The Future of Wireless is Fiber

Cactus Cell Tower
(Image source: www.extremetech.com)

I wrote this on Monday for the National Center for Optics and Photonics August 2017 Newsletter:

In the next few years wireless providers are planning the broad deployment of 5G wireless services. Here’s some details:

• Current International Telecommunication Union (ITU) specifications for 5G specify a total download capacity of at least 20Gbps and 10Gbps uplink per mobile base station.
• In contrast, the peak data rate for current LTE cells is about 1Gbps.
• Under ideal circumstances, 5G networks will offer users a maximum latency of just 4ms, down from about 20ms on LTE 4G networks.
• The 5G specification also calls for a latency of just 1ms for a stepped up service called ultra-reliable low latency communications (URLLC).

In support of the Internet of Things, 5G must also support at least 1 million connected devices per square kilometer (0.38 square miles). This may seem like a lot but when every traffic light, parking space, and vehicle is 5G-enabled, we'll easily start to hit that kind of connection density and will see 5G towers on places like major highways every 100 feet or so.

How is connectivity delivered these days to wireless towers, and how will it be delivered in the future? Fiber! 

5G networks will be predominantly fiber-based due to the combination of tower capacity and distance requirements. We will see limited microwave antennas used in niche cases when fiber is not an option. Technicians will need to have a good understanding of fiber characterization testing and troubleshooting as these super-fast high capacity networks roll out. In addition, skills in troubleshooting dirty or damaged connectors, tight fiber bends, faulty fiber splices, Optical Time Domain Reflectometry (OTDR), attenuation, and chromatic and polarization mode dispersion will become even more critical. 

Fiber to the tower is a critical enabler of 5G wireless services including The Internet of Things. 

For more information see Preparing the Transport Network for 5G: The Future Is Fiber and check out the rest of the OP-TEC August 2017 edition and previous monthly newsletters here.

5G? 6G?? How About 200G?!

Back in 2013, Verizon ran a successful 200 Giga-bits-per-second (200Gbps or 200G) trial in collaboration with communications equipment manufacturer Ciena. The trial was done over optical fiber using a single wavelength. Well - trials are trials - done in optimized and controlled laboratory type settings by people in white lab coats. Experts speculated whether these kinds of bit rates could be achieved in the real world. Well.... guess what?

Earlier this month, Verizon provisioned 200G technology using the same Ciena gear on an ultra-long-haul production network between Boston and New York without impacting live customer traffic on the same network and without making any modifications to the existing fiber or network infrastructure equipment. The new Ciena gear was only added on each end of the communications channel.

Significant? You bet. More information on a single wavelength over long distance without any loss of signal quality. All this without having to upgrade fiber and infrastructure equipment in the field. It opens the door for the possibilities of much higher bit rates over existing fiber-based networks. We'll see 400 Gbps soon and yes even Tera-bit-per-second (Tbps) rates over existing optical fiber infrastructure soon.

SDN: When The Hardware Becomes A Little More Soft

I grew up in the dedicated hardware world. Switches and routers that – sure - included processors and a little bit of memory.  Devices with pretty basic operating systems that kept track of addresses to move content around on a network, making sure stuff gets to where it is supposed to go. Nothing fancy but it has worked pretty good with the build out of the internet over the past 20 years or so. 

Today, we’re seeing a pretty major shift to what people are calling Software Defined Networks (SDNs). You may have seen SDN also referred to as elastic computing and/or elastic networks. The idea with SDNs is to not just try and make the network more efficient but also make it flexible and scalable. The concept is pretty simple and SDN Central explains it pretty well:

Software Defined Networking (SDN) is a new approach to designing, building and managing networks. The basic concept is that SDN separates the network’s control (brains) and forwarding (muscle) planes to make it easier to optimize each. 

In this environment, a Controller acts as the “brains,” providing an abstract, centralized view of the overall network. Through the Controller, network administrators can quickly and easily make and push out decisions on how the underlying systems (switches, routers) of the forwarding plane will handle the traffic.

So, you’ve got a smart controller looking at the entire network including applications running on the end devices. The controller communicates with network controlling devices (switches and routers), adjusting and optimizing the network to real-time conditions. Sort of like a maître d / head waiter in a busy restaurant.

For providers (Verizon, AT&T, etc) , SDNs reduce equipment costs and allow the networks to be more efficiently controlled. These networks are optical fiber-based and that has me pretty excited with my new position at the NSF-funded OP-TEC ATE Center. 

Centralized, programmable optical networks that dynamically adjust to changing requirements. Nice. I’ll be writing more about SDN and a number of other optics based technologies in future posts.

