ZHONE VDSL2 TECHNOLOGY Access Technology for the Future November 2009 CONTENTS Introduction 2 VDSL2 technology 2 VDSL2 Deployments: Zhone findings 4 Zhone s VDSL2 solutions 6 Conclusion 8 Access for a converging world. 2009 Zhone Technologies, Inc., all rights reserved.
INTRODUCTION Since the beginning of the 21 st century, access technologies have rapidly evolved to meet consumer demands. Whereas ADSL (Asymmetric Digital Subscriber Line) evolved and flourished to connect us to the Internet, VDSL2 (Very High Speed Digital Subscriber Line Version 2) emerged to enable us to take advantage of the age of video communication. Spurred by the YouTube generation, video has become the primary traffic element on the Internet and is currently projected to account for 50% of all internet traffic by 2012. Enabling the offering of robust triple play services, VDSL2 allows service providers to extend triple play services with the bandwidth requirements of new services. The average bandwidth requirements for a home are evolving as different tiers of video services become available. Although bandwidth requirements will vary based on the service configuration of each customer, the trend is moving towards high bandwidth homes capable of supporting the latest and greatest video services. Bandwidth requirements for key services include: Service High Definition TV Video on Demand Standard Definition TV Online gaming Web browsing Bandwidth requirements 15 Mbps 4-10 Mbps 2 Mbps 2 Mbps 1 Mbps Today, average bandwidth requirements are projected at 25 Mbps per residential subscriber, assuming a single HD TV in the household. As new services emerge and multiple high bandwidth devices penetrate households, these bandwidth requirements will increase, and thus deploying technology capable of higher bandwidth capabilities is the appropriate long term strategy for service providers. VDSL2 TECHNOLOGY VDSL2 functions over copper wires in much the same way that ADSL2+ functions, although there are some key distinctions. As the most widely deployed access technology to provide high speed data from the central office, ADSL2+ utilizes 12Mhz of bandwidth and is limited to speeds of approximately 28 Mbps and 2.2 Mbps, downstream and upstream, respectively. In contrast, VDSL2 utilizes up to 30 Mhz of bandwidth to provide speeds of 100 Mbps both downstream and upstream within 1000 ft. Data rates in excess of 25 Mbps are available for distances up to 4000 ft. ZHONE VDSL2 WHITEPAPER OCT 2002
In spite of the distance constraints imposed by VDSL2, there is a notable exception. As telephone companies replace many of their main feeds with fiber (fiber to the curb or fiber to the neighborhood for example), this presents an opportunity for an additional application of VDSL2. By placing a VDSL2 transceiver in the home and a VDSL2 DSLAM in a cabinet, the distance constraints that VDSL2 faces past 1000 ft can be overcome by leveraging fiber. The VDSL2 DSLAM addresses the analog to digital to analog conversion problem that disables ADSL over fiber, and will convert the data received transmitting it over the fiber back to the CO where it is routed to its final destination. In effect, VDSL2 is a great fit for service providers deploying fiber strategies across their networks given its ease to connect to these new, fiber networks. Standardized as ITU G.993.2, VDSL2 is an enhancement to G.993.1 (VDSL). Whereas first generation VDSL supported DMT (Discrete Multi-Tone modulation) in the main body and QAM (Quadrature amplitude modulation) in a normative annex, VDSL2 was only specified to support DMT modulation. Because of the underlying DMT modulation code is the same as ADSL and ADSL2+, VDSL2 is fully compatible with existing services and enables backward-interoperability with ADSL. DMT divides signals into 247 individual channels, each 4 Khz wide, which can be thought of as 247 modems connected to a home computer at once. The system constantly shifts signals searching for the best channel - each of the 247 channels is monitored and if the quality is not optimal, the signal will shift to an alternate channel. Monitoring and maintaining all 247 channels, makes DMT a very complex technology to implement; however, because of the large number of channels, there is a guarantee that the service level will maintained as the signal has ample channels to utilize to maintain its service quality. ZHONE VDSL2 WHITEPAPER OCT 2003
Leveraging existing copper infrastructure utilized to provide POTS and ADSL/ADSL2+ service, VDSL2 can deliver up to 15% improvement over ADSL2+ by avoiding ATM cell overhead. Using ADSL2+ based services requires provisioning ATM based bridges for those ports since ADSL2+ standard uses ATM as its underlying protocol while VDSL2 employs EFM. The table below highlights the various profiles available for VDSL2 today, as well as their relevance by region. It is expected that the next iteration of the ITU G.992.3 standard will extend the North American frequency range from 12MHz to 30 Mhz. Regional relevance North America Europe Asia Profiles 8a 8b 8c 8d 12a 12b 17a 30a Bandwidth MHz 8.5 12 17.7 30 Bandwidth KHz 4.312 4.312 4.312 4.312 4.312 4.312 4.312 8.625 Tones D/S 1971 2770 4095 2098 TX Power D/S dbm +17.5 +20.5 +11.5 +14.5 Maximum Throughput (Mbps, downstream) 50 68 100 200 VDSL2 DEPLOYMENTS: ZHONE FINDINGS Actual VDSL2 deployments may vary by customer due to the specific infrastructure and installation circumstances. For example, using outside plant wires for a deployment will provide less optimal performance than utilizing indoor plants wires, while offering the service over longer loop lengths is likely to result in the degradation of service. The VDSL2 profile type selected for the deployment is also an important variable. Lower frequency profiles have better performance metrics over longer loops than