Lutz Lampe

Power line communications : theory and applications for narrowband and broadband communications over power lines

List of Contributors. Preface. List of Acronyms. 1 Introduction (The Editors). References. 2 Channel Characterization (P. Amirshahi, F. Canete, K. Dostert, S. Galli, M. Katayama and M. Kavehrad). 2.1 Introduction. 2.2 Channel Modeling Fundamentals. 2.3 Models for Outdoor Channels: LV Case. 2.4 Models for Outdoor Channels: MV Case. 2.5 Models for Indoor Channels. 2.6 Noise and Disturbances. 2.7 MeasuringTechniques. 2.8 PLC Channel EmulationTools. 2.9 Reference Channels for Access Domain. 3 Electromagnetic Compatibility (H. Hirsch and M. Koch). 3.1 Introduction. 3.2 Parameters for EMC Considerations. 3.3 Electromagnetic Emission. 3.4 Electromagnetic Susceptibility. 3.5 EMC Coordination. 3.6 EMC Regulationin Europe. 3.7 Final Remarks. 4 Coupling (P. A. Janse van Rensburg). 4.1 Introduction. 4.2 Filtering Basics. 4.3 Transformer-Capacitor Coupler Design. 4.4 Impedance Adaptation Concepts. 4.5 Experimental Verification. 4.6 Further Possibilities. 5 Digital Transmission Techniques (M. Ardakani, G. Colavolpe, K. Dostert, H. C. Ferreira, D. Fertonani, T. G. Swart, A. M. Tonello, D. Umehara and A. J. H. Vinck). 5.1 Introduction. 5.2 Modulation and Coding for Narrowband PLC Systems. 5.3 Modulation and Coding for Broadband PLC Systems. 5.4 Conclusion. 6 Protocols for PLC Systems (G. Bumiller, H. Hrasnica, L. Lampe, M. Lobashov and T. Stockhammer). 6.1 Introduction. 6.2 Broadband PLC Media Access Control Layer. 6.3 Protocols for PLC Supporting Energy Management Systems. 6.4 Internet Protocol Television Over PLC. 7 Industrial and International Standards on PLC-based Networking Technologies (Galli, M. Koch, H. A. Latchman, S. Lee and V. Oksman). 7.1 Introduction. 7.2 PLC Standardization by Industrial Alliances. 7.3 International Standards on PLC-Networking Technology. 7.4 ETSI and CENELEC Standards. 7.5 International EMC Product Standardization. 8 Systems and Implementations (I. Berganza Valmala, G. Bumiller, H. A. Latchman, M. V. Ribeiro, A. Sendin Escalona, E. R. Wade and L. W. Yonge). 8.1 Introduction. 8.2 PLC Smart Grid Systems. 8.3 PLC Broadband Access Systems. 8.4 Multimedia PLC Systems. 8.5 DC-PLC Systems. 8.6 PLC in Emerging Countries. 9 Conclusions (The Editors). Index.

Multiple-antenna techniques for wireless communications - a comprehensive literature survey

The use of multiple antennas for wireless communication systems has gained overwhelming interest during the last decade - both in academia and industry. Multiple antennas can be utilized in order to accomplish a multiplexing gain, a diversity gain, or an antenna gain, thus enhancing the bit rate, the error performance, or the signal-to-noise-plus-interference ratio of wireless systems, respectively. With an enormous amount of yearly publications, the field of multiple-antenna systems, often called multiple-input multiple-output (MIMO) systems, has evolved rapidly. To date, there are numerous papers on the performance limits of MIMO systems, and an abundance of transmitter and receiver concepts has been proposed. The objective of this literature survey is to provide non-specialists working in the general area of digital communications with a comprehensive overview of this exciting research field. To this end, the last ten years of research efforts are recapitulated, with focus on spatial multiplexing and spatial diversity techniques. In particular, topics such as transmitter and receiver structures, channel coding, MIMO techniques for frequency-selective fading channels, diversity reception and space-time coding techniques, differential and non-coherent schemes, beamforming techniques and closed-loop MIMO techniques, cooperative diversity schemes, as well as practical aspects influencing the performance of multiple-antenna systems are addressed. Although the list of references is certainly not intended to be exhaustive, the publications cited will serve as a good starting point for further reading.

