20 Dec

Wireless Sensor Networking: Where it all began for Millennial Net

Posted by Dr. Sokwoo Rhee in Medical, Networks of Devices. Tagged: , , , , , .

Millennial Net has been in the business of developing top-notch wireless sensor network technologies for more than a decade.  Today, Millennial Net provides one of the most advanced wireless sensor network technologies in the world under its MeshScape® brand, and is also a major player in the wireless energy management solution market. Millennial Net’s EMS (Energy Management Solution) products, including its wireless pneumatic thermostat, are widely used in many commercial and industrial buildings around the world.

But where did it begin?  Now, I think, it is meaningful to look back on how we started all this.

Back in 2000, I was a grad student working on a biomedical sensor.  It was called “Ring Sensor”.  It was a finger ring type of sensor that people could wear all the time for continuous health monitoring.  Most of my time then had been spent on developing optical sensors to capture clear and reliable signals from a person’s finger in order to monitor vital signs.  After several years of hard work, the sensor part was almost completed.  Next, I needed to work on a way to send and receive data from the sensor.

Ring Sensor included a small coin battery, RF transceiver, CPU, and optical sensors to capture and analyze vital signs.  As you can imagine, all these components had to be miniaturized due to the fact that the device was meant to be worn on a person’s finger, like a ring.  Obviously, all of the components needed to be extremely low power too, since it was not possible to carry around a car battery dangling from a finger ring.

The application scenario was a nursing home.  Imagine a nursing home apartment complex with hundreds of elderly people in residence wearing this “Ring Sensor”.  The sensor would monitor the vital signs of each person continuously, 24 hours a day.  The data would be gathered in a central database and analyzed in real time.  If there was any sign of an abnormal health situation, the system would trigger an alarm and nurses would be informed.

It was impractical to assume that the residents in this scenario would be willing to frequently replace batteries.  The small coin battery had to last at least months or, preferably, years, which meant the whole sensor, including wireless communication, had to run continuously on extremely low power.  Therefore, low power consumption of the wireless link was a very important requirement.  For instance, the residents would move around in the building and might even leave the building for periods of time.  The wireless link would have to be able to dynamically adapt itself to the changing environment, but keep the communication alive, and, since there might be hundreds of people wearing this sensor in a building, the wireless system needed to be capable of handling hundreds of sensors in the network simultaneously.

I tried to find existing wireless communication technology that could satisfy these demanding requirements.  I thought there must be something out there.  To my surprise, I was not able to find any off-the-shelf wireless products that could satisfy the requirements.  None of the available products I researched even came close.

Then I started thinking.  As time goes by, there are going to be more and more sensors in the world.  The number of sensors and sensor applications will only grow, and when there are so many sensors in our everyday life, how are they going to be connected?  One thing I clearly realized during my biomedical sensor research was that a sensor itself was not very useful unless the data captured from the sensor could be made available for analysis.  In many cases, sensor data would need to be gathered and analyzed together at a remote site.  Sometimes sensors themselves would need to talk to each other.  If there are many sensors in the world, there will be also many actuators.  At some point, the sensors and actuators will need to communicate with each other too.  How are they going to do that?

This was a very interesting question, and I became quite intrigued, so, I started developing what I called “network of devices”.  The network had to be self-aware and should not need much human maintenance.  After all, at the end of the day, it would be a “network of devices” and it would not make any sense if a human being needed to spend a lot of time maintaining the network.  The network must be extremely adaptive and low power, and it had to adapt itself to whatever changes it saw.  The network should be like a living thing!

With help from my academic advisor, my colleague Dr. Sheng Liu and I started a company to further develop an adaptive wireless network of devices.  Hence Millennial Net was born!

Nowadays the terms “wireless sensor network” or “wireless mesh network” are quite common, and many technical people understand what they mean, however; back in 2000, that was not the case.  In most of the meetings we had with VCs and prospects, we had to spend a significant amount of time educating the audience about what the sensor network was and how it worked.  It was such a new concept that a very small number of technical people even understood the idea.

Now fast-forward to 2011, WSN is a well-known concept and many applications and business opportunities are arising every day.  I am so happy to see this happening.

The WSN industry is not mature yet.  There are a lot of things yet to do, and a lot of room to grow.  It might be taking a bit longer than I expected, but I am happy to be in the center of this hot new industry with limitless potential for the future.

7 Nov

What will Happen when Devices are Connected?

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , , , .

In a previous post, I listed a few points that I would like to see addressed by the Android@Home initiative by Google.  After all, if we assume for a moment that the world will truly change through the Android@Home or similar initiatives, and all devices will be rapidly connected, what will happen then?  In other words, what is the point of connecting all devices?

To answer this question, we need to look back on the history of communication technologies and why people have used them.

During the last 100 years, there have been many advances in communication technologies.  Among them, the most significant two advances were, arguably, the telephone and the internet.  The telephone allowed people to communicate with each other via voice.  Internet allowed people to communicate with each other via data.  Essentially, the telephone service created a “network of voices” and the internet created a “network of computers.”

