HPNA 2.0 10Mbps Home Phoneline Networking Edward H. Frank and Jack Holloway Broadcom Corporation almost certainly the explosion of the Abstract Internet. In 1995 there were 20 million users on the Internet, by 1998 there were Computers are now in more than 50% of 160 million. It is estimated that by 2003 American homes, and about 20 million there will be 500 million users of these homes have at least two worldwide, and over 14 countries will computers. The multiple PC home, have more than 40% of their population together with the anticipated growth of on-line – countries that represent more Internet appliances, has created the need than half of the world’s GDP. Internet- for a low-cost high-performance home based commerce has grown from networking technology. One approach essentially zero in 1995, to $50B in uses the same pair of wires as the 1998 and is projected to grow to existing analog telephone service $1300B by 2003. There is an (POTS). Standardized under the unprecedented level of investment in auspices of the Home Phoneline Internet-related business ventures – a Networking Association (HPNA), this direct consequence of the appreciation technology is already in its second that the “new world order”, built on a generation, operating at speeds up to 16 wired information network, will Mbps. Phoneline networking, unlike profoundly effect the way we work and traditional Ethernet, must work robustly live. over a widely disparate range of transmission channels that have What is less well appreciated is that the significant dynamic impairments. electronic dendrites of this network will extend beyond the PC to every electronic 1. Introduction device within the home – connecting literally billions of devices (See Figure We live in an age of ever-accelerating 1). technological change. The signal event at the end of the Second Millenium was Satellite and Broadband anytime, anywhere Wireless Service connects every type of device Kid’s Master Bedroom Study Bedroom IPIP TelephoneTelephone Web Browser Cable Web Browser IPIP MPEGMPEG VideoVideo Broadband Service Provider Broadband Access Access Broadband Gateway Local Telephone Provider Terrestrial Living Digital Broadcast Room Kitchen Digital Set-top Box Garage IPIP TelephoneTelephone IntegratedIntegrated WebWeb BrowserBrowser Standard IPIP VideoVideo PhonePhone IPIP VideoVideo PhonePhone Telephone Figure 1: Connectivity in a networked home. Traditional consumer electronics – that entertain, inform, educate, connect television, stereo audio, telephones -- are and increase convenience and choice. already in the process of being redefined To initiate rapid market adoption, these to use digital technology. In the new devices will need to plug-in as simply as era, these devices will be designed with a telephone, with “no new wires”. “the Network” built-in as a standard In the home, there are basically three component, mirroring the absorption of existing wiring infrastructures that can the embedded microprocessor that be exploited: phone wiring, wireless and occurred in the previous era. Network- AC power wiring. It appears that all connected devices will be smarter, easier three will be used, with phoneline to use, easier to maintain. The very networks deployed first. nature of television, radio and the In 1998 the computer and telephone will be transformed. semiconductor industries created an If every consumer electronic product Alliance to select, promote and will have an “Internet Inside” sticker, standardize technologies for Home what connector will be used? How Phoneline Networking (see HPNA 2.0 quickly will network-enabled products system [1] and be adopted if consumers have to install http://www.homepna.org). This group network wiring and learn how to setup has introduced a first generation 1 Mbps and administer a network? Will the technology (based on a system home have to be “network-enabled” developed by Tut Systems), and a before these products can be used? The second generation 10 Mbps technology hard reality is that consumers don’t want based on a proposal from Epigram, Inc. to buy networks – but will be motivated (now part of Broadcom Corporation). to buy smart network-connected devices Home Phoneline Networking is well suited for the interconnection of telephony and other voice broadband voice, video and data within applications; implement the home. Industry reports estimate guaranteed bandwidth for shipments of 1 million HPNA streaming audio and video compatible interfaces by the end of applications. 1999, and somewhere between 5-10 4. Be very robust and provide million interfaces by the end of 2000. connectivity in essentially Networking over the existing home every home. phoneline infrastructure suffers from 5. Support data rates in excess many impairments (as do all no-new- 10BASE-T Ethernet, and wires physical media), namely high scale to 100 Mbps in a way attenuation, reflections, impulse noise, that remains compatible with crosstalk and RFI ingress/egress. These installed earlier generations. challenges must be overcome by a successful technology. 