Adaptive Bandwidth Control Research Articles

Adaptive composite bandwidth and automatic gain control receiver for 6G wireless optical communication

The advent of 6G communication promises a transformative leap in wireless connectivity, ushering in an era of unprecedented data rates, ultra-low latency, and pervasive connectivity. To harness the full potential of 6G networks, it is imperative to address the unique challenges posed by evolving communication environments. In this context, we present a novel framework that integrates Adaptive Composite Bandwidth and Automatic Gain Control techniques into the 6G communication paradigm. Optical wireless receivers experience large input current difference due to the large transmitted power, noise from ambient light and the varying efficiencies of different photodiode receivers. With its large dynamic range of μA to mA, transimpedance amplifiers are suitable to handle photodiode efficiency with a large dynamic range. The receiver design proposed in this article incorporates two characteristic parameter adjustments, namely, bandwidth and automatic gain. By adjusting the bandwidth the signal-to-noise ratio of the incoming signal is automatically controlled. By controlling the bandwidth, the unwanted noise is reduced and amplifier output is liable to low noise and enhances the dynamic range without extra filtering. The automatic gain control adapts its gain based on slight change in the input signal at the receiver front-end. This optimization technique ensures low photo-detection and amplification noise to achieve better quality of service. The results indicate that the bootstrap transimpedance amplifier gain is around 53.3 dB and frequency cut-off at 109.7 MHz. Thus, when gain control capacitance is varied between 50 pF to 1 nF, the bandwidth adjustment falls in the range 7.5–104.1 MHz, and the amplifier’s second stage gain becomes 10.4 dB. The overall gain of the proposed configuration with automatic gain control integrated into the transimpedance amplifier increases up to 31.1 dB, while the bandwidth increases from 9.4 to 60.7 MHz. Consequently, the gain bandwidth product is optimized from 10.4 to 31.1 dB. The main contribution of this work is optimizing the product by selecting a capacitance value within the given range that maximizes the gain-bandwidth product. This optimization paradigm is predicated on identifying a capacitance value that minimizes the gain-bandwidth product, thereby effectuating effective noise mitigation. This proposed framework embodies a significant contribution to the domain of 6G communications, heralding a new epoch in the optimization of wireless connectivity through the strategic integration of adaptive bandwidth and automatic gain control mechanism.

Inter-system interference reduction of adaptive bandwidth control for multi-band wireless transmission

Inter-system interference reduction of adaptive bandwidth control for multi-band wireless transmission

A Ku-Band Fractional-N Frequency Synthesizer with Adaptive Loop Bandwidth Control

This paper presents a Ku-band fractional-N frequency synthesizer with adaptive loop bandwidth control (ALBC) to speed up the lock settling process and meanwhile ensure better phase noise and spur performance. The theoretical analysis and circuits implementation are discussed in detail. Other key modules of the frequency synthesizer such as broadband voltage-controlled oscillator (VCO) with auto frequency calibration (AFC) and programable frequency divider/charge pump/loop filter are designed for integrity and flexible configuration. The proposed frequency synthesizer is fabricated in 0.13 μm CMOS technology occupying 1.14 × 1.18 mm2 area including ESD/IOs and pads, and the area of the ALBC is only 55 × 76 μm2. The out frequency can cover from 11.37 GHz to 14.8 GHz with a frequency tuning range (FTR) of 26.2%. The phase noise is −112.5 dBc/Hz @ 1 MHz and −122.4 dBc/Hz @ 3 MHz at 13 GHz carrier frequency. Thanks to the proposed ALBC, the lock-time can be shortened by about 30% from about 36 μs to 24 μs. The chip area and power consumption of the proposed ALBC technology are slight, but the beneficial effect is significant.

