in H.264 wireless video communication system

PurposeThe purpose of this paper is to introduce an efficient rate control algorithm for the H.264/AVC video coding in wireless communication. The adaptive rate control algorithm can reduce rate fluctuation, effectively prevent the skipping frame, and be suitable to the characteristics of wireless channel. The experimental result indicates that this plan can guarantee the quality of service of video transmission.Design/methodology/approachA motion complexity measure is developed to enhance the existing mean of absolute difference (MAD)‐based algorithm and is applied to bit allocation for rate control. Time and space relativities in frames are also used in the proposed rate control algorithm for MAD prediction. A quantitative parameter (QP) control scheme is used to adjust the computed QP based on actual encoding results of previous coded macroblocks (MBs) in a frame.FindingsThe proposed rate control algorithm always outperforms JM 8.6. The adaptive MAD model can reduce the prediction error. Both the subjective and objective reconstructed video qualities are improved, and the luminance PSNR is increased by up to 0.53 dB (or an average of around 0.37 dB).Originality/valueThe adaptive rate control algorithm based on motion complexity and MAD prediction with space and time relativities will be suitable for wireless communication applications.

Energy-efficient wireless video coding and delivery

Transmitting video over wireless channels from mobile devices has gained increased popularity in a wide range of applications. A major obstacle in these types of applications is the limited energy supply in mobile device batteries. For this reason, efficiently utilizing energy is a critical issue in designing wireless video communication systems. This article highlights recent advances in joint source coding and optimal energy allocation. We present a general framework that takes into account multiple factors, including source coding, channel resource allocation, and error concealment, for the design of energy-efficient wireless video communication systems. This framework can take various forms and be applied to achieve the optimal trade-off between energy consumption and video delivery quality during wireless video transmission.

Power-rate-distortion analysis for wireless video communication under energy constraints

Mobile devices performing video coding and streaming over wireless and pervasive communication networks are limited in energy supply. To prolong the operational lifetime of these devices, an embedded video encoding system should be able to adjust its computational complexity and energy consumption as demanded by the situation and its environment. To analyze, control, and optimize the rate-distortion (R-D) behavior of the wireless video communication system under the energy constraint, we develop a power-rate-distortion (P-R-D) analysis framework, which extends the traditional R-D analysis by including another dimension, the power consumption. Specifically, in this paper, we analyze the encoding mechanism of typical video coding systems, and develop a parametric video encoding architecture which is fully scalable in computational complexity. Using dynamic voltage scaling (DVS), an energy consumption management technology recently developed in CMOS circuits design, the complexity scalability can be translated into the energy consumption scalability of the video encoder. We investigate the R-D behavior of the complexity control parameters and establish an analytic P-R-D model. Both theoretically and experimentally, we show that, using this P-R-D model, the video coding system is able to automatically adjust its complexity control parameters to match the available energy supply of the mobile device while maximizing the picture quality. The P-R-D model provides a theoretical guideline for system design and performance optimization in mobile video communication under energy constraints.

Wireless MPEG-4 video communication on DSP chips

We discuss the design and implementation of wireless video communication systems on DSPs. We cover both video coding and the channel coding aspects of the problem. The emphasis of the article is on highlighting the issues involved both from an algorithmic standpoint as well as from a DSP standpoint. We discuss the first DSP implementation, to the authors' knowledge, of the MPEG-4 simple profile video standard. We give an overview of DSPs and highlight the salient features that make them especially well-suited for wireless applications. We describe MPEG-4 simple profile video coding noting that in order to facilitate interoperability, it is important that wireless devices use standardized compression algorithms. We discuss our implementation of the MPEG-4 simple profile video codec on Texas Instruments' TMS320C54x DSP and discuss the issues involved. We highlight some general and application-specific DSP instructions on the TMS320C54x DSP that enable us to implement the core operations in the video coder efficiently, often in a single cycle, with minimal control overhead. We describe the performance of MPEG-4 video compression for a variety of content and formats. We give a description of channel coding with the H.223 standard. Then, we describe several channel coding experiments using both unequal and equal protection on MPEG-4 video sent through a simulated GSM channel. Unequal error protection, which ensures fewer errors in the important portions of the MPEG-4 video bitstream, provides improved quality when compared to equal error protection under harsh error conditions.