Delivering Gigabit Speeds

English: A gigabit HP-ProCurve network switch ...

English: A gigabit HP-ProCurve network switch in a nest of Cat5 cables. (Photo credit: Wikipedia)

There is a lot of talk about companies like Google and many municipal networks delivering Gigabit speeds to homes and residents. But what is not discussed is the fact is that there are no existing wiring technologies that can deliver the bandwidth for any significant distance. Most people are shocked when they find out how quickly data speeds drop with existing wiring technologies.

Existing wiring is adequate to deliver Gigabit speeds to the smaller homes or to small offices. Carriers have typically used category 5 wiring to deliver data signal, and that technology can deliver 1 Gigabit for about 100 feet from the fiber terminal. But after that the speeds drop off significantly.

Wiring technology was never a significant issue when we were using the wiring to deliver slower data speeds. The same fall-off occurs regardless of the data speeds being delivered, but a customer won’t notice as much when a 20 Mbps data connection falls to a few Mbps as when a Gigabit connection falls to the same very slow speed.

Many carriers are thinking of using the new 802.11ac WiFi technology as a surrogate for inside wiring. But the speeds on WiFi drop off faster than speeds on data cabling. So one has to ask if a customer ought to bother paying extra for a Gigabit if most of it doesn’t get delivered to his devices?

Below is a chart that compares the different technologies used today for data wiring along with a few that have been proposed, like WiGig. The speeds in this table are at the ‘application layer’. That means theoretical speeds but is the easiest number to use in a chart because it is the speeds that each technology touts when being promoted. But you must note that actual delivered data speeds are significantly less than these application layer speeds for every technology listed due to such things as overheads and for the bandwidth due to modulation techniques.

Speeds Chart

The technology that stands out on the chart is ultra-broadband from PulseLink of Carlsbad California. PulseLink uses the radio frequency (RF) spectrum on coaxial cable above 2 GHz and can deliver data rates exceeding 1 Gbps. They are marketing the technology under the name of CWave. This technology uses a wide swath of RF spectrum in the 3 to 5 GHz range. As a result the RF signal is out-of-band (OOB) to both Cable TV and Satellite and will peacefully co-exist with both. Typically RF spectrum above 3 GHz on coax cable has been considered unusable RF spectrum, but due to the unique techniques used Pulse-LINK’s CWave chipset the technology reliably delivers Gigabit data rates while not disturbing existing frequencies used by cable TV and cable modems. Effectively it adds a whole new Ethernet data path over existing coaxial and that needs no new wires when coax is already present.

The differences in the various technologies really matters when you are looking at delivering data to larger buildings like schools and hospitals. As was recently in the news, President Obama announced a ConnectED initiative that has the stated goal of bringing a minimum of 100 Mbps and a goal of 1 Gbps to 99% of students within five years. But there does not seem like any good reason to bring a gigabit to a school if only a tiny fraction of that bandwidth can be delivered to the classrooms. I think that the PulseLink ultrabroadband technology might be the only reasonable way to get broadband to our classrooms.

FCC Makes Changes to 60 GHz Spectrum

United States radio spectrum frequency allocat...

United States radio spectrum frequency allocations chart as of 2003 (Photo credit: Wikipedia)

On August 12, 2013 the FCC, in [ET Docket No 07-113] amended the outdoor use for the 60 GHz spectrum. The changes were prompted by the industry to make the spectrum more useful. This spectrum is more commonly known as the millimeter spectrum, meaning it has a very short wavelength and operates between 57 GHz and 64 GHz. Radios at high frequencies like this have very short antennae which are typically built into the unit.

The spectrum is used today in two applications, a) as outdoor short-range point-to-point systems used in place of fiber, such as connecting two adjacent buildings, and b) as in-building transmission of high-speed data between devices for functions such as transmitting uncompressed high-definition (HD) video between devices like blu-ray recorders, cameras, laptops and HD televisions.

The new rules modify the outside usage to increase power and thus increase the distance of the signal. The FCC is allowing an increase in emissions from 40 dBm to 82 dBm which will increase the outdoor distance for the spectrum up to about 1 mile. The order further eliminates the need for outside units to send an identifying signal, which now makes this into an unlicensed application. This equipment would be available to be used by anybody, with the caveat that it cannot interfere with existing in-building uses of the spectrum.

One of the uses of these radios is that multiple beams can be sent from the same antenna site due to the very tight confinement of the beams. One of the drawbacks of this spectrum is it is susceptible to interference from heavy rain, which is a big factor in limiting the distance.

