Lattice Vector Quantization Applied to Speech and Audio Coding

Lattice vector quantization(LVQ) has been used for real-time speech and audio coding systems.Compared with conventional vector quantization,LVQ has two main advantages:It has a simple and fast encoding process,and it significantly reduces the amount of memory required.Therefore,LVQ is suitable for use in low-complexity speech and audio coding.In this paper,we describe the basic concepts of LVQ and its advantages over conventional vector quantization.We also describe some LVQ techniques that have been used in speech and audio coding standards of international standards developing organizations(SDOs).     

Configurable Media Codec Framework： A Stepping Stone for Fast and Stable Codec Development

Recent advances in reconfigurable computing have led to new ways of implementing complex algorithms while maintaining reasonable throughput.Video codecs are becoming more complex in order to provide efficient compression for video with ever-increasing resolution.This problem is compounded by the fact that spectra of video decoding devices has become wider in the move from traditional TV to cable and satellite TV,IPTV,mobile TV,and Internet media.MPEG is tackling this problem with a reconfigurable video coding(RVC) framework and is standardizing a modular definition of tools and connections.MPEG’s work started with video coding and has recently extended to graphics data coding.RVC will be supported by non-MPEG standards such as the Chinese audio-video standard(AVS).This article gives a brief background to the reconfigurable codec framework.The key to this framework is reconfigurability and reducing granularity to find commonality between different standards.     

Throughput analysis of two-hop wireless networks with network coding

A Two-hop Wireless Network (TWN) is the basic topology structure that provides network coding opportunity for improving throughput. Network coding on a homogeneous TWN, in which all the data flows have the same packet size and all the links have the same transmission rate, has been extensively investigated. In this paper, network coding on more practical heterogeneous TWNs, featured by various packet sizes and transmission rates, is studied. Based on the Markov model, the throughput of the proposed network coding scheme, together with the throughput gain, is derived, which matches the simulation results very well. Numerical analyses indicate that, encoding the packets with close size and close transmission rate and enlarging buffer size at the relay node help in improving the throughput gain.     

Unveiling the Challenges in Improving Data Availability in Vehicular Networks with Network Coding

Retrieving data from mobile source vehicles is a crucial routine operation for a wide spectrum of vehicular network applications, in-cluding road surface monitoring and sharing. Network coding has been widely exploited and is an effective technique for diffusing in-formation over a network. The use of network coding to improve data availability in vehicular networks is explored in this paper. Withrandom linear network codes, simple replication is avoided, and instead, a node forwards a coded block that is a random combinationof all data received by the node. We use a network-coding-based approach to improve data availability in vehicular networks. To deter-mine the feasibility of this approach, we conducted an empirical study with extensive simulations based on two real vehicular GPStraces, both of which contain records from thousands of vehicles over more than a year. We observed that, despite significant improve-ment in data availability, there is a serious issue with linear correlation between the received codes. This reduces the data-retrievalsuccess rate. By analyzing the real vehicular traces, we discovered that there is a strong community structure within a real vehicularnetwork. We verify that such a structure contributes to the issue of linear dependence. Then, we point out opportunities to improve thenetwork-coding-based approach by developing community-aware code-distribution techniques.     

AVS 3D Video Coding Technology and System

Following the success of the audio video standard(AVS) for 2D video coding,in 2008,the China AVS workgroup started developing 3D video(3DV) coding techniques.In this paper,we discuss the background,technical features,and applications of AVS 3DV coding technology.We introduce two core techniques used in AVS 3DV coding:inter-view prediction and enhanced stereo packing coding.We elaborate on these techniques,which are used in the AVS real-time 3DV encoder.An application of the AVS 3DV coding system is presented to show the great practical value of this system.Simulation results show that the advanced techniques used in AVS 3DV coding provide remarkable coding gain compared with techniques used in a simulcast scheme.     

