Data Transmission Techniques Research Articles

AOMDV의 특성과 진동 센서를 적용한 이동성과 연결성이 개선된 WSN용 LEACH 프로토콜 연구

As the growth of ubiquitous services, various types of ad hoc networks have emerged. In particular, wireless sensor networks (WSN) and mobile ad hoc networks (MANET) are widely known ad hoc networks, but there are also other kinds of wireless ad hoc networks in which the characteristics of the aforementioned two network types are mixed together. This paper proposes a variant of the Low Energy Adaptive Cluster Hierarchy (LEACH) routing protocol modified to be suitable in such a combined network environment. That is, the proposed routing protocol provides node detection and route discovery/maintenance in a network with a large number of mobile sensor nodes, while preserving node mobility, network connectivity, and energy efficiency. The proposed routing protocol is implemented with a multi-hop multi-path algorithm, a topology reconfiguration technique using node movement estimation and vibration sensors, and an efficient path selection and data transmission technique for a great many moving nodes. In the experiments, the performance of the proposed protocol is demonstrated by comparing it to the conventional LEACH protocol.

Interference Cancellation with RZF Equalization for the Downlink MC-CDMA Systems

The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very attractive multiple access technique for high-rate data transmission in the future wireless communication systems. The advantage of MC-CDMA systems that is work in frequency domain. Recently, MC-CDMA with any equalization scheme has attracted much attention for its ability to obtain an excellent performance even in strong frequency selective fading channels. In this paper, the two proposed architecture of the downlink MC-CDMA is based on the regularized zero forcing equalizer (RZF) with parallel interference cancellation (PIC) RZF-PIC) and the rake receiver with parallel interference cancellation (PIC) (RAKE-PIC) to suffer from the intersymbol interference (ISI) and multiple access interference (MAI). Two schemes are implemented in frequency domain. The effects of the tentative decision functions, the user loading on the performance of the proposed receivers architecture, and the number of cancelled users are discussed in this paper. Simulation results show the advantageof the RZF equalizer result over rake receiver and show that the combination of PIC and equalization provides an efficient solution to suppress the MAI and ISI in downlink MCCDMA systems over frequency selective fading channels.

Parallel Interference Cancellation with MMSE Equalization for the Downlink MC-CDMA Systems

The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very attractive multiple access technique for high-rate data transmission in the future wireless communication systems. MC-CDMA systems transmitting over multipath channels suffer from intersymbol interference (ISI) and multiple access interference (MAI). Recently, MCCDMA with equalization has attracted much attention for its ability to obtain an excellent performance even in strong frequency selective fading channels. In this paper, the proposed architecture uses the minimum mean square error (MMSE) with parallel interference cancellation (PIC) for downlink MC-CDMA system and compared with another system based on the rake receiver with PIC for downlink MC-CDMA system. A comparison between such architectures is presented. The effect of the tentative decision functions, the number of cancelled users and the effect of the loading users on the performance of the two proposed receivers are discussed and presented in this paper. Simulation results show that the combination of tentative decisions with PIC and equalization provides an efficient solution to suppress the MAI and ISI in downlink MC-CDMA systems over frequency selective fading channels.

Wireless power and data transmission strategies for next-generation capsule endoscopes

Capsular endoscopy is becoming increasingly popular as an alternative to traditional gastro-intestinal (GI) examination techniques. However, the breakthrough of these devices is hindered by the limited amount of power that can be stored in a tiny pill. Most commercial devices use two watch batteries that can only provide an average power of 25 mW for about 6 h, certainly not sufficient for advanced robotic features. A dedicated inductive powering system, operating at 1 MHz to limit the human body absorption, has been developed which was proven to support the transfer of over 300 mW. The system relies on a condensed set of orthogonal ferrite coils, embedded in the capsule, and an external unit based on a Helmholtz coil driven by a class E amplifier. Control data can be sent through the inductive link by modulating the power carrier, whereas a dedicated high data rate RF link is used to transfer the images from the capsule to the base station. Besides evaluating the compatibility with radio transmission, several demonstrators were assembled combining the wireless powering system with various locomotion strategies and LED illumination. This paper describes the design and implementation of the inductive powering system, its combination with data transmission techniques and the testing activity with other capsule-dedicated modules.

