Bandwidth Reductions Research Articles

Evaluating the Impact of Mid-Link Bandwidth Constraints on Video Streaming Performance Using NS2

A detailed simulation study of video streaming over a simple best-effort network topology is conducted using Network Simulator 2 (NS2). The simulation involves transmitting a video stream across a simple network topology where the central link's data rate varies to simulate different cases. The network topology consists of : node 0 (sender), node 3 (receiver), and nodes 1 and 2 as intermediate nodes. The study aims to examine the impact of mid-link bandwidth variations on packet loss during video transmission. Specifically, the mid-link connecting nodes experience bandwidth reductions to 10, 8, and 5 Mbps. By adjusting the mid-link bandwidth, we simulate scenarios that typically cause packet drops and measure the resulting packet loss for each bandwidth configuration. The simulation results provide insights into how bandwidth constraints affect video streaming performance, emphasizing the correlation between reduced mid-link capacity and increased packet drop rates. The results indicate that maintaining the video encoding constant while reducing the mid-link bandwidth to half of its required capacity results in an approximately 30% rise in dropped packets and a fivefold increase in end-to-end delay. This significant packet loss severely degrades the video quality, highlighting the importance of adequate mid-link bandwidth for maintaining high-quality transmission.

Influence of network latency and bandwidth on robot-assisted laparoscopic telesurgery: A pre-clinical experiment.

Telesurgery has the potential to overcome spatial limitations for surgeons, which depends on surgical robot and the quality of network communication. However, the influence of network latency and bandwidth on telesurgery is not well understood. A telesurgery system capable of dynamically adjusting image compression ratios in response to bandwidth changes was established between Beijing and Sanya (Hainan province), covering a distance of 3000km. In total, 108 animal operations, including 12 surgical procedures, were performed. Total latency ranging from 170ms to 320ms and bandwidth from 15-20Mbps to less than 1 Mbps were explored using designed surgical tasks and hemostasis models for renal vein and internal iliac artery rupture bleeding. Network latency, jitter, frame loss, and bit rate code were systemically measured during these operations. National Aeronautics and Space Administration Task Load Index (NASA-TLX) and a self-designed scale measured the workload and subjective perception of surgeons. All 108 animal telesurgeries, conducted from January 2023 to June 2023, were performed effectively over a total duration of 3866min. The operations were completed with latency up to 320ms and bandwidths as low as 1-5Mbps. Hemostasis for vein and artery rupture bleeding models was effectively achieved under these low bandwidth conditions. The NASA-TLX results indicated that latency significantly impacted surgical performance more than bandwidth and image clarity reductions. This telesurgery system demonstrated safety and reliability. A total of 320ms latency is acceptable for telesurgery operations. Reducing image clarity can effectively mitigate the potential latency increase caused by decreased bandwidth, offering a new method to reduce the impact of latency on telesurgery.

Mach-Zehnder Modulators for Microwave Polarization Measurement in Astronomy Applications.

This paper presents a study of the performances of different Mach-Zehnder modulation technologies with applications in microwave polarimeters based on a near-infrared (NIR) frequency up-conversion stage, allowing for optical correlation and signal detection at a wavelength of 1550 nm. Commercial Mach-Zehnder modulators (MZMs) are traditionally implemented using LiNbO3 technology, which does not enable integration for the fabrication of MZMs. In this work, we propose the use of an alternative technology based on InP, which allows for integration in the fabrication process. In this way, it is possible to obtain advantages in terms of bandwidth, cost, and size reductions, which yield results that are very interesting for wide-band applications such as microwave instrumentation for the study of the cosmic microwave background (CMB). Here, we describe and compare the modulation performances of different MZMs, with one commercial unit presenting a higher bandwidth than those in previous works, and another three InP integrated units provided by the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institute (HHI). Then, these modulators were coupled to a microwave polarimeter demonstrator, which has also been presented previously, to compare the polarization measurement performances of each of the MZMs.

