Internet has been a major driver for the evolution towards broadband creating a new experience for the customers offering new services such as e-mail, browsing, access to the World Wide Web and “online” services such as digital photo lab, ticket booking etc. Meanwhile, telecom operators around the globe are working to generate new revenue by expanding their services beyond their traditional business foundation. Once broadband was all about the delivery of high-speed Internet access and services to a PC. It is now driven beyond the PCs to include other devices and services in the home including the mobile devices, and therefore “Triple Play”. Broadband network is itself getting redesigned to deliver increasingly new services in addition to the traditional Internet access, among which telephony and IPTV (Internet Protocol Television) are the major business models usually known as Triple-play (voice, video and data).
Triple-play is mostly provided using the digital subscriber line technology over an existing PSTN (Public Switched Telephone Network) twisted pair cable as the last mile access to the customer’s home. Similarly, cable television operators use their access architecture to bring broadband to their clients, with the help of the available coaxial cable rather than the twisted pair. The subscriber’s situate could be a residence, multi-dwelling units, or even a small business enterprise. Multiple devices are needed to share the broadband connection. Game consoles, PCs, telephones and IPTV set-top boxes all require a broadband connection, so the consumer has to distribute that connection between these devices, simultaneously. What is needed is a mode to turn on the device and obtain access to network based services. Data can cross a wide variety of physical media, from radio to power line, from twisted pair to coax and fibre. The customer just wants it to work, without having to understand all the complexities of the protocols running behind it.
Rubbing The Genie’s Lamp
A user requests to access broadband services from any appropriate appliance in the home, which means that devices must be integrated with the home environment and services need to be adapted to the capabilities of the home network. New services need to be adapted to the capabilities of the home network. New services can be created by combining the different possibilities of devices at home e.g. using the different displays and speakers to enable rich video communication. The customers also demand the facility to exchange multimedia content simply and easily between devices. A basic modern together with a wireless enabled modern/router in multi-dwelling units would be sufficient to provide broadband access at customer premises but this equipment was not capable of supporting the next generation of services. This drove the need for a more capable device known as the ‘Residential/Professional Gateway’ that ensures a range of services to be consumed reliably and securely by the customer, whilst being quality-assured by the service provider. The key distinguishing factorfor the Residential Gateway (RG), object of our study, as compared with the modem/router, is that it is managed by the operator who also provides support for value added services.
The RG (Figure 1) is the device offering secure broadband connectivity to the home, and delivering services to the home environment with guaranteed service levels. It is the equipment that makes the home part of the broadband network. It has to:
- Remotely manage services for the devices.
- Allow the right device, or application, to connect to the appropriate service platform with the required QoS.
- Act as a proxy for those devices in the home that are not capable of communicating over the broadband network and, thus hide the complexities of the home network to the broadband network, and vice versa. This class of devices include legacy telephones and consumer electronics.
- Facilitate secure access to home based services and devices.
- Recognize and potentially unite devices capabilities and service offerings to create a better integrated home environment and blended services.
- Personalize user experience from any terminal.
Thus the RG is a box that sits anywhere in the house where it is unlikely to be disturbed by household activities. Once RG is installed, it enables access to a variety of traditional and emerging services, and protects both the access provider and the consumer from obsolescence. It often combines the functions of an IP router, multi-port Ethernet switch and Wi-Fi access point. The RG uses Asymmetric Digital Subscriber Line (ADSL) technology and plugs into the regular phone jack, and provides broadband connection for all home communication services. Surfing the Internet, watching TV, enjoying Video on Demand (VoD), making Voice over Internet Protocol (VoIP) phone calls or video calls, etc., are a part of RG’s services. Equipped with an ADSL modern with Ethernet, Wi-Fi and Bluetooth interfaces to accommodate all types of devices, it becomes a single point of entry for an entire world of high-tech entertainment and communication services, explaining the spectacular growth of this market.
Emerging applications through RG
A non-exhaustive list of these applications includes:
- Telecommuting (through secure high speed access)
- Distance learning (education at home)
- Telemedicine (in-home monitoring, remote diagnostics)
- Video telephony (TV or PC)
- On-line gaming
- Home appliance management and integration, e.g., smoke alarm alerting fire house or closing vents
- Security systems management (low bit rate video monitoring, video sensors, etc.)
- In-home power regulation and management
- Video (300+ channels)
- VoD
- CD jukebox (music, music videos, movies, family photos/video)
- On-line advertising and electronic catalogues
- Cut and paste video clips from Internet etc
Offering triple-play service is not as easy as it seems, because determining the right business model, backend processes, customer care support and economic environment plays a pivotal role. Also, there are number of technical difficulties with regard to the triple-play services. Voice, video and high speed data all have different characteristics and place different burdens on the network that provides access to these services. Within these challenges, the service provider has to assure the QoS in order to make the user a profitable subscriber.
