Plug-and-play, the HomePlug way: Q&A with Rob Ranck, President, HomePlug Powerline Alliance
Wireless is all the rage in consumer devices, but there’s something to be said about the reliability and performance of a wired network. Rob discusses the capabilities and advantages of HomePlug’s interoperable technologies and previews upcoming standards that promise to further improve home networking.
IES: What is the current state of HomePlug technology, and are the networks compatible with today’s HDTV requirements?
RANCK: HomePlug technology continues to evolve rapidly as the demands of home networking and the smart grid keep growing. Just in the past few months we’ve announced support for the IEEE P1905.1 convergent digital home network standard, launched the Smart Energy Profile 2.0 Certification program along with Wi-Fi Alliance and ZigBee Alliance, and held educational meetings in Asia. In addition, the five major German auto manufacturers – Audi, BMW, Daimler, Porsche, and Volkswagen – announced their backing of the HomePlug Green PHY (GP) standard for electric charging stations.
Today HomePlug devices account for more than 90 percent of the world’s broadband-speed power line communications market. The HomePlug standards family includes HomePlug AV for broadband applications such as HD video streams, HomePlug GP for smart grid applications, and soon HomePlug AV2, the next-generation Gigabit-class broadband standard – all fully interoperable with each other and the IEEE 1901 power line standard.
Regarding HDTV support, HomePlug AV enables a broadband-strength network connection via electrical wiring for high-demand applications such as streaming movies or online gaming. Since the introduction of the HomePlug AV standard back in 2006, its purpose has been to provide high-quality, multistream, entertainment-oriented networking over existing AC wiring within the home. HomePlug AV employs advanced PHY and Medium Access Control (MAC) technologies that provide a 200 Mbps class power line network for video, audio, and data.
The MAC layer is designed to be highly efficient, supporting both Time Division Multiple Access (TDMA) and Collision Sense Multiple Access (CSMA)-based access with AC line cycle synchronization. The TDMA provides quality of service assurances including guaranteed bandwidth reservation, high reliability, and tight latency and jitter control. The CSMA provides four priority levels. AC line cycle synchronization provides superior channel adaptation in the face of common line cycle synchronized noise. The central coordinator controls network activities, allocating time for CSMA use and scheduling TDMA use.
HomePlug PAV aims to be the network of choice for distributing data and multistream entertainment, including HDTV, SDTV, and audiophile-quality audio throughout the home. It’s designed to provide the best connectivity at the highest quality of service of the home networking technologies competing for these applications. HomePlug AV enables all devices with a power plug to have broadband-strength network connections.
IES: How do the latest HomePlug technologies deal with former complaints such as whole home coverage, node cost, phase coupling, and neighborhood bandwidth sharing?
RANCK: The main challenges of using power outlets to connect devices in the home include a lack of industry specifications, multiple sources of electric noise, and difficulty passing through phases in the home. HomePlug technology has overcome these challenges by creating specifications with advanced, optimized algorithms that are realized in semiconductor technology. HomePlug AV addresses these shortcomings – and stay tuned for the HomePlug AV2 standard currently in development.
The reliability of a wired connection for high-speed connections has always been an advantage of HomePlug power line networking, and HomePlug AV and HomePlug AV2 include improvements to achieve nearly 100 percent coverage. Everyone enjoys the mobility of a wireless connection, but when a consumer is running a demanding application such as streaming video or online gaming, the wireless signal often isn’t strong enough. Appliances such as HDTVs, computers, or gaming consoles are most often stationary in the home, so HomePlug provides a perfect solution to deliver a broadband-strength network to these always-plugged-in devices simply via a nearby electrical outlet.
The cost of HomePlug products has been declining rapidly during the past few years. Multiple chip vendors are competing aggressively with interoperable products, and the standardization of HomePlug AV as IEEE 1901 has attracted large global players such as Broadcom, Qualcomm, and STMicroelectronics to the HomePlug market.
Since it was first introduced in 2001, HomePlug technology has delivered true plug-and-play throughout the home (see Figure 1). HomePlug can easily span multiple electrical circuits in a home, so it doesn’t need any special phase coupling that older, low-speed control technologies such as X-10 required. By using much higher frequencies and bandwidth, HomePlug completely avoids neighborhood interference in single-family homes. For applications in multidwelling units such as apartments and condos, HomePlug includes features for isolating and optimizing neighbor networks’ performance.
