Data Rate Information Research Articles

Integrated OFDM Waveform Design for RadCom System-Based Signal-to-Clutter Noise Ratio Maximization

Integrated Radar and Communication (RadCom) Systems have become more crucial ingredients in the next generation of networks due to numerous types of characteristics, including reducing the system size, minimizing power consumption, and mitigating spectrum scarcity. In this paper, we propose an integrated Orthogonal Frequency Division Multiplexing (OFDM) waveform design strategy for RadCom system-based Signal-to-clutter Noise Ratio (SCNR) maximization. The multi-carrier OFDM waveform is exploited at the RadCom transceiver to perform the functions of the radar system and communication system concurrently. We aim to improve the radar detection performance by maximizing the SCNR and maintaining the Data Information Rate (DIR) thresholds for communication system metrics. The maximization problem is posed as a convex optimization model and solved analytically using KKT conditions to find an optimal integrated waveform design. The findings obtained via simulation verify that the proposed strategy is capable of solving the waveform design issue for RadCom systems with low complexity. In addition, the proposed strategy effectively improves radar target detection and power consumption for RadCom systems.

Experimental Evaluation of a Real-Time FPGA Platform for Multichannel Coherent Acoustic Communication

This article describes a field-programmable gate array (FPGA) based multihydrophone receiver, and evaluates its real-time performance in various shallow-water channels. The receiver, built around an integer precision multichannel linear equalizer, uses the Least Mean Squares Algorithm for filter tap updates. Combined with a 64-hydrophone line array in the very high-frequency band, the receiver achieves information data rates up to 465 kb/s over 100 m, and rates up to 155 kb/s over 1000 m.

Experimental Evaluation of JANUS Fast Modes in Very High Acoustic Frequency Bands

This article presents extensive field tests of a fast-mode operation of the JANUS acoustic communication standard where the signals occupy high-frequency bands of 38 kHz spanning from 96 to 134 kHz instead of the nominal frequency band of 4.1 kHz spanning from 9.44 to 13.6 kHz specified in the standard. The fixed 32-chip preamble and the 144-chip baseline JANUS packet utilize the frequency-hopped binary frequency shift keying with 13 frequency pairs as defined in the standard while the cargo packets use the single-carrier <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> -ary phase shift keying modulation with a center frequency of 115 kHz and a symbol rate of 23 ksps or up to 34.5 kb/s information data rate with high-order phase shift keying (PSK) and rate-1/2 forward error correction codes. The original JANUS receiver algorithm is modified to improve the frame/symbol synchronization for the fast mode and increase the decoding success rate of the baseline JANUS packet in difficult multipath channels. More than 10 experiments were conducted using a field-programmable-gate-array-based hardware platform consisting of a single transmit projector and a single receive hydrophone. The experiment results show that the JANUS fast mode worked well with both the original JANUS receiver algorithm and the modified receiver algorithm, yielding zero bit error in most of the baseline JANUS packets. The modified receiver algorithm is able to reduce 30% of error packets to zero error in the experiment experiencing difficult multipath channels where the original JANUS receiver algorithm suffers from large bit error rates (BER). Meanwhile, the cargo packets utilize the linear minimum mean-square error turbo equalizer and achieve a BER around 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−3</sup> .

Robust adaptive orthogonal frequency division multiplexing integrated radar and communications waveform design under clutter circumstances

To improve the target recognition and classification performance of integrated radar and communications system in signal-dependent interference, we propose an innovative robust adaptive orthogonal frequency division multiplexing integrated radar and communications waveform design taking into account the clutter. We set the uncertainty class for clutter and other prior information to solve the problem of system performance degradation caused by inaccurate information in actual environments. Then, we formulate the optimization function to maximize the normalized weighted sum of mutual information and data information rate subject to the constraint of the total transmitted energy. To solve the optimization problem, we propose a maximum marginal allocation algorithm that transforms the original problem into a multi-stage energy distribution problem, and performs optimal energy distribution in each stage according to the optimization criteria. Moreover, by considering a more practical scenario of multiple downlink communication users, a joint scheme for channel allocation and waveform design is presented to ensure the fairness of multiple communication users. Simulation results show the effectiveness and feasibility of the designed waveform and channel allocation method.

