Wayne, N.J. — A chip set from startup Entropic Communications lets end users turn their coaxial connections into a backbone network in the home.
Wireless connections-mostly wireless-LAN links-are quickly becoming the de facto approach for distributing broadband connections and multimedia content from a router to a node, such as a laptop. But Wi-Fi systems struggle to penetrate some walls and thus fall short in providing total coverage in a home. That coverage issue will loom larger as end users start to distribute HDTV connections over Wi-Fi channels.
To help solve the problem, equipment vendors have considered establishing a backbone network in the home. With the EN1010 RF front-end IC and the EN2010 baseband controller IC, Entropic (San Diego) gives equipment vendors a way to tap into coaxial connections and establish a backbone that can deliver a peak performance of 270 Mbits/second and real throughput of better than 100 Mbits/s.
The EN1010/EN2010 chip set (also called c.LINK) is developed around a time-division-duplex, time division/multiple-access solution. Through this TDMA approach, the c.LINK chip set assigns a rotating time slot to every connection on the backbone network, thus avoiding collisions and improving quality-of-service across the link. "Each node gets a slot so designers know what's transmitted and when," said Michael Librizzi, vice president of marketing at Entropic.
To ensure proper delivery, Entropic's c.Link chip set wraps a header around the packet being transported across the backbone. "We don't touch the payload," Librizzi said. "Our job is to get it to the other side." The benefit of that approach is that Entropic's system can handle multiple digital rights management (DRM) approaches and other secure streams without forcing equipment vendors to tamper with the underlying packet.
To handle the delivery of data, Entropic's c.Link chip set works above the frequency range used to carry cable and HDTV channels. Coaxial cables are designed to operate from dc to 2 GHz. But as Librizzi pointed out, cable and HDTV signals cap out at 860 MHz. "Above 860 MHz is free space," Librizzi said. "It's unregulated and available."
Librizzi did not provide specifics on what frequency Entropic tapped into to deliver data services over coaxial cables. But he did say that the chip set uses a 50-MHz signal bandwidth and that it can support up to 10 simultaneous channels.
Inside the set
The EN1010 RF chip, housed in a 48-pin QFN, delivers upconversion, downconversion and on-chip digital-to-analog and analog-to-digital converters. The EN2010 baseband controller, which is delivered in a 336-pin BGA, is developed around a MIPS processing core and delivers approximately 96 kbytes of memory.
On the media-access control front, Entropic chose to implement the MAC using software that resides on an external nonvolatile memory. At power-up, the MAC functions are moved from the memory and executed in instruction sets on the baseband controller, Librizzi said.
The c.Link chip set can handle multiple high-density/standard-density MPEG transport streams as well as Ethernet packets. When handling MPEG streams, the chip set delivers a latency of approximately 5 milliseconds. The chip set also supports both isochronous and asynchronous transmission.
Samples of the c.Link chip set are available now with volume shipments slated for the fourth quarter of 2004. In volume, the chip set will be priced below $20.