IES: What security provisions are included in HomePlug protocols to prevent unauthorized access?
RANCK: Mission control procedures ensure that only permitted devices are allowed into the HomePlug AV Logical Network (AVLN). A station’s ability to maintain multiple security keys allows it to participate in multiple AVLNs. All data traffic and nearly all control traffic within the AVLN – the exception being an extremely limited set of control messages that simply cannot be encrypted – is secured by 128-bit Advanced Encryption Standard (AES), providing a high level of security. The encryption uses the Network Encryption Key (NEK) and is performed on individual segments as the MAC protocol data units are created. The NEK can be changed automatically and dynamically.
To join an AVLN, a station must maintain a Network Membership Key (NMK). If it already possesses an NMK, it can join the network immediately; otherwise, it must be provided with the NMK. This provisioning can occur in a variety of ways, including:
- Using the default NMK that is programmed into all AV stations. While this default NMK provides a seamless plug-and-play experience when the equipment is initially installed, it does not provide any privacy because it is known by every HPAV-certified station.
- The user can define and enter a Network Password (NPW) directly into a new station. This NPW is hashed to create an NMK, a 128-bit encryption key. The user must enter an NPW on at least one station to initially define the NMK for the HVLN.
- All AV stations are programmed with a unique Device Access Key (DAK). The user can enter this key into any suitably programmed station already in the AVLN, and that station will use the DAK to encrypt the NMK and broadcast it. Since only the new station has the DAK, it will be the only station capable of decrypting the broadcast message, so it and only it will receive the new NMK.
- Using asymmetric public/private key encryption, the AV stations give the user the ability to join the new station to the AVLN without needing to remember or enter passwords. This may be as simple as having the user press a button or make a menu selection on the new station and on a station already in the AVLN.
When a station has the correct NMK and joins the AVLN, it will be given the current NEK, which is used to encrypt data during segmentation in the MAC. The design also allows encryption key management by higher-layer security and authentication standards such as 802.1x and Extensible Authentication Protocol (EAP).
IES: How does HomePlug technology mesh with smart grid communications protocols?
RANCK: The HomePlug GP specification is a new power line technology designed to the specific requirements of smart grid applications while interoperating with HomePlug AV products and the IEEE 1901 standard. It was developed in cooperation with major utilities in an effort to dramatically reduce power consumption and cost.
HomePlug GP targets smart grid applications such as HVAC/thermostats, smart meters, home appliances, and plug-in electric hybrid vehicles. HomePlug GP is a trimmed-down, lower-data-rate, lower-power (an estimated 75 percent) version of HomePlug AV, making it easier for multiple silicon suppliers to produce Green PHY chips with relative ease and speed. HomePlug GP was developed as a certification profile of the IEEE 1901 standard, meaning it is fully interoperable with HomePlug AV and IEEE 1901 products.
HomePlug is also supporting a new, upcoming standard for power line communications called IEEE P1901.2. This standard will be ideal for smart grid applications that are outside the home such as meter-to-grid solutions.
IES: What features and bandwidths are planned for the future?
RANCK: The next big step is the release of HomePlug AV2. It represents the next generation of technology from the HomePlug Powerline Alliance, delivering Gigabit-class broadband speeds anywhere in the house. That’s a projected increase of 2x to 5x over HomePlug AV (greater than 1 Gbps-class PHY rate).
You’re also going to see more work supporting the hybrid network – a combination of power line and wireless – which is really what the consumer wants. We all enjoy the great mobility of wireless but sometimes need the rock-solid performance of a wired network. As I said earlier, we recently announced our support of the IEEE P1905.1 working group’s efforts to define the first standard for hybrid home networks. This includes combinations of stationary home networking devices such as set-top boxes, home gateways, Blu-Ray players and televisions, and mobile devices like laptops, tablets, and cell phones. Also, stay tuned for more support of growing smart grid standards such as Smart Energy Profile 2.
It’s an exciting time. Across the globe, companies and consumers are showing a lot of interest in adopting HomePlug standards to deliver ever-increasing network capabilities and interoperability.
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