Closing the loop with IP/Optical Integration

I've spent the last 17 years focused on Internet Protocol (IP) over various transport systems - wired (copper), wireless and optical. With the explosion of video, social media and other bandwidth hungry applications we've seen fiber moving closer and closer to the end user. Wireless is the perfect example with towers back-hauled into the network by fiber. It's really just the last mile/final connection that is typically not optical fiber based for most of us.

We're seeing IP/optical integration today really ramping with these things called software defined networks (SDNs). I wrote a post defining and describing SDN's last month titled SDN: When The Hardware Becomes A Little More Soft

With the move to all-IP, SDN and cloud services, many service providers are now integrating IP routing and transport. In this short 4 minute and 50 audio clip, Arnold Jansen discusses how IP/optical control integration can help operators simplify and streamline their operations and drive better cost synergies.



 Smart, fast, efficient. Good stuff.

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.

Storage Tiering

This is another topic I’ve been reading a lot about lately.  Storage tiering uses expensive faster access drives for frequently used data and slower less expensive  access drives for older archive type data. 

Typical fastest level tiers in a data center will use an optically connected fiber channel disk array, followed by Small Computer System Interface (SCSI) attached drives, followed by Serial Advanced Technology Attachment (SATA) drives followed sometime even by tape drives. Tape drives – I know – but yes they are still used - typically to take content completely offline and store.

Mechanical drives have been historically used for the fastest tier but as prices drop and operating systems include better support , we’re seeing a lot of much faster solid state memory devices (solid-state drives (SSDs) and I/O accelerator cards (sometimes referred to as solid-state accelerators [SSAs]) used for the faster level  tiers now.

What’s the difference between a SSD and an SSA? They both basically do the same thing – the only difference is the data interface. 

• SSD’s look like a mechanical hard drive and the server operating system uses standard BIOS calls to access. 
• SSA’s are a little different and use a PCI Express (PCIe) interface. The operating system must use a unique set of software drivers specific to the SSA device being used. 

Because SSA’s use drivers that have been tuned specific to the device, they tend to be a little faster. Both SSD and SSA devices can work together on the same server.

Cloud Computing Closer Look - Infrastructure as a Service (Iaas)

Let’s take a quick closer look at cloud computing today starting with Infrastructure as a Service (IaaS). IaaS is one of the three main categories of cloud computing services. The other two are Software as a Service (SaaS) and Platform as a Service (PaaS) – we’ll cover the last two in later posts.

So, basically an organization (larger or small) outsources equipment (hardware) that can include servers, routers, switches, storage, backup, etc. The service provider handles all of the maintenance, updating, connectivity, etc and the client pays on a per-use basis. Some of the common IaaS components include:

• Billing.
• Automation of administrative tasks.
• Dynamic scaling.
• Desktop virtualization.
• Policy-based services.
• Internet connectivity.

IaaS is a cost effective option, especially for small companies that do not want to invest directly in hardware and staff to maintain it. That’s why it is sometimes (and perhaps more accurately) referred to as Hardware as a Service (HaaS).

Who are the big IaaS service providers? Today it’s Amazon, Google and Microsoft. Security has always been a concern when it comes to cloud-based processes and there are a number of smaller enterprise level companies involved including Adallom, Alert Logic, FireBlade, FortyCloud, HyTrust, Imperva, JumpCloud, and Porticor.

The Rise Of The HetNet

I’m starting to see the term HetNet used in my reading and even had a student ask me for details this morning. That said – I figured it would make a good blog post.

HetNet is short for Heterogeneous Network and is a term currently being used in the wireless world. Most of us are carrying around smartphones with a number of different antennas built in for access via different network technologies. The neat thing about HetNets is they are able to maintain mobile connectivity (no dropped connections) when switching between different wireless connection technologies. 

The three different connection technologies getting all the HetNet buzz right now are LTE, Carrier WiFi, and enterprise femtocells. LTE is 4G cellular service and Carrier WiFi is just WiFi service provided by a wireless carrier. Femtocells are small cell devices that are connected to an Internet broadband connection. 

So HetNets allow a user device to seamlessly switch from network type to network type– LTE to WiFi to femtocell and vice-versa back and forth without dropping a connection. Pretty neat.