Resource Configuration for Full-Duplex-Aided Multiple-Access Edge Computation Offloading

Multiple-access edge computation offloading (MECO) systems have been highlighted as a solution for extending the battery life and computation capability of mobile devices. However, in scenarios where information data and computation offloading (CO) data coexist, CO users and information users affect each other. It means that the communication resources for information data transmission are inevitably reduced by the communication resources allocated for CO in the conventional half-duplex (HD) based systems. Hence, improving the spectral efficiency of MECO systems in coexistence scenarios is essential, and we investigate a full-duplex (FD)-aided MECO (FD-MECO) system. A step-wise resource configuration is proposed to improve the performance of computation offloading under the information data rate constraint. The main idea is to improve spectral efficiency by maximizing the opportunity of operating in FD mode. By comparing all the communication phases in FD-MECO systems, the proposed resource configuration maximizes the amount of delivered CO data while guaranteeing the required information data rate. The simulation results show that FD-MECO systems with the proposed resource configuration always outperform HD-MECO systems.

Performance Investigation of a High Data Rate Mode Division Multiplexed-Free Space Optics Link Under Harsh Weather Conditions

The requirement of high data rate information transmission is rising exponentially for supporting different services including social networking, web streaming, and biomedical sensor data transmission. Such services required high channel bandwidth with secure information transmission and immunity to electromagnetic interference. Radio over free space optics (RoFSO) is witnessed as a promising technological solution to provide high data rate transmission over free space channel. We report on the design of a 2×10 Gb/s-10 GHz RoFSO transmission system using the mode division multiplexing technique and evaluate its transmission performance over varying levels of dust weather conditions. The comparison of non-return to zero (NRZ) and return to zero (RZ) binary digital optical modulation techniques is carried out in the proposed system. It is found that the proposed system using NRZ modulation serves 14.5 km transmission range; however, in the case of RZ modulation, it was restricted to 10 km for a target bit error rate (BER) of 10−6, thus resulting in a noticeable link enhancement of 4.5 km. Also, we demonstrate NRZ-based MDM-RoFSO link performance and availability in dust weather conditions using the BER, maximum reachable link range, and eye diagram as key performance parameters. We obtain a reliable transmission of 20 Gb/s-20 GHz data through HG00 and HG01 channels over a link range of 2500–108 m depending on the external dust weather condition. Furthermore, since this investigation shows the feasibility of RoFSO for small size cells, which is an essential feature of 5G mobile network, the proposed system can thus be implemented as a backhaul/fronthaul link for high-band (above 6 GHz) 5G services and for providing secure transmission of biomedical sensor data.

Multi-Criteria Prediction Mechanism for Vehicular Wi-Fi Offloading

The growing demands of vehicular network applications, which have diverse networking and multimedia capabilities that passengers use while traveling, cause an overload of cellular networks. This scenario affects the quality of service (QoS) of vehicle and non-vehicle users. Nowadays, wireless fidelity access points Wi-Fi access point (AP) and fourth generation long-term evolution advanced (4G LTE-A) networks are broadly accessible. Wi-Fi APs can be utilized by vehicle users to stabilize 4G LTE-A networks. However, utilizing the opportunistic Wi-Fi APs to offload the 4G LTE-A networks in a vehicular ad hoc network environment is a relatively difficult task. This condition is due to the short coverage of Wi-Fi APs and weak deployment strategies of APs. Many studies have proposed that offloading mechanisms depend on the historical Wi-Fi connection patterns observed by an interest vehicle in making an offloading decision. However, depending solely on the historical connection patterns affects the prediction accuracy and offloading ratio of most existing mechanisms even when AP location information is available. The present study proposed a multi-criteria wireless availability prediction (MWAP) mechanism, which utilizes historical connection patterns, historical data rate information, and vehicular trajectory computation to predict the next available AP and its expected data capacity in making offloading decisions. The proposed mechanism is decentralized, where each vehicle makes the prediction by itself. This characteristic helps the vehicle users make a proactive offloading decision that maintains the QoS for different applications. A simulation utilizing MATLAB was conducted to evaluate the performance of the proposed mechanism and benchmark it with related state-of-the-art mechanisms. A comparison was made based on the prediction error and offloading ratio of the proposed mechanism in several scenarios. The MWAP mechanism exhibited a lower prediction error (i.e., below 20%) and higher offloading ratio (i.e., above 90%) than the existing mechanisms for several tested scenarios.

