Exploring Home Networking Options: MoCA, HomePNA, Powerline (HomePlug), Ethernet, 802.11n, and G.hn (HomeGrid)
The desire to stream or access entertainment media anywhere inside the home is driving renewed interest in a next-generation home entertainment network. Yet, this network must provide greater bandwidth to handle the requirements of high-definition video with great quality-of-service assurances so that pristine high-definition programs can be streamed around the home fast enough to avoid glitches or annoying visual artifacts.
In the next decade, consumer video electronics with embedded Internet and IP video support will be widely available. The Diffusion Group (TDG) (http://tdgresearch.com) anticipates that by 2020 there will be 3.6 billion non-portable network-enabled video nodes in homes worldwide, and over 5 billion by 2030. Furthermore, TDG expects the number of homes worldwide with broadband video service will almost triple between 2010 and 2030, from 440 million to 1.2 billion. In the same period, the number of in-home networks that are broadband enabled will increase by almost 7 times, from 150 million to over 1 billion.
With this tremendous market potential, telcos and cable/MSOs must invest in new technology to achieve operational advantages that will build customer loyalty, lower customer churn and enable new video services, including multi-room digital video recorder (MR-DVR) sharing and other multimedia sharing. To enable these new sharing services, service providers must ensure the in-home network can deliver guaranteed throughput to deliver a positive customer experience. The in-home network must be transformed to support enhanced service and meet customers’ insatiable demands for enhanced video experiences.
The Home Networking Standard Debate
As the in-home network almost directly correlates to customer experiences, service providers have evaluated a number of home networking standards to understand which platform can best share content between DVRs; stream TV shows, music, and high-definition (HD) video between rooms; connect computers in different rooms together for Internet access and file sharing; yet offer the highest levels of bandwidth capacity and reliability.
For the most part, Multimedia over Coax Alliance (MoCA) has taken a commanding lead as the technology of choice for North American service providers — whom have already leveraged the technology standard as the basis for their MR-DVR sharing and other multimedia services.
Despite, MoCA’s dominance in the home networking standard landscape, there remains confusion and interest in understanding all of the options in the market. This article provides a brief overview of each networking technology.
MoCA (www.mocalliance.org) is an association of consumer electronics retailers and manufacturers, communications services providers, silicon vendors, and test and measurement equipment vendors developing and promoting the de facto connected home entertainment standard operating over coaxial cabling. The primary goal of MoCA is to develop a high-performance, high-capacity home networking technology suitable for transporting multiple streams of HD multimedia content that leverages existing residential coaxial cabling.
In 2005, the alliance approved the MoCA 1.0 standard supporting 135 Mbps of throughput. That capacity was increased to 175 Mbps with the release of MoCA 1.1 in October 2007, and in July 2010 the alliance approved the MoCA 2.0 spec, which offers 2 new performance modes with net or actual throughputs of 400 and 800 Mbps, respectively, each with a corresponding turbo mode. MoCA 2.0 is both evolutionary and revolutionary. Like MoCA 1.1, MoCA 2.0 is backward interoperable with MoCA 1.0 to ensure preservation of operator investment in current equipment.
MoCA offers double the speed and performance over other home networking technologies. It has been widely deployed throughout North America, principally to support video-on-demand services and multi-room DVR. MoCA is already widely used in Verizon’s FiOS fiber-to-the-home deployments. It is also used by DirecTV, Comcast, Cox Communications, Time Warner Cable, as well as a series of other service providers across North America and Europe.
MoCA is not limited to uses in just single family homes. With a point-of-entry filter installed at the coax cable’s multi-taps, where the cable is split to serve the various units within an MDU, MoCA home networks can be set up within apartments or condominiums. All residents can still receive their existing television or Internet services, but now have the ability to use the coax cables in their units to connect all their computers and A/V entertainment devices onto a common high speed entertainment network.
HomePNA (www.homepna.org) is a consortium of technology organizations that developed a series of recommendations for transporting multi-play services and multimedia content over twisted pair telephone wires in consumer residences. HomePNA technology has since migrated to using coax cables just like MoCA and has been widely deployed primarily by telcos in the North American market who have leveraged the recommendation to deliver IPTV and multi-room entertainment services to consumers.