Radios in this spectrum can deliver up to 7 Gbps of ethernet (minus some for overheads) and so this is intended an alternative to fiber drops to buildings needed less bandwidth than that limit. A typical use for this might be to connect to multiple buildings in a campus or office park environment rather than having to build fiber. The FCC sees this mostly as a technology to be used to serve businesses, probably due to the cost of the radios involved.

Under the new rules the power allowed by a given radio is limited to the precision of the beam created by that radio. Very precise radios can use full power (and get more distance) while the power and distance are limited for less precise radios.

The FCC also sees this is an alternative for backhaul to 4G cellular sites, although the one mile limitation is a rather short one. Most 4G sites that are already within a mile of fiber have largely been connected.

This technology will have a limited use, but there will be cases where using these radios could be cheaper than installing fiber and/or dealing with inside wiring issues in large buildings. I see the most likely use of these radios to get to buildings in crowded urban environments where the cost of leasing fiber or entrance facilities can be significant.

The 60 GHz spectrum has also been allowed for indoor use for a number of years. The 60GHz band when used indoors has a lot of limitations related to both cost and technical issues. The technical limitations are 60 GHz must be line-of-sight and the spectrum doesn’t go through walls. The transmitters are also very power consumptive and require big metal heat sinks and high-speed fans for cooling. Even if a cost effective 60 GHz solution where to be available tomorrow battery operated devices would need a car battery to power them.

One issue that doesn’t get much play is the nature of the 60 GHz RF emissions. 60 GHz can radiate up to 10 Watts with the spectrum mask currently in place for indoor operation. People are already concerned about the 500mW from a cell phone and WiFI and it is a concern in a home environment to have constant radiation at 10 Watts of RF energy. That’s potentially 1/10 the power of a microwave oven radiated in your house and around your family all of the time.

Maybe at some point in the distant future there may be reasonable applications for indoor use of 60 GHz in some vertical niche market, but not for years to come.

New and Better WiFi

Wi-Fi Signal logo

Wi-Fi Signal logo (Photo credit: Wikipedia)

There are two new standards for WiFi that will be hitting the market in the next few years. The standards are 802.11ac and 802.11ad. The two new standards use different spectrum with 802.11ac at 5 GHz and 802.11ad at 60 GHz. Both new Wifi standards will be able to deliver up to 7 gigabits per second, compared to today’s WiFi that tops out at 600 megabits per second.

Looking at basic spectrum characteristics there are four major differences in the way these two standards will use the spectrum:  bandwidth available, propagation characteristics, antenna size and interference.

The maximum data speed that can be delivered by any radio spectrum is limited by the amount of spectrum used and the signal-to-noise ratio. This limit is defined by the Shannon-Hartley Theorem. The 802.11ac at 5 GHz can use about 0.55 GHz of spectrum. The 802.11ad at 60 GHz can use up to 7 GHz. 802.11ac has channels that are 160 MHz wide while 802.11 will have channels that are 2,160 MHz wide. But the channels in 802.11ac can be bonded which will allow it to deliver almost as much bandwidth as 802.11ad.

802.11ac will use the same 5 GHz spectrum that is used by today’s Wifi and will have similar propagation characteristics. But the 802.11ad spectrum at 60 GHz will not travel through bricks, wood or paint and thus this technology will be most useful as an in-room technology.

For these spectrums to achieve full potential they need to be able to transmit multiple signals, meaning that they need multiple antennas. Antenna size is proportional to the wavelength being transmitted. A 5 GHz antenna has to be about an inch long and spaced at least an inch apart to be effective. But 60 GHz antennae only need to be 1/10 inch long and apart. This is going to make it easier to put 802.11ad into handsets or into any small device.

Finally is the issue of interference. There is already a lot of usage in the 5 GHz band today. In addition to being used for WiFi the spectrum is used for weather Doppler radar. There are also a few other channels in the band that have been allowed for other uses. And so 802.11ac will have to work around the other uses in the spectrum. The 60 GHz spectrum range is mostly bare today, and since this will go such short distances there should be very few cases of interference. However, multiple 801.11d devices in the same room will interfere with each other to some extent.

The standard is pretty much set but won’t be fully certified until 2014. However, there are already devices being shipped that include some of the features of the standard. For example, it’s included in the Samsung Galaxy S4 and MacBooks. But today’s version uses beamforming to send the signal to one device at a time. Beamforming means that the signal is sent to one device from each separate antenna in an array, but at slightly different times.