Now, not too long ago, it was believed LTE would be the dominant mobile technology and there would not be a need to alternative type technologies like Carrier WiFi and femotocells. But think about it…… there is only a limited amount of spectrum and bandwidth so providers are looking for ways to lower the number of devices per cell. There are also advantages to having users as close as possible to the different types of base stations. 

As a result, we’re seeing providers like Verizon Wireless and AT&T use HetNets to improve the coverage of their network, increase network capacity to match user demand. enhance the user experience, and lower the cost of delivering mobile broadband services.

Online Tracking, Consumer Profiling, Data Collection and You

Well - it's the holidays when we're using the web along with those credit cards a lot more frequently. Ever wondered who's watching you online?  And who the heck you are giving your personal card info to when making online purchases? Ever also wondered if there was anything you could do to protect yourself a little more? Well, others have too.

Abine, a Massachusetts company spun out of MIT in 2008, has developed some pretty nice tools that allow web users more control over their personal data. These accessible tools allow you to choose when you want to share your information, control your personal data, and provide the ability to protect your online privacy. Before we get to the products - here's some interesting tidbits from an Abine fact sheet:

Online tracking, consumer profiling, and data collection are happening wherever consumers go on the web, usually without their knowledge or approval. Consumers are the product being sold. Social networks, ad networks, and e-commerce sites collect every last byte of personal information they can, combining consumers’ online activity with their offline lives. The consequences of all this data collection are growing and real: lost job opportunities, higher prices, more spam, lower credit scores, identity theft, and more. Let's look at some tracking info and stats:

A tracker is a connection that your browser makes when it loads a webpage that’s intended to record, profile, or share your online activity. Usually these connections are made to entirely different companies than the website you’re actually visiting. The most common types of trackers are:

• Javascript: 43% 

• Images, such as 1-pixels: 14% 

• iFrames: 14% 

• Flash cookies: 5% 

Abine collaborates with the UC Berkeley Center for Law and Technology on a recurring Web Privacy Census. The most recent Census found:

• The use of third-party tracking cookies on the 100 most popular websites increased by 11% from May to October 2012. 

If present trends continue, the amount of online tracking will double on about 2.5 years. 

• Google has a presence on 712 of the top 1,000 websites 

• 26.3% of what your browser does when you load a website is respond to requests for your personal information, leaving the remaining 73.7% for things you actually want your browser doing, like loading videos, articles, and photos.

• Google makes 20.28% of all tracking requests on the web 

• Facebook makes 18.84% of all tracking requests on the web 

5% of the top 1,000 websites use social networking code that can match users’ online identities with their web browsing activities, and nearly 25% of the web’s 70 most popular sites shared personal data, like name and email address, with third-party companies (Wall Street Journal, 12/2012).

So... how do you protect yourself?
Abine has just rolled out DoNotTrackMe 3.0, a browser extension that stops online trackers from finding your contact and credit card info.  Here's a DoNotTrackMe sample screen shot.

In addition, the company is giving out unlimited Masked Cards through December 26. The Masked Cards work with any credit or debit cards you have, allowing you to create disposable credit card numbers for each online purchase you make, preventing having to give out your real card info. 

The company also makes a product called MaskMe which keeps you private as you browse and shop the web, and creates and manages secure passwords and DeleteMe which removes your public profile, contact and personal info, and photos of you from leading data sites. 

Cool stuff. Check them all out.

A Family Without A Phone

I probably should be writing something about iOS7 but.... just a minute..... I gave this assignment the first week in a telecom class I'm teaching this semester. The short student essays (I know, not really technically an essay at 200 words) have just blown me away. It's so different today compared to growing up in the 60/70's. Here's what I asked them to do:

Growing up I had a friend who’s family did not have a telephone. His Mom used to whistle (really distinctively and loudly) when she wanted him to come home. When he was over our house or we were out in the woods playing we were all tuned in, listening for her whistle. Everyone knew what it meant and she was good - to this day I’ve never heard anyone who could whistle like her. 

