Fig 1. Designed for the G.hn home networking standard, the Marvell 88LX3142 digital baseband IC provides a data rate up to 1 Gbit/s on coax, twisted pair, or the ac power line for HDTV distribution. It comes in a 128-pin quad flat pack (QFP).
Fig 2. The Marvell G.hn chipset connects to the network device via an Ethernet connection on the left. It then provides for three interfaces to the coax, phone line, or power-line medium on the right. RAM and flash are external.
Marvell’s ITU-T G.hn-compliant transceiver chipset solves the wired home networking challenge. It accommodates all three existing home wiring network media—ac power line, telephone wiring, and cable TV coax—to reduce overall cost, design complexity, and time-to-market for system designers.
Any of these media can be used to distribute video and audio content to more consumer electronic devices throughout the home. The chipset also can provide for expanded home networks that address the coming desire for electrical appliance, home HVAC system, and security system monitoring and control as well as electric meter and Smart Grid connectivity.
Home networking has long been the dream of many communications technology companies that see the huge consumer potential of products that can connect to one another, the Internet, and other outside sources. The home networking movement has developed slowly over the past decade with a wide variety of standards and products.
Wired Versus Wireless
Today, home networking is dominated by Wi-Fi, the ubiquitous wireless local-area networking (LAN) technology now built into every laptop, tablet, smart phone, and other mobile device. Many homes now have their own Wi-Fi network so multiple computers and other devices can share an Internet connection. Even some TV sets and set-top boxes (STBs) incorporate Wi-Fi.
Wired technologies have also made progress, but the proliferation of multiple standards has slowed adoption because of the lack of interoperability between connected devices. With the introduction of the G.hn wired home networking standard, there is greater potential for more widespread adoption. G.hn is the ITU-T’s standard for wired home networking.
While Wi-Fi 802.11a/b/g/n wireless still dominates home networking installations, there is a growing consumer interest in an alternative high-speed and highly robust wired home networking technology such as G.hn.
Marvell’s G.hn chipset appears ideal for the wired distribution of bandwidth-intensive and real-time applications such as HD Internet Protocol television (IPTV), Voice over Internet Protocol (VoIP), gaming, multi-room DVR, and video surveillance. It has the potential to deliver a theoretical data rate up to 1 Gbit/s with an expected realistic data rate in the 200- to 400-Mbit/s range.
G.hn and Its Competition
The big question today is if G.hn will become the wired home networking standard of choice. The question is relevant given the many other wired networking choices available.
The Multimedia over Coax Alliance (MoCA) standard has been around for several years, and many cable companies have adopted it for STB connectivity over existing home cable TV wiring. AT&T has adopted HomePNA for video distribution over home telephone wiring. The HomePlug standard dominates ac power-line networking. Add the IEEE’s 1901 and 1905 standards, and the result is a real mix that confuses not only the consumer but also the STB industry and others seeking to cash in on home networking opportunities.
G.hn is an attempt to create one standard that can use any of the existing wired media with a consistent protocol and convention so devices using it would be interoperable despite the medium choice. The Home Grid Forum, the organization promoting and supporting G.hn adoption, has created and implemented a testing and certification program to ensure the desired interoperability of all products.
The G.hn Chipset
Marvell’s G.hn chipset comprises the 88LX3142 digital baseband processor and the 88LX2718 analog front-end (AFE) interface. The 88LX3142 includes a powerful CPU and a full set of serial interfaces, while the 88LX2718 AFE includes two fully programmable receiving and transmitting paths that enable multiple-input multiple-output (MIMO) operation. While MIMO is generally considered a wireless technology, it works well over a wired medium where multiple streams of parallel data boost the data rate while providing a more reliable connection in the presence of noise and interference.
The 88LX3142 fully complies with the ITU-T G.hn standards including G.9960/61/72 on any wireline like coax, twisted pair, or ac power line (Fig. 1). It can achieve data rates up to 1 Gbit/s and supports all the various baseband band plans with bandwidths of 25, 50, and 100 MHz. The chipset is also compatible with the G.hn low-complexity profile (LCP) for low-speed devices such as Smart Grid metering and smart appliance monitoring and control.