Coordinating collaborative assembly involving heterogeneous computer-aided design agents by an automated coordinator

This article presents a new automated modelling system to aid in collaborative designing with heterogeneous computer-aided design (CAD) agents. It is a multi-user based modelling process but is less time consuming. The article presents an effective data transmission and transformation technique to ease the mode of information sharing. The complete assembling system has been considered as a discrete event system with an automated coordinator. The automated coordinator has all the logical inputs to make the decisions. Our idea focuses on application of automata theory to the coordination of heterogeneous CAD systems. The proposed methodology has been applied to an illustrated example taken from literature for a better understanding of the model.

Dynamic Data Transmission Technique for Expendable Current Profiler

As an expendable profiler in marine environment, XCP (Expendable Current Profiler) is mainly to measure current speed, direction and temperature. The paper is to research dynamic sinking data transmission technique for XCP. Data transmission medium is a varnished wire with diameter of 0.1mm, length of 1,800m and two parallel wires. Transmission characteristics of varnished wires can be tested by experiment and computation. The paper is to research and design a kind of base band transmission system and analyze its characteristics and performance. By utilizing digital base band signaling transmission technique, indoor and marine testing results show that designed data transmission system can reach 1,800m on varnished wires with diameter of 0.1mm if XCP probe sinks dynamically by speed of 4m/s and transmission speed is 2,400bps.

UDT 환경에서 혼잡상황 예측 및 패킷손실을 고려한 성능향상 기법

최근 네트워크 기술의 비약적인 발전으로 사용자가 이용할 수 있는 대역폭이 증가하고 있다. 이에 따라 대용량 고속 네트워크에서 보다 신속하고 안정적인 전송기법이 요구되고 있다. UDT(UDP based Data Transfer protocol)는 UDP 기반의 전송 프로토콜이며, 일정 SYN time마다 rate control을 진행함으로써 긴 RTT 환경에서 TCP 보다 두드러진 성능을 보인다. 하지만, NAK 발생시 고정적인 sendInterval의 증가와, 이전 시간의 RTT에 기반한 flow control로 인해 최적의 성능을 기대하기 힘들다. 본 논문에서는 실험에 의한 결과값을 바탕으로 NAK 수신시 RTT 구간에 따라 sendInterval을 조절하는 rate 제어기법을 제시한다. 또한 TCP vegas에 기반하여 네트워크 혼잡을 예측하는 향상된 flow 제어기법을 제시한다. 실제 Testbed를 구성하여 실험한 결과, 각각의 제안기법에 대해 약 20Mbps정도 향상된 throughput이 측정되었다. 또한, 두 기법을 혼합 적용한 결과에서는 최고 26Mbps의 성능 향상을 확인하였다. Recently, the bandwidth available to an end user has been dramatically increasing with the advancing of network technologies. This high-speed network naturally requires faster and/or stable data transmission techniques. The UDT(UDP based Data Transfer protocol) is a UDP based transport protocol, and shows more efficient throughput than TCP in the long RTT environment, with benefit of rate control for a SYN time. With a NAK event, however, it is difficult to expect an optimum performance due to the increase of fixed sendInterval and the flow control based on the previous RTT. This paper proposes a rate control method on following a NAK, by adjusting the sendInterval according to some degree of RTT period which calculated from a set of experimental results. In addition, it suggests an improved flow control method based on the TCP vegas, in order to predict the network congestion afterward. An experimental results show that the revised flow control method improves UDT's throughput about 20Mbps. With combining the rate control and flow control proposed, the UDT throughput can be improved up to 26Mbps in average.

