Reliable vocoder data transmission over fading HF channels

Performance Analysis of 16-QAM using OFDM for Transmission of Data over Power Lines

FIFO is a first-in first-out data storage and buffer, which can cache the continuous data stream to prevent data loss during incoming and storing operations. A special interface technology, asynchronous FIFO, needs to be introduced to ensure the correct data transmission when data needs to be transmitted between different clock domains or when the input device and the output device do not match the data interface width. This paper uses Verilog HDL language to design an asynchronous FIFO which can realize the conversion of different data bit widths. In the paper, the difficulties of this design are analyzed in detail, including the method of synchronizing different clock domains, the judgment of FIFO's empty and full state, the method of reducing metastability during data transmission and the method of data bit width conversion. Finally, the designed program is simulated and verified by modelsim software, and the waveform results obtained by simulation are analyzed in detail.

In this paper, we present the application of wireless sensor technology and the advantages it will inherently have for neonatal care and monitoring at Neonatal Intensive Care Units (NICU). An electrocardiography (ECG) readout board and a wireless transceiver module developed by IMEC at the Holst Centre in the Netherlands are embedded in the proposed wireless sensor systems in combination with the signal processing and software interface developed at the Department of Industrial Design, Eindhoven University of Technology (TU/e). Through development of this prototype system, we opt to ensure correct data transmission, detection and display. The wireless system is designed to be suitable for integration into non-invasive monitoring platforms such as a smart neonatal jacket developed at TU/e. Experiments at Maxima Medical Centre (MMC) in Veldhoven, the Netherlands demonstrate the wireless transmission of ECG data from the smart jacket integrated with textile electrodes.

While the telephone network has progressed in the process of transmitting and switching information based on the digitization of voice, leading to the integrated digital network (IDN), the rapid advances in computer and data communication technologies have evolved and have generated their own need for network capability to meet data needs. This has led to the realization that the same digital techniques can be used for data or voice transmission and switching. With ever-increasing demand for efficient interconnection of voice and data customers, the differences between voice and data switching and transmission have led to the study and development of integrated systems to transmit, switch, and process all types of digital signals. The final evolution of these systems is the integrated service digital network (ISDN). With the IDN having the inherent capability of handling both voice and data in digital form, the ISDN provides end-to-end digital connectivity, supporting a full range of services by means of standardized local access arrangements to a “transparent” transport medium.

This paper states about the voice communication and data transmission at a time on a single existing power line that reduces the complexity of so much wires used in communication system and it is applicable in a large automated area with low cost and easy installation process. The message (voice, tone or digital data) is modulated with a high frequency carrier by frequency modulation (FM) or frequency shift keying (FSK) process and after amplification it passes to the power line through the bidirectional coupler. At the receiver section the signal (FM or FSK) is recovered by coupler and then demodulated. The demodulated signal is then passed through the low pass filter to recover the voice or tone signal and a comparator is used to recover data signal. Here the authors use different carrier frequencies for different users and also use corresponding filter and comparator. A trap circuit is used here to localize the communication area which obstructs the transmitted signal to pass out of that area and hence losses are reduced.

Future mobile communication systems will provide multimedia services to users in every environment through uniform access procedures. In this scenario, it is essential to define efficient medium access control (IMAC) protocols that are suitable for both terrestrial and satellite systems (integrated networks). This paper envisages packet reservation multiple access (PRMA) for supporting voice and data transmissions in low Earth orbit (LEO) mobile satellite systems. In particular, a modified PRMA (MPRMA) protocol is proposed and analyzed. Simulation results are also presented in order to validate the analytical approach. A parameter optimization has been carried out to improve the protocol performance. Finally, a comparison with PRMA has permitted to highlight the advantages of the new MPRMA scheme.

Integration of data networking into traditional voice only systems, such as SINCGARS and HAVEQUICK, is necessary to meet evolving multimedia communication requirements. The success of this integration is dependent on the development of improved channel-access and network protocols that allow simultaneous voice and data information transfer. In previous work we investigated a system design that includes a new waveform and channel-access protocols to support integrated voice and data transmissions in a multiple-hop packet radio network. In this article we present network protocols that support multiple-hop relaying of data packets in a mobile packet radio network. An adaptive forwarding protocol is defined that can respond quickly to local changes in the environment and traffic load. An OPNET simulation, which models the physical, channel-access, and network layers, is implemented to characterize the performance of the network protocols. We show the ability of the network to support relaying of data traffic, and we show the improvement in performance that is achieved through the use of the adaptive forwarding protocol.

We present a protocol for reliable communication between search and rescue robots, which is synthesized from a high-level temporal logic specification. The protocol ensures provably correct data transmission on an asynchronous point-to-point link in the presence of an adverse environment. We synthesize the protocol into correct-by-construction transceiver controllers that can be included as building blocks in a larger design. The viability of our approach of synthesizing controllers with clearly defined interfaces and the validity of our protocol is demonstrated by implementing controllers for robots searching cooperatively for a moving target.