Implementation of DSSS system of image using MATLAB

In direct sequence spread spectrum systems, pseudo sequence random (PN) are used to spreading data bits. There are various type of PN sequences are available with good correlation properties, on mostly are generating pn by linear feedback shift register (LFSR). Will examine in this paper we describe spreading binary random and spreading the image As well as studying probability bit error rate of DSSS system with change of the channel (Add white Gaussian noise channel, Rayleigh fading channel, Rician fading channel). Our study will be performed using MATLAB. Terms of completed my articles in building system developed to security transmitter and receiver the information of theft against communication digital system talk as well as the increase of data rate information. Was this design a way process of his used in applications military and have a major role also in the most applications requiring protect high for many information binary data and image. So that the system designed as fits practice and prevent the overlap the outside after it has become send signals in communication system exhibition penetration and Intentional attacks or other breaches.

Implementation of DSSS system of image using MATLAB

In direct sequence spread spectrum systems, pseudo sequence random (PN) are used to spreading data bits. There are various type of PN sequences are available with good correlation properties, on mostly are generating pn by linear feedback shift register (LFSR). Will examine in this paper we describe spreading binary random and spreading the image As well as studying probability bit error rate of DSSS system with change of the channel (Add white Gaussian noise channel, Rayleigh fading channel, Rician fading channel). Our study will be performed using MATLAB. Terms of completed my articles in building system developed to security transmitter and receiver the information of theft against communication digital system talk as well as the increase of data rate information. Was this design a way process of his used in applications military and have a major role also in the most applications requiring protect high for many information binary data and image. So that the system designed as fits practice and prevent the overlap the outside after it has become send signals in communication system exhibition penetration and Intentional attacks or other breaches.

Quantized Stabilization of Continuous-Time Switched Linear Systems

In this letter, we study the problem of stabilizing continuous-time switched linear systems via mode-dependent quantized state feedback. We derive a closed-form expression for the minimal information data rate from the coder to the controller necessary to achieve stabilization of the system. In particular, it is shown that the evaluation of the minimal data rate for stabilization reduces to the computation of the Lyapunov exponent of some lifted switched linear system, obtained from the original one by using tools from multilinear algebra, and thus can benefit from well-established algorithms for the computation of the Lyapunov exponent. In a second time, drawing upon this expression, we describe a practical coder-controller that stabilizes the system, and whose data rate can be as close as desired to the optimal data rate.

Robust Power Allocation for Parallel Gaussian Channels With Approximately Gaussian Input Distributions

In both wired and wireless communication networks, power allocation is an important technique to improve system performance. This paper investigates the power allocation problem for parallel Gaussian channels from an information-theoretic perspective with the aim of maximizing the sum of mutual informations ( i.e. , an achievable data rate). If all the inputs are Gaussian, it is well-known that the waterfilling policy provides an optimal solution. For arbitrary input distributions, a generalization of waterfilling, so-called mercury/waterfilling, provides an optimal solution in terms of the minimum mean square errors (MMSEs). However, the difficulty of obtaining closed-form analytical expressions of the MMSE often makes computing the mercury/waterfilling solution challenging. This paper proposes a robust waterfilling power allocation (RPA) policy for parallel Gaussian channels when the input distributions are close to Gaussian distributions in the Kullback-Leibler (KL) divergence (relative entropy). First, it is shown that the proposed policy results in water-levels that are close to the optimal ones in a well-defined sense. Second, tight bounds for the loss in mutual information (data rate) are given. This bounded loss property makes the proposed power allocation policy robust and approximately optimal, which is illustrated by means of various simulation setups. Moreover, the RPA policy provides a general framework for solving the power allocation problem for parallel channels, with the classical waterfilling being included as a special case. Finally, the RPA policy is argued to be scalable with the number of users since it inherently uses the classical low complexity waterfilling.

An Optimizing Method of OFDM Radar Communication and Jamming Shared Waveform Based on Improved Greedy Algorithm

Orthogonal frequency division multiplexing (OFDM) has been widely used as radar, communication, and jamming shared waveform. To improve the power utilization and efficiency of radar, communication, and jamming integrated system, we propose an adaptive OFDM shared waveform design method. Considering the problem of jamming path propagation loss and sensitivity of frequency response error of radar and communication channels, we propose a robust OFDM shared waveform design method. Firstly, the suppressed jamming entropy model, the detection probability (Pd) of the stationary point target model, the data information rate (DIR) model with a given bit error rate (BER) are formulated. With the constraints on total power and BER, the adaptive and the robust OFDM optimization problems are formulated. Then we derive the Karush-Kuhn-Tucker (KKT) conditions of the two optimization problems and an improved greedy algorithm is proposed to solve the optimization problems, and the optimal power and bit allocation schemes for the two problems are obtained. Finally, we present several numerical results to demonstrate the effectiveness of the proposed method.