Performance of TZCD-MBOK watermarking scheme in T-DMB systems

Recently, watermarking based data transmission techniques using terrestrial digital TV signal have been proposed since they are also cost-free and can overcome the limitations of GPS. However, in the previous watermarking based methods, the detection accuracy is low and additional data rate is too low. Thus, we propose the throughput enhancement method by employing the TZCD-MBOK watermarking technique in T-DMB system. By applying the proposed scheme to T-DMB, it allows additional data transmission for disaster broadcasting and improves efficiency of data transmission in shadow region and indoor to mobile environment through watermarking spread code. From the simulation results, we confirm the proposed watermarking scheme affected on the existing T-DMB signal. Moreover, it was also confirmed that the system capacity increases as the power of additional watermarking signal rose. The results of the paper can be applied to wireless multimedia digital broadcasting systems.

An Energy-Efficient Communication Scheme for Wireless Networks: A Redundant Radix-Based Approach

We propose a redundant radix based number (RBN) representation for encoding and transmitting data for applications which typically utilize low cost devices and demand low power operations with simple modulation techniques like ASK, OOK and FSK. Coupled with silent periods for communicating the digit zero, this encoded communication scheme, called as RBNSiZeComm, provides a highly energy-efficient technique for data transmission. Considering an n-bit data representation and assuming that each of the 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</sup> binary strings is equally likely to occur, theoretically obtainable fraction of energy savings by using our proposed RBNSiZeComm transmission protocol is, on an average, 1 - n+2/4n. A hybrid modulation scheme using FSK and ASK with non-coherent detection based receiver for the RBNSiZeComm protocol has been presented. Assuming equal likelihood of all possible binary strings of a given length, there is nearly 53% savings in energy on an average at the transmitter relative to binary FSK, over additive white gaussian noise (AWGN) channels. Simulation results demonstrate that compared to binary FSK, our proposed implementation can extend the battery life of devices from about 33% to 62% on an average in applications like remote healthcare and wireless sensor networks for agriculture.

Inverse calculation approaches for source determination in hazardous chemical releases

Source determination is vital in decision making and emergency planning involving hazardous chemical releases. This work was concentrated on inverse calculation approaches for source determination as well as current trends and future perspectives. In this paper, these different approaches are reviewed by dividing them into two categories: probability modeling methods and optimization modeling methods. The traits of these approaches are comparatively analyzed. Then it is shown how these approaches behave when applied to practical cases, and their feasibility, applicability, stability, and limitation in determining the location and strength are presented. It is argued that when experimenting with potential terrorist attacks involving hazardous chemical releases, observation points should be around the main line of the downwind direction when the source is known; while the uniform distribution of observation points is an efficient solution for unknown incidents. Probability modeling methods are demonstrated to be insufficient during emergency responses due to their lacking of enough prior information of unknown parameters, while optimization modeling methods are efficient and become a new trend in source determination. Findings reflect an urgent need for the development of high-accuracy detectors and further research of data transmission techniques in order to ensure the validity of these approaches.

A Low Cost Wireless Data Acquisition System for a Remote Photovoltaic (PV) Water Pumping System

This paper presents the design and development of a 16F877 microcontroller-based wireless data acquisition system and a study of the feasibility of different existing methodologies linked to field data acquisition from remote photovoltaic (PV) water pumping systems. Various existing data transmission techniques were studied, especially satellite, radio, Global System for Mobile Communication (GSM) and General Packet Radio Service (GPRS). The system’s hardware and software and an application to test its performance are described. The system will be used for reading, storing and analyzing information from several PV water pumping stations situated in remote areas in the arid region of the south of Tunisia. The remote communications are based on the GSM network and, in particular, on the Short text Message Service (SMS). With this integrated system, we can compile a complete database of the different parameters related to the PV water pumping systems of Tunisia. This data could be made available to interested parties over the Internet.