Bandwidth Control Mechanism and Extreme Gradient Boosting Algorithm for Protecting Software-Defined Networks Against DDoS Attacks

Software-Defined Networking (SDN) is an emerging network architecture that addresses the limitation of the traditional network by providing centralized management through a central controller that decouples the control and data planes. However, this development has made the controller a severe target for malicious users to execute attacks such as Distributed Denial of Service (DDoS) attacks. Several schemes have been proposed to mitigate DDoS attacks in SDN, but the challenges still exist. This paper proposes a DDoS mitigation scheme for SDN to ensure accurate attack detection and efficient network resource utilization. The scheme employs two stages: a bandwidth control mechanism and Extreme Gradient Boosting (XGBoost) Algorithm. The bandwidth control mechanism utilizes an adaptive bandwidth profile-based threshold and bandwidth control algorithm that trigger the XGBoost algorithm in case of threshold violations. The use of multiple bandwidth profiles in stetting the threshold ensures the threshold's adaptivity to consider the network traffic variation and reduce the packets drop ratio, which shows an outstanding result. The XGBoost algorithm classifies network traffic flow that violates a set threshold into normal or abnormal traffic. We evaluated the performance of our scheme using CICDDoS2019, NSL-KDD, and CAIDA datasets. Furthermore, we validated our proposed solution in real-time with the SDN environment. The results obtained show that our scheme protects SDN against DDoS attacks with high accuracy, low error, and efficient utilization of the network resources. The proposed system achieved 99.9% accuracy in detecting DDoS attacks with a low false-positive rate of 0.0002% in SDN.

Adaptive bandwidth control for multi-band OFDM transmission with spectrum sharing

Adaptive bandwidth control for multi-band OFDM transmission with spectrum sharing

An Adaptive Framework for Improving Quality of Service in Industrial Systems

Limited memory bandwidth is considered as the major bottleneck in multimedia cloud computing for more and more virtual machines (VMs) of multimedia processing requiring high memory bandwidth simultaneously. Moreover, contending memory bandwidth among parallel running VMs leads to poor quality of service (QoS) of the multimedia applications, missing the deadlines of these soft real-time multimedia applications. In this paper, we present an adaptive framework, Service Maximization Optimization (SMO), which is designed to improve the QoS of the soft real-time multimedia applications in multimedia cloud computing. The framework consists of an automatic detection mechanism and an adaptive memory bandwidth control mechanism. With the automatic detection mechanism, the critical section to the multimedia application performance in the VMs is detected. Then, our adaptive memory bandwidth control mechanism adjusts the memory access rates of all the parallel running VMs to protect the QoS of the soft real-time multimedia applications. From the case studies with real-world multimedia applications, our SMO significantly improves the QoS of the soft real-time multimedia applications with a negligible penalty on system throughput.

Beachfront commons

Technology competition between wireless communication technologies can lead to new, more or less disruptive services. A potentially disruptive technology would be to have unlicensed transmission in the lower UHF bands at power levels up to, e.g. 2 W EIRP. This would give citizens a share of the best spectrum for free use. Tools against congestion could be based on mandatory stochastic channel back-off or, if multiple users are present, on adaptive power and bandwidth control. Compared to the FCC TV white space regulation, no back link would be needed as the spectrum would be used exclusively by wireless devices. In an environment of shrinking interest in terrestrial TV broadcasting, such a regulation is expected to create a new market for high-range consumer devices, competing with licensed communication, while also being suitable for offloading traffic from licensed operations. Furthermore, the approach will allow for efficient digitization of equipment for Programme Making and Special Events (PMSE), but could also be made compatible with novel disaster relief services. To enable accurate interference prediction, it is proposed that, instead of only providing transmitter regulation, receivers should also be regulated, such as be required to adhere to a certain minimum selectivity. The proposal should be taken up in the WRC process.

Adaptive Bandwidth Control for Dynamic Spectrum Control Aided Spectrum Sharing in Private Wireless Networks

This paper proposes an adaptive bandwidth control scheme for the private wireless networks. Carrier sense multiple access with collision avoidance (CSMA/CA), which is commonly used within the private networks, is not efficient in terms of spectral efficiency due to its strict collision avoidance process. In order to relax the collision avoidance rule, this paper employs dynamic spectrum control (DSC), in which a certain number of discrete spectra having the higher channel gain is selected in a selfish manner with each link allowing a partial band interference. Such interference may be suppressed by the equalizer at the receiver. Aiming at optimal selection of the bandwidth for the selfish DSC according to channel realizations, in the sense of throughput maximization, this paper proposes a channel capacity maximization-based BAR control scheme. Computer simulations validate that the proposed scheme achieves high throughput efficiency.

