1394 on the coaxial cable
Currently, cable TV operators use cable set-top boxes installed on each television receiver to transmit MPEG-2 program signals over coaxial cable.
Since coaxial cable is so common in American homes, the proponents of IEEE 1394 have developed a new specification called “1394-over-coax†that connects devices in various rooms to each other by sending 1394 baseband signals over coaxial cables. 1394 bus.
The 1394 TA has defined specifications for Category 5 copper wire, plastic optical fiber, and glass fiber but has always lacked the coaxial cable portion. In the latest 1394-over-coax specification, the organization will use UWB as a physical layer. But here, UWB should not be confused with wireless messaging. "We use UWB to modulate the signal. Once modulated, the signal is stored in the coaxial cable instead of being transmitted around." said Hans van der Ven, Chairman of the 1394-over-coax Working Group inside the 1394 TA. "Using UWB will Raising the signal to 3.3 to 4.7 GHz can reduce the signal amplitude and minimize interference.†In essence, the UWB of a coaxial cable can be used as a waveguide to achieve higher accuracy and increase cable length. In addition, the 1394-over-coax standard uses the IEEE 802.15.3 MAC layer as UWB.
The Multimedia over Coax Alliance (MoCA) is also actively promoting its new proposal to use splitters to transmit analog TV programs and 100 Mbps Ethernet signals over coaxial cable. But 1394 advocates think they can do better. They claim that the data throughput of 1394-over-coax can reach 400Mbps, which is four times that of MoCA 95Mbps.
IEEE 1394 networking technology
Jalil Oraee, founder and CTO of Oxford Semiconductor, United Kingdom, said that when the industry talks about home networks based on wireless or wired Ethernet or MoCA's home network based on the old (but well-performing) coaxial cable, Still no other better technology has been found to have enough bandwidth and transmission distance to transmit multiple high-definition television data streams while providing clock synchronization, data, and QoS.
"Even the best Ethernet devices can easily crash and cause random delays. With 1394, we can not only send IP packets but also ensure QoS," Oraee said.
On the technical level, many people in the industry agree that IEEE 1394 may still have many advantages to be developed. "The failure to activate the home network market is not the fault of 1394," said Richard Doherty, director of research at the Envisioneering Group. In addition, the initial enthusiasm of the consumer electronics (CE) industry for 1394 was also stifled by the cable industry's negative or even conscious evasion, Doherty pointed out.
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HANA-based home network architecture |
In fact, in some respects, IEEE 1394 has had the advantage of being the first choice for home network media. Previously, the cable and CE industry finally reached a unanimous agreement after long and arduous negotiations, that is, US cable operators installed 1394 in each set-top box. The agreement was approved by the Federal Communications Commission (FCC). Despite long waits and finally getting approval from the FCC, James Snider, executive director of 1394 TA, complained a few days ago: "Most American cable operators do not provide 1394 ports."
Doherty confirmed the above statement. "There are 1394 connectors now, but there is no software protocol," he added. "Comcast categorically refuses to provide 1394 set-top boxes for cable users, even though the 2004 FCC directive requires them to do so."
Other industry analysts also believe that Scientific-Atlanta, one of the two major set-top box vendors that controls the US market, will not provide a 1394 software stack in its set-top box that can work with 1394. Why does this happen? These analysts said that because US cable operators and cable set-top box suppliers do not want to see their traditional closed-end business invaded by the CE industry.
Brian O'Rourke, a senior analyst at In-Stat, frankly stated: "The 1394 has performed quite well as an interface technology, but as a networking technology it has been failing." But O'Rourke also believes in the CE field. The emerging HANA may bring "evangelism" to 1394. "HANA provides an opportunity for 1394 to become a viable networking technology," he said.