To make the whole RG environment ready to offer the required QoS, service providers must pay special attention to the dependability and security issues including reliability, availability, and safety etc. Dependability is the guarantee of a service accomplishment if there is no violation in environmental conditions, whereas resilience is the guarantee of right services even in the presence of changes, i.e., the persistence of dependability.
Access infrastructure for RGs
As seen in the figure 2, data is multiplexed by the RG from different in-home networks onto a single broadband trunk. Each service in the home is connected by a “virtual wire” to its respective service platform. RG multiplexes these virtual wires onto a single access trunk to the access network, where they are routed to their respective services platforms.
The access network needs to guarantee Quality of Service (QoS) connections irrespective of the contents of any data stream it carries. Transporting these data independent of the contents allows new services to be added without redesigning the network. In order to provide triple play services, Asynchronous Transfer Mode (ATM) could be the preferred access network since it provides reliable connections between end points with a guaranteed QoS. It uses a single connection mechanism for all services. Each “virtual wire” from a service provider to a home network is implemented as an ATM virtual wires, which are created dynamically as ATM switched virtual circuits. Both wired and wireless services are supported over this unified connection model.
Once the RG is connected to the ADSL router, services start to get initiated by checking the validity of its traffic with the Digital Subscriber Line Access Multiplexer (DSLAM). Authentication is the next step that will be taken care by Broadband Remote Access Server (BRAS) via the Point to Point Protocol (PPP). Then the service provider checks the RG for the kind of services it is registered with. A full-fledged RG can have all services (VoIP, Internet and TV/ADSL), or only Internet and TV/ADSL, etc. According to the registered services, the remote management and the RG communicate with each other to download the required software files with necessary permission. The desired service platform and the RG interacts using appropriate protocols, while data and packets are being transferred through a secured channel.
Even though most Telcos follow the new commercial tendency, switching from techno push to market pull, the launching of RG in Indian markets purely depends upon ISPs’ reputation and their telecom infrastructure. The challenge is assuring the triple-play services to the customers without compromising the dependable qualities like reliability, availability and security. Reliability is defined as the ability to deliver a continuous service. Readiness of service when the user asks for is called availability. Protection of users’ data and prevention of attacks are some aspects of security, usually apprehended in denominations such as confidentiality, integrity etc.
Resilient Architecture
Ultimately, the goal is to develop a versatile RG that will support QoS and paves way to increase the revenues for service providers as well as satisfying the user needs. Consumers do not tolerate invasion of privacy or hacking into mission-critical services by strangers of neighbours. The RG should also be user-friendly. Services must be easy to install, intuitive to learn and use. Finally, utility and home services must provide an obvious consumer value. All these requirements indicte the need to build a resilient RG. Also, the infrastructure must allow different service providers to share the resource without adversely affecting each other’s services. These providers must have flexibility in defining their business model. Modification and upgrading services on the existing technology should be future-proof and require a minimal consumer involvement.
To meet industry-wide standards, a product and its associated architecture (access network in our case) must meet certain levels of system availability, transmission quality, scalability, and maintainability. Individual elements, and the system as a whole, must be made more reliable by applying strong standards, including high fault tolerance and redundancy measures iinto every design step.
Design Requirements
It is obvious that problems at any device section in the overall end-to-end path coupled with the complexity and scale system can significantly cause performance degradations that affect end-user experience. There are numerous technologies and recommendations which aim at addressing various performance measurement issues related to the end-user experiences. For example, RG firewall must omit all the unwanted packets, thus providing the maximum security to customer’s data. Mechanisms to protect the provider’s network from hackers who try to steal the service are mandatory. Updating the firmware should be maintained time to time. Also, the traffic in the network needs to managed efficiently, especially when there is a huge demand for a special service.
Some features of RG are the following:
- Fault Management
- Address Translation
- Accounting
- Easy access to heterogeneous home devices
To offer uninterrupted services, reliability needs to be maintained in all phases of network starting from RG to the service platforms. The term flexibility refers to the adaptation of hardware and software in the RG for various new services. QoS need to be assured on the core network rules and finally, to offer reliable services, service platform availability should be guaranteed.
Finally, IP-based convergence is inevitable and will result in newer services and newer demands in the market. India is an open market for the ISP to collaborate triple-play services with existing traditional methods as there are no active players currently dominating this trend-setting technology.
Author Profile
Mr. Sayee Kumar, is an Assistant Professor at Muthayammal Engineering College.