Gateway Strategies for VoIP Traffic over Wireless Multihop Networks

When supporting both voice and TCP in a wireless multihop network, there are two conflicting goals: to protect the VoIP traffic, and to completely utilize the remaining capacity for TCP. We investigate the interaction between these two popular categories of traffic and find that conventional solution approaches, such as enhanced TCP variants, priority queues, bandwidth limitation, and traffic shaping do not always achieve the goals. TCP and VoIP traffic do not easily coexist because of TCP aggressiveness and data burstiness, and the (self-) interference nature of multihop traffic. We found that enhanced TCP variants fail to coexist with VoIP in the wireless multihop scenarios. Surprisingly, even priority schemes, including those built into the MAC such as RTS/CTS or 802.11e generally cannot protect voice, as they do not account for the interference outside communication range. We present VAGP (Voice Adaptive Gateway Pacer) - an adaptive bandwidth control algorithm at the access gateway that dynamically paces wired-to-wireless TCP data flows based on VoIP traffic status. VAGP continuously monitors the quality of VoIP flows at the gateway and controls the bandwidth used by TCP flows before entering the wireless multihop. To also maintain utilization and TCP performance, VAGP employs TCP specific mechanisms that suppress certain retransmissions across the wireless multihop. Compared to previous proposals for improving TCP over wireless multihop, we show that VAGP retains the end-to-end semantics of TCP, does not require modifications of endpoints, and works in a variety of conditions: different TCP variants, multiple flows, and internet delays, different patterns of interference, different multihop topologies, and different traffic patterns.

Short locking time and low jitter phase-locked loop based on slope charge pump control

A novel structure of a phase-locked loop (PLL) characterized by a short locking time and low jitter is presented, which is realized by generating a linear slope charge pump current dependent on monitoring the output of the phase frequency detector (PFD) to implement adaptive bandwidth control. This improved PLL is created by utilizing a fast start-up circuit and a slope current control on a conventional charge pump PLL. First, the fast start-up circuit is enabled to achieve fast pre-charging to the loop filter. Then, when the output pulse of the PFD is larger than a minimum value, the charge pump current is increased linearly by the slope current control to ensure a shorter locking time and a lower jitter. Additionally, temperature variation is attenuated with the temperature compensation in the charge pump current design. The proposed PLL has been fabricated in a kind of DSP chip based on a 0.35 μm CMOS process. Comparing the characteristics with the classical PLL, the proposed PLL shows that it can reduce the locking time by 60% with a low peak-to-peak jitter of 0.3% at a wide operation temperature range.

Adaptive Mode-Suppression and Disturbance-Rejection Scheme With Application to Disk Drives

The goal of a track-following controller for a disk drive is to maintain as close to perfect tracking as possible. Better tracking allows for more data to be stored on a single disk. There are several factors which make this control problem difficult, such as high-frequency resonant modes, unknown disturbances, and a preset sampling rate. The resonant modes of a disk drive are often uncertain and vary between units and can also lie near or beyond the Nyquist frequency. Suppressing these modes can be difficult. However, a multirate adaptive notch filter and adaptive bandwidth controller is proposed to suppress these resonant modes. A robust online estimator that estimates the mode frequencies is used to allow the multirate adaptive notch filter to track the disk drive's modes. By adding a multirate scheme to the adaptive notch filter, it can suppress modes at higher frequencies, which are close to or beyond the Nyquist frequency of the preset sampling rate. As the multirate adaptive notch filter tracks the plant mode frequencies, the adaptive bandwidth controller ensures that stability and performance requirements are satisfied by using the online estimate of the mode frequencies. An adaptive disturbance rejector is added to the adaptive mode-suppression scheme and broken into two parts: a part to suppress the repeatable runout and another to attenuate the residual disturbance by using a neural model. Both parts are adapted online and combined with the mode-suppression scheme to ensure good disturbance rejection even in the presence of unknown or changing resonant modes. Simulation results with a hard disk drive as the application are included and show that the adaptive mode-suppression scheme is able to maintain stability and better performance than a nonadaptive counterpart for an uncertain resonant-mode frequency. When combined with the adaptive disturbance-rejection scheme, stability is maintained and an improvement of as much as 14.3% in 3sigma is seen. This improvement in tracking can allow for data to be stored more densely on a single disk, providing larger storage media for the same size of disk drive.