The network of voices enabled people to share information one-to-one. The internet, enables people to share information, many-to-many, much faster and more efficiently than the telephone.  Each time a new communication technology was invented and adopted, the goal was to enable more people to share more information faster and more accurately.  As more information often means more power and advantage in business, education and everyday life, people will always be eager to adopt advanced communication technologies to more acquire information.  These are the reasons Google, and the internet as a whole, have become so successful.

Now, if and when the latest communication technologies connect all devices, what can people do with it?  There are many things, but to cite a couple, people can turn on lights remotely (which we can do today), and control building energy consumption efficiently and economically (which is becoming more and more popular).  However, the most important benefit is something different.

As of today, people must “search” to find the information they want.  Companies like Google are very successful in providing this service and running business with it, and people use Google search engine because they want to find information reliably and quickly – possibly faster than anyone else finds it.  That is the key.  People want to find and access information faster than others, but there is a limitation that this approach cannot overcome.

For people to want to find information, they first have to realize that they need it.  After realizing they need it, they have to spend time searching for it, and after spending a lot of time on the search process, they may not find enough or even correct information.

So, what’s the next step?  People should not have to find information. Information should find people.  Information should actively get to people even before they realize they actually need it.

Today, information is stored in many servers around the world, and people log onto these server islands to find what they need.  These server islands are part of an “information-centric” architecture.  However, in the world of connected devices, each person could become the center of the ocean of information and information could automatically arrive at the person who is supposed to need it.  One great example of this approach is “push email”.  Instead of people “checking” emails every day, emails are pushed to us. (i.e. Emails find us.)

In a world of truly connected devices, information from devices surrounding a person will automatically report to the person.  In the battlefield, sensors and actuators will feed information to every soldier before he/she even realizes the need.  Whenever a soldier moves, the “circle of information (COI)” will move along with the soldier, and any information that comes into the circle of information will be captured and supplied to the soldier to aid him/her to make the best decision possible at the given time.  For instance, soldiers will be informed any threats lying ahead in their path.

In commercial buildings, people will walk around and devices will automatically “talk” to the people who walk into the circle of information, but only to the people who need or want the information.  People will be able to know what is coming up in real time in the real world via wireless sensor networks.  They will be able to know how many people are on the other side of a door before walking into a room.  By receiving information from your surroundings, you will be able to make more efficient and informed decisions. The devices around you will collectively understand your intent and assist you wherever you go, by providing necessary information in advance.

Maybe it sounds too much like a Sci-Fi movie, but we are not very far from this future.  The Siri application recently included in iOS5 from Apple is a great example of how we can get closer to this future. Imagine Siri starts proactively providing real-time information to the user inside the COI, not just responding to the requests from the user. It can be a huge step forward to the true world of connected devices.

The future is nearer than a lot of people think.

16 Sep

Wearable Technology in Medical Applications

Posted by Dr. Sokwoo Rhee in Medical, Networks of Devices. Tagged: , , , , , , , , .

A couple of weeks ago, I had a chance to participate in a panel discussion at 2011 IEEE EMBS conference.

For those who may not be familiar with EMBS (Engineering in Medicine and Biology Society), it is one of the largest and most prestigious societies of biomedical engineers and scientists. It is a division of IEEE (Institute of Electrical and Electronics Engineers). Just like any other division of IEEE, the group hosts many conferences and events in its area of expertise. This year, the annual conference was held in Boston and it had a mini-conference focused on wearable technology for medical applications. (Technically, it was called “Un-conference”. Instead of traditional conference format of giving one-way presentations to the audiences, this format allowed the participants to actively engage in the selection of topics and bi-directional discussions.)

There were many discussion topics including technology development, legal issues, role of government, availability of funding, etc. But at the end of the day, the main theme was “How can we get wearable technology in medical applications more widely accepted in the market?” Ironically, the mere fact that the conference was focusing on this theme already implied that the industry had not found a breakthrough in making wearable technology widely adopted within the mass market.

There were discussions about the difficulty of getting funding for research and development. There were lots of discussions regarding how the government needs to act to bring down the legal barriers for wearable technology in the medical market. And there was a particularly interesting panel discussion.

Dr. Ravi Ramachandran from Vertex Pharmaceuticals made an interesting comment. He was from the pharmaceutical industry and his assessment of the current status of wearable technology in medical applications was a typical example of “a solution looking for a problem”. He compared it to pharmaceutical industry, where the problems already exist (i.e. diseases) and the effort is focused on finding solutions for the existing problems.

I had to agree with him, but to only half of his comment. From my view, it is not like there is no problem to solve, that we are aware of. We know many problems that can be solved by the concept of wearable technology. However, the current state of technology is so limited that people are having a hard time finding problems that can be solved by the existing limited wearable sensor technology, and making it a “success” story. This is not necessarily the issue of “wearable” or “communication” technology. Rather, it is more a question of “How practical and useful can today’s wearable sensor technology be in real everyday life?”