Steganographic Technique for High Volume Secrete Data Transmission through Colour Image (STHVSDTCI)

This paper presents a novel steganographic technique which demonstrates the secrete data transmission technique through colour image in frequency domain based on the Discrete Fourier Transformation (DFT) which pertain to colour image authentication. Secrete transmission is done by hiding secrete message/secrete image into the transformed frequency component of source image. The DFT is applied on sub-image block called mask of size 2 x 2 in row major order. Three secrete message/image bits are fabricated within the transformed real frequency component of each source image byte except the LSB of first frequency component of each mask. After embedding, a delicate readjust phase is incorporated in all the frequency component of each mask, to keep the quantum value positive and non fractional in spatial domain. Robustness is achieved by hiding an authenticating or secretes message/image in the frequency component with both positive and negatives quantum values and invisibility is satisfied in spatial domain using delicate re-adjust phase. Inverse DFT (IDFT) is performed as final steps after embedding to transform embedded image in frequency domain to spatial domain. Experimental results conformed that the proposed algorithm performs better than discrete cosine transformation (DCT), Quaternion Fourier Transformation (QFT) based scheme and Spatio Chromatic DFT (SCDFT). Keywords: QFT, DFT, IDFT, DCT, MD and SCDFT

BER Degradation of MC-CDMA at High SNR with MMSE Equalization and Residual Frequency Offset

Multicarrier Code Division Multiple Access (MC-CDMA) is an attractive technique for high speed wireless data transmission in view of its advantages over orthogonal frequency division multiplexing. In this paper, we analyze the performance of fully loaded downlink MC-CDMA systems with minimum mean square error (MMSE) equalizer in the presence of residual frequency offset (RFO) in multipath Rayleigh fading channels. We first show that as the SNR is increased beyond a value, referred as threshold SNR, the performance degrades. We then analyze the cause for this behavior and propose a remedy to prevent the degradation by regularizing the coefficient(s) of the equalizer, and use the regularized equalizer for SNRs beyond the threshold value. We suggest two methods for estimating this SNR, one gives close to the true value but requires the knowledge of RFO and the channel state information (CSI), while the other gives an approximate value but requires only CSI. We show that the regularization based on the approximate value also prevents the degradation, but the performance at higher SNRs is slightly poorer compared to that with the better estimate. Numerical and simulation results are provided to support the analysis.

Secure image transmission using steganographic methodologies

The new invention in the field of communications especially the 3G mobile technologies are in double role, some of the benefits of the system are face-to-face communication, video-on-demand, multimedia facilities and some of the setbacks include face trap, voice capturing, image manipulations etc. The new communication technology should be more secure and be useful for the national security system, intelligence bureaus, internet banking system, geographical information system, image based communication and wherever the security of the system is required. In this proposed work, we suggest a novel highly secured steganographic data transmission techniques by hiding the image of a sender into speech or text data file. By concealing the secret image file, we can maintain the high level of security with low bandwidth.

Wellbore Path Estimation Using Measurement While Drilling Techniques: A Comparative Study and Suggestions for Improvements

The complexity of wells being drilled has increased over the past few years in order to fulfill the worldwide increase in energy demand. The existing drilling technologies make it possible to construct boreholes with different directions. However, the control of paths and trajectories within the operator requirement is a non-obvious task, because of the data transmission time and the space discretization for measurements. This article aims at reviewing the most common techniques of curvature measurements and data transmission. It also compares them by outlining their advantages and weaknesses.

Prediction-Based Haptic Data Reduction and Transmission in Telementoring Systems

In this paper, two novel prediction-based haptic data reduction and transmission techniques are presented to reduce data traffic in telementoring systems. The prediction approach relies on the least-squares method and median filtering to reduce the number of packets transmitted, and efficiently reconstruct unsuccessfully received data samples. Knowledge from human haptic perception is also used and incorporated into the architecture of the two methods. The techniques are initially evaluated in a basic experimental setting to validate their performance. Their application in a haptic-enabled telementoring surgery simulation is also demonstrated. The experimental results prove the effectiveness of the proposed approach as haptic data packets can be reduced by as much as 96% while preserving the overall quality of the telementoring environment.