Times have certainly changed. I’ve had almost instant contact with my two children with text and voice over the past ten years. Most recently we’ve all got smart phones and we’ve been able to add email and social media (Facebook, Twitter, etc) to our mobile communications tool list along with video applications like Skype and FaceTime. Although some may disagree, the ability to connect or be connected with them no matter where they are in the world has a level of assurance I know my friend’s whistling Mom did not have 45-50 years ago. 

This week, prepare a 200 word (plus or minus 10 words) essay describing how mobile technology has impacted your life.

My friend's family did not have a television either!

FCC Connect America Fund Phase I Round Two

Last week, the Federal Communications Commission (FCC) posted an interactive map (embedded below) showing the locations where new higher-speed broadband may be deployed as the result of the second round of Connect America Phase 1 funding.

Back in 2011, the FCC launched the Connect America Fund (CAF) and it has had limited success. Round one of funding only dispensed $115 million of $300 million in available funds. I'm not sure why the FCC has had difficulty giving this money out - currently the FCC defines broadband as 768 Kbps downstream and 200 Kbps upstream. In this next round the FCC has decided to offer two levels of subsidy in the current round - $775 per location to bring broadband into underserved locations (where broadband does not exist) and an additional $550 per location (where lower speed broadband does exist) to bring broadband speeds up to 3Mbps downstream and 768 Kbps upstream.

Coverage includes over 600,000 homes and businesses in the United States and the map shows the number of homes and businesses along with the amount of subsidy ($775 or $550) for each location.

Four rural telcos are receiving most of the funds:

CenturyLink - $54 million
Frontier Communications - $72 million
AT&T - $100 million
Windstream - $124 million

Interesting that Verizon Landline (with regional sell-offs over past few years) does not appear to be a rural player any more.

Crowdfunding a Super-Smartphone

Well..... it's been a while since I posted here. I like to think I took a little sabbatical for the past four months. Most of my summer was spent on the road so it feels pretty good to be back at home for at least a little while. Even though I was not posting here I was still keeping up with technology and the business of technology.

Today I wanted to write a bit about a company called Canonical that's run by Mark Shuttleworth. You may not have heard of Mark or Canonical but you probably have heard of a version of the Linux operating system called Ubuntu that Canonical makes. Ubuntu is used on millions of servers around the world - basically big high horsepower computers used to host websites, etc.

Mark has this idea to launch what many call a super-smartphone - basically a tablet computer that has all the functionality of a PC called the Ubuntu Edge.  Now, Mark happens to be a billionaire but decided back in July he wanted to crowdfund the project to the tune on $32 million using the crowdfunding website Indiegogo. Well long story short, Mark failed - at least with the crowdfunding idea. Canonical raised a little under $13 million ($12,813,501 to be exact) of the $32 million Mark was looking for.

The phone that was spec'd sounded pretty nice - a multi-core processor (fastest on the market), at least 4GB of RAM, 128 GB of storage, a sapphire crystal screen (only a diamond can scratch it), a high capacity silicon anode battery, GPS, gyro, accelerometer, proximity sensor, compass, barometer, HDMI interface for TVs and monitors, dual-LTE, dual band 802.11n WiFi, Bluetooth 4, and near field communications.

I found Mark's crowdfunding approach interesting because with Indiegogo there are two options - an all or nothing approach (that's the one Mark picked) or the second option where the company keeps everything pledged whether the stated goal is met or not.

Why did it fail? Mark may have been asking for too much. Donors that wanted to get one of the first phones made were required to pledge at least $725. Initially the campaign set crowdfunding speed records but in the end stalled once the buzz wore off.

Is it over? For Canonical it may be for now. Mark has said he will not use his own funds for the project. But Mark is not the only one with  super-smartphone desires - on July 16 (when I was in Poland right next door) Alexey Miller, chief executive officer of a Russian natural gas exporter called Gazprom offered to pay $3.7 million to anyone who could come up with one.

Crosstalk and Copper Wires

Electrical current flowing through any conductor (like the copper wires connecting his phone) will produce a surrounding electromagnetic field. If another conductor is within the surrounding field, an inductively coupled current will flow through the adjacent conductor.

