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.

An Experience With An Intelligent Car

Yesterday I attended an excellent advisory board meeting for a National Science Foundation funded eBook project called E-MATE at Brookdale Community College in Lincroft, NJ. Mike and Kelly are doing some really cutting edge ground-breaking work in the development of electronic instructional materials and it was an excellent meeting. I need to do some writing here about the work they are doing. Today though – I want to write about cars.

Diane was away and I had the chance to drive her car (a 2014 Volvo XC70) back and forth to the meeting. We leased this car in December 2013 and she’s the primary driver.  Yesterday was my first opportunity to take this car solo (solo is the key word here) on a road trip of almost 500 miles. The car is loaded with just about every option including the technology package and I’ve been chomping at the bit to really give the technologies a test, especially after seeing one of the autonomous Google self-driving cars in downtown Mountain View a few weeks ago.

Volvo does not offer a self-driving package (yet) but my experience - it is pretty darn close to self-driving with the technology package that adds adaptive cruise control, automatic high beam control, frontal collision warning, automatic braking for frontal collision crash mitigation, a driver inattention monitor, blind-spot warning system, active xenon headlights, and lane-departure warning to an already incredibly safe and comfortable car.

Now - driving from Massachusetts to New Jersey on a weekday is always an experience – New York City cannot be avoided unless you want to add hours to the trip and that means bumper-to-bumper traffic, crazy drivers and lots of intense time behind the wheel.

I was so impressed with the car – stop and go for at least a couple of hours and no need to hit the brakes or the accelerator. It took some time to get used to – I had to “trust” the car but once I did – amazing! An alarm that goes off if the car starts to drift outside the lane (unless a directional has been used). Sensors that monitor and determine whether the driver is becoming tired and inattentive. Cameras that watch for speed limit signs and indicate when the speed limit has changed. A blind spot warning system that indicates a car is coming up from behind on either side. Sensors that monitor oncoming traffic and control high beams.

Does the car drive itself – no – not yet but it is pretty close. Did I push the technology? I don't think so. I let the car do what it is designed to do. What did I do? I pretty much steered and adjusted the cruise control up and down. I did not have to use the accelerator or brakes unless I wanted to on the highway, whether I was going 70 mph or in a stop and go traffic jam.

As an FYI Volvo in 2017 will start testing 100 "production-viable" autonomous self-driving cars in Sweden with real drivers like you and me. These test cars have 28 cameras, lasers, sensors, and radar units along with integrated computers and communications systems that make up the self-driving system.  How soon will we have the chance to purchase a self-driving car? Right now it is looking like 2020.

With my new position at the Center for Optics and Photonics Education and my past position at the Information and Communications Technologies Center, cars (and a lot of other devices) are really hitting a sweet tech spot for me. Infrared lasers, optical sensors, integrated GPS, radar and cameras collecting large amounts of data, onboard computers processing the data, communicating back to the car and driver and making intelligent "pretty-big-data" decisions. Super cool stuff and I’ll be writing over the summer about some of these individual technologies and how they work.

Now for me – it is back to my older Toyota product with none of the car sensor and intelligent technologies (it does have a back-up camera and Bluetooth). I have to remember when I’m driving my car all of the “intelligence” is up to the driver. Ohhhh Noooo :)

Pushing Optics Closer to the CPU

There's something very important I forgot to tell you! Don't cross the streams… It would be bad… Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

—Egon Spengler (Harold Ramis) on crossing proton streams, Ghostbusters

Well.... as we learned later in the movie, crossing streams is not always a bad thing.... As part of my work with the National Center for Optics and Photonics Education (OP-TEC: www.op-tec.org) I've been spending a lot of time learning new technical content while still staying current in the computing and communications field. I've been reading (and tweeting) recently about pushing optics closer and closer to the processor in computing systems. Here's more.

Last week, IBM announced the integration of a silicon photonic chip on the same package as a CPU. Why is this important? A couple of reasons -  if on-chip and chip-to-chip communications can use silicon as an optical medium, processing will be significantly faster, consume much less power and produce much less heat than the copper wires used today.

Extreme Tech published a nice diagram (below and based on the IBM announcement) last week showing the current state of silicon photonics technology. Notice the optical connection is currently at the board edge. With this IBM breakthrough, designers will begin to start moving the silicon photonics array closer and closer to the CPU, eventually building the optics into the CPU package itself.

The technology will initially be limited to the world of supercomputing but it will only be a matter of time before we see it trickle down to consumer level devices like PC's, tablets and smartphones. 

I love it when streams converge.

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.

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?

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.