6. Provide reasonable privacy at the physical layer. (Wireless and powerline require some level of encryption to achieve 2. Requirements for Home wired equivalent privacy.) Networking 7. Be future safe, employing It is our belief that for a home designs that are scalable and networking technology to be successful, extensible so that users do it must properly address the following not have to do “fork-lift” major issues: replacements when 1. Leverage existing wiring upgrading their networks in infrastructure and be easy to the future. install. 8. Be implementable with 2. Leverage existing standards sufficiently low cost to allow and interwork with common inclusion as standard in a operating systems and wide variety of products. software platforms. Table 1 summarizes how well the 3. Implement a quality of principal choices for home networking service (QOS) mechanism technology meet these criteria. that provides low latency for Parameter HPNA 2.0 Wireless Powerwire Ethernet (Cat 5) 1. Leverage existing Good Good Good Poor infrastructure 2. Leverage Standards Good Medium Poor Excellent (802.3 (too many (no standards) compatible) standards1) 3. QOS Support Good Good to Poor Unknown Medium (some (Simple hubs don’t standards support QoS. More have no QoS expensive switches provision) may.) 4. Robustness Good Medium Unknown Good (Highly impaired channel) 5. Performance >10 Mbps, 1 to 11 Mbps Unknown 10, 100, 1000 Mbps 100 Mbps (Highly Up to 50 next variable Mbps at 5 generation channel GHz capacity) 6. Privacy of Physical Good Poor Poor Good Medium 7. Future-safe Good Poor Unknown Good (too many standards, potential for interference) 8. Cost Good Medium Unknown Medium (RF circuitry (but should be (low hardware cost, is harder to comparable to but higher cost if one integrate) HPNA) considers installation of new wiring) Table 1: Comparison of networking technologies. 1 Several competing systems are under development and proposed for the unlicensed 2.4 GHz band (Bluetooth, HomeRF, 802.11b). The 2.4 GHz band has multiple sources of interference such as DECT phones and microwave ovens. The 5 GHz NII spectrum may also be used for home networking, using 802.11a or some other standard. Other standards and frequencies are proposed for systems to be used in Europe and Japan. Existing InsideLine™ iLine10 Premises Phone Wire MAC Ethernet CSMA/CD with QoS iLine10 QAM modulation PHY 4 - 256 QAM 2 - 25 Mbaud 2 - 25 Mbaud iLine10 iLine10 Down- POTS POTS Upstream stream 4MHz 10MHz POTS xDSL HPNA 2.0 35kHz 100kHz HPNA 1.0 Figure 2: A view of the HPNA stack and spectrum 3. The HPNA 2.0 System Physical Layer Figure 2 is an illustration of the HPNA At the Physical layer, the system is 2.0 system from the point of view of frequency division multiplexed on the network stack and frequency spectrum. same wire as standard analog phone The HPNA 2.0 system is a multi-point service (POTS), as well as other CSMA/CD packet network that supports splitterless ADSL[2]. Analog telephony unicast, multicast, and broadcast. As uses the low part of the spectrum below will be discussed in this section, and 35 kHz. ADSL (both G.Lite and illustrated in Figure 7, it has the look G.Heavy) use spectrum up to 1.1 MHz. and feel of Ethernet. However, it differs HPNA selected the 4 to 10 MHz band from 10BASE-2 and 10BASE-T in a for several reasons. The lower limit of 4 number of respects. First and foremost, MHz was chosen to make it feasible to HPNA 2.0 places no restrictions on implement the filters needed to reduce wiring type, wiring topology, or out-of-band interference between HPNA termination. Moreover, like 10BASE-2, and splitterless ADSL. After modeling but unlike 10BASE-T, HPNA 2.0 uses a several thousand representative shared physical medium with no need networks with capacitive telephones and for a switch or hub. 10BASE-T on the common wire lengths, it was determined other hand requires dedicated point-to- that the spectrum above 10 MHz was point CAT-3 or CAT-5 wires. much more likely to have wider and deeper nulls caused by reflections [3]. Crosstalk between phonelines increases with frequency, and the analog front end have the problem that the is harder to implement at higher communications channel can be severely frequencies. The particular choice of 4 impaired. The nature of the impairments to 10 MHz only overlaps a single is illustrated in Figure 3 and Figure 4, Amateur Radio band (40 meters), which which shows the kind of channel simplifies ingress and egress filtering. response one might find on a typical The no-new-wires media that are phone wire loop inside of a house. available for networking within homes 150 ft. 17 ft. 96 ft. BR1 Kitchen BR3 BR2 NID 35 ft. 4 Figure 3: Topology of a simple home network Figure 4: The channel response of a simple home phonewire network.