A New Method for Format Preserving Encryption in High-Data Rate Communications

In some encryption systems it is necessary to preserve the format and length of the encrypted data. This kind of encryption is called FPE (Format Preserving Encryption). Currently, only two AES (Advanced Encryption Standard) modes of operation recommended by the NIST (National Institute of Standards and Technology) are able to implement FPE algorithms, FF1 and FF3. These modes work in an electronic codebook fashion and can be configured to encrypt databases with an arbitrary format and length. However, there are no stream cipher proposals able to implement FPE encryption for high data rate information flows. The main novelty of this work is a new block cipher operation mode proposal to implement an FPE algorithm in a stream cipher fashion. It has been called CTR-MOD and it is based on a standard block cipher working in CTR (Counter) mode and a modulo operation. The confidentiality of this mode is analyzed in terms of its IND- CPA (Indistinguishability under Chosen Plaintext Attack) advantage of any adversary attacking it. Moreover, the encryption scheme has been implemented on an FPGA (Field Programmable Gate Array) and has been integrated in a Gigabit Ethernet interface to test an encrypted optical link with a real high data rate traffic flow.

Joint Subcarrier Assignment and Power Allocation Strategy for Integrated Radar and Communications System Based on Power Minimization

This paper investigates the problem of power minimization-based joint subcarrier assignment and power allocation (PM-JSAPA) for an integrated radar and communications system (IRCS). In the considered system, the integrated transmitter is responsible to fulfill both radar and communications purposes simultaneously. The proposed PM-JSAPA strategy aims to minimize the total radiated power of the IRCS by jointly optimizing the available subcarriers and power resource allocation in order to achieve improved power-saving performance, subject to a predetermined mutual information (MI) for target parameter estimation and a specified data information rate (DIR) for wireless communications. The formulated problem falls into a mixed integer nonlinear programming (MINLP) problem, which is generally NP-hard. Then, an efficient three-step resource allocation framework is designed to solve the resulting optimization problem. Specifically, in Step 1, the subcarrier assignment for both radar and communications purposes is determined. In Step 2 and Step 3, we perform power allocation for different applications with the obtained subcarrier assignment results in Step 1, respectively. Finally, numerical simulation results are presented to demonstrate the superior power-saving performance of the proposed PM-JSAPA strategy and the effectiveness of the proposed solutions.

Robust OFDM integrated radar and communications waveform design based on information theory

An integrated radar and communications system (IRCS) where a monostatic radar transceiver is employed for target classification while simultaneously used as a communications transmitter is considered. The radar combined propagation-target response (joint response of the radar propagation channel and target) and communications channel response are generally frequency selective but the corresponding frequency response functions are not exactly known. In particular, these frequency response functions are only known to lie in an uncertainty class. To ensure the IRCS simultaneously provides acceptable target classification performance and communications rate, a robust orthogonal frequency division multiplexing (OFDM) integrated radar and communications waveform (IRCW) design method is proposed. The approach finds a waveform that simultaneously provides a sufficiently large weighted sum of the communications data information rate (DIR) and the conditional mutual information (MI) between the observed signal and the random target impulse response over the entire uncertainty class. First, the conditional MI and DIR based on the OFDM IRCW are derived. Then, a robust OFDM IRCW optimization problem based on the minimax design philosophy is developed such that closed-form solution is derived. Finally, several numerical results are presented to demonstrate the effectiveness of the proposed method.

Rate Adaptation Mechanism with Available Data Rate Trimming and Data Rate Information Provision for V2I Communications

We study a rate adaptation mechanism for improving communication performance between a connected vehicle and a roadside unit (RSU) using Wi-Fi during movement in a vehicle-to-infrastructure (V2I) environment. Wi-Fi communication provides various attractive services to connected vehicles during movement. However, as a connected vehicle is generally moving at high speed, the communication performance with an RSU that works as an access point is degraded because wireless link quality fluctuates abruptly and continuously. We then propose a rate adaptation mechanism employing the following two main features to mitigate such deterioration in communication performance: available data rate trimming and data rate information provision. To alleviate degradation of communication, the former avoids usage of excessively low data rates and the latter then provides data rate information suitable for channel quality from a dataset of adequate data rates based on the vehicle’s location and speed. However, the data rate information provided from a dataset may not always be appropriate because of various indefinite factors such as multipath fading and shadowing. Thus, the proposed method also employs a measurement-based function to compensate for such a drawback of the dataset. Simulation experiments evaluate communication performance for 10, 60, and 100 km/h in single-vehicle and multiple-vehicles cases. Simulation results showed that the proposed method overall provides superior communication performance in situations involving more than one vehicle, in comparison with existing counter- and sample-based methods.

