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RGs to overcome triple-play hurdles

Posted: 01 Mar 2007 ?? ?Print Version ?Bookmark and Share

Keywords:home network? residential gateway? triple-play challenges? overcome triple-play challenges with residential gateway? quadruple-play challenges residential gateway?

Many high-bandwidth applications that will be managed by next-generation residential gateways (RGs) argue for a high-performance home-embedded device that can handle just about anything thrown at it. However, consumers have diverse tastes and preferences, and a one-size RG does not address all consumer needs. While some may be interested in VoIP replacement for analog-phone service, other consumers want a basic home network. And still others require a gateway with local storage, where movies, music and other content can be accessed anywhere in the home via a local network or worldwide via Internet connection.

Different service providers may choose a variety of home-networking technologies to address several market segments. Yet, all service providers will want flexibility to adapt their solution to changing market needs and new product opportunities. An adaptable, reconfigurable gateway platform is needed to implement service providers' segmentation strategies.

Carriers are moving to supplement declining voice revenues by increasing revenues from their broadband infrastructure. The current broadband infrastructure is capable of delivering a variety of new differentiated services that combine data, video and voice to offer greater value to consumers. To maximize the value to the consumer, these services need to connect to various digital devices, voice and data communications platforms, and entertainment systems that are cropping up in homes.

Current DSL and cable modems provide a broadband connection designed for Internet-data delivery in the home. However, they don't address the needs of next-generation triple-play (data, phone and video) and quadruple-play (data, phone, video and wireless) services. The complexity caused by the presence of more digital devices and the increasing volume of multimedia content requires a new approach that can support many new services, offering more connectivity options and delivering higher data throughput rates. Next-generation RGs are designed to meet these needs.

New capabilities
Next-generation RGs will provide leading-edge data capabilities. They can also serve as the lynchpin of the home's voice and digital communications. Some RGs will support standard plain old telephone service replacement VoIP, but others will go further by providing a platform for fixed mobile convergence. This will enable consumers to use Wi-Fi-enabled cellphones that work like regular handsets, handling calls and Internet access over the cellular network when the consumer is outside the house. When the consumer returns home, the phones will sense and associate with the WLAN and function as cordless VoIP phones. iSuppli found out that 22 million cellphones with Wi-Fi connectivity were sold in 2006; iSuppli predicts that figure to grow to 285 million in 2010.

Many telco providers are also eyeing IPTV as a key part of their product offerings. Routing, managing and guaranteeing bandwidth for multiple IPTV streams will test the performance capabilities of next-generation RGs. These gateways will need to control multiple HDTV streams, each operating at 9Mbps or more. While earlier video codecs such as MPEG-2 have stabilized, higher-efficiency codecs such as MPEG-4 and H.264 are still undergoing refinements. Consideration must be given to the potential for changes during the development process and future upgrades.

Distributing broadcast-quality video throughout the home will require the RG to integrate multiple wired and wireless technologies, security features and QoS capabilities. RGs will need to support the latest wireless networking technologies, such as 802.11g and the emerging 802.11n, 802.11d/e and 802.11r standards. A wide range of wired home-networking technologies are being considered, so RGs should be able to support Ethernet, Multimedia of Coax Alliance (MoCA), Home Phoneline Networking Alliance (HPNA), HomePlug Powerline Alliance (HPPA) and the Universal Powerline Association standards.

Ease-of-use and reliability are critical considerations in any consumer product. The next-generation RG must be easy to set up and configure. Moreover, its operation must be relatively transparent to consumers. To enable rapid troubleshooting and quick resolution of issues, the RG should be equipped with software subsystems that enable remote management and provisioning. Even though many devices connected to the RG will not be the responsibility of the service provider, the RG should include visibility beyond the gateway box itself and, where possible, into the attached devices. This will save time by making it possible for the service provider to direct consumers to the appropriate parties for support.

IC manufacturers are responding to these needs by developing powerful platforms with the performance, flexibility and serviceability to meet these requirements. Typical feature sets include multiple processors and a rich set of LAN interfaces. Multiple processors dedicated for specific services guarantee high system performance and high QoS for end-users.

The figure shows an example of such architecture, an SoC, with integrated ADSL and VDSL2 broadband connection. Featuring a multimedia gateway processor that runs at 400MHz, it doubles the performance of the previous generation. Additional hardware accelerators and 32bit wide memory interface further increase the networking capabilities of the gateway.

The VoIP subsystem is based on a dedicated high-performance DSP that handles voice processing for up to four phone lines without any performance impact on other functions in the gateway. Each voice line can run one of many possible wireline or wireless voice codecs. This architecture is future-proofed to handle emerging technologies, such as FMC.