higher frequencies but at the cost of slower speeds per user. Figure 1, shows test results 1 for Zhone s VDSL2 products for frequency profiles, 8ad, 12a & b, 17a, and 30a. Profiles 8a-d maintain high data speeds over longer loops but only reach downstream data speeds as high as 80000 kbps per second. Thus, Profiles 8a-8d offer improved reliability at longer loops at the expense of reduced data rates at shorter loops, and are ideal for longer loop applications such as FTTN (Fiber to the Node) deployments. VDSL2 profiles 12a & 12b offer similar downstream performance to 8a-d, but much higher upstream capabilities. In an age where consumers are increasingly become producers of content, faster upstream capabilities will become an asset enabling a more robust access offering. Profiles 17a and 30a offer much higher downstream data rates although within much shorter distances than profiles 8 and 12. Confined by limited loop length, 30a is ideally suited for fiber to the building or fiber to the home deployments, offering data rate speeds upwards of 100000 kbps, while 17a is ideal for fiber to the curb 1 Line rates are the speed at which data bits are physically transferred over the communications medium, a more exact measurement of the true capabilities of a VDSL2 solution. ZHONE VDSL2 WHITEPAPER OCT 2004
deployments. As a lower cost option, 17a is an attractive alternative when the higher upstream rates of 30a are not required. FIGURE 1A- VDSL2 PROFILES 8A-8D: DOWNSTREAM/UPSTREAM LINE RATES 100000 80000 Kbps 60000 40000 20000 0 0 1000 2000 3000 4000 5000 6000 Distance (ft) 8a - DS Line Rate 8a - US Line Rate 8b - DS Line Rate 8b - US Line Rate 8c - DS Line Rate 8c- US Line Rate 8d - DS Line Rate 8d - US Line Rate FIGURE 1B VDSL2 PROFILES 12A-12B: DOWNSTREAM/UPSTREAM LINE RATES 100000 80000 Kbps 60000 40000 20000 0 0 1000 2000 3000 4000 5000 6000 Distance (ft) 12a - DS Line Rate 12b - DS Line Rate 12a - US Line Rate 12b - US Line Rate ZHONE VDSL2 WHITEPAPER OCT 2005
FIGURE 1C VDSL2 PROFILE 17A: DOWNSTREAM/UPSTREAM LINE RATES 140000 120000 100000 Kbps 80000 60000 40000 20000 0 0 1000 2000 3000 4000 5000 6000 Distance (ft) DS Line Rate US Line Rate FIGURE 1D VDSL2 PROFILE 30A DOWNSTREAM/UPSTREAM LINE RATES 140000 120000 100000 Kbps 80000 60000 40000 20000 0 0 1000 2000 3000 4000 5000 6000 Distance (ft) DS Line Rate US Line Rate ZHONE S VDSL2 SOLUTIONS Zhone's VDSL2 solution offers full-rate VDSL and VDSL2 performance for packetbased service delivery. This low-power, fully programmable, high performance solution enables service providers to cost-effectively generate additional revenue through their triple-play offering, including the different iterations of video services ZHONE VDSL2 WHITEPAPER OCT 2006
emerging in the marketplace. As an end-to-end solution, Zhone offers VDSL2 CPE and CO products to offer high-speed, long reach and low cost solutions for multitenant and multi-dwelling unit (MxU), remote terminal and CO deployments. Zhone s Bitstorm-HP VDSL2 solutions are offered as either a 1U fully-integrated model, ideal for deployment in space constrained indoor MDU or external cabinet applications, or as a hardened, weather-proof, outside model for easy installation in any location. A High Performance, 24 port VDSL2 Symmetrical 100Mbps Up/Down IP-DSLAM, the Bitstorm is designed with efficient power and space considerations. Zhone s Bitstorm-HP fully interoperates with Zhone s VDSL2 CPE 6652-A2 (30a, Bridge/Router). Bitstorm-HP IP-DSLAMs also feature ADSL2+ fallback when connecting to an ADSL2+ CPE providing easy migration for users running legacy services while providing expanded revenue opportunities for operator's deploying new high-speed services. Bitstorm-HP delivers line-rate performance and supports multi-play services implemented on a powerful Network Processor. Bitstorm-HP-160 is architected with distinct control and data paths which allow high bit-rate services while supporting advanced L2/L3 features such as - DHCP (Option-82), IGMP Snooping/Proxy, IP/ARP Spoofing, Forced MAC Forwarding, QoS and Security/Filtering in either Bridged or, VLAN Switched operating modes. As an ideal solution suited for deployment in Multi Dwelling Units, the Bitstorm-HP enables delivery of bandwidth intensive services such as HDTV, Video Conferencing, Interactive Gaming and symmetric business E-Line services. ZHONE VDSL2 WHITEPAPER OCT 2007
CONCLUSION The potential bandwidth demands that we can expect to see from the average household are challenging service providers to start building futuristic networks that can fully support existing services and new ones to come. Although higher bandwidth demands are likely, exact needs are undetermined and thus deployment of flexible, robust access technologies is essential for service providers to who wish to maintain a competitive advantage. Fully interoperable with legacy technologies like ADSL, ADSL2+ and VDSL, VDSL2 is a safe, reliable solution for service providers offering the security of easy integration with the existing network, as well as complete functionality with key network enhancements like the addition of fiber. ZHONE VDSL2 WHITEPAPER OCT 2008
About Zhone Zhone Technologies, Inc. (NASDAQ: ZHNE) is a global leader in multi-service access solutions, supporting more than 700 of the world's most innovative network operators. The company offers the industry's only fully-integrated portfolio of MSAP, FTTx, EFM and Wi-Fi access technologies, improving network agility and reducing the costs of delivering the full spectrum of access services, including residential and business broadband, VoIP, and High-Definition IPTV over copper, fiber, and wireless. Zhone is headquartered in California, and its MSAP products are all manufactured in the USA, in a facility that is emission, waste-water, and CFC free. ZHONE VDSL2 WHITEPAPER OCT 2009