G.hn uses orthogonal frequency division multiplexing (OFDM), but it also includes various techniques for added reliability such as low-density parity check (LDPC) forward error correction (FEC), an automated block-level error detection and retransmission scheme, an enhanced selective repeat ARQ-based (automatic repeat request) acknowledge character (ACK) algorithm, and a special robust communications mode for high-noise environments.
In addition, the standard features automatic mesh networking that provides for relaying between nodes that cannot connect directly. Security is provided by 128-bit AES CCMP encryption, end-to-end encryption with pairwise keys, and strict authentication rules.
The 88LX3142’s full set of on-chip interfaces includes Fast Ethernet MDI, MII and RGMII, two SPI, two UART, SDIO 2.0, GPIO, DDR2, and JTAG. And, the 88LX3142 baseband device comes in a QFP128 package (Fig. 1).
The 88LX2718 is all a user needs to accommodate the signal between the 88LX3124 G.hn baseband digital processor and the coax, phoneline, or power-line line transformer. It integrates all of the circuitry—amplifiers, active filters, line drivers—required for this function (Fig. 2).
The AFE is built upon two transmission/reception paths to enable true MIMO operations. Each transmission path integrates a low-pass filter, a programmable gain amplifier, and a line driver to condition the OFDM signal provided by the 88LX3142 circuit to the coax, phone, or power-line transformer. The output of the transmission path directly drives the line transformer input through an external decoupling capacitor. The AFE comes in a QFN32 package.
The Marvell chipset is complemented by field-proven SPIRIT firmware for Universal Powerline Association (UPA) Powerline Communications (PLC) that provides full coexistence with millions of deployed legacy UPA PLC products. It has a powerful application programming interface (API) for broad customization. The software is also optimized for HD IPTV and has full TCP/IP stacks for IPv4 and IPv6. Embedded TR-069 and TR-111 with smart repeating are included as well.
G.hn is still new and in its acceptance and adoption phase. It competes with previous wired technologies like HomePlug and IEEE 1901 power-line technology, MoCA on coax, and HomePNA on twisted-pair phone lines or coax, but it can be faster than any of them. IEEE’s 1905.1 is also competitive with G.hn and is compatible with both the MoCA and HomePlug standards but does not support phone-line twisted pair.
Furthermore, G.hn provides for coexistence with the IEEE 1901 networks (G.cx). If you’re designing IPTV or over-the-top (OTT) STBs, broadband gateways and routers, and other networking equipment, the Marvel G.hn chipset is worth evaluating. It’s available in samples now with full production available in the second quarter of 2012. A reference design is also available.
A Word About G.hn
G.hn is a worldwide wired home networking standard from the International Telecommunication Union (ITU). More formally designated G.9960 and G.9961, it is a relatively new standard and not yet widely implemented (see “G.hn Standard Promises Compatibility At Home” at www.electronicdesign.com). As new transceiver chips become available, its adoption will grow.
Other home networking standards that have been around for years are better entrenched, such as the HomePlug power-line standard, the Home PNA coax and phone-line twisted-pair standard, and the Multimedia over Coax Alliance (MoCA) coax cable TV standard (see “MoCA Challenges Wireless For Home Networking Dominance” at www.electronicdesign.com). G.hn has an uphill battle to gain some acceptance in this market. However, with its flexibility and new ICs, G.hn will eventually gain some market share.
The main benefit of G.hn is its ability to address any of the three common wiring types in homes: telephone twisted pair, cable TV coax, or the ac power line. It uses a common protocol with different physical-layer (PHY) interfaces. The PHY is a generic orthogonal frequency-division multiplexer (OFDM) operating from 2 to 30 MHz, which should work over any wired medium. Also, it offers up to 250 nodes on each network. With such options, G.hn can address almost any home networking application ranging from TV transmission with rates to 1 Gbit/s to appliance and energy monitoring and control (see “HANs Promise Energy Savings For All” at www.electronicdesign.com).
Work on the G.hn standard continues at the ITU with modifications such as multiple-input multiple-output (MIMO). The G.9963 standard uses well-known wireless MIMO techniques to improve channel reliability in the presence of noise, increase range, and boost data rates. The G.9972 modification called G.cx is a feature that lets G.hn products coexist with other power-line communications standards. Watch for new G.hn products coming soon.