Inductively Coupled Electromagnetic Flux

In the figure above current flowing through the conducting wire will produce an inductively coupled current in the adjacent wire. If the varying signal current represents a voice transmission the conversation can crossover from one line to another and voices can be heard on one line from another line conversation. Usually this is only an annoyance since crosstalk signal levels are typically low when compared with the signal levels of the conversation on the primary line. On the other hand digital data transmissions are extremely sensitive to crosstalk. Crosstalk can cause bit misinterpretation and will typically require a retransmission of the damaged data.

There are two types of crosstalk, near end and far end.

Near End Crosstalk (NEXT)

Near end crosstalk occurs between a transmitted signal and a received signal. Transmitted signals are typically stronger that a signal that is being received and interfere with the received signals.

Near End Crosstalk

Far End Crosstalk (FEXT)

Far end crosstalk occurs between two signals transmitted in the same direction. The adjacent conductors each produce a magnetic field and can interfer with each other.

Far End Crosstalk

The most common way to reduce crosstalk between adjacent wires is to twist the wires together in a way that cancels the crosstalk flux. That's why Unshielded Twisted Pair (UTP) cabling is used for high speed data cabling like Ethernet. In addition shielding, in the form of foil or metallic braid is also used in Shielded Twisted Pair (STP) cable.

Watching What You Do While You Watch TV

Verizon recently filed a patent application that would target television ads using real time information collected by infrared cameras and microphones in you DVR. This is wild stuff - here's some examples of how this system would work right out of the filed document:

• if detection facility 104 determines that a user is exercising (e.g., running on a treadmill, doing aerobics, lifting weights, etc.), advertising facility 106 may select an advertisement associated with exercise in general, a specific exercise being performed by the user, and/or any other advertisement (e.g., an advertisement for health food) that may be intended for people who exercise. 

• if detection facility 104 detects that a user is playing with a dog, advertising facility 106 may select an advertisement associated with dogs (e.g., a dog food commercial, a flea treatment commercial, etc.). 

• if detection facility 104 detects one or more words spoken by a user (e.g., while talking to another user within the same room or on the telephone), advertising facility 106 may utilize the one or more words spoken by the user to search for and/or select an advertisement associated with the one or more words. 

• if detection facility 104 detects that a couple is arguing/fighting with each other, advertising facility 106 may select an advertisement associated marriage/relationship counseling. 

• if detection facility 104 detects a particular object (e.g., a Budweiser can) within a user's surroundings, advertising facility 106 may select an advertisement associated with the detected object (e.g., a Budweiser commercial). 

•  if detection facility 104 detects a mood of a user (e.g., that the user is stressed), advertising facility 106 may select an advertisement associated with the detected mood (e.g., a commercial for a stress-relief product such as aromatherapy candles, a vacation resort, etc.).

The image posted is also from the patent application and shows the detection zone. 

Pets, people, conversations, moods, beer cans?? I don't think this is something I'd want in my home.

Global Mobile Stats - Google Our Mobile Planet

In a project called Our Mobile Planet, Google's been collecting mobile stats from 27 countries. Dan Swinhoe from IDG Connect Global has picked this data apart and written a very nice post titled The App Revolution: How this Varies By Market. Here's a few interesting tidbits from Swinhoe's excellent piece:

• Japan is the most ‘appy', but Germany is amongst the most keen to pay.
• According to 148apps, the Apple store has 719,452 apps available, and to buy them all would set you back a hefty $1,307,715.69.
• Angry Birds Star Wars is currently dominating the App store charts.
• By the end of the year, over 45 billion apps will have been downloaded - around 15 billion of those from Google, but you can expect Android to take the majority share in 2013 due to the sheer number of devices being sold using the search engine's OS. 
• Microsoft's own appstore is yet to make significant inroads in any market but, depending on the success of its Surface tablet this could well change after Christmas.
• Custom-app building continues to grow, today's estimates putting the average cost of development at around $30-40,000. 
• According to a report by Appaccelerator, Apple has become the chosen platform for enterprise app development, with 53.2% of developers picking iOS for corporate app development.
• In all the charts, no matter what system or country, games feature heavily in both free and paid for.
• While things such as social media and certain business software are now fully-apped, other areas are still a while off. For example media outlets are still struggling to cope with apps (web is still a struggle for many), while the largest programs - CAD/CAM and other large engineering/graphics programs simply are too big and complex for apps and mobile devices. At least for now.