For example, I saw a lot of demos of “wearable EKG” and “wearable heart monitoring” devices, mostly from academic research. I understand these types of new devices can help reduce the number of wires in ICU and other hospital settings. However, in ICU and many hospital settings, it is already assumed that patients are less mobile in controlled environments. Also, the patients may need to be connected to other types of life-supporting systems such as an oxygen mask. In this environment, I am not quite sure how much additional benefit “wearable technology” can provide.

The real market for wearable technology, in my opinion, is ambulatory monitoring for in-home healthcare. However, the requirements for useful wearable medical sensors in home healthcare are much more difficult to fulfill. As I already stated in my previous post, the current status of wearable sensor technology is simply not at the point where it is attractive to mass market.

In the panel discussion, I brought up the example of the hype of wearable non-invasive glucose monitoring sensors for long-term monitoring (see my previous blog for details) which never got successfully realized up to the commercial level, although there were some recent progresses in laboratory environments such as this research from MIT. There were people in the audience who seemed very interested in this concept. This is a kind of wearable sensor that will surely appeal to the mass market if it can be made reliable, convenient and affordable. Unfortunately, existing technologies cannot meet these requirements yet. Everyone knows glucose monitoring is a huge market. Everyone knows this is a problem (or inconvenience) that should open up a huge business case if it can be solved. So, we know the problem. We just don’t have a decent technical solution today.

So, what should we do? Should we simply give up since we know we are not there yet?

During the recent legal dispute between Samsung and Apple, an interesting story came out. Samsung argued that Apple’s iPad tablet computer and its design was not a new idea. As a proof, Samsung attorneys brought up a screenshot of a movie made back in the 1960’s, which showed a person using a gadget similar to today’s iPad. Yes. iPad was already “invented” more than 40 years ago. We all know the concept has existed for a long time. However, without the numerous efforts (or “failures”, you might call them) that did not blossom over the last 40 years, today’s iPad would not exist. Without Microsoft’s early efforts for tablet PCs, which did not really take off, iPad would not exist today. Without the early failures of Apple’s Newton device, iPhone would not exist.

So, what does history tell us? The day will come when we will all enjoy the beauty of wearable sensors, as a part of the world of connected devices. But that day cannot come unless we keep trying and learn from the failures, just like any new technology and market. We need to continuously push the limits and stay on top of the cutting edge – and that is what Millennial Net does in WSN world.

23 Aug

Issues in Healthcare Applications of Wireless Sensor Network

Posted by Dr. Sokwoo Rhee in Medical, Networks of Devices. Tagged: , , , , , .

Millennial Net has a long history of applying wireless sensor network technology to healthcare and medical applications. (We will get into more details of the history in a separate blog.) Healthcare/medical application was probably one of the most promising applications that early WSN pioneers thought to be a great fit to wireless sensor technology. It was easy to conceive of a scenario where patients carry a sensor that can detect health-related parameters (including glucose level, heart rate, etc.) and monitor the patient continuously via wireless network. Some researchers imagined a scenario where many sensors are placed on human body, wirelessly connected and sharing information. There is even a name for the concept – BAN (Body Area Network). The concept was conceived and demonstrated more than a decade ago in both academia and industry. However, we still do not see many successful products generally accepted by the mass market. Why is this?

Some people say the biggest drawback is the lack of a “standard” to increase customer adoption of WSN technology in healthcare/medical field. Others say that the strict approval process dictated by a government agency (notably FDA) is the problem, but my view is somewhat different. The lack of a standard or a slow government approval process is not the “cause” of less-than-impressive adoption of WSN technology in healthcare/medical field. It is more a “result” of the reality.

For a new technology to be adopted by the mass market, it has to be proven that the new technology offers a significantly higher benefit than existing technologies. The benefit must be so significant that people are willing to put up with any inconvenience that comes with the new technology. The inconvenience may be in many forms, including additional financial obligations and even taking the risk of possible side effects. If the technology is not advanced enough to provide tangible benefits to overcome the “inconvenience”, most likely it will just remain a “technology” instead of a “business opportunity”. In some cases, the technology is very much advanced, but not enough for a specific application, so it is hard to provide any tangible benefit for the application.

From this perspective, the concept of remote healthcare using wireless sensor network (or wireless technology in general) may not be in the position to change the way people use medical devices or sensors yet. The issue may not be the WSN technology itself. Rather, it may be other factors such as battery technology, sensor technology, ease of use, or all of the above.

There are a few different categories for wireless medical devices. Some of them are designed to be used only within the confines of relatively controlled environments (such as hospitals) where a medical staff is available. Other devices are designed to be used in an environment where little or no immediate medical attention can be provided. Although wirelessly enabling in-hospital equipments can be an interesting discussion topic, I will first discuss wireless medical devices that people can use in everyday life to continuously check their health status. This is called “ambulatory health monitoring”.

