The Impact Of Triple Play

Confluence of voice, video and data moves from multiple networks and chips to a single device; power planning becomes critical.

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By Ann Steffora Mutschler
Not so long ago there were multiple networks that supported different kinds of traffic—a telecommunications network based on high-reliability protocols, the Internet for burst-centric data traffic and video distribution networks.

From the consumer standpoint that was highly inefficient. Managing three subscriptions from three service providers was unnecessary, which is why the concept of bundled services a single broadband line has become increasingly popular. This so-call triple play
is focused on efficiency and flexibility, and over time these services have been layered on top of Internet Protocol using a single broadband connection.

“The implications for this is that when you send all of this data on a single broadband, you need to be able to manage the priorities of traffic and be able to provision the network to give the guy that’s paying extra for high-speed Internet the quality of service that he is expecting to receive,” noted Del Rodillas, director of marketing for networking at MIPS. Obviously the silicon at the heart of the delivery devices needs to be pretty smart to accommodate all of this.

Designing for a triple-play environment does dictate certain specifications. “In the absence of different types of traffic you have very predictable traffic profiles,” he explained. “For instance, if I say I’m only going to get voice, I will ensure that every 125 microseconds that I’m processing a voice channel and I can support x number of channels. If you have predictable traffic, you can provision your design to assume that, and you don’t have to plan for highs and lows in terms of traffic.”

Rodillas also pointed out that once you have this packet traffic that’s very bursty in nature you need to provide some headroom in your design and the ability to prioritize. “Typically what happens when you implement a triple play design, you need to put in some traffic management/packet classification. If you didn’t have this, it’s pretty straightforward. It’s called framing the data. Bringing in video, voice and voice over IP, your design needs to be a lot smarter and that’s really where processors come in. Processors give the ability to identify what kind of traffic, what kind of quality of service is assigned to that packet and the rest of the hardware can take action based on the intelligence provided by the processors.”

Along these lines, Steve Roddy, VP of marketing at Tensilica, said that in triple play applications there are generally two classes of designs: wired access (DSL modems, powerline modems) and wireless terminals (LPE designs, etc.). “Both classes of products have high-speed modem, packetized data, IP protocol, various classes of service for audio, video, data, etc. And all of them seem to have the same philosophical approach to the architecture that is the modem itself is obviously integrated–there is one pipe. Speeds there keep increasing and they attack the other elements in the design separately.”

In other words there will be a separate control subsystem, audio subsystem, video subsystem, packet forwarding/routing data subsystem. “If a video stream comes in it is steered or directed into the video subsystem, which is a pretty much standalone entity unto itself so the integration challenge seems to be solved by the divide and conquer approach of these various specialized subsystems,” he explained. For the most part these specialized subsystems are a big benefit to power.

The use of multithreading in processors allows different types of traffic to be directed to different threads, while schedulers inside cores work with the processors to set priorities to achieve the most optimized and efficient use of the processor for the task at hand.

Power planning for mobile vs. connected home

Planning for power looks different depending on the target platform, such as a smartphone versus a set-top box. “In bigger equipment, you have a little bit more of a power budget so the ability to run the core at very high frequency is an option,” MIPS’ Rodillas said. “The ability to run multiple cores is also an option. But once you get into the mobile environment, you need to start being more wary of throwing bandwidth or processing power at the problem.”

Instead of running one core very fast, one option in a mobile application would be to run several cores with the frequency scaled down, which reduces power consumption. Another approach would be to utilize virtual processors, which are essentially threads by themselves that allow different types of processing capabilities to be run on virtual processors. Instead of using two actual processors, an SoC could be designed to use just one processor that contains two virtual processors, thereby reducing the area and power consumption by half.

Jim McGregor, chief technology strategist at In-Stat, sees the definition of triple play changing drastically. “We used to think of it in the home–entertainment services, phone services, etc., but that has really changed. Even looking at the home, everything goes IP. First we saw people cutting their cords from home phones going cellular. Now the cellular technology is going to IP technology based on OFDM (orthogonal frequency division multiplexing), whether it is WiMAX, LTE or whatever. But also, when you start looking at the home people are now cutting their cable cords because they can get everything downloaded off the Internet. All you need is a high-speed Internet connection. It kind of goes to the point about everything—whether it’s voice communications, data communications, entertainment—it all goes through the Internet.”