Be sure to check out Dan's full post linked here and also take a look at Google's Our Mobile Project - all pretty interesting stuff.

Memories of September 11, 2001

I first published this four years ago.

I was walking into the office when our technician told me a plane had hit one of the towers - he said "they think it was a small plane" and I did not think too much about it. 20 minutes or so later I was in a meeting and the same tech came in saying it was an airliner. We all left the meeting and turned on a small television in our lab. I also made sure I had a computer close by so I could watch email.......

At the time we were running a national listserv for a large group of community college faculty and administrators involved in a Working Connections grant with Microsoft and the American Association of Community Colleges (AACC). I've pulled out a few emails that came to the list. Here's one of the first from Mete at Borough of Manhattan Community College (BMCC):

11:50 AM, 9/11/01

It is chaos here, but everybody at BMCC is OK. We are closed for the day and the roads/subways to in/out of Manhattan are blocked. I am in Brooklyn (home) now and the sky is dark from smoke/ash/soot. I have a feeling it is going to take a long time to recover from this one.
Hope all is well with everyone around the country,

Mete

BMCC is on Chambers Street, next to ground zero and a college building was damaged from the attack. Mete was on the subway on his way in when the attack started and I believe he walked home to Brooklyn.

Here's a reply message from Lynn at the AACC in Washington, DC::

12:05AM, 9/11/01
We are ok here, but our office is closing so people can try to get home. The smoke from the Pentagon is visible from our 4th floor conference room. Most of the federal offices have now closed, a couple of subway stations near the Pentagon are closed, the streets are crowded with people driving and walking home from downtown offices, and cars with sirens go by every 5 minutes or so. Folks who live near Capitol Hill are sticking around the office until things calm down in that part of town.

Lynn

A flurry of emails went back and forth during the day from people all around the coutry. We were all worried, frustrated and upset about the attacks and our friends in New York, Washington and Pennsylvania. Here's a sample of the response from Paula at Richland College in Dallas:

11:50AM, 9/11/01
Thank you both for taking the time to provide us with an update of your safety. Our prayers are with you and all Americans during this tragedy. As in other states, thousands are donating blood. A major sports arena in Dallas has been setup as a blood donation facility. Churches are conducting special services. Please assist us to remain informed as to organizations/drives that are established that will provide direct support.

Paula

This came from Chris at the Fashion Institute of Technology (FIT) in New York City a few days later:

10:50AM, 9/14/01
FIT is safe and sound and open for business but few classes are running normally. It is hard to describe the experience of walking south on Manhattan's avenues and seeing a column of smoke where the World Trade Towers should be. When the wind shifts, the smell of the fire comes to Chelsea with a light dusting of the cement that is ankle deep a few blocks away.

We are glad to hear that all are well at BMCC and in Washington.

Chris

Here's a followup from Mete that was also sent on September 14:

12:36AM, 9/14/01

The building that we (CIS) dept was suppose to move this Sept., (but did not because of delays) is quite damaged. They are using our main building as command/triage/morgue center. We will be closed until the end of next week. The cleanup is going very slowly and there is very limited access to downtown Manhattan.

The subways are not running and all the outer borough are choked with traffic with people bringing their cars and parking them as close to Manhattan as possible. The air quality is bad, there is possibility that some more buildings (including our own that was next to a collapsed building) may come down aggravating the situation.

There are a number people that I know, with families, that perished in the bombings (we were going go to a 10th bday party this weekend, but the mother is missing - what do we do now ??) from my daughter's school and our neighborhood. But they are defiant, and most of the businesses try to operate as usual with a backdrop of surrealism...

Thanks for all of your e-mails and good wishes. We appreciate it and find comfort in them.

Mete

Hundreds of emails went back and forth over the next few weeks on the listserv. I've saved them all.

Data Transmission on T1 Carriers - Part 2

In Part 1of this topic I described how a T1 carrier is used to transmit data. Data transmission by nature is "bursty" meaning large amounts of information are typically transmitted and then followed by relatively quiet transmission periods. This can cause transmission problems for T-carrier systems since they rely on timing synchronization. Let's take a look how this potential problem is avoided.