A number of the recommendations authored by the members of the HomePNA have been adopted and standardized by the ITU-T. The most recent recommendation, HomePNA 3.1 (ITU-T G.9954), specifies a home networking protocol with a physical layer that supports transmitting and receiving frames using quadrature amplitude modulation (QAM) over twisted-pair wiring or coaxial cabling. The twisted-pair physical layer specification defines 2 frequency ranges, 4–20 MHz and 12–28 MHz, with QAM constellation sizes between 2–10 bits per symbol and data rates from 4–160 Mb/s. The coaxial cabling physical layer specification, by contrast, specifies 4 frequency ranges between 4–52 MHz, QAM constellation sizes between 2–10 bits per symbol and data rates between 4–320 Mb/s. Though the HomePNA 3.1 physical layer recommendation assures interoperability with ADSL, VDSL and other services operating below 12 MHz, HomePNA 3.1 will not support sharing the cable plant with VDSL services using profiles above 12 MHz and cable television services using the 5–42 MHz and 5–65 MHz return paths.
The HomePNA 3.1 media access control (MAC) layer is based on a carrier sense multiple access with collision avoidance (CSMA/CA) architecture. A device is assigned the master role. The master node controls media access by planning device transmit times and advertising the plan to the other nodes. The nodes synchronize to the media access plan and time transmissions accordingly. The master node also has responsibility for network admission and security, which is based on shared-key encryption. Notably, the HomePNA 3.1 MAC layer also includes 2 techniques for differentiating the quality of service (QoS) offered by the network: 1 technique based on priority and another technique that allocates capacity to unidirectional flows based on a service profile.
The HomePlug Powerline Alliance (www.homeplug.org) is a trade association that has developed a series of specifications that define how residential electrical wiring may be leveraged to transport voice, video and data services between networked devices in a home. Generally, HomePlug is deployed throughout the European Union, telcos being the leading adopters. In the North American market, however, there is not yet a significant installed HomePlug base as MSOs have elected to leverage existing in-home coaxial cabling to transport multimedia content. The primary applications to date for HomePlug technologies are residential IPTV and other multimedia content. Two specifications targeting in-home networking have been released by the HomePlug Powerline Alliance.
HomePlug 1.0: HomePlug 1.0 was published June 2001 and defined a physical layer based on orthogonal frequency division multiplexing (OFDM) operating at 14 Mb/s and using the frequency band 4.5-21 MHz. Eighty-four (84) equally spaced, discrete differential binary phase-shift keying/differential quadrature phase-shift keying (DBPSK/DQPSK) modulated carriers transport the bit stream. The physical layer requires forward error correction (FEC) and interleaving. The MAC layer is based on a CSMA/CA architecture that is enhanced to accommodate the noise and interference characteristics of the media and to guarantee QoS to multimedia applications. HomePlug 1.0 uses shared-key 56-bit DES encryption for security.
HomePlug AV: Targeting the ability to transport multiple in-home multimedia streams, the HomePlug AV specification significantly increased the theoretical maximum physical layer data rate to 200 Mb/s. This was accomplished by allowing adaptive modulation (BPSK-1024 QAM) over a maximum of 1,155 OFDM subcarriers occupying the frequency range 2-28 MHz. Additional enhancements include a MAC layer based on both time division multiple access (TDMA) and CSMA/CA architectures and security based on 128-bit AES encryption and dynamic key generation and exchange.
Originally developed by Xerox Palo Alto Research Center in the late 1970s and standardized by IEEE 802.3 in the early 1980s, Ethernet has become the predominant local area networking technology for enabling data communications and recently has evolved to be the technology of choice for transporting voice, video, and data traffic over metropolitan and wide area networks. The 802.3 family of standards includes specifications for Ethernet operating at 10 Mb/s — 100 Gbps over a range of media types.
Residential networks have principally used 10/100 Ethernet over twisted pair to communicate between hosts in the home. Traditionally, residential Ethernet has supported data communications between personal computers and the Internet, though increasingly home Ethernet networks are used to deliver voice and video over IP, gaming, and other applications for the entire range of consumer electronics in the home.