Attenuation in Fiber Communications Systems

I'm teaching a fiber optics communications course this semester and - like just about every communications course - we started out talking about attenuation.

Attenuation is just a fancy word for loss. In any communications system you've got a certain amount of signal strength going in and a certain amount of signal strength coming out. If there is no amplification in a system there is always going to be loss and the output signal will always be weaker than the input signal.

In fiber systems attenuation is caused by three things:

1. Absorption - Glass, whether it is fiber or the windows in your house, will always absorb a small amount of light going through it. The amount depends on the wavelength of light and what the glass is made of.
2. Scattering - Atoms in glass cause a certain amount of scattering of light and scattered light will not emerge at the output.
3. Leakage - Light will leak out of fiber, especially if the are a lot of bends in the fiber.

Fiber manufacturers typically provide specifications for all three of these, along with total attenuation per kilometer.

One of the primary goals in any communications system is to keep the attenuation to a minimum. Even so, there will always be a loss in signal intensity when comparing output power to input power. Calculating attenuation in a system is pretty simple. Attenuation is cumulative so basically you just add up the signal loss for each component in the system. Here's an example:

Question: A 50 km fiber run has been spec'd at 99% transmission per km. What percentage of light will emerge at the output?

Answer:

The fiber run is transmitting 99% per km so after the first km 99% of the input signal will be available, after the second km, 99% of what's left after the first km will be available, etc. So we can say:

60.5% of the original input signal strength will emerge at the output.

SONET Packet-Oriented Data Framing

In my last legacy PSTN post I discussed how Synchronous Optical Network (SONET) is used to multiplex, transmit and then de-multiplex voice calls. Today, let’s take a look at how SONET  is being used to transmit packet-oriented data (in today’s world - basically Ethernet).

In that last SONET post we said the SONET international equivalent is called Synchronous Digital Hierarchy (SDH). Now, when we talk about data at the SONET/SDH level we’re talking frames (think layer 2 OSI model) and the base unit of framing for SDH is something called a Synchronous Transport Module, level 1 (STM-1) with operates at 155.52 Mbps. 

In the post I also said the base SONET standard bit rate is 51.84 Mbps and is referred to as Optical Carrier  (OC) -1 or Synchronous Transport Level  (STS) -1. Now, because we’re talking 3 times an STS-1 and it is concatenated (combined), the base SONET data framing unit (running at 155.52 Mbps)  is referred to as a STS-3c (Synchronous Transport Signal 3, concatenated) which is also referred to as an OC-3c (Optical Carrier - 3c). 

Now that I have you completely confused (!) lets’s talk a little more about packet frames. A typical packet frame consists of a header, payload (the actual data being sent) and some kind of trailer. I like to use a letter analogy to understand what is going on - someone writes a letter (think of the letter as the payload or data). It gets put on an envelope (think of the envelop as the header and trailer for now). At the sending end the letter gets a destination address, a return address, etc and gets delivered. At the receiving end the letter gets opened, the envelop discarded and the letter itself saved and used.

For an STS-3c framing unit, the payload rate is 149.76 Mbit/s and overhead is 5.76 Mbit/s.

If we look at an individual SONET STS-3c frame - it’s  2,430 octets long. SONET systems transmit nine octets of overhead and then 261 octets of payload in sequence. This transmission is  repeated nine times in 125 micro-seconds until 2,430 octets have been transmitted. 

Timing is critical here (that's why it's called synchronous) for communications across the entire network.

Wavelength Division Multiplexing (WDM)

In my last legacy Public Switched Telephone Network (PSTN) post I covered Statistical Time Division Multiplexing (STDM).  In this post let's take a look at Wavelength Division Multiplexing (WDM and DWDM) methods.

As bandwidth requirements continue to grow for both the legacy Public Switched Telephone Network and the emerged Internet/IP network most of the high bandwidth backbone transmission is being done with fiber optics and a method called Wavelength Division Multiplexing or WDM. WDM functions very similarly to Frequency Division Multiplexing (FDM). With FDM different frequencies represent different communications channels with transmission done on copper or microwaves. WDM uses wavelength instead of frequency to differentiate the different communications channels.

Wavelength

Light is sinusoidal in nature and wavelength, represented by the Greek letter lambda (λ) is a distance measurement usually expressed in meters. Wavelength  is defined as the distance in meters of one sinusoidal cycle.