A Quality-of-Experience-Aware Framework for Versatile Video Coding-Based Video Transmission

Multimedia applications have expanded and resulted in huge demands for high resolution videos in order to enhance the end user Quality of Experience (QoE). Therefore, QoE becomes a critical factor that is often addressed in design considerations of Consumer Electronics (CE) devices. Furthermore, error prone transmission conditions can influence the QoE, potentially degrading the end-user multimedia experience. Although video coding standards such as Versatile Video Coding (VVC) take potential mitigation measures to improve the bandwidth reductions, it fails to address other significant network Quality of Service (QoS) parameters that impact transmission based QoE such as transmission delay and Packet Loss Rate (PLR) in the encoding processes. In response, this paper first derives a relationship between QoE that addresses the network QoS parameters and VVC dependent parameters. Subsequently, the derived QoE model is used with the VVC encoding process to adaptively optimize Lagrange parameters as well as the quantization parameter. Extensive experiments report significant improvements to VVC Test Model (VTM) 7.0, achieving superior QoE gains over the state-of-the-art research and up to 3.41% over the anchor implementations.

Parallel Implementations of RCM Algorithm for Bandwidth Reduction of Sparse Matrices

The Reverse Cuthill-McKee (RCM) algorithm is a well-known heuristic for reordering sparse matrices. It is typically used to speed up the computation of sparse linear systems of equations. This paper describes two parallel approaches for the RCM algorithm as well as an optimized version of each one based on some proposed enhancements. The first one exploits a strategy for reducing lazy threads, while the second one makes use of a static bucket array as the main data structure and suppress some steps performed by the original algorithm. These related changes led to outstanding reordering time results and significant bandwidth reductions. The performance of two algorithms is compared with the respective implementation made available by Boost library. The OpenMP framework is used for supporting the parallelism and both versions of the algorithm are tested with large sparse and structural symmetric matrices.

Slow waves in locally resonant metamaterials line defect waveguides

Many efforts have been devoted to wave slowing, as it is essential, for instance, in analog signal computing and is one prerequisite for increased wave/matter interactions. Despite the interest of many communities, researches have mostly been conducted in optics, where wavelength-scaled structured composite media are promising candidates for compact slow light components. Yet their structural scale prevents them from being transposed to lower frequencies. Here, we propose to overcome this limitation using the deep sub-wavelength scale of locally resonant metamaterials. We experimentally show, in the microwave regime, that introducing coupled resonant defects in such metamaterials creates sub-wavelength waveguides in which wave propagation exhibit reduced group velocities. We qualitatively explain the mechanism underlying this slow wave propagation and demonstrate how it can be used to tune the velocity, achieving group indices as high as 227. We conclude by highlighting the three beneficial consequences of our line defect slow wave waveguides: (1) the sub-wavelength scale making it a compact platform for low frequencies (2) the large group indices that together with the extreme field confinement enables efficient wave/matter interactions and (3) the fact that, contrarily to other approaches, slow wave propagation does not occur at the expense of drastic bandwidth reductions.

An evaluation of reordering algorithms to reduce the computational cost of the incomplete Cholesky-conjugate gradient method

This paper is concerned with applying bandwidth and profile reduction reordering algorithms prior to computing an incomplete Cholesky factorization and using this as a preconditioner for the conjugate gradient method. Hundreds of reordering algorithms have been proposed to solve the problems of bandwidth and profile reductions since the mid-1960s. In previous publications, a large range of heuristics for bandwidth and/or profile reductions was reviewed. Based on this experience, 13 heuristics were selected as the most promising methods. These are evaluated in this paper along with a variant of the breadth-first search procedure that is proposed. Numerical results confirm the effectiveness of this modified reordering algorithm for linear systems derived from specific application areas. Moreover, the most promising heuristics for several application areas are identified when reducing the computational cost of the incomplete Cholesky-conjugate gradient method.