A 125–1250 MHz Process-Independent Adaptive Bandwidth Spread Spectrum Clock Generator With Digital Controlled Self-Calibration

A process-independent adaptive bandwidth spread-spectrum clock generator (SSCG) with digitally controlled self-calibration techniques is proposed. By adaptively calibrating the VCO gain (K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</sub> ) and charge-pump (CP) current over C (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CP</sub> /C), the SSCG can realize not only adaptive bandwidth but also process independence at each operating frequency. The innovative point is the adaptive bandwidth control using K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v</sub> and I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CP</sub> /C calibration. This control enabled a test chip to keep a sharp triangular SSC profile while operating over a wide frequency range (125 to 1250 MHz). The variations of VCO gain and CP current are reduced to one third those of the conventional architecture. At 1250 Mbps (625 MHz) the reduction of spectrum peak amplitude is 18.6 dB which is 2.3 dB better than the reduction obtained without calibration.

VHDL implementation of neuro-fuzzy based adaptive bandwidth controller for ATM networks

The modern intelligent asynchronous transfer mode (ATM) networks need a scheme to maintain quality of service (QoS) towards different traffic constraints in real time environment for effective control and optimal system utilisation. This paper proposes the VHDL implementation of neuro-fuzzy based adaptive bandwidth controller. The intelligent control is used to manage the adaptive bandwidth prediction, congestion control and call admission control (CAC) of ATM networks simultaneously. This integrated hybrid mechanism reduces the decision errors of conventional CAC policies and operating errors occurred on fuzzy based CAC in ATM networks. The individual blocks needed to implement adaptive bandwidth controller for ATM networks are modelled using VHDL. The timing analysis for the validation, functionality and performance of the model is analysed using Altera Quartus II (5.1 version) HDL software and the logic synthesis is performed. The required codes are downloaded into FPGA Cyclone device.

Transceiver Macro with Spread-Spectrum Clocking Capability for AC-Coupled Cable Interfaces

A transceiver macro for high-speed data transmission via cable in vehicles is proposed. The transceiver uses ac coupling and bidirectional interface topology for protecting LSIs against unexpected short of cable and harness/chassis and has a spread-spectrum-clocking (SSC) generator that reduces noise due to electromagnetic interference. A driver current control has been used for fast switching of data direction on accoupled interfaces. An adaptive bandwidth control has been used in a ΔΣ PLL to improve SCC significantly. A test chip has been fabricated and shows stable and bi-directional data communication with data rate of 162 to 972 Mbps through 20-m cable. Thanks to an optimum calibration of the SSC-PLL bandwidth, it reduces peak power at 33kHz by -23dB and provides 2% modulation at a data rate of 810Mbps.

A 4–6.4 GHz LC PLL With Adaptive Bandwidth Control for a Forwarded Clock Link

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A wide range differentially tuned LC PLL using dual switched capacitor VCOs was designed in a 65 nm standard CMOS process for a forwarded clock link. Bandwidth and stability were maintained across the operating range by using open-loop Auto Frequency Calibration (AFC) tuning techniques and an adaptively biased bit-sliced charge pump. The PLL is capable of supporting spread spectrum clock (SSC) modulation with a low peak VCO gain by limiting its operation to the high gain region of the varactors where the capacitance versus voltage curves exhibit the greatest linearity. The VCOs support a frequency range of 4.0–4.8 GHz and 5.87–6.4 GHz. The 2-UI jitter of the forwarded clock at 6.4 Gb/s is 0.9 ps RMS while the long term acumulated <formula formulatype="inline"> <tex Notation="TeX">$N$</tex></formula>-UI jitter for large <formula formulatype="inline"> <tex Notation="TeX">$N$</tex></formula> is 2.1 ps RMS. </para>