Wavelength Measurement

Wavelength indicates the color of light. For example, the human eye can see light ranging in frequency from approximately 380 nm (dark violet) to approximately 765 nm (red). WDM multiplexers use wavelength, or color, of light to combine signal channels onto a single piece of optical fiber. Each WDM signal is separated by wavelength “guardbands” to protect from signal crossover. One of WDM’s biggest advantages is that it allows incoming high bandwidth signal carriers that have already been multiplexed to be multiplexed together again and transmitted long distances over one piece of fiber.

Wavelength Division Multiplexing

In addition to WDM systems engineers have developed even higher capacity Dense Wavelength Division Multiplexing (DWDM) systems. Just this past week, Cisco and US Signal announced the successful completion of the first 100 Gigabit (100G) coherent DWDM trial. As backbone bandwidth requirements continue to grow these WDM and DWDM systems are significantly reducing long haul bandwidth bottlenecks.

Don't Forget About Fixed Broadband Services

With the upcoming push towards 4G mobile broadband services by providers like AT&T and Verizon Wireless along with Verizon's winding down of FiOS fiber to the home services, some of us have been looking beyond fixed broadband service offerings towards an all mobile world. Well maybe some day but.... not so fast!

Fixed services are not going away according to a recent research report from ABI Research titled Broadband Subscriber Market Data. The report estimates that the number of worldwide fixed broadband subscribers will rise to 548 million in 2015, a 2010-2015 CAGR of 3%.

Here's more highlights from the report:

• Fixed broadband subscribers totaled 430.7 million in 2009 which represents approximately a 13% increase over 2008.
• Fixed broadband is an attractive platform for the delivery of IPTV, gaming services with low latency, rapid access to web content, and secure access to non-building access points (e.g. vehicular traffic monitoring units), Technologies such as fiber-to-the-home, VDSL and GPON are helping to keep fixed broadband relevant to end-users – both in the home and office.
  
• Fixed broadband services will continue to complement mobile broadband services with some carriers intending to use in-the-building broadband connection to hand off femtocell-connected wireless traffic.
• At present, the DSL platform dominates the market with 65% market share; cable and fiber represented 24% and 11% market share respectively in 2009.
• South Korea and Japan are the countries with highest fiber broadband penetration. In Japan approximately 55% of broadband subscribers are using fiber broadband. In Korea, fiber broadband customers represent 49% of overall broadband users.
• Growing customer demand for speed will continue to drive more fiber broadband adoption in future. ABI Research forecasts that fiber broadband subscribers will total almost 134 million by 2015.
• North America has the highest broadband penetration in the world. According to analyst Khin Sandi Lynn, “We expect broadband penetration in North America to be accelerated by federal government initiatives which aim to roll out broadband access in rural areas of the US.”
  

Get more info on this ABI Research report here and for more information on femtocell technology listen to Mike Q and my femtocell podcast linked here.

Will Verizon Finally Announce a Fiber To The Node Product?

The New York Times ran an Associated Press article a few days ago titled Verizon winds down expensive FiOS expansion. Here's a couple of interesting quotes from the piece:

.... Verizon is nearing the end of its program to replace copper phone lines with optical fibers that provide much higher Internet speeds and TV service. Its focus is now on completing the network in the communities where it's already secured ''franchises,'' the rights to sell TV service that rivals cable, said spokeswoman Heather Wilner.

That means Verizon will continue to pull fiber to homes in Washington, D.C., New York City and Philadelphia -- projects that will take years to complete -- but leaves such major cities as Baltimore and downtown Boston without FiOS.

Here's more:

Verizon doesn't appear to have ruled out further FiOS expansion, but doesn't have any plans, either. The economics apparently are not attractive enough: TV service carries fairly low margins compared to Verizon's phone business, according to analyst Craig Moffett at Sanford Bernstein.

And some more:

The recruitment of new FiOS TV subscribers slowed last year. In the fourth quarter, it added 153,000 subscribers, little more than half of the number it added in the same period the year before.

At the end of last year, Verizon had 2.86 million FiOS TV subscribers and 3.43 million FiOS Internet subscribers (most households take both).

Wiring a neighborhood for FiOS costs Verizon about $750 per home. Actually connecting a home to the network costs another $600.

The total cost from 2004 to 2010 was budgeted at $23 billion by Verizon.

In 2004 FiOS seemed like a smart technical decision for Verizon. At the time AT&T was trialing a Fiber To The Node (FTTN) product (now called U-verse) and were having technical difficulties getting it to work. Over the past few years though FTTN bugs have been worked out and both AT&T and Qwest have launched successful implementations.