An evaluation of four reordering algorithms to reduce the computational cost of the Jacobi-preconditioned Conjugate Gradient Method using high-precision arithmetic

In this work, four heuristics for bandwidth and profile reductions are evaluated. Specifically, the results of a recent proposed heuristic for bandwidth and profile reductions of symmetric and asymmetric matrices using a one-dimensional self-organising map is evaluated against the results obtained from the variable neighbourhood search for bandwidth reduction heuristic, the original reverse Cuthill-McKee method, and the reverse Cuthill-McKee method with starting pseudo-peripheral vertex given by the George-Liu algorithm. These four heuristics were applied to three datasets of linear systems composed of sparse symmetric positive-definite matrices arising from discretisations of the heat conduction and Laplace equations by finite volumes. The linear systems are solved by the Jacobi-preconditioned conjugate gradient method when using high-precision numerical computations. The best heuristic in the simulations performed with one of the datasets used was the Cuthill-McKee method with starting pseudo-peripheral vertex given by the George-Liu algorithm. On the other hand, no gain was obtained in relation to the computational cost of the linear system solver when a heuristic for bandwidth and profile reduction is applied to instances contained in two of the datasets used.

An evaluation of low-cost heuristics for matrix bandwidth and profile reductions

Hundreds of heuristics have been proposed to resolve the problems of bandwidth and profile reductions since the 1960s. We found 132 heuristics that have been applied to these problems in reviews of the literature. Among them, 14 were selected for which no other simulation or comparison revealed that the heuristic could be superseded by any other algorithm in the analyzed articles with respect to bandwidth or profile reduction. We also considered the computational costs of the heuristics during this process. Therefore, these 14 heuristics were selected as potentially being the best low-cost methods to solve the bandwidth and/or profile reduction problems. Results of the 14 selected heuristics are evaluated in this work. For evaluation on the set of test problems, a metric based on the relative percentage distance to the best possible bandwidth or profile is proposed. The most promising heuristics for several application areas are identified. Moreover, it was found that the FNCHC and GPS heuristics showed the best overall results in reducing the bandwidth of symmetric and asymmetric matrices among the evaluated heuristics, respectively. In addition, the NSloan and MPG heuristics showed the best overall results in reducing the profile of symmetric and asymmetric matrices among the heuristics among the evaluated heuristics, respectively.

CHive: Bandwidth Optimized Continuous Querying in Distributed Clouds

Bandwidth efficient execution of online big data analytics in telecommunication networks demands for tailored solutions. Existing streaming analytics systems are designed to operate in large data centers, assuming unlimited bandwidth between data center nodes. Applying these solutions unmodified to distributed telecommunication clouds, overlooks the fact that available bandwidth is a scarce and costly resource making the telecommunication network valuable to end-users. This article presents Continuous Hive (CHive), a streaming analytics platform tailored for distributed telecommunication clouds. The fundamental contribution of CHive is that it optimizes query plans to minimize their overall bandwidth consumption when deployed in a distributed telecommunication cloud. Additionally, these optimized query plans have a high degree of parallelism built-in, benefiting speed of execution. Early experiments on data from a large mobile operator, indicate that CHive can yield bandwidth reductions upwards of 99 percent

An X-Band Radar Transceiver MMIC with Bandwidth Reduction in 0.13 µm SiGe Technology

This paper presents an X-band chirp radar transceiver with bandwidth reduction for range detection. The radar transceiver includes a super-heterodyne receiver including an ADC, a direct-digital synthesizer (DDS) based transmitter and a phase-locked loop (PLL) synthesizer. In a modified Weaver architecture, the down-converted baseband signal is further mixed with another chirp signal through stretch processing. The resulting waveform bandwidth is greatly reduced and thus relaxes the power and bandwidth requirements of the on-chip ADC. Therefore, the proposed radar transceiver achieves power and bandwidth reductions without degrading its range resolution. The radar-on-chip (RoC) MMIC was implemented in a 0.13 µm SiGe technology with die area of 3.5 × 2.5 mm 2 . With a 2.2 V supply for analog/RF circuits and a 1.5 V supply for the digital portion, the chip consumes 326 mW in the receive mode and 333 mW in the transmit mode, respectively.

A constructive bandwidth reduction algorithm

In this paper, a viable bandwidth minimisation algorithm based on graphs, for reducing the bandwidth of sparse symmetric matrices, is presented. The algorithm is tested for various sparse symmetric matrices arising from standard structured and random graphs. Bandwidth results for these matrices are also obtained using the existing algorithms and compared. The proposed algorithm is easy to implement and the bandwidth reductions obtained with the proposed algorithm are good when compared with the existing algorithms.