Still to come is the best feature of, which is to support separate sessions with different devices, different priorities and different power needs. This feature is called multi-user MIMO and it will revolutionize the way that WiFi is used. For example, you will be able to make a WiFi voice call while simultaneously downloading a video from another device. Your WiFi chip will determine the location of each device you will be talking to and will initiate a prioritized session with each. In this example it can give priority to the voice call.

The fully deployed will be the first generation wireless that is getting ready for the Internet of Things. It will be able to communicate with multiple devices in the environment at the same time. It will turn smartphones and tablets into workhorses able to gather data from sensors in the environment.

802.11ad is going to be far more limited due to its inability to pass through barriers. The most likely use for the spectrum will be to create very high-speed wireless data paths between devices, such as connecting a PC or laptop to a wireless network. It should be able to achieve speeds approaching 7 Gbps with only one device and one path in play.

One would expect by 2016 or 2017 for devices using these two technologies will become widespread. Certain in the telecom industry an upgrade to 802.11ac will allow carriers to deliver more bandwidth around a home or office and be able to handle multiple sessions with wireless devices. This new technology is a fork-lift upgrade and is not backwards compatible with earlier WiFi devices. This means it will take some time to break into the environment since all of the local wireless devices will need to be upgraded to the new standard. One would expect first generation 802.11ac routers to still include 802.11n capabilities.

How Much Bandwidth Can a Cable TV System Deliver?

Cut showing the composition of a coaxial cable.

Cut showing the composition of a coaxial cable. (Photo credit: Wikipedia)

There are a number of techniques that are available for a traditional cable TV network to upgrade the bandwidth on the network available for customer data. If you are operating or competing against a cable TV system you should recognize that there are a number of upgrades that can when combined can drastically improve data speeds. Each of these upgrades comes at a cost, but you can’t discount the technical capabilities of an HFC network if data delivery becomes the primary goal of the network.

  1. Increase System Bandwidth. An example of this kind of upgrade is when a system is upgraded from 750 MHz to 1,000 MHz (or 1 GHz). This upgrade provides more bandwidth by widening the frequencies that are available on the coax. A system bandwidth can be a major upgrade and can involve replacing all of the power taps in the system, and in some systems even requires replacing the coaxial cable.
  1. Reducing Node Size. A node in an HFC system is a neighborhood of homes and/or businesses that share the same bandwidth. Typically there is fiber built to a node and then coax cable from the node to each customer. Historically, before cable modems, nodes were large, often at 1,000 homes or more. But many cable companies have deployed more fiber and reduced node sizes and some cable companies now have nodes in the 200 customer range. Making smaller nodes creates smaller pools of shared bandwidth, meaning there is more bandwidth available to customers at peak times.
  1. MPEG4 Compression. A lot of cable systems still use a compression technique known as MPEG2. This technology is used to compress the digital channels on a network today so that up to ten digital channels will fit into one 6 MHz analog slot. But with MPEG4 as many as 20 digital channels can fit into the same 6 MHz slot. The biggest issue with this conversion is that older set-top boxes won’t recognize MPEG4.
  1. Deploy DOCSIS 3.0. DOCSIS 3.0 is a bandwidth management technology that allows a cable modem to use a larger window of RF frequency for data. The way this works is that a cable system can ‘bond’ multiple channel slots together to that the cable modems can use more than one 6 MHz channel slow for data.
  1. Migrate Analog Channels to Digital. A cable provider can gain some bandwidth space by migrating analog channels to an existing digital line-up. There are often contractual requirements with programmers that make this difficult to achieve. However, as mentioned above, as many as 20 digital channels can fit in the same sized slot as an analog channel. There are always customer issues to also consider since this kind of conversion will shrink the analog offering and expand the digital tiers.
  1. Full Digital Conversion. In a full digital conversion all channels are converted to digital. Once completed, every customer needs a set-top box or other device in order to decode and view channels. There is now a device called a Digital Television Adapter (DTA) that is less costly than a set-top box that can support a customer remote. It is possible to send the ‘basic’ channels through the network un-encoded so that customers with a digital QAM tuner in their TV will be able to see these channels without a DTA.
  1. Deploy Data QOS. This technique does not increase system bandwidth, but rather allows the cable provider to sell faster data to some customers by allowing those customers to use a frequency allocation that is only used by these faster data customers. For example, Comcast advertises 100 Mbps service in most large cities, and they would deliver that kind of speed by giving the 100 Mbps customer priority over other customers in the node by having those customers send their data over a lesser-used frequency on the COAX. Of course, as the priority customer gets more bandwidth, everybody else in the node gets degraded service, and if too many premium services are sold then even the priority customer can’t get the promised bandwidth. But this technique does allow the cable company to selectively compete against fiber for selected customers willing to pay for the extra speed.
  1. Convert to IPTV. This conversion would allow a cable system to use more of the RF frequency on the network for bandwidth. On an IPTV system the programming, voice and cable modem service are all sent over shared bandwidth. An IPTV conversion does not automatically gain a lot of extra bandwidth and any savings come from the fact that the company does not have to broadcast all channels to all nodes all of the time, but rather can just those channels that somebody in the node is watching. There is a benefit, but it is not as large as the extra bandwidth gained by other strategies.
  1. Higher Spectral Efficiency. This technique involves converting to DOCSIS 3.1 and also changing the system modulation techniques. The traditional modulation technique is called QAM (Quadature Amplitude Modulation) and uses a 6 MHz frequency allocation.  The new technique is ODFM (Orthogonal Frequency Division Multiplexing) which uses a higher QAM modulation.  Where Current DOCSIS capabilities achieve approximately 6.3 bits per Hertz, DOCSIS 3.1 can achieve 10 bits per Hertz. New modulation techniques can create much larger bandwidth slots and can at the same time increase the bits to Hz efficiency of the frequency being used. In effect, this technology turns the cable system into a DSL system, with the difference being that there is more frequency available on a coaxial cable than is available on a telephone copper cable, but that a CATV node is then shared by multiple subscribers.