87 Million 4G Devices Will Ship In 2012

According to a recent ABI Research report, 4G devices are moving rapidly from the assembly line to retail stores.

Here's some details:

• Refers to a range of 4G-enabled mobile devices, from USB dongles, smartphones, tablets, 4G portable hotspots, and wireless broadband CPE modems
•  4G devices are expected to generate 87 million in unit sales in 2012, up 294% year-on-year.
• 61 million 4G handsets being shipped in 2012.
• 26 million 4G non-handset products (e.g. USB dongles for legacy laptops and netbooks, by premise equipment, home modems, etc) will be shipped
• The lion’s share of the market is now backing LTE as service provider and vendor support has fallen away from WiMAX.
• There is a natural evolutionary demand from 3G end-users, both business and consumer, to jump onto the 4G data bandwagon. 
• Mobile device vendors are experiencing intense competitive pressure, which is expected to bring down LTE handset prices, estimated at 10 to 20 percent over the next two years.

It's not all good though. There are still some big technical issues that need to be worked out including the recent Australian iPad 3 promotion fiasco, when iPad 3s were being promoted as being ‘LTE-ready,’ even though the modem is unable to access the Australian LTE spectrum band. 

In addition, some customers will not be ready this year to pay a premium for 4G handsets and 4G services. 

As a reference, in a February 2012 report Forrester predicted by 2016 one billion people will own smart phones. 

Data Transmission on T-1 Carriers Part 1

Back in December I wrote a post here titled T1 Lines - What They Are. In the post I discuss the Digital Signal (DS) Level System and how combining the equivalent of 24 DS-0 voice channels along with overhead consisting of timing and synchronization bits brings the DS-1 bit rate to 1.644 Mbps - that's a T1. In this post, let's have a look in more detail to get a better idea of how the entire system works. 

The T-1 Carrier uses time division multiplexing and was designed for voice call transmission. When used for data one would think it would be possible to achieve a data bit rate of 64 Kbps over a T-1 carrier. Looking a little closer one sees that data on T-1 carriers is transmitted in the form of only 7 bit words, all eight bits are not used. Why? 

Remember the T carrier system was initially designed for voice. The first signal synchronization used for the T-1 carrier substituted a single in band signaling bit, used for control, for each of the 24 channels in every sixth frame. This means in the sixth and twelfth frames of every T-1 carrier master frame there is a bit used for in-band signaling. This is referred to as bit-robbing. Bit robbing is usually not a problem when transmitting voice. Even though the signal is slightly distorted, the listener on the receiving end cannot perceive the distortion. However this is a major problem when transmitting data as any data received with missing bits will be distorted and received incorrectly. To eliminate the problem caused by bit robbing data on the T-1 carrier is limited to seven bits per frame in all frames. By decreasing the number of bits transmitted the data bit rate is reduced.

For this reason, 56 Kbps Clear Channel Capability is the term used to refer to the T-1 carrier single channel maximum data bit rate.

T-1 Carrier Pulse Cycles

If we look closer at a T-1 Carrier signal we see there are negative and positive pulses combined in the digital pulse train. A sample T-1 signal pulse train is shown in the figure below.

Sample T-1 Pulse Train

It has been found that alternating positive/negative pulse trains (bipolar) produces fewer transmission errors than all positive or all negative pulse trains. These pulses are used to represent binary 1’s and each pulse, when non-zero, is positive half the non-zero cycle (50%) and negative half the non-zero cycle. We can look at an example of a positive (cycle 1) and negative (cycle 4) pulse from the above figure.

Sample T-1 Positive and Negative Going Pulses

In the figure above, T represents the period, or time it takes to complete a single pulse cycle. We can calculate the percent duty cycle using the following equation:

The pulses here are not zero for one half of the pulse period and have a 50% duty cycle. Let’s go back now and look at the original pulse train diagram and look at each cycle:

You can now see that if a pulse is present within a cycle time slot, whether positive or negative, it represents a 1 bit and if no pulse is present, it represents a 0-bit.

In Part 2 of this series I'll cover something called Bipolar with Zero Substitution (B8ZS) for T-1 signal synchronization.

