Novel fabrication technique for planar glass waveguides

A novel technique has been developed for the deposition of low-loss planar glass waveguides by directly spin coating from the liquid, thus overcoming the problems of reproducing glass stoichiometry when depositing from the vapour

Reduced Complexity MIMO Channel Estimation and Equalization using a Polynomial-Predictor Based Vector GLMS Algorithm

A reduced complexity multiple-input multiple-output (MIMO) channel estimator known as the polynomial-predictor-based vector generalized least mean squares (VGLMS) estimator is developed. It is a simplification of a previously developed polynomial-predictor-based vector generalized recursive least squares (VGRLS) estimator, achieved by replacing the online recursive computation of the ‘intermediate’ matrix by an offline pre-computed matrix. Similar to the VGRLS estimator, it is able to operate in Rayleigh or Rician fading environments without reconfiguration of the state transition matrix to accommodate the non-random mean components. It is seen to offer a trade-off between reduced complexity channel estimation and good system performance

Implementation of Four Real-Time Software Defined Receivers and a Space-Time Decoder using Xilinx Virtex 2 Pro Field Programmable Gate Array

This paper describes the concept, architecture, development and demonstration of a real time, high performance, software defined 4-receiver system and a space time decoder to be implemented on a Xilinx Virtex 2 Pro Field Programmable Gate Array. It is designed and developed for research into receiver diversity and multiple input and multiple output (MIMO)wireless systems. Each receiver has a Freescale DSP56321 digital signal processor (DSP) to run synchronization, channel state estimation and equalization algorithms. The system is software defined to allow for flexibility in the choice of receiver demodulation formats, output data rates and space-time decoding schemes. Hardware, firmware and software aspects of the receiver and space time decoder system to meet design requirements are discussed

Space-Frequency Equalization for Broadband Single Carrier MIMO Systems

In this paper, a frequency domain (FD) receiver architecture implemented using estimated channel parameters is derived for broadband single carrier modulations. Co-channel and inter-symbol interferences are compensated by a minimum mean squared error based integrated space-frequency-equalizer (SFE) using the estimated parameters. The integrated SFE in the FD consists of coupled FIR structures, that are jointly optimized by maximizing the desired signal to interference plus noise ratio. We develop analytical expressions and present simulation results for the integrated SFE. Simulation results demonstrate that excellent receiver performance is achieved even for channels with large ISI spans. The proposed SC-SFE outperforms previous layered space frequency (LSF) receivers with imperfect channel knowledge. Further, the parallel receiver architecture yields equal diversity gains to all data streams without the error propagation that is common to most LSF schemes

Transmitted Energy as a Basic System Resource

Energy is a basic resource in digital transmission links. Physically, radio channels correspond to passive circuits and most of the transmitted energy is lost in the channel. Two alternative approaches are used for performance measurements in terms of energy. Either the average transmitted or received energy per bit is used, both usually normalized by the receiver noise spectral density. This leads to the average transmitted or received signal-to-noise ratio (SNR) per bit, respectively. However, the transmitted energy is the basic system resource. The average energy gain of a channel depends on the transmitted signal. For convenience, the transmitted SNR referred to the receiver is defined to be the product of the transmitted SNR and the representative energy gain, which is defined as the average energy gain of a signal that is uniformly distributed in all dimensions: time, frequency and space. An explicit relationship between the transmitted and received SNR’s using the covariance concept is derived. Limitations of the use of different SNR definitions are summarized

Improved Information Outage Rate in Certain MIMO Systems

We propose a simple class of encoding/decoding techniques which can be used to improve the information outage rate of certain multiple-input multiple-output (MIMO) systems. Gains in outage rate can be achieved at low to moderate signal to noise ratios in MIMO systems which have fewer receive antennas than transmit antennas. This performance improvement is due to extra ``virtual'' receive antennas which are created with low complexity signal processing. A simple space-time block code system using virtual receive antennas is also investigated

Two-user Cooperative Transmission Using Superposition Modulation and Soft Information Combining

We propose a cooperative transmission scheme for two users with one common relay using superposition modulation. It uses distributed Turbo codes (DTCs) for each user. The relay always decodes, then interleaves and re-encodes the decoded data. A new packet is formed by combining the re-encoded packets from both users using superposition modulation. This packet is forwarded to the destination with the average receive SNRs of each user. The destination uses the cooperative Turbo decoder of [1] to improve performance. Simulation results show the proposed scheme outperforms XOR based schemes and is simple to implement

Cooperative Relaying with CPFSK and Distributed Space-Time Trellis Codes

Cooperative relaying allows single antenna users to achieve diversity and coding gains by utilizing nearby users' transmitting capabilities. We consider a relay system employing constant envelope continuous phase frequency shift keying. Distributed space-time trellis codes are implemented with a novel multiple relay protocol

Cooperative Relaying with CPFSK and Distributed Space-Time Trellis Codes

Cooperative relaying allows single antenna users to achieve diversity and coding gains by utilizing nearby users' transmitting capabilities. We consider a relay system employing constant envelope continuous phase frequency shift keying. Distributed space-time trellis codes are implemented with a novel multiple relay protocol