As can be seen, a cable company has a lot of options to increase bandwidth. So, how much bandwidth can be delivered? There are a lot of cable networks that have been upgraded through step 7 above. These systems can support some selected customers up to 100 Mbps download. But these systems probably only support 30 Mbps for all subscribers if the nodes are small enough. A system that is upgraded through step 8 can probably deliver 50 – 60 Mbps to most customers with selected customers being able to get much faster speeds. But a full upgrade to through step nine would allow a cable system to match the overall bandwidth delivered by a fiber PON system, although it is then shared with a lot more customers.

These upgrades are expensive. But if you are competing against a cable company, don’t assume that they are incapable of delivering very decent internet speeds if they are willing to make enough investment in their network.

If you have questions or want to discuss this further call Derrel Duplechin at CCG at (337) 654-7490.

HD Voice

A spectrogram (0-5000 Hz) of the sentence &quo...

A spectrogram (0-5000 Hz) of the sentence “it’s all Greek to me” spoken by a female voice (Image:en-us-it’s_all_Greek_to_me.ogg). (Photo credit: Wikipedia)

HD voice (or wideband audio) is a technology that delivers the full frequency range of the human voice.  Traditional telephony has delivered a narrowband voice transmission and only transmitted sounds between 300 Hz and 3.4 kHz. However, the human voice extends between 80 Hz and 14 kHz, so traditional telephone has chopped off parts of every voice transmission.

The range of frequency was curtailed for traditional telephony based upon the limited bandwidth available for transmitting voice calls over a twisted copper pair. But voice that is sent over an IP path does not have those limitations and can send the full range of the human voice.

There has been an industry standard for wideband voice since 1987. However, until recently the only uses of the standard were in high-end video conferencing systems and for transmitting sports announcers back to the home station for rebroadcast.

But the industry is starting to use the HD voice protocol for calls made over VoIP. For example, Skype and some other PC-to-PC voice providers use the full HD voice bandwidth and the higher quality of the call can be experienced by a caller using a high-quality headset or handset. These same calls don’t sound better when listened to on a standard phone due to limitations in the speakers. There are also a number of vendors offering wideband telephones such as Avaya, Cisco, Grandstream, Gigaset, Polycom and others. These sets are capable of both sending and receiving a wideband voice signal, but the phones at both ends must be wideband capable to engage in an HD quality call.

So what are the business opportunities with HD Voice? Businesses are interested in having high-quality calls, particularly in conference rooms, noisy areas and other places where the quality can make a difference. The business opportunity is to make the phones available to businesses that are served with IP voice paths. HD Voice can then be sold as an add-on feature or as a more expensive voice line. A company that wants the higher quality calling is a great candidate for moving off of traditional TDM services onto VoIP, IP Centrex or other IP voice solution.