Introduction to the High-Efficiency Video Coding Standard

The high-efficiency video coding(HEVC) standard is the newest video coding standard currently under joint development by ITU-T Video Coding Experts Group(VCEG) and ISO/IEC Moving Picture Experts Group(MPEG).HEVC is the next-generation video coding standard after H.264/AVC.The goals of the HEVC standardization effort are to double the video coding efficiency of existing H.264/AVC while supporting all the recognized potential applications,such as,video telephony,storage,broadcast,streaming,especially for large picture size video(4k × 2k).The HEVC standard will be completed as an ISO/IEC and ITU-T standard in January 2013.In February 2012,the HEVC standardization process reached its committee draft(CD) stage.The ever-improving HEVC standard has demonstrated a significant gain in coding efficiency in rate-distortion efficiency relative to the existing H.264/AVC.This paper provides an overview of the technical features of HEVC close to HEVC CD stage,covering high-level structure,coding units,prediction units,transform units,spatial signal transformation and PCM representation,intra-picture prediction,inter-picture prediction,entropy coding and in-loop filtering.The HEVC coding efficiency performances comparing with H.264/AVC are also provided.     

WAVELET－BASED FINE GRANULARITY SCALABLE VIDEO CODING

This letter proposes an efficient wavelet-based fine Granularity Scalable(FGS)coding scheme,where the base layer is encoded with a newly designed wavelet-based coder,and the entancement layer is encoded with Progressive Fins Granularity Scalable(PFGS)coding.This algorithm involves multi-frame motion compensationk,rate-distortion optimizing strategy with Lagrangian cost function and context-based adaptive arithmetic coding.In order to improve efficiency of the enhancenent layer coding,an improved motion estimation scheme that uses both information from the base layer and the enhancement layer is also proposed in this letter.The wavelet-based coder significantly improves the coding efficiency of the base layer compared with MPEG-4 ASP(Advanced Simple Profile)and H.26L TML9.The PFGS coding is a significant improvement over MPEG-4 FGS coding at the enhancement layer.Experiments show that single layer coding efficiency gain of the proposed scheme is about 2.0-3.0dB and 0.3-1.0dB higher than that of MPEG-4 ASP and H.26L TML9,respectively.The overall coding efficiency gain of the proposed scheme is about 4.0-5.0dB higher than that of MPEG04 FGS.     

A Framework for the Service Model of NFC Stack

Abstract--Near field communications （NFC） is a newly thrived technology in recent years. This technology has been installed on many kinds of mobile phone systems, especially the Android. However, there is no unified and complete framework to access NFC so far. The current software stack of NFC merely implements data obtaining features, ignoring the post-processing of data and lacking a certain security mechanism for NFC, which results in inefficiency and inconvenience for software development and maintenance. Above all, security problems could be caused due to the absence of the security mechanism. To propose a solution, this paper presents a brand-new framework for NFC utilization by analyzing and constructing a service model. Thus, the proposed framework encapsulates the current NFC stack on Android, formulating a three-layer structure after implementing the encapsulation and parsing of NFC records, which ultimately enables an XML document to describe the configuration of NFC and its related service flow. Simultaneously, a context-awareness model is proposed and built in this paper to equip the framework with the capability of adapting to different＇physical environment.     

A novel QC-LDPC code based on the finite field multiplicative group for optical communications

A novel construction method of quasi-cyclic low-density parity-check(QC-LDPC) code is proposed based on the finite field multiplicative group,which has easier construction,more flexible code-length code-rate adjustment and lower encoding/decoding complexity.Moreover,a regular QC-LDPC(5334,4962) code is constructed.The simulation results show that the constructed QC-LDPC(5334,4962) code can gain better error correction performance under the condition of the additive white Gaussian noise(AWGN) channel with iterative decoding sum-product algorithm(SPA).At the bit error rate(BER) of 10-6,the net coding gain(NCG) of the constructed QC-LDPC(5334,4962) code is 1.8 dB,0.9 dB and 0.2 dB more than that of the classic RS(255,239) code in ITU-T G.975,the LDPC(32640,30592) code in ITU-T G.975.1 and the SCG-LDPC(3969,3720) code constructed by the random method,respectively.So it is more suitable for optical communication systems.     

Complement block coding scheme for reducing peak-to-average power ratio of OFDM systems

A new scheme termed as Complement Block Coding (CBC) technique is proposed to reduce the Peak-to-Average Power Ratio (PAPR) of OFDM signals. Utilizing the complement bits which are added to the original information bits, this method can effectively reduce the PAPR of OFDM systems with random frame size N and the coding rate R≤(N - κ)/N, where k is a positive integer and k≤N/2. The performance results obtained with CBC are given and compared with that of some well known schemes, such as Simple Block Coding (SBC), Modified Simple Block Coding (MSBC) and Simple Odd Parity Code (SOPC) for the same purpose. The results show that, at the same coding rate 3/4, the CBC can achieve almost the same performance as SBC, MSBC, but with lower complexity, and that the same performance can be obtained with higher coding rate by using CBC. At the same coding rate (N - 1)IN, the PAPR reduction ofCBC is almost the twice as that of SOPC when N≥16. Further more, the PAPR reductions with coding rate (N - 1)IN are almost the same as that with coding rate less than (N - 1)/N,so the proposed scheme CBC is more suitable for the large frame size with high coding rate and can provide error detection.     