Noncoherent receivers for differential space-time modulation

In this paper, noncoherent receivers for differential space-time modulation (DSTM) are investigated. It is shown that the performance of the previously proposed conventional differential detection (DD) receiver is satisfactory only for very slow flat fading channels. However, conventional DD suffers from a considerable loss in performance even for moderately fast fading, especially if more than one transmit antenna is used. In order to overcome this problem, two improved noncoherent receivers are considered. The first one is the multiple-symbol detection (MSD) receiver. Because of the high computational complexity of MSD, also a low-complexity decision-feedback differential detection (DF-DD) receiver is derived. Analytical and simulation results confirm that both receivers perform equally well and can take full advantage of the enhanced diversity provided by multiple transmit antennas even for fast fading.

Power line communication networks for large-scale control and automation systems

Power line communications uses the existing power line infrastructure for communication purposes. While the majority of recent contributions have discussed PLC for high-data-rate applications like Internet access or multimedia communication serving a relatively small number of users, in this article we are concerned with PLC as an enabler for sensing, control, and automation in large systems comprising tens or even hundreds of components spread over relatively wide areas. Typical examples of such systems are energy management (Smart Grid) and facility automation systems. We provide a discussion of the communication network requirements common to such systems and present transmission concepts for PLC to make use of the existing infrastructure resources (i.e., power lines) to meet these requirements.

Distributed transmit power allocation for multihop cognitive-radio systems

In this paper, we consider a relay-assisted wideband cognitive-radio (CR) system under the assumption that the frequency band chosen by the CR relay network for unlicensed spectrum usage overlaps with one or more bands dedicated to primary (e.g., licensed) narrowband links. Our objective is to optimize the performance of the CR system while limiting the interference in direction of the primary receivers, without requiring any adaptation of the transmitted signal spectra at the cognitive nodes. To this end, we study appropriate transmit power allocation (TPA) strategies among the cognitive relays. We first investigate the optimal centralized (OC) TPA solution and show that it can be formulated as a linear program. Since the OC-TPA solution requires a considerable amount of information exchange between the cognitive nodes, we develop two distributed TPA schemes, namely (i) a fully decentralized (FD) TPA scheme and (ii) a distributed feedback-assisted (DFA) TPA scheme. The FD-TPA scheme aims at maximizing the output signal-to-interference- plus-noise ratio (SINR) at the destination node of the CR network according to a best-effort strategy. It requires neither feedback information from the destination node nor an exchange of channel state information between the cognitive relays. The DFA-TPA scheme, on the other hand, utilizes feedback information from the destination node, in order to achieve a predefined target output SINR value, while minimizing the overall transmit power spent by the relays. Analytical and simulation-based performance results illustrate that notable performance improvements compared to non-cooperative transmission (i.e., without relay assistance) are achieved by the proposed schemes, especially when more than two hops are considered. In particular, the proposed distributed TPA schemes typically perform close to the OC-TPA solution.

Cognitive Radio for Smart Grid Communications

One of the key foundations of smart grid (SG) is a reliable communications infrastructure which is a sophisticated, multi-layer network carrying different classes of data. SG communications needs to be designed to accommodate the current energy management requirements as well as the potential demand of future applications. In this paper, we propose the application of cognitive radio (CR) based on the IEEE 802.22 standard in the SG wide area networks (WANs). We discuss the benefits of the proposed scheme including opportunistic access of TV bands, extended coverage, ease of upgradability, self-healing and fault-tolerant design. The proposed scheme can work as a secondary radio particularly in urban areas and as a backup in disaster management. In rural areas, however, a stand-alone radio based on IEEE 802.22 can effectively provide broadband access because of the wide area coverage due to the good propagation characteristics of TV bands.

