Larry Yonge

An overview of the upcoming HomePlug AV standard

In 2000, the HomePlug organization has developed the HomePlug 1.0 standard which became the basis for the worlds most widely deployed power line communication system. Now the organization is undertaking the task of developing the specifications for a second generation technology, HomePlug AV, which will be geared towards the distribution of voice, video, and data throughout the home, once again over the power line medium. This specification is targeted for release in the second quarter of 2005. In this paper, we give an introduction to some of the basic elements of the MAC and PHY layer of the HomePlug AV specification. We describe how some of the system level choices are influenced by either the characteristics of the power line channel, by the regulatory environment, by application requirements, or by implementation constraints. Finally, we discuss the performance of the proposed system measured with prototypes of the proposed system in typical North American homes.

Power line local area networking

he use of ubiquitous electrical wiring as a potential medium for communication signals has been suggested over past generations. Indeed, for some decades now, power line wires have been used for low-speed data communication, culminating in such standards and products as LonWorks, CEBus, and X-10, as well as many proprietary systems for the transmission of control and management signals. However, the power line has largely been dismissed as being too noisy and unpredictable to be useful as a practical high-speed communication channel. On the other hand, recent advances in communicat ion and modulation methodologies, as well as in adaptive digital signal processing and error detection and correction, have opened the way for the development of effective medium access control and physical layer protocols that support power line communications (PLC) networks operating at speeds comparable to those obtained from specially wired and more recent wireless local area networks. In mid-2001, an industrial standards organization called the HomePlug Powerline Alliance, originally founded by 13 companies including Cisco, Motorola, Intel, Panasonic, and Texas Instruments, announced the completion of the HomePlug 1.0 specification for a 10 Mbis class in-home power line networking technology based on orthogonal frequency-division multiplexing (OFDM). Products based on this industry standard are enjoying much positive attention in the market press from industry and product analysts based on performance and ease of use. It was clear at the January 2003 Consumer Electronics Show that HornePlug is now recognized as one of three attractive in-borne networking solutions, together with Ethernet and Wi-Fi (IEEE 802.11~). The HomePlug Powerline Alliance recently announced an effort to establish a 100 Mbis class in-home power line networking standard, called HomePlug AV, to provide distribution of data and multistream video and audio, including high-definition television (HDTV) throughout the home. Measurements and analysis of in-home power line channel capacity demonstrate that this goal is fe.asible. This new technology will be well positioned to revolutionize in-home entertainment networking by providing a simple, reliable, and cost-effective solution for consumer products such as personal video recorders, media centers, and flat panel televisions. In addition to developments associated with in-building PLC LANs, progress has also been made in the use of the powerline as an alternative to DSL and cable modems for broadband Internet access. The purpose of this feature topic in IEEE Communications Magazine is to highlight and document the significant progress in high-speed digital communication over power lines that is precipitating a new genre of wired local area and access networks requiring no new or specialized wiring. There are five articles in this series of articles. The article “Power Line Communications: State of the Art and Future Trends” by Niovi Pavlidou, Han Vink, Javad Yazdan, and Bahram Honary gives an overview on the history of PLC as well as a description of ongoing research, applications, regulatory activities, market perspectives, and

Protecting domestic power-line communications

In this paper we describe the protection goals and mechanisms in HomePlug AV, a next-generation power-line communications standard. This is a fascinating case-history in security usability. There are also novel protocol issues; interactions with mechanisms at other layers; and opportunities for both researchers and third-party vendors to build on the mechanisms provided. The central problem -- being sure whether a device being enrolled in the network is the device you think, not a similar one nearby -- is not well solved by conventional mechanisms such as public-key infrastructures, but appears to require either very old-fashioned or very novel approaches.

Joint optimization of transmit pulse shaping, guard interval length, and receiver side narrow-band interference mitigation in the HomePlugAV OFDM system

The primary subject of this paper is the selection of a pulse-shaping waveform for in-home power line communications. As system performance is also determined by other parameters affecting the length and shaping of the OFDM symbol, the problem formulation is expanded to also include the simultaneous selection of guard interval length and Hanning window length, creating a joint optimization problem. Given the constraints of allowing no transmit notch filters, and adequate receive side mitigation of narrow band jammers, we jointly optimize the selection of guard interval length, transmit pulse-shaping and receive side windowing for throughput performance on the average power line channel. Throughput performance is inferred from SNR data and associated guard interval overhead. We also present results of performance assessment and parameter selection, for the average power line channel, based on a collection of 120 measured power line channel impulse responses.

HomePlug AV Security Mechanisms

This paper describes the security mechanisms provided in the HomePlug AV specification. It highlights the AV approach for solutions to problems in detection of other nodes with which to form a network, efficient transmission of the initialization vector (IV), reducing risks of key and IV reuse, and implementing push-button security for casual users. A novel key agreement protocol based on channel adapted powerline communications is described and analyzed. It also describes mechanisms to allow extensibility for higher layer key distribution protocols.

Field performance comparison of IEEE 802.11b and HomePlug 1.0

The HomePlug 1.0 standard allows high-speed communication on low-voltage power lines without a requirement for new wires. Effective use of the power line bandwidth requires a robust medium access control (MAC) protocol to mitigate the harsh conditions of the power line channel as well as the capability to support prioritized multimedia traffic. This paper briefly describes the HomePlug 1.0 MAC and PHY protocols, which allow prioritized channel access. It then presents field test results comparing this with the more familiar IEEE 802.11b protocol.

Efficient framing and ARQ for high-speed PLC systems

In powerline communications (PLC) more so than in many other media, there is a strong interaction between the medium access control (MAC) layer and the physical (PHY) layer. This paper investigates one of the manifestations of this interaction, that of MAC framing and error recovery with PHY transmission characteristics. MAC framing for high-speed PLC systems should be capable of concatenating multiple MAC service data units (MSDUs, e.g., Ethernet or IP packets) in order to amortize the high and fixed overheads associated with each MAC protocol data unit (MPDU). By itself, this is easy. However, transmission errors may damage portions of an MPDU, which can further rob a system of efficiency. This paper presents a 2-level MAC framing mechanism that enables efficient retransmission of corrupted data. Both analytical and simulation results are used to compare the performance of the proposed MAC framing scheme with other existing viable approaches. The results show that the proposed scheme is significantly superior to existing approaches. A slightly modified version of this 2-level framing mechanism provided in this paper was used in the new generation 200 Mbps class homeplug standard, homeplug A V.

Signal processing challenges in the design of the HomePlug AV powerline standard to ensure co-existence with Homeplug 1.0.1

The HomePlug 1.0.1 standard was released in 2000 by the HomePlug Powerline Alliance and is now in use worldwide in powerline communication products for in-home LANs and for broadband powerline (BPL) Internet access, providing typical aggregate TCP throughput of 5-7 Mbps. The HomePlug AV standard, expected to be released in mid 2005, will provide a tenfold improvement in average throughput over 1.0.1. While AV is optimized for multimedia audio-visual (AV) communication, it is important that AV devices coexist with those of 1.0.1. To achieve this, the preamble which begins all AV packets should be robustly detectable by both AV and 1.0.1 nodes. AV devices must also be capable of transmitting 1.0.1 compatible priority and control waveforms, which conform to each regions spectral mask. This paper describes the hurdles that needed to be scaled to generate the compliant waveforms for coexistence, using the AV structures.