Recent MPEG Standardization Activities on 3D Video Coding

The Moving Picture Experts Group(MPEG) has been developing a 3D video(3DV) coding standard for depth-based 3DV data representations,especially for multiview video plus depth(MVD) format.With MVD,depth-image-based rendering(DIBR) is used to synthesize virtual views that are based on a few transmitted pairs of texture and depth data.In this paper,we discuss ongoing 3DV standardization and summarize coding tools proposed in the responses to MPEG’s call for proposals on 3DV coding.     

Construction of a new regular LDPC code for optical transmission systems

A novel construction method of the check matrix for the regular low density parity check （LDPC） code is proposed. The novel regular systematically constructed Gallager （SCG）-LDPC（3969,3720） code with the code rate of 93.7% and the redundancy of 6.69% is constructed. The simulation results show that the net coding gain （NCG） and the distance from the Shannon limit of the novel SCG-LDPC（3969,3720） code can respectively be improved by about 1.93 dB and 0.98 dB at the bit error rate （BER） of 10^-8, compared with those of the classic RS（255,239） code in ITU-T G.975 recommendation and the LDPC（32640,30592） code in ITU-T G.975.1 recommendation with the same code rate of 93.7% and the same redundancy of 6.69%. Therefore, the proposed novel regular SCG-LDPC（3969,3720） code has excellent performance, and is more suitable for high-speed long-haul optical transmission systems.     

Relay algorithm based on network coding in wireless local network

The network coding is a new technology in the field of information in 21st century. It could enhance the network throughput and save the energy consumption, and is mainly based on the single transmission rate. However, with the development of wireless network and equipment, wireless local network MAC protocols have already supported the multi-rate transmission. This paper investigates the optimal relay selection problem based on network coding. Firstly, the problem is formulated as an optimization problem. Moreover, a relay algorithm based on network coding is proposed and the transmission time gain of our algorithm over the traditional relay algorithm is analyzed. Lastly, we compare total transmission time and the energy consumption of our proposed algorithm, Network Coding with Relay Assistance (NCRA), Transmission Request (TR), and the Direct Transmission (DT) without relay algorithm by adopting IEEE 802.11b. The simulation results demonstrate that our algorithm that improves the coding opportunity by the cooperation of the relay nodes leads to the transmission time decrease of up to 17% over the traditional relay algorithms.     

Multi-Source Spinal Coding for Coded Caching Multicast Transmissions in Wireless Networks

Recently,coded caching has been treated as a promising technique to alleviate the traffic burden in wireless networks.To support high efficient coded caching multicast transmissions,the time-varying heterogeneous channel conditions need to be considered.In this paper,a practical and novel multi-source spinal coding(MSSC)scheme is developed for coded caching multicast transmissions under heterogeneous channel conditions.By exploring joint design of network coding and spinal coding(SC),MSSC can achieve unequal link rates in multicast transmissions for different users.Moreover,by leveraging the rateless feature of SC in our design,MSSC can well adapt the link rates of all users in multicast transmissions without any feedback of time-varying channel conditions.A maximum likelihood(ML)based decoding process for MSSC is also developed,which can achieve a linear complexity with respect to the user number in the multicast transmission.Simulation results validate the effectiveness of the MSSC scheme.Compared to the existing scheme,the sum rate of MSSC in multicast transmissions is improved by about 20%.When applying MSSC in coded caching systems,the total transmission time can be reduced by up to 48% for time-varying channels.     