Distributed space-time block coding

In this paper, a new class of distributed space-time block codes (DSTBCs) is introduced. These DSTBCs are designed for wireless networks which have a large set of single-antenna relay nodes Nscr, but at any given time only a small, a priori unknown subset of nodes SsubeNscr can be active. In the proposed scheme, the signal transmitted by an active relay node is the product of an information-carrying code matrix and a unique node signature vector of length Nc. It is shown that existing STBCs designed for Nc2 co-located antennas are favorable choices for the code matrix, guaranteeing a diversity order of d=min{NS,Nc} if NS nodes are active. For the most interesting case, NSgesNc, the performance loss entailed by the distributed implementation is analytically characterized. Furthermore, efficient methods for the optimization of the set of signature vectors are provided. Depending on the chosen design, the proposed DSTBCs allow for low-complexity coherent, differential, and noncoherent detection, respectively. Possible applications include ad hoc and sensor networks employing decode-and-forward relaying

Data-aided and blind stochastic gradient algorithms for widely linear MMSE MAI suppression for DS-CDMA

In this paper, three novel stochastic gradient algorithms for adjustment of the widely linear (WL) minimum mean-squared error (MMSE) filter for multiple access interference (MAI) suppression for direct-sequence code-division multiple access (DS-CDMA) are introduced and analyzed. In particular, we derive a data-aided WL least-mean-square (LMS) algorithm, a blind WL minimum-output-energy (MOE) algorithm, and a WL blind LMS (BLMS) algorithm. We give analytical expressions for the steady-state signal-to-interference-plus-noise ratios (SINRs) of the proposed WL algorithms, and we also investigate their speed of convergence. Wherever possible, comparisons with the corresponding linear adaptive algorithms are made. Both analytical considerations and simulations show, in good agreement, the superiority of the novel WL adaptive algorithms. Nevertheless, all proposed WL algorithms require a slightly lower computational complexity than their linear counterparts.

Location Assisted Routing Techniques for Power Line Communication in Smart Grids

Smart Grid collectively refers to various visions of how energy generation, distribution, and consumption should be managed to overcome many of the shortcomings of todays electricity grids and to sustain our ever more electricity dependent societies. One important enabling component of Smart Grid will be a fine-grained and reliable communications infrastructure that links together the many elements of the grid. Since by definition all these elements are connected to power lines, power line communications (PLC) technology is a natural candidate to build parts of such an infrastructure. In this paper, we consider the use of PLC in low- and medium-voltage distribution grids to connect network nodes (e.g., meters, actuators, sensors) through multihop transmission. In particular, we address the problem of routing of unicast messages making use of the stationarity of nodes. To this end, we motivate and investigate the application of geographic routing protocols and gauge their performance with respect to energy consumption and transmission delay.

Distributed space-time coding for multihop transmission in power line communication networks

In this paper, we consider transmission in relatively wide-stretched power line communication (PLC) networks, where repeaters are required to bridge the source-to-destination distance. In particular, it is assumed that each network node is a potential repeater and that multihop transmission is accomplished in an ad hoc fashion without the need for complex routing protocols. In such a scenario, due to the broadcasting nature of the power line channel, multiple repeater nodes may receive and retransmit the source message simultaneously. It is shown that, if no further signal processing is applied at the transmitter, simultaneous retransmission often deteriorates performance compared with single-node retransmission. We therefore advocate the application of distributed space-time block codes (DSTBCs) to the problem at hand. More specifically, we propose that each network node is assigned a unique signature sequence, which allows efficient combining at the receiver. Most notably, DSTBC-based retransmission does not require explicit collaboration among network nodes for multihop transmission and detection complexity is not increased compared with single-node retransmission. Numerical results for multihop transmission over PLC networks show that DSTBC-based retransmission achieves a considerably improved performance in terms of required transmit power and multihop delay compared with alternative retransmission strategies.