Full-Rank and Rank-Deficient Precoding Schemes for Single-Carrier Block Transmissions

In block-mode transmission, inserting a cyclic prefix (CP) between two consecutive blocks provides an efficient way of removing interblock interference and simplifies equalization of frequency-selective channels at the receiver. Here, we address optimal training design for channel estimation in such systems. Our investigations focus on affine precoding schemes. In designing the precoder, least squares channel estimation is constrained to be decoupled from symbol detection, which results in orthogonal precoding schemes. If the precoding matrix is full-rank, the data rate (or bandwidth) has to be traded off to accommodate training. We propose a full-rank orthogonal single-carrier (FROSC) precoding with a low peak-to-average power ratio. Then, in order to improve bandwidth efficiency, we propose a rank deficient orthogonal single carrier (DROSC) precoding scheme. Symbol recovery is still possible thanks to the finite alphabet property of the data symbols.     

A Novel Blind Channel Identification and Equalisation Algorithm Based on Maximum Likelihood

A novel blind non-decision directed maximum likelihood algorithm for fractionally-spaced nonminimum phase FIR channel identification and equalisation is presented. The algorithm results from using the low signal to noise approximation to the average of the likelihood function with respect to the transmitted data sequence. The channel estimation equation is derived in a closed form. The resulting algorithm has two distinct advantages. The first is that the channel estimates are asymptotically consistent, and the second is that the algorithm is computationally efficient since it only requires the calculation of one eignevector. Simulation results are presented to show the performance of the proposed algorithm.     

One-dimensional linear periodically time-varying structures:derivations, interrelationships and properties

The author presents all the derivations of, and the interrelationships for, four principle models of a one-dimensional, linear periodically time-varying (LPTV) system. These results are then used to both analyse cascade and parallel structures and solve the LPTV inverse filter problem     

Multiple packet reception in wireless ad hoc networks using polynomial phase-modulating sequences

This paper proposes a blind interference cancellation algorithm that is able to provide multiple packet reception capability for asynchronous random access wireless mobile ad hoc networks. The algorithm exploits the fact that the baseband signal exhibits cyclostationarity properties, which are induced at the transmitters by means of modulating the symbols with polynomial phase sequences. This modulation does not expand the bandwidth and can be considered as a "color code" that can be used to distinguish one transmission from the others (i.e., packets from other users). The proposed technique does not require knowledge of the starting time of transmission of the desired signal and can also be applied to time-dispersive multipath channels. In addition, a practical way of assigning the color codes via the use of a common codebook known to all nodes is proposed, and the impact on local throughput of such a scheme is analyzed. Simulation results illustrate the excellent performance of the proposed approach.     

Exploring Student Engagement in Construction Law Education

This paper reports on an analysis of study traits and approaches to learning of undergraduate and postgraduate students of construction law. It draws on a longitudinal study of construction law education and on reflections on educational practice in a U.K. university. This paper concentrates on student engagement with the study of construction law and presents two examples from practice of what works well and what does not work so well in terms of engaging students in the teaching and learning of construction law. Using some pedagogic theory, a rationale for improving the teaching, learning, and assessment régime of construction law is proposed.     

Relationship between an LPTV system and the equivalent LTI MIMO structure

It is understood how to transform a linear periodically time-varying (LPTV) filter/ difference equation into an equivalent multiple-input/multiple-output (MIMO) structure, or transfer matrix, with linear time-invariant (LTI) elements, but no published method exists for the reverse operation. The paper presents a technique to transform from the LTI MIMO structure to the original single-input/single-output LPTV difference equation and discusses its implications. In addition, it is shown how this new result is then used to represent parallel and cascade connections of LPTV systems as single LPTV filters, implement order reduction of an LPTV difference equation, and finally obtain an LPTV difference equation representation that is equivalent to an LPTV state-space structure.     

Blind channel equalization using chirp modulating signals

This paper addresses the problem of blind channel equalization in the context of digital communications. Recent results have shown that certain operations applied to the source signal at the transmitter help in the blind identification and equalization of the channel at the receiver. In this paper, the baseband data signal is multiplied with a chirp sequence. Exploiting certain structural properties arising from this operation, a batch-type algorithm is obtained for calculating the equalizer's coefficients. Conditions on the chirp sequence parameters are obtained that guarantee an equalization solution. A low-complexity adaptive algorithm is also proposed. Finally, extensive simulations, and comparisons with other well-known blind techniques, illustrate the excellent performance of this algorithm.