Just as there are several fundamental requirements in wireless sensor network technologies, there are many important technical issues that need to be addressed in wireless medical devices for ambulatory health monitoring.

Take battery life for example. Most users of ambulatory health monitoring devices will either be patients or elderly people who may not be very happy to replace or recharge batteries everyday. Unlike cell phones which you can simply put on a charger before going to sleep, most ambulatory health monitoring devices must work continuously, 24 hours a day. Some devices may need to be implanted in the body and the batteries cannot be easily replaced. So, it is critical that the wireless medical devices should operate for a long time without replacing or recharging the battery. In practice, this means that many wireless medical devices must work with small-sized battery (such as a coin-sized battery) and should last for months or years.

Sensor technology is another issue. Let’s take glucose monitoring for example. Glucose monitoring was probably one of the most hyped applications for ambulatory health monitoring. Unlike most “invasive” approaches to take glucose measurements today, it was promised that more advanced “non-invasive” glucose sensors would be coupled with wireless technology and provide 24-hour continuous glucose monitoring for the patient. There has been tons of research and development in both academia and industry about these non-invasive glucose sensors (based on optics, ultrasounds, electro spectroscopy, etc.), and some of the results have even been productized. However, the reliability of these non-invasive glucose sensors is still far behind the traditional finger-stick measurements to be used in everyday life. The same issue exists in blood pressure monitoring. There have been hypes of continuous blood pressure monitoring technologies for decades, but none of the technologies have been commercially successful yet, especially not in the form that people feel comfortable wearing continuously.

In addition, there are more technical issues such as “motion artifact”. Ambulatory monitoring devices need to work while the user carries out normal everyday life activities. Many sensors used for ambulatory monitoring rely on either the optical or electrical properties of the human body. When the human body moves, the sensors may be subject to noises and artifacts caused by the motion. Since most of the sensors used for ambulatory monitoring are very sensitive, it is a big issue to make the device work reliably under different physical conditions, especially when it is worn by a person during normal everyday life.

Last but not least, the ambulatory health monitoring device must be comfortable to wear. Ideally, the user should not feel that a special device is on them. As soon as the user starts feeling the “existence” of the device attached to the body, there will be a psychological and/or physical impact on everyday life. Although some level of inconvenience can be acceptable, it should be minor enough that the user does not need to feel burdened.

For wireless technology to seriously contribute to medical applications, many other technologies such as sensors for ambulatory health monitoring should come together. Once the necessary medical sensing technologies are available and mature enough to make ambulatory health monitoring attractive to mass market, it will be natural to combine the sensors with wireless networking technology. Until then, the discussion of standards for wireless technologies or FDA approval process may not have a lot of impact on the market adoption. In short, sensing technology has to come first before wireless technology for wide-spread adoption of wearable, ambulatory health monitoring technology. As of today, it does not seem that this is the case.

4 Aug

Finding A Killer App For Wireless Sensor Networks

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , , , .

In a previous post, we discussed about the dilemma of “killer-app” for wireless sensor networks. Now that we understand the difficulty of finding a killer-app, what should we do to increase the chance of creating or discovering the killer-app for wireless sensor network? Does it even exist? What do we have to do to get closer to it?

First, we should not be buried in the technology, but should look at WSN from the eyes of typical consumers.  We should be able to see WSN as a “tool” to make our lives easier, more convenient, and more secure.  Unless we find real applications that can truly and significantly benefit our lives, WSN will be just another great technology without a home.

At the end of the day, simply connecting all of the devices in the world has no value to people unless it benefits people.  Even though the hot topic today is internet of “things”, it must be human beings who eventually perceive the benefit, not devices.  When consumers become engaged and excited, when they see the value of an application, they will begin to “pull” the application in the market, creating demand.  Then we will know that we have a true killer app.

From this perspective, it is difficult to find a WSN application that has yet reached “killer app” status, even including the much-anticipated smart grid application. Energy management market has a great potential as was shown in an example, but it will take time to see if it is a true killer-app for wireless sensor networks. Google’s recent announcement is interesting. But it still remains to be seen if Google truly understands what it takes to make a wireless sensor network application successful.

As we discussed before, today’s conventional WSN technology is still not enough to implement the “dream scenario” of the future world of connecting “everything”.  Consider where the WSN idea first came from.  Twenty years ago, DARPA imagined spreading a bunch of “sensors” from helicopters to be used for surveillance in the battlefield. As of today, even this seemingly “simple and useful” application does not yet have many reliable solutions. However, there remain many applications that can be implemented using existing advanced WSN technologies, and several more advanced WSN technologies such as MeshScape are showing up to address shortcomings of conventional WSN technologies such as Zigbee. We just need to apply the right “existing” technology to the right application under the right circumstances.

