Broadband Gear Report for 1/3/2008

Broadband Gear Report for January 3, 2008

BGR FEATURE

Building for Bandwidth on the Home Network

By Assaji Aluwihare and Rob Flask, JDSU

Aluwihare

Flask

It is clear that the home network requires formidable backbone bandwidth to support current and emerging applications. IPTV, multi-room DVR, multimedia networking, online gaming and other applications easily demand a physical data rate of 100 Mb/s. Adding time-sensitive VoIP onto the network brings another layer of complexity into design. There are a variety of standards-based home networking technologies to choose from to meet system demands many of which reuse the existing cabling. (See Table 1.)

While CAT5 or CAT5e Ethernet offers a physical data rate of 100 Mb/s and an informational data rate of more than 80 Mb/s, yet few premises have this grade of connectors and twisted-pair cable installed.

MoCA works well over an existing coax network. It occupies only a 50 MHz band, enabling multiple high-speed channels to coexist. With up to eight nodes per channel, one frequency can be used for a 100 Mb/s data network and a separate frequency can be used for a 100Mb/s IPTV network. MoCA provides a true peer-to-peer mesh network.

MoCA	>100Mb/s typ. 140 MB/s max	>300 ft.
HPNAv3	86-128 Mb/s typ	>400 ft
TVnet	70-100Mb/s	>250 ft.
802.11a/g	<20Mb/s @ 25 ft- no walls	<65 ft
HomePlug A/V	150Mb/s Max published	??
TMT	116 Mb/s Max downstream published 23 MB/s Max upstream (calculated)	>400 ft

Table 1: Home Networking Data Rates

HPNAv3 can be transmitted via twisted-pair or coax and is a good candidate for QoS-sensitive applications such as live HDTV or VoIP. It operates in 4-21 MHz range, which may prevent it from operating in a system with a DOCSIS cable modem or an interactive cable set-top. The technology is well suited to overlay satellite services and enables direct peer-to-peer communications with a master communications element.

The upcoming HomePlug A/V standard promises the convenience of reuse of existing AC wiring. It operates in the 2-28 MHz range and purports to achieve a 200Mb/s physical rate and 150Mb/s information data rate.

Used to establish wireless data connections to PCs, portable laptops, printers, 802.11 a/b/g-based wireless solutions have become ubiquitous. RF propagation issues limit distance and data rates. (See Table 2.)

The Standards	802.11a	802.11b	802.11g
Raw Data Rate	54 Mbps	11 Mbps	54 Mbps
Frequency Band	5 GHz	2.4 GHz	2.4 GHz
Modulation	OFDM	DSSS	OFDM
Full Rate Range	7 meters / 23 feet	20m / 65 ft	20m / 65 ft
Channels / non-overlapping	12 / 8	11 /3	11/3

Table 2: 802.11 a/b/g Technology Comparisons

The proprietary Coaxys' TVnet supports data services over existing coax wiring by converting Ethernet to a proprietary communications over coax. TMT Coaxial Networks' HomeRAN HD, another proprietary solution, also communicates over coax.

Service Considerations and Premises Network Transport

The types of services operators and installers offer and support impact the demands and requirements placed on the home network. However, the biggest influence comes from consumer expectations of the service quality of live video and on-demand video content. This makes the number of entertainment outlets planned for each home and the type of content to be viewed or experienced important design criteria.

When transporting services such as VoIP and video, network performance metrics such as latency and jitter can have a significant impact on service quality. Because latency is a critical factor for VoIP quality, latency must be accounted for in the overall latency budget.

VoIP Service Quality

HFC systems face some inherent challenges when providing VoIP services. In "Maintenance of VoIP Service Quality," Trilithic's Steve Windle explains how these challenges can be met with a proper maintenance program that includes vigilant monitoring and proper installation alignment and testing. Download it here.

SDV - Using Bandwith More Efficiently

In this white paper, which is available here, Motorola describes an end-to-end solution that allows cable operators to leverage their existing infrastructure to offer more channels and deliver a wide spectrum of niche programming to attract additional subscribers.