Fuzzy-Based Adaptive Bandwidth Control for Loss Guarantees

This paper presents the use of adaptive bandwidth control (ABC) for a quantitative packet loss rate guarantee to aggregate traffic in packet switched networks. ABC starts with some initial amount of bandwidth allocated to a queue and adjusts it over time based on online measurements of system states to ensure that the allocated bandwidth is just enough to attain the specified loss requirement. Consequently, no a priori detailed traffic information is required, making ABC more suitable for efficient aggregate quality of service (QoS) provisioning. We propose an ABC algorithm called augmented Fuzzy (A-Fuzzy) control, whereby fuzzy logic control is used to keep an average queue length at an appropriate target value, and the measured packet loss rate is used to augment the standard control to achieve better performance. An extensive simulation study based on both theoretical traffic models and real traffic traces under a wide range of system configurations demonstrates that the A-Fuzzy control itself is highly robust, yields high bandwidth utilization, and is indeed a viable alternative and improvement to static bandwidth allocation (SBA) and existing adaptive bandwidth allocation schemes. Additionally, we develop a simple and efficient measurement-based admission control procedure which limits the amount of input traffic in order to maintain the performance of the A-Fuzzy control at an acceptable level.

MPEG-2 stereoscopic video coding technique using adaptive bandwidth control

According to recent advances in three-dimensional display systems, interest in stereoscopic video coding and reconstruction has been increased in various fields of video processing. Efficient video coding techniques are required to reduce the amount of data. In this paper, we propose an effective algorithm that improves the quality of moving picture experts group-2 stereoscopic sequences, in which optimal quantization parameters (QPs) are selected for pairs of corresponding macroblocks in left and right frames taken at the same time instants but from different view angles. The proposed algorithm reduces the binocular redundancy between the left and right frames. To minimize the total distortion, it adaptively determines QPs and the bandwidth for encoding of pairs of the frame sequence. The proposed algorithm is compared with the conventional video encoding methods in terms of the video quality and the use of bandwidth. Especially for video sequences containing a number of moving blocks and scene changes, the proposed algorithm shows better performance than the conventional methods in terms of the performance of disparity estimation and adaptive bandwidth control.

A survey of adaptive bandwidth control algorithms

In packet-switched network traffic management and control, efficiently allocating bandwidth to provide quantitative packet-level QoS to aggregate traffic has been difficult due to unpredictable, unknown statistical characteristics of the aggregate traffic. With inaccurate traffic information, using static bandwidth allocation results in the network being underutilized, or the QoS requirement not being satisfied. An alternative is to use adaptive bandwidth control (ABC), whereby the allocated bandwidth is regularly adjusted over the packet-level time scale to attain a given QoS requirement. This paper provides a literature review of ABC algorithms that guarantee aggregate traffic packet-level QoS metrics, such as the average queue length, packet loss, and packet delay. We describe different ABC algorithms, identify their advantages and shortcomings, and provide some comparative performance evaluation results. Open issues in ABC for future research directions are also discussed.

Adaptive Miller capacitor multiplier for compact on-chip PLL filter

An adaptive Miller capacitor multiplier is proposed to reduce on-chip phase-locked loop (PLL) capacitor area and improve lock speed. Fabricated in 0.5 µm standard CMOS, an effective capacitance of 576 pF is achieved with a polycapacitor of only 192 pF (62% die area saving) and 0.43 mA current consumption. The lock time is reduced by 36% due to the adaptive loop bandwidth control during PLL settling.

Adaptive bandwidth control for efficient aggregate QoS provisioning

The paper proposes an adaptive bandwidth control algorithm that efficiently provides an aggregate loss guarantee to resolve the problem of inefficient bandwidth allocation due to incomplete, inaccurate traffic descriptors supplied by users. Because the control attempts to allocate only just enough bandwidth to meet the QoS requirement, the amount of bandwidth saving compared to static allocation can be substantial. Another distinct advantage of our control algorithm is that no a priori information on the traffic characteristics of the aggregate is required. From the simulation study, the proposed control can maintain the packet loss QoS while attaining very high utilization, and is robust against different system configurations and controller parameters.