The future will come when “everything” is connected, just as “Internet of Things” hopes for, but that future will not automatically materialize. We must continue to make progress with WSN technology.  The vision of a connected world will only be realized when real applications with tangible benefits to consumers gain momentum and reach a boiling point.  No one can pinpoint exactly when this will happen, but just as we keep making progress, the day will eventually come when everyone in the world will benefit from WSN/IoT technology.

27 Jul

Where Should Google Go with Android@Home? (Re-posting)

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , , , .

(This is simple a re-posting of the latter part of my previous post. If you have read it already, you can skip this article, or you can certainly enjoy reading it again!)

So, what is the right approach for Google’s Android@Home?  It may be as simple as following or repeating what Google has done with Android smart phone.  The wireless sensor network (WSN) platform used by Android@Home should provide highly robust and reliable data link as well as rich and easy API (Application Programming Interface) to the application developers, and leave it at that.  Application developers should be given ultimate freedom to come up with as many crazy applications as they can without worrying about the robustness of the wireless network platform, and their imagination and innovation should not be limited by authorities of “profiles” defined by one company or organization.

Why is this important?  Because of where WSN industry is at the moment.  In a  separate blog article, I explained the importance of “killer-apps” for WSN.  As mentioned in the article, the industry has not yet found a true “killer-app” for WSN, even if many experts have been looking for one for more than 10 years.  To find (or nurture) a true killer-app, we should be able to develop and test as many applications as possible in the market.  You cannot come up with a “profile” behind closed doors of an alliance and expect a killer-app to suddenly emerge out of nowhere.  The market needs to test as many WSN applications as possible and a true killer app will emerge.  For this, the WSN platform at the application level must be as easy and open as possible to application developers.

Another important factor is that Google should pay attention to the participation of as many hardware manufacturers as partners.  Actually, Google can learn from its own experience of less-than-expected performance of PowerMeter program due to the lack of participation from utilities.  On the other hand, I am sure Google has already gone through this process successfully while growing the Android handset market.  However, the issue in the home automation market may be somewhat different.  In the smart phone market, there exist relatively small number of major players such as Motorola, Samsung, HTC, and LG.  Google simply had to cut deals with a handful of mega-manufacturers and support them.  In home automation market, there are many more players than with the smart phone.  The home automation market is much more fragmented and the requirements are much more diverse.  Therefore, Google must be prepared to deal with a higher number of partners with more diverse requirements.  From a technical point of view, this means the Android@Home platform must be as agile and self-supporting as possible.  It also means that the platform must be very reliable and scalable from the beginning.  Unlike smart phone, WSN-enabled home automation devices will be relying on each other for continuous operation.  For example, when your smart phone stops working, it does not affect the operation of your friend’s smart phone.  In WSN-enabled networks one troubled device may affect the operation of other devices.  This is where reliable mesh network capability as well as other requirements are crucial for Android@Home platform.

Finally, Google must think about how it can expand Android@Home beyond a mere home network platform.  Building home networks should not be the ultimate goal.  The ultimate goal should be to connect all the devices in the world reliably and safely to benefit people as a whole.  I encourage Google to spend a serious amount of time thinking about how to create real value for people by connecting devices as well as spending time thinking about how to connect devices.

Eventually, devices will be networked and they will all talk to each other.  The devices will be “friends” to each other and will work together. The air conditioner in my family room will be sharing my temperature preference information with my car.  I am sure a smart phone will be at the center of the connected world.  Now, the important question is this : When everything is connected, what will it do for us?

(I am planning to write a blog post for this question. Stay tuned.)

Update : See my article “What will Happen when Devices are Connected?” for my answer to this important question.

25 Jul

Where Should Google Go with Android@Home?

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , , .

Google seems to be doing many things at the same time.  In addition to its core business of advertizing by search engine, Google is/has been working on social networks (Buzz, Google+), emails (Gmail), software-as-a-service (Google Doc), library (Google Books) and many others.  In addition to the more established services, Google also has (or had) many experimental projects – robotic cars, Google PowerMeter, etc.  Although it is generally understood that Google’s core business is search engine, one can see that they are trying many things beyond their traditional comfort zone.  I understand that this is what big companies tend to do – like GE’s diverse projects – but sometimes I cannot get away from the feeling that Google is trying too many things at the same time without fully understanding the nature of the projects it is jumping into.

Now, Google has added yet another project to their list: the Android@Home initiative.  As expressed in a previous post about where Google appears to be going with this initiative, I think it is a great idea and I believe this is kind of thing Google should be doing.  However, to make this initiative successful, Google should carefully review what happened with their previous successful projects (like Android for smart phone) and those that were not as successful (like Buzz or PowerMeter).