Back in late 2008 I posted the following question in a blog post Will Verizon Offer A Fiber To The Node Product In 2009?. I stuck my neck out then and said Verizon would in 2009. I was wrong then but I'm thinking I may have missed it by a year. So....... I'm now predicting Verizon will be offering a FTTN product sometime in 2010.

The only other competitive option the company has right now to get into areas not already served by FiOS is 4G LTE (Long Term Evolution) wireless service based. This could bypass land-line delivery completely....... but....... can LTE handle the load?

Some Thoughts on Google's Fiber To The Home (FTTH) Experiment

Last week, Google announced plans to test ultra-high speed broadband networks in one or more trial locations across the country. The company is saying these test networks will deliver Internet speeds more than 100 times faster than what most Americans have access to today, over 1 gigabit per second, fiber-to-the-home connections to at least 50,000 and potentially up to 500,000 people.

The company wants to experiment with new ways to help make Internet access better and faster for everyone. Here are some specific things that they have in mind:

• Next generation apps: Google wants to see what developers and users can do with ultra high-speeds, whether it's creating new bandwidth-intensive "killer apps" and services, or other uses we can't yet imagine.
• New deployment techniques: They will test new ways to build fiber networks, and to help inform and support deployments elsewhere, will share key lessons learned with the world.
• Openness and choice: Google will operate an "open access" network, giving users the choice of multiple service providers.

I like it, I like it a lot. Not because I think Google will single-handedly solve the broadband access and availability problems in our country but, because Google is trying to do things a little differently. High-bandwidth delivery efforts in the United States to this point have worked in some areas but not in others.

A few weeks ago I wrote as far as broadband goes - things have not got much better since 2007 in most of the rural communities in our country - in many places I would argue access today is worse than it was in September 2007. Things have been pretty dismal in many parts of our country. Now maybe we've got a glimmer - just a glimmer - of excitement and (dare I use the word) hope.

From now until March 26th, Google is asking interested municipalities to provide information about their communities through a Request for information (RFI), which the company will use to determine where to build their network. You can get more information on Google's experimental fiber network plans on the Official Google Blog.

Someone is going to figure out how to do this and so far I'm really liking Google's "experiment".

ICT Center Video: The Index of Refraction and Snell's Law

A few years ago, former ICT Center Co-Principal Investigator Jim Downing received a project grant from the National Science Foundation to create a series of Information and Communications Technologies (ICT) hands-on videos. John Reynolds our ICT Center New Media Designer is in the process of converting these videos and posting them on our ICT Center YouTube Channel. Here's the first 8 minute and 37 second video explaining Snell's Law and demonstrating how to measure the index of refraction of a material using some simple optical equipment.

Watch this blog and our ICT Center YouTube Channel for more from this video series.

New Fixed Broadband Subscriber Data Study

ABI Research has a new study out titled Broadband Subscribers Market Data. This study is updated quarterly and profiles subscriber trends categorized by operator, by country, and by technology. Detailed market trends and market forecast information for key regions and countries around the globe are provided where available. The database forms part of the company’s Home Networking Research Service.

Here's some highlights from that latest quarterly report:

The number of fixed broadband subscribers will rise to 501 million at the end of 2014. Of those, about 106 million will subscribe to services delivered via fiber.

Fiber broadband subscribers totaled 44 million at the end of 2009.

The number of fixed broadband subscribers totaled more than 422 million at the end of 2009, a 9% increase from 2008.

Among the three broadband technologies, 65% of worldwide fixed broadband consumers subscribe to DSL, 25% to cable and 11% to fiber broadband services.

The number of fiber broadband subscribers is increasing fastest, showing a compound annual growth rate of 20% from 2008 to 2014.

The Asia-Pacific region has the highest fiber broadband penetration, followed by North America.

Asia-Pacific represents nearly 84% of worldwide fiber broadband subscribers.

South Korea and Japan have the highest fiber broadband penetration.

NTT is the largest fiber broadband operator with approximately 12 million subscribers.

In 2009, Western Europe had only about two million fiber broadband subscribers — a very low penetration compared to North America and Asia Pacific, although Western European countries are planning to accelerate fiber broadband penetration.

You can find additional information in the study press release, linked here.

OECD Statistics: U.S. Broadband Penetration Rate Still Low

The Organisation for Economic Co-operation and Development (OECD) has released their June 2008 international broadband statistics. Here are some of the highlights:

The upgrade to fibre-based connections continues in the OECD. Fibre subscriptions comprise 9% of all broadband connections in the OECD (up from 8% in December 2007).

Fibre overtakes DSL/Cable in Korea and Japan and now accounts for 45% of all Japanese broadband subscriptions and 39% in Korea. Korea’s fibre penetration alone (12.2 per 100 inhabitants) is higher than total broadband penetration in 5 OECD countries.