Adaptive channel and power allocation of downlink multi-user MC-CDMA systems

The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very attractive multiple access technique for high-rate data transmission in the future wireless communication systems. This paper is focused on the joint channel and power allocation in the downlink transmission of multi-user MC-CDMA systems and considers the throughput maximization problem as a mixed integer optimization problem. For simple analysis, the problem is divided into two less complex sub-problems: power allocation and channel allocation, which can be solved by a suboptimal Adaptive Power Allocation (APA) algorithm and an optimal Adaptive Channel Allocation (ACA) algorithm, respectively. By combining APA and ACA algorithms, an adaptive channel and power allocation scheme is proposed. The numerical results show that the proposed APA algorithm is more suitable for MC-CDMA systems than the conventional equal power allocation algorithm, and the proposed channel and power allocation scheme can significantly improve the system throughput performance.

An overlapping and pipelining data transmission MAC protocol with multiple channels in ad hoc networks

In mobile ad hoc networks (MANETs), the IEEE 802.11 DCF protocol is commonly used at the medium access control (MAC) layer to reduce collision and contention. However, mobile nodes, before send out data, need to wait for other in-process data transmission in the same range to be completed. In this paper, we address this performance degradation problem in the DCF mechanism and propose an overlapping and pipelining data transmission MAC protocol to enhance throughput. The protocol regulates the actions of the neighboring nodes of both the sender and the receiver and enables the utilization of the same channel simultaneously by these neighboring nodes. A multiple sub-channel technique is proposed to avoid the interference problem caused by the control and data signals of different communication mobile node pairs. With the regulated actions and the multiple channel technique, multiple pairs of mobile nodes are provided with the desired feature of utilizing the same data sub-channel simultaneously without interfering with one another. Although the overlapping data transmission technique can increase the number of simultaneous communication pairs, an efficient bandwidth allocation of the control and data sub-channels to maximize utilization is critically important. Therefore, we further propose a bandwidth allocation strategy in which the control signals and data signals are pipelined. Performance simulation results prove the efficiency of the proposed bandwidth allocation strategy with better channel utilization. In addition, the proposed MAC protocol with the bandwidth allocation strategy, combined with the overlapping and pipelining data sub-channel technique, outperforms the IEEE 802.11 DCF in throughput (kB/s) by about 43.76%.

Throughput Performance of MC-CDMA HARQ Using ICI Cancellation

Multi-carrier code division multiple access (MC-CDMA) is a promising wireless access technique for the next generation mobile communications systems, in which broadband packet data services will dominate. Hybrid automatic repeat request (HARQ) is an indispensable error control technique for high quality packet data transmission. The HARQ throughput performance of multi-code MC-CDMA degrades due to the presence of residual inter-code interference (ICI) after frequency-domain equalization (FDE). To reduce the residual ICI and improve the throughput performance, a frequency-domain soft interference cancellation (FDSIC) technique can be applied. An important issue is the generation of accurate residual ICI replica for FDSIC. In this paper, low-density parity-check coded (LDPC-coded) MC-CDMA HARQ is considered. We generate the residual ICI replica from a-posteriori log-likelihood ratio (LLR) of LDPC decoder output and evaluate, by computer simulation, the throughput performance in a frequency-selective Rayleigh fading channel. We show that if the residual ICI is removed, MC-CDMA can provide a throughput performance superior to orthogonal frequency division multiplexing (OFDM).

Integrated voice and data transmission employing adaptive modulation in wireless networks

In this paper, we propose an integrated voice and data transmission technique using adaptive modulation, wherein the effective data transmission rate (throughput) is improved by allowing the bit-error rate (BER) for voice to increase beyond the BER needed for data. In a given integrated frame with data and voice bits, voice bits are allowed to use higher-order modulation as compared to data bits due to the higher tolerance of voice to BER. This leads to a larger symbol duration for voice which is subsequently shrunk into fewer bits, provided the resulting increase in voice BER does not exceed its maximum acceptable limit. This shrinking operation releases some bits from the voice quota, which are eventually utilized for data transmission in addition to the predefined data bits in the same frame. In this work, we first examine the feasibility of the proposed scheme for a time-invariant AWGN channel. Subsequently, we use our methodology in an adaptive manner for fading channels. We also examine the performance of the proposed scheme for a Global System for Mobile communication (GSM) system. Using the proposed scheme, our analysis indicates that one can dynamically enhance the overall throughput significantly in a broadband wireless network.