There are many reasons why Android has been a big success.  First, the technology worked. This is usually the very first and most important concern. Yes, there have been many complaints about the “immaturity” of initial versions of Android, but at the end of the day, Android was significantly faster and easier to use than other competing outdated smart phone OS.  Android is an open platform – open to the point that the source code is open which means it is free.  Smart phone developers do not need to pay for using Android other than perhaps technical support from Google.  Android also has easy-to-use application programming interfaces so that many developers can easily come up with numerous interesting applications.  The first wide-spread operating system for smart phone was not Android or Apple’s iOS.  They were Nokia’s Symbian and Microsoft Windows Mobile 5.0, which eventually disappeared from the market due to its heavy overhead, its closed platform and slow speed, and complicated programming environments.  In the home networking/automation market, there are already several existing wireless technologies that look much like Microsoft Windows Mobile or Symbian.

Let’s take Zigbee as an example. In addition to its technical limitations, although Zigbee claims it is an “open standard”, it is not difficult to see that it is actually very much like a closed system once you look into its architecture.  Zigbee defines everything from low layers (PHY, MAC, NET) up to top application layers (Profiles).  In other words, if someone comes up with a “crazy but innovative application”, it cannot be easily and widely adopted on top of Zigbee unless Zigbee Alliance endorses the application by authorizing a “profile” for the application.  Basically, Zigbee standard defines pretty much everything from top to bottom. Although this approach may help promote its claim of interoperability (which is not yet proven at the end-product level) it may actually hinder innovations.

So, what is the right approach for Google’s Android@Home?  It may be as simple as following or repeating what Google has done with Android smart phone.  The wireless sensor network (WSN) platform used by Android@Home should provide highly robust and reliable data link as well as rich and easy API (Application Programming Interface) to the application developers, and leave it at that.  Application developers should be given ultimate freedom to come up with as many crazy applications as they can without worrying about the robustness of the wireless network platform, and their imagination and innovation should not be limited by authorities of “profiles” defined by one company or organization.

Why is this important?  Because of where WSN industry is at the moment.  In a  separate blog article, I explained the importance of “killer-apps” for WSN.  As mentioned in the article, the industry has not yet found a true “killer-app” for WSN, even if many experts have been looking for one for more than 10 years.  To find (or nurture) a true killer-app, we should be able to develop and test as many applications as possible in the market.  You cannot come up with a “profile” behind closed doors of an alliance and expect a killer-app to suddenly emerge out of nowhere.  The market needs to test as many WSN applications as possible and a true killer app will emerge.  For this, the WSN platform at the application level must be as easy and open as possible to application developers.

Another important factor is that Google should pay attention to the participation of as many hardware manufacturers as partners.  Actually, Google can learn from its own experience of less-than-expected performance of PowerMeter program due to the lack of participation from utilities.  On the other hand, I am sure Google has already gone through this process successfully while growing the Android handset market.  However, the issue in the home automation market may be somewhat different.  In the smart phone market, there exist relatively small number of major players such as Motorola, Samsung, HTC, and LG.  Google simply had to cut deals with a handful of mega-manufacturers and support them.  In home automation market, there are many more players than with the smart phone.  The home automation market is much more fragmented and the requirements are much more diverse.  Therefore, Google must be prepared to deal with a higher number of partners with more diverse requirements.  From a technical point of view, this means the Android@Home platform must be as agile and self-supporting as possible.  It also means that the platform must be very reliable and scalable from the beginning.  Unlike smart phone, WSN-enabled home automation devices will be relying on each other for continuous operation.  For example, when your smart phone stops working, it does not affect the operation of your friend’s smart phone.  In WSN-enabled networks one troubled device may affect the operation of other devices.  This is where reliable mesh network capability as well as other requirements are crucial for Android@Home platform.

Finally, Google must think about how it can expand Android@Home beyond a mere home network platform.  Building home networks should not be the ultimate goal.  The ultimate goal should be to connect all the devices in the world reliably and safely to benefit people as a whole.  I encourage Google to spend a serious amount of time thinking about how to create real value for people by connecting devices as well as spending time thinking about how to connect devices.

Eventually, devices will be networked and they will all talk to each other.  The devices will be “friends” to each other and will work together. The air conditioner in my family room will be sharing my temperature preference information with my car.  I am sure a smart phone will be at the center of the connected world.  Now, the important question is this : When everything is connected, what will it do for us?

Update : See my article “What will Happen when Devices are Connected?” for my answer to this important question.

 

19 Jul

Saving Energy in Schools – Tyngsborough High School

Posted by Dr. Sokwoo Rhee in Energy Management. Tagged: , , , .

In this slow economy, many organizations are facing less-than-ideal budget situations, and  educational institutions are not exceptions.  An increasing number of schools are feeling financial pressure and while budgets are being cut, the cost of many indispensible items just keeps rising; among them, the cost of energy.  Whether it is electricity or heating oil, energy usage consumes a substantial portion of a school’s annual budget.