Adaptive Receiver-Window Adjustment for Delay Reduction in LTE Networks

The cellular network keeps the vast capacity of queue space at eNodeBs (base stations) to reduce the queue overflow during the burst in data traffic. However, this adversely affects the delay sensitive applications and user quality of experience. Recently, few researchers have focused on reducing the packet delay, but it has a negative impact on the utilization of network resource by the users. Further, it fails to maintain fairness among the users, when competing for a shared resource in coexistence with conventional TCP or UDP users. Therefore, in this paper, the adaptive receiver-window adjustment (ARWA) algorithm is proposed to efficiently utilize the network resources and ensure fairness among the users in resource competitive environment, which requires slight modification of TCP at both the sender and receiver. The proposed mechanism dynamically varies the receiver window size based on the data rate and delay information of the packets, to enhance the performance of the system. Based on extensive experiments, the results illustrate that the ARWA algorithm reduces the delay of TCP packet and increases fairness among the users. In addition to that, it enhances the packet delivery fraction (PDF) and maintains the throughput of the system. Moreover, it competes with other conventional TCP users for the shared network resources in a fair manner.

An underwater acoustic direct sequence spread spectrum communication system using dual spread spectrum code

With the goal of achieving high stability and reliability to support underwater point-to-point communications and code division multiple access (CDMA) based underwater networks, a direct sequence spread spectrum based underwater acoustic communication system using dual spread spectrum code is proposed. To solve the contradictions between the information data rate and the accuracy of Doppler estimation, channel estimation, and frame synchronization, a data frame structure based on dual spread spectrum code is designed. A long spread spectrum code is used as the training sequence, which can be used for data frame detection and synchronization, Doppler estimation, and channel estimation. A short spread spectrum code is used to modulate the effective information data. A delay cross-correlation algorithm is used for Doppler estimation, and a correlation algorithm is used for channel estimation. For underwater networking, each user is assigned a different pair of spread spectrum codes. Simulation results show that the system has a good anti-multipath, anti-interference, and anti-Doppler performance, the bit error rate can be smaller than 10−6 when the signal-to-noise ratio is larger than −10 dB, the data rate can be as high as 355 bits/s, and the system can be used in the downlink of CDMA based networks.

Improved multiple access resource allocation in visible light communication systems

Discrete multi-tone (DMT) and optical orthogonal frequency division multiplexing (OFDM) modulations are well-known methods used to transmit high data rate information in visible light communication (VLC) applications over the illumination infrastructure. However, the use of these techniques in a multi-user environment requires effective subcarrier and power allocation design in order to achieve the maximum data rate offered by the spatial distribution of the transmitters and receiver as well as to minimize the efficiency reduction of the illumination system due to the communication. This could be achieved by minimizing the communication signal power in an appropriate way. In this paper, we propose a heuristic allocation algorithm that minimizes the system subcarrier transmitter power while keeping the required data rate and error bit rate. The numerical calculation was done for given parameters. The results indicate that transmitter power reduction of more than 10% in a most scenario is achieved in comparison to previous algorithms.

Consensus in topologically interacting swarms under communication constraints and time-delays

The emergence of collective decision in swarming systems underscores the central role played by information transmission. Using network-control- and information-theoretic elements applied to a group of topologically interacting agents seeking consensus under switching topologies, the effects of constraints in the information capacity of the communication channel are investigated. This particular system requires us to contend with constantly reconfigurable and spatially embedded interaction networks. We find a sufficient condition on the information data rate guaranteeing the stability of the consensus process in the noiseless case. This result highlights the profound connection with the topological structure of the underlying interaction network, thus having far-reaching implications in the nascent field of swarm robotics. Furthermore, we analyze the more complex case of combined effect of noise and limited data rate. We find that the consensus process is degraded when decreasing the data rate. Moreover, the relationship between critical noise and data rate is found to be in good agreement with information-theoretic predictions. Lastly, we prove that with not-too-large time-delays, our system of topologically interacting agents is stable, provided the underlying interaction network is strongly connected. Using Lyapunov techniques, the maximum allowed time-delay is determined in terms of linear-matrix inequalities.