JPEG2000의 웨이블릿 변환용 메모리 크기 및 대역폭 감소를 위한 새로운 Embedded Compression 알고리즘

JPEG2000 시스템에서 요구하는 메모리의 크기와 대역폭을 감소시키기 위하여 본 논문은 약간의 화질 손실이 있는 새로운 임베디드 압축(Embedded Compression) 알고리즘을 제안한다. 또한, 메모리 내의 압축된 데이터에 임의 접근성(Random Accessibility)과 짧은 지연 시간(Latency)을 보장하기 위해서 매우 단순하면서도 효율적인 하다마드(Hadamard) 변환 기반의 부호화 방식을 제안한다. JPEG2000 표준안의 알고리즘에 변경을 주지 않고, 제안한 EC 알고리즘을 통해 LL 임시 메모리의 크기와 코드블록 메모리의 크기를 약 2 배로 줄이며, 약 52~73%의 메모리 대역폭을 감소시킬 수 있다. To alleviate the size and bandwidth requirement in JPEG2000 system, a new Embedded Compression(EC) algorithm with minor image quality drop is proposed. For both random accessibility and low latency, very simple and efficient hadamard transform based compression algorithm is devised. We reduced LL intermediate memory and code-block memory to about half size and achieved significant memory bandwidth reductions(about 52~73%) through proposed multi-mode algorithms, without requiring any modification in JPEG2000 standard algorithm.

An embedded compression algorithm integrated with Motion JPEG2000 system for reduction of off-chip video memory bandwidth

In Motion JPEG2000, huge bandwidth requirement of off-chip memory access is the bottleneck in required system performance. For the alleviation of this bandwidth requirement, a low complexity and lossless embedded compression algorithm is devised. And for both random accessibility and low latency, we propose simple and efficient entropy coding algorithm. We achieved significant memory bandwidth reductions (75%), without requiring any modification or performance degradation in JPEG2000 standard algorithm.

Reducing the Total Bandwidth of a Sparse Unsymmetric Matrix

For a sparse symmetric matrix, there has been much attention given to algorithms for reducing the bandwidth. As far as we can see, little has been done for the unsymmetric matrix A, which has distinct lower and upper bandwidths l and u. When Gaussian elimination with row interchanges is applied, the lower bandwidth is unaltered, while the upper bandwidth becomes $l+u$. With column interchanges, the upper bandwidth is unaltered, while the lower bandwidth becomes $l+u$. We therefore seek to reduce $\min (l,u)+l+u$, which we call the total bandwidth. We compare applying the reverse Cuthill–McKee algorithm to $A+A^T$, to the row graph of A, and to the bipartite graph of A. We also propose an unsymmetric variant of the reverse Cuthill–McKee algorithm. In addition, we have adapted the node‐centroid and hill‐climbing ideas of Lim, Rodrigues, and Xiao to the unsymmetric case. We have found that using these to refine a Cuthill–McKee‐based ordering can give significant further bandwidth reductions. Numerical results for a range of practical problems are presented and comparisons made with the recent lexicographical method of Baumann, Fleischmann, and Mutzbauer.

Efficient scalable encoding for distributed speech recognition

The problem of encoding speech features in the context of a distributed speech recognition system is addressed. Specifically, speech features are compressed using scalable encoding techniques to provide a multi-resolution bitstream. The use of this scalable encoding procedure is investigated in conjunction with a multi-pass distributed speech recognition (DSR) system. The multi-pass DSR system aims at progressive refinement in terms of recognition performance, (i.e., as additional bits are transmitted the recognition can be refined to improve the performance) and is shown to provide both bandwidth and complexity (latency) reductions. The proposed encoding schemes are well suited for implementation on light-weight mobile devices where varying ambient conditions and limited computational capabilities pose a severe constraint in achieving good recognition performance. The multi-pass DSR system is capable of adapting to varying network and system constraints by operating at an appropriate trade-off point between transmission rate, recognition performance and complexity to provide desired quality of service (QoS) to the user. The system was tested using two case studies. In the first, a distributed two-stage names recognition task, the scalable encoder operating at a bitrate of 4.6 kb/s achieved the same performance as that achieved using uncompressed features. In the second study, a two stage multi-pass continuous speech recognition task using HUB-4 data, the scalable encoder at a bitrate of 5.7 kb/s achieved the same performance as that achieved with uncompressed features. Reducing the bitrate to 4800 b/s resulted in a 1% relative increase in WER.