Wireless Shift: LTE Macrocells -> Small Base Stations

I’ve written about femtocells here in the past - basically micro-cell antennas that users attach to their broadband network. They are used to fill in areas where coverage is weak or does not exist. It looks like this idea is catching on. With increasing traffic demands along with OPEX and CAPEX savings in mind we’re starting to see a shift in the deployment of small range cell base stations (what some are calling simply “small cell”). 

Looking at a recent ABI Research report that examines the ecosystem and outlook for LTE base stations titled “The LTE Base Station Market,” we see the uptake of small cells and remote radio heads (RRHs) as elements of the distributed base station. 

Here’s some detail from the report:

• Operators will initially deploy small cell equipment as in fills on the pico and microcell layers, but will quickly transition to deploying them as a fundamental part of a network rollout. 
• The number of LTE small cells sold (127,000) will surpass the number of LTE macrocells, forecast at 113,000, as early as 2014. 
• Semiconductor suppliers are positioning themselves to participate in this market with TI, Freescale, Cavium, Mindspeed, and DesignArt among the manufacturers offering new “base station-on-a-chip” SoCs.
• However, LTE base station revenues will continue to be dominated by macro base station revenue with small cell revenue of $1.09 billion representing only 5.2% of the total revenue of $20.86 billion in 2014 and growing to $4.44 billion or 23.9% of the total $18.60 billion LTE base station market by 2016.
• Equipment manufacturers have been quick to respond to this shift in RAN (Radio Access Network) architecture. Ericsson acquired BelAir networks as part of its “HetNet” initiative, Nokia Siemens Networks announced Flexi Zone, Alcatel-Lucent continues to expand its lightRadio™ portfolio and Huawei has announced its AtomCell products.

Nick Marshall, principal ABI Networks Analyst, comments regarding the report, “This mobile broadband-driven data storm is stretching traditional macrocell network capacity to the limit and driving the move to heterogeneous networks.” Nick continues, saying, “These base station baseband SoCs (System on a Chip) are among the most complex ICs on the market today and raise the bar in terms of complexity.”

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.

Synchronous Optical Network - SONET

Here's another entry for what I've been calling the legacy Public Switched Telephone Network (PSTN) series. In my last legacy post we covered the European or “E” carrier system. Today, let's look at SONET.

In the United States T-1 carriers have been replaced in many locations with Synchronous Optical Network (SONET) systems. Internationally, the SONET equivalent is called Synchronous Digital Hierarchy (SDH). Both SONET and SDH systems consist of rings of fiber capable of carrying very high bit rates over long distances. Copper has been replaced by fiber to inter-connect most Central Offices (CO’s) in the United States at bit rates ranging from the SONET base rate of 51.84 Mbps up to 39,813,120 Gbps. 

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. SONET uses a synchronous structure for framing that allows multiplexed pieces down to individual DS-0 channels to be pulled off a SONET signal without having to demultiplex the entire SONET signal. We can look at a table of SONET bit rates.

[The OC-3072 (160 Gbps) rate level is next in the sequence but has not yet been standardized.]

The OC-1 base is used for all higher level SONET specifications. For example, a SONET specification of OC-48 can be calculated by taking the OC-1 base rate of 672 DS-0 channels and multiplying it by the OC-48 suffix of 48.

We can do the same calculation for the OC-192 specification.

It is common to run SONET rings CO to CO with all SONET connected CO’s having SONET multiplexers that can demultiplex all the way down to an individual DS-0 channel level without having to demultiplex the entire SONET frame. 

In my next legacy post I'll take a look at how SONET is used for packet-oriented data transmission (e.g. Ethernet).

Facebook IT Operations Director: Improving ICT Education in Challenging Times

In January for the past few years, our NSF funded National Center for Information and Communications Technologies has been co-sponsoring a Winter 2012 ICT Educator's Conference in San Francisco in collaboration with the Mid-Pacific Information and Communications Technologies Center. 

This year the conference was held at the Microsoft offices in downtown San Francisco and we were fortunate to have Facebook's Director of IT Operations, Steven Ruggiero as one of the keynotes. Heres his presentation - it's really good.  



Thinking about a technical career or know someone who is? Good stuff for students, parents, educators, guidance counselors, etc.