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Communication using power line as a medium provides a convenient and inexpensive way for data transmission and control signaling in the households. In this paper, we will introduce a power-line channel model as well as architecture of a spread-spectrum baseband transceiver integrated circuit (IC) for a power-line modem. The modulation and spreading scheme used in the proposed transceiver is M-ary bi-orthogonal keying (MBOK). This transceiver runs at a chipping rate of 256 kHz and provides 128-Kbps data rate. Simulation results as well as FPGA emulation verify the effectiveness of the proposed architecture for household data communication. Index Terms--Home automation, modern, power line, spread spectrum.

A novel algorithm for the optimal design of bandlimited Nyquist-type signal shapes for data communications has been developed. The proposed approach maximizes its energy in a given time interval and is based on the periodically nonuniform sampling theory that utilizes the linear splines. The computation is simple and the constraint for intersymbol interference is easy to include in the problem. It is also shown that the optimal signal shapes are almost shielded from small offsets at the sampling instants.

We present a throughput analysis for the memory automatic repeat request (ARQ) schemes with self-decodable frame retransmissions, taking into account frame header and frame acknowledgment failure probability. A lower bound on the throughput is obtained for a very general class of schemes which encompasses many of those proposed in the literature. Numerical results are given for several example systems, and suitable header and acknowledgment forward error correction (FEC) encodings are determined. Index Terms - ARQ, copy combining, error correction coding, header failure, memory ARQ, throughput.

This paper describes a novel solution to the problem of bandwidth-efficient digital signal transmission in the presence of dynamic multipath distortion. A burst transmission is comprised of two consecutive data blocks with Identical data that have been processed differently. The two data blocks are transmitted adjacent to each other In time so that the time-variable transmission channel will apply approximately the same linear distortion to each block. At the receive site, the two blocks are captured and processed together to cancel the effects of the linear distortion, while adding the signal energy from each block.

Massive uniform nested loops are broadly used in multidimensional digital signal processing (DSP) applications. Due to the large amount of data handled by such applications, the optimization of data accesses by fully utilizing the local memory and minimizing communication overhead is important in order to improve the overall system performance. Most of the traditional partition strategies do not consider the effect of data access on the computational performance. In this paper, a multilevel partitioning method, based on a static data scheduling technique known as carrot-hole data scheduling, is proposed to control the data traffic between different levels of memory. Based on this data schedule, optimal partition vector, scheduling vector and the partition size are chosen in such a way to minimize communication overhead. Nonhomogeneous size partitions are the final result of the partition scheme which produces a significant performance improvement. Experiments show that by using this technique, local memory misses are significantly reduced as compared to results obtained from traditional methods. This method can be used in application specific DSP system design and compiler for DSP processors. Index Terms - Data scheduling, memory access, multidimensional applications, multilevel partitioning, nested loops.

In a noncellular or large cell-size mobile radio communication system, log-normal shadowing as well as Rayleigh fading becomes the predominant source of system degradation. This paper proposes an efficient stop and wait automatic repeat request (SAW-ARQ) protocol with adaptive packet length to provide reliable mobile data packet transmission. The adaptive SAW-ARQ protocol controls the transmitting packet length according to the time-varying channel condition estimated with the number of ACK (acknowledgment packet) and NACK (negative-acknowledgment packet). Computer simulation results show that the proposed protocol can achieve high throughput and reduce the number of retransmission effectively for slow and fast Rayleigh fading/log-normal shadowing conditions.

This paper examines a radio-based indoor communication network with a single radio channel shared by several data terminals. By enabling the terminals to communicate with each other and access the resources of a wired network, the system is a potential provider of in-building LAN-like services. In this indoor fading environment, a base-station approach is assumed. In the analysis, a two-state Markov chain model is used to model the nonstationary transmission channel. Two preemptive polling multiple-access schemes combine with ARQ error-control schemes to counteract the effects of a nonstationary transmission channel. The main idea here devised is that of making the service interruption dependent on the propagation conditions of the transmission channel by monitoring the outcomes of the data packet transmission attempts. A performance comparison reveals the superiority of the preemptive polling systems with respect to a classical TDMA scheme.

The development of a simulator - ALSIM for the ALICE Data Acquisition System is described. ALSIM models front-end data readout, event building, data reduction and data storage. Technology dependent implementations can be linked in and various topologies can be defined dynamically by means of description files. The simulation environment will be described as well as details of the model.

The Atlas detector [1] for the LHC accelerator at CERN requires a trigger and data acquisition (DAQ) system capable of handling bunch crossings every 25ns. A three level trigger has been proposed. While the first level, which processes events synchronously, can be investigated analytically, the second level onwards, which processes events asynchronously, requires detailed modelling. SIMDAQ, a tool to model trigger and DAQ systems, is described in this paper, along with preliminary results from simulation studies of the Atlas trigger and DAQ system using SIMDAQ.

A new object-oriented Real Time System Simulator (RTSS) with the capability for simulation graphics and animation, has been developed and used for modeling the distributed data acquisition and processing systems at JET and ASIPP. Simulation allows estimates of response time, throughput and resource utilization for a variety of configurations to be investigated. Performance measurements, simulation and analysis are used together to calibrate and validate each other.