While jitter can be overcome by increasing jitter buffers of the receiving equipment, the larger the jitter buffer, the greater the cost of the equipment and the longer the delay. However, if the jitter buffer is too small, transmissions will suffer from higher packet loss or bit error rate (BER) and the resulting negative effect on service quality.

The BER, or packet error rate (PER), has a direct impact on the perceived quality of service. BER and PER can occur from noise on the system or from service capacity issues. For services such as VoIP or IPTV, which operating using a real-time protocol (RTP), lost packets are not retransmitted - a direct hit on quality.

Charter Picks BigBand

Charter is the latest MSO revealing plans to use SDV as a bandwidth-saving measure to expand its HDTV programming options. The op recently selected BigBand Networks SDV solution to expand HDTV services in its LA-area system, including Malibu, Burbank and Glendale, CA. BigBand reports that with the Charter deal, the five largest cable ops in the U.S. have now selected its SDV.

Charter selected BigBand's universal edge QAM-the BEQ6000-to deliver switched programming. The op also is using BigBand's switched video analysis (SVA) viewership and performance analysis app to determine when and where to roll out new switched programming.

"Switched digital video is helping cable operators close the gap between the amount of television programming produced, and the amount of programming available for viewing," Amir Bassan-Eskenazi, BigBand's CEO, says.

Architectural Considerations

In greenfield deployments, service providers may choose the system that best meets performance and price targets. In overlays, it is important to map the home network architecture to determine which technologies are most appropriate for each home. Understanding which services will coexist on home wiring is critical for success, as shown in Table 3.

	Satellite	Broadcast TV	Basic CATV	CATV w/STB	DOCSIS	MoCA	HPNAv3
802.11b/g	Yes	Yes	Yes	Yes	Yes	Yes	Yes
HomePlug A/V	Yes	Yes	Yes	Yes	Yes	Yes	Yes
MoCA	Yes	Yes	Yes	Yes	Yes	Yes	Yes
HPNAv3	Yes	Yes	Yes	No	No	Yes	No
TVnet	Yes	Yes	Yes	Yes	Tvnet/C	TVnet/s	Yes
HomeRAN	Yes	Yes	Yes	Maybe	Maybe	Yes	No

Table 3: Technology Compatibility With Other Services

Coaxial cables and connectors are designed to be shielded in order to prevent over-the-air signals from mixing into the signals carried over the center conductor. However, coaxial home wiring networks are susceptible to ingress noise if the shielding, connectors or terminations are substandard or damaged.

Often presenting itself in the same frequency as desired signals, ingress noise can disrupt or disturb analog or digital services running over coaxial plant. Disruptive ingress noise can come from blenders, bread makers, vacuum cleaners, remote control cars, cordless phones, ham radio, machinery and microwave ovens. This noise can affect signals being transmitted within DSL, HPNAv3, DOCSIS, DSL, MoCA and video home networks.

Because ingress can occur intermittently and at different levels and frequencies, it can be difficult to diagnose during installation or when troubleshooting. This is further complicated by the fact that most installations are performed during the day when potential sources of ingress noise are at their lowest.

To prevent noise issues, all coaxial installations should be verified. Verification should include the replacement of any sub-standard connectors, splitters, wire and terminals; elimination of any un-terminated cable ends; and termination of any unused ports.

Summary

Each home networking technology provides different bandwidth rates, types of connectivity and conveniences to end users. Each of the networking technologies discussed in this article is capable of providing an excellent solution when applied appropriately.

Service providers and installers who know which technologies will provide the best cost/performance tradeoffs and plan their home networking strategies upfront will be in the best position to offer their customers a better broadband experience and the reliability they expect.

Assaji Aluwihare is general manager of network and enterprise test for JDSU's Communications Test and Measurement Division. Rob Flask is product line manager for JDSU's Cable Networks Division.