Optical phase conjugation (OPC) for focusing light through/inside biological tissue

Optical phase conjugation(OPC) is a technique that generates a light field with reversed wavefront and identical amplitude distribution as the incident light. It has a unique feature of suppressing the aberration of incident beam induced by inhomogeneous or disturbing medium. Although this technique has been extensively studied since the 1970s, it has become more attractive because of unprecedented achievements and prospective potentials in biomedical applications. OPC-based techniques have been successfully utilized to form a focus through/inside highly scattered biological samples. It opens a new avenue by significantly enhancing the light delivery in biological tissue for high-resolution imaging, diagnosis and treatment of medical diseases. In order to provide insight into its further development, recent progress of OPC techniques for focusing light through/inside biological tissue was summarized.     

Ultra-Low Power Pipeline Structure Exploiting Noncritical Stage with Circuit-Level Timing Speculation

With the increase of the clock frequency and silicon integration,power aware computing has become a critical concern in the design of the embedded processor and system-on-chip(SoC).Dynamic voltage scaling(DVS) is an effective method for low-power designs.However,traditional DVS methods have two deficiencies.First,they have a conservative safety margin which is not necessary for most of the time.Second,they are exclusively concerned with the critical stage and ignore the significant potential free slack time of the noncritical stage.These factors lead to a large amount of power waste.In this paper,a novel pipeline structure with ultra-low power consumption is proposed.It cuts off the safety margin and takes use of the noncritical stages at the same time.A prototype pipeline is designed in 0.13 m technology and analyzed.The result shows that a large amount of energy can be saved by using this structure.Compared with the fixed voltage case,50% of the energy can be saved,and with respect to the traditional adaptive voltage scaling design,37.8% of the energy can be saved.     

Investigation on the Gain of Multi—wavelength Pumping Broadband Raman Amplifier

The Stokes spectrum in the stimulated Raman scattering(SRS)is very complicated.In this article,we use both Gaussian and Lorentz approximation to investigate the gain properties of multi-pumping broadband Raman amplifier,and present some schemes for flattening the gain.All the results show that the flatness of the gain spectrum is closely related to the pumping frequency grid.By researching the gain properties of Raman amplifiers of such ITU-T fibers as G.652,G.653,G.655 and large effective area non-zero dispersion flattening fiber,we find that the Raman gain is associated with the fiber type and its transmission characteristics,especially it decreases with the increase of the effective core area.     

Test Case Generation from Conjunctions of Predicates with Model Checking

Automatic test case generation from a pre- post style formal specification must deal with the issue of how to generate test cases from a conjunction of atomic predicate expressions, but unfortunately this problem has not been effectively solved due to its intrinsic difficulty. We describe a practical approach to tackling this problem by utilizing the model checking technique. An algorithm that converts test case generation from a conjunction of atomic predicate expressions into model checking is proposed. We discuss how the algorithm deals with atomic predicate ex- pressions involving only variables of numeric types, and extend the discussion to variables of compound types such as set, sequence, and composite types. Case studies are presented to assess the feasibility and effectiveness of our approach.     

Technique of Embedding Depth Maps into 2D Images

This paper proposes a new technique that is used to embed depth maps into corresponding 2-dimensional(2D) images. Since a 2D image and its depth map are integrated into one type of image format, they can be treated as if they were one 2D image. Thereby, it can reduce the amount of data in 3D images by half and simplify the processes for sending them through networks because the synchronization between images for the left and right eyes becomes unnecessary. We embed depth maps in the quantized discrete cosine transform(DCT) data of 2D images. The key to this technique is whether the depth maps could be embedded into 2D images without perceivably deteriorating their quality. We try to reduce their deterioration by compressing the depth map data by using the differences from the next pixel to the left. We assume that there is only one non-zero pixel at most on one horizontal line in the DCT block because the depth map values change abruptly. We conduct an experiment to evaluate the quality of the 2D images embedded with depth maps and find that satisfactory quality could be achieved.     

A novel high reliability CMOS SRAM cell

A novel 8T single-event-upset(SEU) hardened and high static noise margin(SNM) SRAM cell is proposed. By adding one transistor paralleled with each access transistor,the drive capability of pull-up PMOS is greater than that of the conventional cell and the read access transistors are weaker than that of the conventional cell.So the hold,read SNM and critical charge increase greatly.The simulation results show that the critical charge is almost three times larger than that of the conventional 6T cell by appropriately sizing the pull-up transistors.The hold and read SNM of the new cell increase by 72%and 141.7%,respectively,compared to the 6T design,but it has a 54%area overhead and read performance penalty.According to these features,this novel cell suits high reliability applications,such as aerospace and military.