Current issues in packet switch design

Addressing the ever growing capacity demand for packet switches, current research focuses on scheduling algorithms or buffer bandwidth reductions. Although these topics remain relevant, our position is that the primary design focus for systems beyond 1 Tb/s must be shifted to aspects resulting from packaging disruptions. Based on trends such as increased link rates and improved CMOS technologies, we derive new design factors for such switch fabrics. For instance, we argue that the packet round-trip transmission time within the fabric has become a major design parameter. Furthermore, we observe that high-speed fabrics have become extremely dependent on serial I/O technology that is both high speed and high density. Finally, we conclude that in developing the architecture, packaging constraints must be put first and not as an afterthought, which also applies to solving the tremendous power consumption challenges.

Dominant wave directions and significant wave heights from synthetic aperture radar imagery of the ocean

We show that quasi‐linear theory accounts for dominant wave directions observed in synthetic aperture radar (SAR) imagery of the ocean for range‐to‐velocity (R/V) ratios up to 70 s. We also show that when used in combination with Alpers and Hasselmann's [1982] model of signal‐to‐noise ratios in SAR imagery, this theory yields significant wave heights in good agreement with those actually observed. We have found that the apparent dominant wave direction in SAR imagery taken at a 45° incidence angle can differ from the true wave direction by as much as 40° under certain conditions. To understand such differences, we simulated SAR image spectra using quasi‐linear theory, a surface wave spectrum measured by a buoy but with a variable angular spread, coherence times calculated from line‐of‐sight velocity spreads, and modulation transfer functions based on a functional form developed from Bragg scattering theory and data obtained during the SAR X Band Ocean Nonlinearities‐Forschungsplatform Nordsee (SAXON‐FPN) experiment. We carried out these simulations for a 45° incidence angle, L, C, and X bands, both horizontal/horizontal (HH) and vertical/vertical (VV) polarization, three different flight altitudes, and a variety of flight directions to compare the predicted apparent wave directions with those observed in the SAR imagery collected during SAXON‐FPN. The difference between the SAR‐derived dominant wave direction and the one measured by the buoy could be predicted well as a function of the true wave direction relative to the flight direction. The parameters of the quasi‐linear theory that produced the best fit to the directional data differed somewhat from those measured by tower‐based radars during SAXON‐FPN, however. Significant wave heights obtained using the parameters that best fit the directional data were in good agreement with those measured by the buoy. The SAR‐derived wave heights were consistently higher than the measured ones, however, unless the full system bandwidth was used in determining the clutter level, that is, unless bandwidth reductions due to azimuthal presumming and multilook averaging were removed. Finally, the prediction and observation of spectral splitting in SAR spectra of azimuthally traveling waves are also reported.

Observation of photodetector nonlinearities

A heterodyne technique is used to characterise the nonlinear response behaviour of microwave pin photodetectors in terms of 3 dB bandwidth reduction and signal distortion of the sinusoidal input/output. Bandwidth reductions from 20 to 2.5 GHz (at 1.6mW) are observed.

Reducing execution parameters through correspondence in computer architecture

The purpose of this study is to develop and extend techniques to provide architectural correspondence between high-level language objects and hardware resources so as to minimize execution time parameters (memory traffic, program size, etc.). A resulting computer instruction set called Adept has been emulated, and a compiler has been developed with it as the target language. Although the study was restricted to Pascal, the resulting data are generally applicable to the execution time environment of any procedure-based language. Data indicate that significant bandwidth reductions are possible compared to System/370, VAX, P-code, etc. Specifically, the average improvement ratios realized were instruction bandwidth reduction: 3.46; data read reduction (in bytes): 5.42; data write reduction (in bytes): 14.72.