The Unified DSL PHY supports data rates up to 60Mbps (in VDSL2 mode), enabling delivery of multiple HDTV streams to the house. The DSL PHY also supports all the legacy ADSL modes (ADSL, ADSL2 and ADSL2+).

Broadband connection
A more robust DSL connection is required to support real-time services such as IPTV. Error-correction techniques increase latencies in the gatewayhowever, the amount of latency that different applications can tolerate varies. For example, IPTV can tolerate latency in the order of several hundred milliseconds, while gaming requires minimal delay.

One of the main sources of noise on the DSL is impulse noise, which corrupts a stream of consecutive data bytes on the DSL. The Impulse Noise Protection (INP) error correction strategy in a DSL RG involves a combination of Reed-Solomon coding with convolutional interleaving. On the transmit side, Reed-Solomon coding adds redundancy bytes to each block of data bytes, generating a Reed-Solomon codeword. Then, the Interleaver mixes consecutive data bytes in the time domain.

In the receiver, first the de-interleaver restores the correct byte order, then each Reed-Solomon codeword is decoded, with possible correction of corrupted data bytes. The result is that the number of corrupted data bytes in each Reed-Solomon codeword is reduced to within the correction capability of the Reed-Solomon codeword.

Next generation RGs will enable optional INP capability of at least 16 DMT symbols (INP = 16), which protects against impulse noise of up to four milliseconds. Yet, increasing the INP also increases the latency of the data arrival to the end-user. Next-generation platforms will offer multiple data paths in the DSL PHY. Then, one data path can be configured for maximum robustness (with INP = 16), and another data path can be configured for minimum delay (INP = 0). Then, IPTV can be processed through the robust data path (with some acceptable delay) while voice and gaming packets can be processed through the fast path (INP = 0).

By implementing two or more independent data paths in the DSL PHY, each programmable with different Reed-Solomon coding and interleaver configurations, next-generation RGs can guarantee for each type of service the right trade-off between robustness and low latency.

The PSTN has built-in mechanisms for assuring low end-to-end delay and robustness. It also includes a set of tools that enable the service provider to monitor the network and to test every single telephone line. When the customer calls the customer-support desk, the customer-support technician can test the line that is connected to the specific customer in real-time. These tools enable the service providers to identify early problems in the PSTN network, proactively solve problems detected, increase customer satisfaction, reduce customer churn and drastically reduce the need in expensive truck rolls.

These mechanisms do not exist in the Internet or the current IP networks, presenting new challenges to service providers to offer and scale high-quality VoIP service. Next-generation RGs need to integrate tools that will solve this problem in IP networks.

Next-generation RGs need to integrate tools that will solve this problem in IP networks. Today, companies are working with service providers, third parties and other vendors to generate an echo system that will give the end-user a better voice experience than the current PSTN network, while reducing operators' operating and capital expenses. VoIP products (both for the infrastructure and for customer premise equipment) will integrate quality management tools designed to help debug and manage the IP network. These quality management tools enable the discovery, monitoring and repair of services, devices and networks, allowing service providers to proactively manage factors like echo, dropped-packets and line-delay. By sending messages every second to the network manager with information about the quality of the connection from the RG, real-time calculations instantly assess quality parameters related to the user's experience, allowing the service provider to adapt to changing conditions and make real-time adjustments in the IP network.

Integrated voice
Next-generation RGs will include support for up to four voice lines with three-way conferencing. DSP-based implementation provides improved voice-processing performance relative to a GPP core, which requires 2x to 3x as many cycles as a DSP. A high-performance programmable voice subsystem makes it possible to support various low-bit-rate codecs, wireless codecs, wideband codecs and advanced features, such as fax and modem relay, packet-loss minimization and noise-reduction algorithms.

FMC solutions available today enable wireline carriers to recapture lost revenue and subscribers by extending mobility into the enterprise while keeping wireless minutes on the wireline network. These solutions use dual-mode handsets to seamlessly roam between Wi-Fi and cellular networks, and provide users with only one set of telephony features, phone number, bill and user interface.

New technology platforms will provide the foundation for new-generation RG solutions that will enable next-generation services along with the flexibility to differentiate offerings with new, advanced features. These new highly flexible architectures can be adapted quickly and cost-effectively to deliver multiple offerings that exceed the expectations of consumers, service providers and equipment manufacturers.

- Alick Einav
Product Line Manager, Residential Gateways Business Unit
Texas Instruments Inc.

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