The IEEE 802.11 standard provides a specification for transporting information over the unregulated 2.4 GHz and 5 GHz frequency bands. Two amendments to the 802.11 standard, 802.11b and 802.11g, have become the most commonly utilized wireless networking technologies. The 802.11b amendment uses direct sequence spread spectrum modulation at 11 Mb/s over the 2.4 GHz band with a maximum indoor range around 100 feet and a maximum outdoor range around 300 feet. 802.11g provides the same coverage, but the physical layer is enhanced to use OFDM, which increases the maximum supported rate to 54 Mb/s. Both 802.11b and 802.11g operate on 22 MHz channels and use CSMA/CA. All 802.11g capable devices are backward-compatible and interoperable with devices supporting 802.11b.
The 802.11b/g networks are deployed globally, particularly for residential networks to connect personal computers and access the Internet. The performance of 802.11b/g networks, however, is significantly degraded in areas with many base stations using the same channels, or due to interference from other equipment (e.g. cordless phones, security systems, remote sensors) operating in the 2.4 GHz band. Additionally, the actual throughput offered by 802.11b/g networks is insufficient to transport high bandwidth multimedia content. This has driven the telecommunications industry to develop new wireless local area networking technologies.
802.11n promises to significantly enhance the throughput and coverage of 802.11 wireless networks. Ratified by the IEEE during September 2009, 802.11n also operates over the 2.4 MHz and 5 MHz frequency bands and specifies maximum physical layer bit rates reaching 600 Mb/s and MAC layer throughput exceeding 100 Mb/s. Many consumer electronics manufacturers and service providers globally plan to use the data rate enhancements to transport multimedia content between residential gateways, STBs, gaming equipment, personal computers and other consumer devices connected to home networks.
A number of technical advancements in 802.11n permit improved performance. The physical layer supports Multiple Input Multiple Output (MIMO) signal processing and spatial multiplexing, which increases data rates significantly while improving signal-to-noise ratios. Additionally, the MAC layer supports frame aggregation, which allows multiple frames to be combined and transported using one data unit, thereby reducing transport header overhead. The MAC layer also includes a block acknowledgment mechanism, which increases the efficiency of the MAC layer significantly. Finally, 802.11n supports channel bonding, which allows two adjacent 20 MHz channels to be combined into a single 40 MHz channel, effectively doubling the transmission capacity.
G.hn describes the ITU-T standardization effort tasked with developing a universal next-generation home networking transceiver that operates at gigabit-per-second data rates over all three primary types of residential cable plants — electrical wiring, twisted pair, and coaxial cabling. The study group’s first recommendation, G.9660, was approved in December 2008 and specifies the G.hn physical layer and systems architecture. The full G.hn recommendation, including the G.hn MAC layer and security architecture, has reached the ITU-T baseline text stage.
The primary goal of the G.hn standard is to transport multimedia content between devices connected to the home network. Consumer electronics, including televisions, STBs, residential gateways, and personal computers have been targeted for G.hn support. Additional G.hn applications will include home automation and a range of smart grid features, including energy demand management and others. G.hn chipset availability is expected during 2011 and G.hn capable devices are projected to become available in the 2011-2012 timeframe. A number of technology organizations established the HomeGrid Forum (www.homegridforum.org) to promote G.hn standardization and encourage the industry to adopt the G.hn specifications.
Notably, the G.hn specifications do not offer backward compatibility with either MoCA or HomePlug networks. Many North American and European operators have deployed MoCA or HomePlug networks widely and do not envision migrating to G.hn without support for these existing home networking standards. The G.hn specification includes a physical layer that uses OFDM to divide traffic over multiple subcarriers using QAM. The G.hn spectrum usage depends on the physical media type.
Most home networking standards, wired and wireless, were designed with data transfer as their primary objective, and most are more than adequate for those applications. However for video delivery, and especially the delivery of HD programming, service providers must look to deliver a satisfactory video viewing experience that guarantees a high level of reliability.
Upon comparing the various home networking standards, MoCA is truly the only platform that can deliver the required performance, speed and reliability to support broadcast video services with quality, credibility, customer satisfaction, and operational efficiencies, which will ultimately deliver service provider revenue.
The goal of MoCA is to create specifications and certify products that will tap into the vast amounts of unused bandwidth available on the in-home coax without the need for new connections, wiring, point-of-entry devices, or truck rolls. The Multimedia over Coax Alliance Promoters include major players from the retail, consumer electronics, telco, satellite and cable multiple system operator (MSO) industries. For more information, visit www.mocalliance.org.