IEEE802.11 employs distributed coordination function (DCF) as a media access control method. In order to address the hidden terminal problem, the DCF equips the virtual carrier sensing function in addition to the traditional carrier sensing function, CSMA. The virtual carrier sensing is realized by the RTS/CTS short packets exchange and the NAV. The RTS/CTS exchange can keep terminals other than the sender and the receiver silent for ensuring a data packet transmitted correctly. The NAV is a timer that indicates the amount of time that the medium will be reserved. The first modification is to replace the NAV for RTS of DCF to the one used in the protocol MACA (the idea of RTS/CTS exchange is originally proposed in the MACA). Simulations show that this modification improves the throughput performance. On the other hand, the DCF is designed to use ACK packet for ensuring correct data transmission in the media access control layer, while the ACK did not used in the MACA. We secondly show that the use of the ACK reduces the throughput performance of DCF when the RTS/CTS exchange is in use, concluding that by omitting the ACK from the DCF, the performance can be improved. This paper not only shows that these two simple modifications can improve the performance of the DCF but also points out that the functions being implemented in the DCF do not always work well for realizing higher performance.

Proper handling and communication of data on chemical systems require knowledge about the mathematical characteristics of different types of property and the unambiguous representation of singular properties. Using the terminology of the International Organization for Standardization (ISO), the concept "property" is generically divided according to various statistical characteristics of property values. The formatting of representation of dedicated kinds-of-property as elaborated by clinical chemists in the International Union of Pure and Applied Chemistry (IUPAC) and the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) should ensure correct data transmission between laboratory dialects in any chemical discipline.

Data aggregation, information trust, and fault tolerance is considered to enhance the correctness and trustworthiness of collected information. It is based on the multilayer aggregation architecture of WMSNs, existing trust-based framework for data aggregation with fault tolerance with a goal to reduce the impact of erroneous data and provide measurable trustworthiness for aggregated result. DAG method provides fault tolerance for packet loss by forming a Directed Acyclic Graph (DAG), which allows a node to have multiple parent nodes. This method can ensure correct data transmission timing, according to the actual hop count of the edge of the DAG.

In this paper, a compressed sensing based scalable video coding using discrete wavelet transform (DWT) for space applications is presented. The proposed method is aimed at reducing the requirement of on-board memory, station contact time and data archival volume. Compressive sensing (CS) has been applied to encode the distributed wavelet coefficients into linear measurements. Since prior knowledge of the compressively sampled measurements is not available, a modeler is employed to determine the context of the measurement vector. Based on the statistics provided by the context modeler, the samples are entropy coded for transmission. A part of the compressive sampling measurements with near uniform distribution are encoded through adjusted binary coding, and the rest are encoded through Golomb-Rice coding. Run length encoding is implemented for exploiting the redundancy in the binary data further. At the receiver end, the original spatial signal is reconstructed from the CS samples by approximate message passing (AMP) algorithm and inverse discrete wavelet transform (IDWT) for video decompression. Simulation of the proposed approach has demonstrated an efficient compression of the video cubes with lower complexity at the transmitter end.

OPTICAL COMMUNICATIONS USING SURFACE ACOUSTIC WAVES

The implementation of timing recovery circuits in multigigabit/s optical regenerators becomes increasingly difficult because of the complexity of nonlinear circuit elements at such high data rates. We propose and demonstrate a new method of data regeneration without nonlinear retiming circuits. In the proposed scheme, the clock is superimposed on the data signal at the transmitter end and is separated from the composite signal at the receiver end by means of a novel microstrip directional filter for data regeneration. This scheme offers significant reduction in circuit complexity over conventional regenerator designs and has less pattern dependence and systematic jitter since the clock is not derived from the baseband data. A compact regenerator at 2.4 Gbit/s has been implemented using this technique and transmission over 35 km of dispersion-shifted fiber (DSF) with a 1550-nm DFB laser has been demonstrated.

In this paper, a microwave photonic dual band radar based on a photonic-assisted de-chirp processing receiver is proposed. The dual band operation is realized independently and simultaneously with a single set of hardware. At a transmitter end, two linear frequency-modulated signals separately located in C-band and Ku-band are transmitted, echoes are collected and sent to a receiver to implement photonic-assisted de-chirp processing. At the receiver end, a main modulator with a special structure, which consists of four parallel sub-modulators, is employed. The echoes and reference signals of C-band and Ku-band are applied to two pairs of sub-modulators of the main modulator, which are biased at the peak points for C-band and biased at the null points for Ku-band. In this case, the intermediate frequency signals of C-band and Ku-band produced by de-chirp processing locate at two different frequencies. Thus operation in different bands based on a unified system is achieved. An experiment operating in C-band and Ku-band with a bandwidth of 700 MHz and 3600 MHz is conducted. The results verify the concept of the dual band radar and show the potential of photonic technology to improve the performance of modern radar system.