A significant number of educational institutions are housed relatively old buildings.  Few of these buildings have advanced building management systems with the capability of effectively minimizing energy costs.  In some instances, the HVAC systems of these buildings are simply not designed to work with conventional building management systems, i.e., pneumatic heating systems.  Many school buildings with pneumatic heating systems run heaters and boilers almost 24 hours a day during winter months, as there is no easy way to effectively enforce energy policy.  We’ve all heard the stories, or have experienced ourselves, classrooms in which teachers have had to open windows in the winter because the classroom was too hot and the thermostat was covered with plastic box to prevent anyone from changing its settings.

Of course, one solution for energy efficiency, control and comfort in old school buildings could be to rip out existing HVAC systems and install new, advanced systems with state-of-the-art building management.  However, this approach can be too invasive and, in the current economic climate, prohibitively expensive; especially if a building’s HVAC is based on a pneumatic heating system.

Tyngsborough High School was facing a similar situation.  Their energy costs were soaring, their heating system was inefficient, and teachers and students were not very happy with environmental controls or the comfort of the classrooms. The school had to find a cost-effective way to enforce an energy policy without huge capital investment.  Millennial Net worked with Tyngsborough High School to install its Wireless Energy Management Solution (Wi-EMS) in answer to their challenges.

One of the benefits of Millennial Net’s Wi-EMS that Tyngsborough High School has since experienced is its ability to control the heating/cooling of individual classrooms.  With the old system, classrooms could have different class schedules, yet they were all being equally heated and air-conditioned, almost 24 hours a day, sometimes 7-days a week.  With Millennial Net’s solution, changing that was as simple as logging into Millennial Net’s Wi-EMS web site and using schedulers to set an energy policy.

With Millennial Net’s Wi-EMS, the temperature of each classroom can be individually controlled and enforced via a simple web-based user interface.  And, IT investment is not needed, since all configurations and monitoring/control are managed through the internet and the database is managed in a cloud environment.

We have worked with many schools and produced great energy savings for them.  Please watch the video below to see the example of Tyngsborough High School and learn how Millennial Net helped this local school save energy.

You can also see the video about Tyngsborough High School at Millennial Net’s home page and learn more.

Energy Saving in Tyngsborough High School

13 Jul

Where is Google going with the “Android@Home” initiative?

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , , , .

The recent announcement and demo of the “Android @ Home” initiative by Google is quite interesting in many aspects. In addition to the fact that Google is now officially jumping into the home automation market, what is also interesting to us is the news that Google is developing a “new wireless mesh network” technology (i.e. Wireless Sensor Network – WSN).

Google seems to be doing many things at the same time.  In addition to its core business of advertizing by search engine, Google is/has been working on social networks (Buzz, Google+), emails (Gmail), software-as-a-service (Google Doc), library (Google Books) and many others.  In addition to the more established services, Google also has (or had) many experimental projects – robotic cars, Google PowerMeter, etc.  Although it is generally understood that Google’s core business is search engine, one can see that they are trying many things beyond their traditional comfort zone.  I understand that this is what big companies tend to do – like GE’s diverse projects – but sometimes I cannot get away from the feeling that Google is trying too many things at the same time without fully understanding the nature of the projects it is jumping into.

Now, Google has added yet another project to their list: the Android@Home initiative.  As expressed in a previous post about where Google appears to be going with this initiative, I think it is a great idea and I believe this is kind of thing Google should be doing.  However, to make this initiative successful, Google should carefully review what happened with their previous successful projects (like Android for smart phone) and those that were not as successful (like Buzz or PowerMeter).

There are many reasons why Android has been a big success.  First, the technology worked. This is usually the very first and most important concern. Yes, there have been many complaints about the “immaturity” of initial versions of Android, but at the end of the day, Android was significantly faster and easier to use than other competing outdated smart phone OS.  Android is an open platform – open to the point that the source code is open which means it is free.  Smart phone developers do not need to pay for using Android other than perhaps technical support from Google.  Android also has easy-to-use application programming interfaces so that many developers can easily come up with numerous interesting applications.  The first wide-spread operating system for smart phone was not Android or Apple’s iOS.  They were Nokia’s Symbian and Microsoft Windows Mobile 5.0, which eventually disappeared from the market due to its heavy overhead, its closed platform and slow speed, and complicated programming environments.  In the home networking/automation market, there are already several existing wireless technologies that look much like Microsoft Windows Mobile or Symbian.

Let’s take Zigbee as an example. In addition to its technical limitations, although Zigbee claims it is an “open standard”, it is not difficult to see that it is actually very much like a closed system once you look into its architecture.  Zigbee defines everything from low layers (PHY, MAC, NET) up to top application layers (Profiles).  In other words, if someone comes up with a “crazy but innovative application”, it cannot be easily and widely adopted on top of Zigbee unless Zigbee Alliance endorses the application by authorizing a “profile” for the application.  Basically, Zigbee standard defines pretty much everything from top to bottom. Although this approach may help promote its claim of interoperability (which is not yet proven at the end-product level) it may actually hinder innovations.