The number of broadband subscribers in the OECD reached 251 million by June 2008, an increase of 14% from June 2007. This growth increased broadband penetration rates to 21.3 subscriptions per 100 inhabitants, up from 20% in December 2007.

Denmark, the Netherlands, Norway, Switzerland, Iceland, Sweden, Korea and Finland lead the OECD with broadband penetration well above the OECD average, each surpassing the 30 subscribers per 100 inhabitants threshold.

The strongest per-capita subscriber growth over the year was in Luxembourg and Germany. Each country added more than 5 subscribers per 100 inhabitants during the past year. On average, the OECD area increased 2.7 subscribers per 100 inhabitants over the year.

The United States is the largest broadband market in the OECD with 75 million subscribers. US broadband subscribers consistently represent 30% of all broadband connections in the OECD.

Even though the United States has the largest broadband market, our penetration rate continues to be low with a ranking of 15th in the world.

Find all international statistics on the OECD Broadband Portal linked here http://www.oecd.org/sti/ict/broadband

Fiber Deployment Status in the U.S.

The FTTH Council has released an interesting report detailing broadband and fiber to the home deployment in the U.S. Here's some key information points from the report:

Current Status of U.S. Internet Use:

22% No Internet
17% Dial-up Only
61% Broadband (based on the 200 Kbps FCC broadband definition)

Fiber to the Home is being used for services such as television, Internet, telephone, security, and meter reading. Here's March 2008 U.S. data from the report:

11,763,000 FTTH Homes Passed
10,082,065 FTTH Homes Marketed
2,912,500 Homes Connected

Even though coverage is expanding, it is not evenly distributed:

In the U.S. in areas covered by Verizon or Tier 3 ILECS (representing about 1/3 of homes) 5.8% of homes are directly connected with fiber.
In the U.S. in areas covered by AT&T, Qwest or Tier 2 ILECS (representing about 2/3 of homes) 0.6% of homes are directly connected with fiber.
In North America Outside of the U.S., only 0.1% of homes are connected with fiber.

Regarding television (March 2008 data):

8,061,620 homes have been offered television over fiber 1,641,000 homes are currently subscribed to television over fiber

Higher speed data service have yet to be offered widely by providers (March 2008 data):

Only 17,021 homes offered 100Mbps Internet

The FTTH Council has been a strong advocate for 100 Mbps services, urging legislators and regulators to adopt a “100 Megabit Nation” policy and reduce barriers to next-generation broadband deployment.

The overall customer take rates are increasing in areas where FTTH services are being offered and providers are offering a variety of delivery technologies.

The biggest concern of some, including myself, is uneven distribution and the potential creation of a "broadband divide" with broadband "haves" and "have nots" in the U.S.

There is an excellent 32 page presentation from the FTTH Council titled North American FTTH/FTTP Deployment Status in PDF format linked here.

Verizon Demonstrates 100 Gbps FiOS TV Connection Between Tampa and Miami

In a press release today Verizon announced they have completed a 100 Gbps optical communications test between Tampa and Miami, FL. The two cities are 312 miles apart. Here's a couple of quotes from the press release:

Verizon has successfully concluded the industry's first field test of 100 gigabits per second (Gbps) optical transmission, on a live, in-service 312-mile (504 kilometer) network route between Tampa, Fla., and Miami.

The test, which utilized a live video feed from Verizon's national FiOS TV network as the "payload," was successfully completed Friday (Nov. 16). The 100 Gbps transmission was conducted on a Verizon Business ultra long-haul optical system carrying other live traffic at 10 Gbps. The test demonstrated that by deploying advanced electronics, an existing network system can easily and quickly be upgraded to 100Gbps.

The test was done using existing fiber that had been installed for 10 Gbps service. Here's a couple more quotes from the press release:

Unlike other trials that used 10 separate 10 Gbps wavelengths to carry 100 Gbps, the Verizon test utilized a 100 Gbps signal on a single wavelength, demonstrating Verizon's drive to promote "true" 100 Gbps in a serial fashion on just one transmission wavelength.

Like the equipment in the company's 40 Gbps trial in June 2004, the 100 Gbps equipment used in the field trial was implemented with a "plug and play" approach. This is a key objective for future commercial implementation, and means the technology was used without any changes to the fiber, amplifiers and other embedded equipment.

Amazing bandwidth obtained using existing fiber - the trial only swapped electronics using, according to the press release, Alcatel-Lucent's 1625 LambdaXtreme Transport system.