HANA promises to transmit 5 high-definition signal streams simultaneously within the home. HANA asserts that the 400 Mbps transfer rate (through the 1394 specification) can accomplish this, while also ensuring the security of content with the help of the "5C" content protection mechanism. HANA has a wide range of backers behind it, including movie companies (Warner Bros. and NBC/Global), Cable Company (Charter), CE (Samsung), and Chip Manufacturers (TI). "We have 400 Mbps as the minimum requirement," Van der Ven said. He explained that even if consumers do not have 5 HDTVs in their homes, they may perform “Trick Play†(Note: when watching live broadcasts, such as suspending or rewinding), such as 20Mbps HD in home networks. Fast forward on the signal stream, so that it is easy to reach 5 times the transmission rate. HANA has established a blueprint for development and plans to increase the transmission rate to 800 Mbps in 2009, according to van der Ven.
When asked about the role played by 1394 in HANA, van der Ven, who served as a freelance consultant for PC & TV-AV Connections in Japan, replied: “The prospects of HANA planning, we write standards.†1394-over The -coax specification is designed to make full use of coaxial cables that have already been installed in many American homes. "Consumers need 1394. There are two main reasons for this," van der Ven concludes. "One is that users need to record HD programs, and the other is that users want to be able to move devices around the house." Despite being a cable set-top box (or The point-to-point interface between HDTV receivers and monitors, 1394 was overtaken by high-definition multimedia interfaces (HDMI), but HDMI is not ideal as an interface between set-top boxes and home recording devices. Because HDMI is a one-way interface for sending uncompressed digital signals from one device to another device, it cannot send too large files to the recording device. Otherwise, the storage capacity of the recording device may be compromised. In contrast, 1394 is designed to send compressed signals optimized for recording and playback from digital television.
Increase bandwidth
Even Microsoft seems to recognize 1394. Although the computer software giant did not plan to support 1394b in the upcoming OS Vista, it plans to launch a service pack that supports 1394b. "We have aroused the interest of PC OEMs; 1394 is very important to high-bandwidth enthusiasts and can be used as an interface to external storage systems," said Mark Slezak, project director of Microsoft's Windows Device Experience Group.
However, the HANA camp lacks heavyweight companies in the CE industry, such as Sony or Mitsubishi. Both companies are working to promote Ethernet as the A/V home networking medium through the Digital Living Network Alliance (DLNA).
Paul Liao, vice president and CTO of Panasonic North America, acknowledged that Matsushita has not yet joined HANA. He explained: "Today, all types of networks, including WAN, LAN, data, voice, video, etc., are moving toward IP-based protocols. Because of this, Panasonic believes that for home video and audio entertainment networks, The use of an IP-based protocol rather than the IEEE 1394 protocol will bring greater benefits, and the latter is the basis of HANA."
1394 TA and HANA advocates do not agree with the above statement. Chairman of the HANA, Jack Chaney, who is also the director of the Samsung DMS Lab, said in a tone of voice: "HANA is based on IP and can ensure the quality of transmission." Peter Johansson, Vice President of Congruent Software Inc., also believes: "Ethernet and IP are not the same thing. IP is very easy to load, Ethernet can load IP, 1394 can, coaxial cable can also be."
Chaney is still convinced that there will be other companies joining HANA. “The strategy of large companies is complex and confidential,†he said. “If the goals of HANA and 1394 TA are achieved on schedule, these large companies will join HANA in succession.â€
The technical work within the 1394 team focused on the IP control plane for all network devices (more precisely, TCP/IP packets for A/V devices). Johansson recommends that the A/V signal stream be transmitted as out-of-band synchronization data and use an L3 bridge to connect segmented links.
In this proposed HANA-based home network architecture (using 1394 and 1394-over-coax), the working group plans to add a "bridge" in place to convert the 1394 bus to 1394-over-coax; in the future, It is also possible to add another controller that bridges 1394 and Ethernet. It will also install a proxy device to help the network discover legacy devices and send control commands. The proxy device will translate the HANA commands transmitted over IP into A/V device commands and send them, Johansson explained.
Indeed, in view of 1394 advocates, in addition to the lack of clock synchronization, the biggest problem with DLNA is how to handle its original A/V equipment. Van der Ven said: "The new Ethernet routers with the latest universal plug-and-play capabilities can talk to DLNA devices, but they don't consider the original equipment at all. It's clear that they have left the legacy of new home networking technology. product."
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