So, what is the right approach for Google’s Android@Home?  It may be as simple as following or repeating what Google has done with Android smart phone.  The wireless sensor network (WSN) platform used by Android@Home should provide highly robust and reliable data link as well as rich and easy API (Application Programming Interface) to the application developers, and leave it at that.  Application developers should be given ultimate freedom to come up with as many crazy applications as they can without worrying about the robustness of the wireless network platform, and their imagination and innovation should not be limited by authorities of “profiles” defined by one company or organization.

Why is this important?  Because of where WSN industry is at the moment.  In a  separate blog article, I explained the importance of “killer-apps” for WSN.  As mentioned in the article, the industry has not yet found a true “killer-app” for WSN, even if many experts have been looking for one for more than 10 years.  To find (or nurture) a true killer-app, we should be able to develop and test as many applications as possible in the market.  You cannot come up with a “profile” behind closed doors of an alliance and expect a killer-app to suddenly emerge out of nowhere.  The market needs to test as many WSN applications as possible and a true killer app will emerge.  For this, the WSN platform at the application level must be as easy and open as possible to application developers.

Another important factor is that Google should pay attention to the participation of as many hardware manufacturers as partners.  Actually, Google can learn from its own experience of less-than-expected performance of PowerMeter program due to the lack of participation from utilities.  On the other hand, I am sure Google has already gone through this process successfully while growing the Android handset market.  However, the issue in the home automation market may be somewhat different.  In the smart phone market, there exist relatively small number of major players such as Motorola, Samsung, HTC, and LG.  Google simply had to cut deals with a handful of mega-manufacturers and support them.  In home automation market, there are many more players than with the smart phone.  The home automation market is much more fragmented and the requirements are much more diverse.  Therefore, Google must be prepared to deal with a higher number of partners with more diverse requirements.  From a technical point of view, this means the Android@Home platform must be as agile and self-supporting as possible.  It also means that the platform must be very reliable and scalable from the beginning.  Unlike smart phone, WSN-enabled home automation devices will be relying on each other for continuous operation.  For example, when your smart phone stops working, it does not affect the operation of your friend’s smart phone.  In WSN-enabled networks one troubled device may affect the operation of other devices.  This is where reliable mesh network capability as well as other requirements are crucial for Android@Home platform.

Finally, Google must think about how it can expand Android@Home beyond a mere home network platform.  Building home networks should not be the ultimate goal.  The ultimate goal should be to connect all the devices in the world reliably and safely to benefit people as a whole.  I encourage Google to spend a serious amount of time thinking about how to create real value for people by connecting devices as well as spending time thinking about how to connect devices.

Eventually, devices will be networked and they will all talk to each other.  The devices will be “friends” to each other and will work together. The air conditioner in my family room will be sharing my temperature preference information with my car.  I am sure a smart phone will be at the center of the connected world.  Now, the important question is this : When everything is connected, what will it do for us?

Update : See my article “What will Happen when Devices are Connected?” for my answer to this important question.

 

12 Jul

The Killer-App for Wireless Sensor Network

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , .

Recently, I came across a blog written by Dominique Guinard on “Web of Things”.  It was about his interview for an article on “Internet of Things” published in Discovery Magazine.  The article itself was interesting, but what really caught my eye was his description of the reaction of the interviewer (David H. Freedman) on the following question.

“What are the killer apps of the Internet/Web of Things?”

This is a million-dollar question. Yes. A lot of WSN gurus and experts claim they “know” what the answer is. Many of them actually list tens of (if not hundreds) examples of “killer apps” for WSN. However, it is interesting to see that everyone has a different set of answers. The mere fact that you have to list tens of examples of “killer apps” shows it is not easy to find a true “killer app” for WSN.

So, what is the reality?

The “killer app” has always been a critical question for WSN and IoT.  We all assume/know that WSN and IoT will shape the future world of “connected devices”. However, the question is, “if and when all the devices are connected, how much will it benefit consumers and at what cost?”  Simply saying “the refrigerators will be able to talk to TV sets” will not drive the adoption of WSN and IoT.  Or even arguing “you will be able to save $10 a month on your electric bill” will not drive the adoption much either. We need to begin with very real applications that consumers can feel and understand the benefits of and be willing to pay for, even if those applications are mundane or unattractive.

Frankly, today’s conventional WSN technology cannot fulfill the requirements to implement the world of true ubiquitous computing.  Today’s technology still cannot connect millions of self-powered (or no-powered) devices/sensors/actuators and let them communicate intelligently and reliably; and these are some of the reasons why conventional WSN and IoT remain in niche markets only.

This reality, of course, will change in the future.  Between now and then, we need to get down to earth and think about what kind of application can truly benefit and excite consumers.

Update : Also see my follow-up article here.

11 Jul

Integrating MeshScape GO Wireless Sensor Network into End-User Products

Posted by Dr. Sokwoo Rhee in Announcements, Networks of Devices. Tagged: , , , .

It is always good to have a developer’s kit available for customers who want to quickly experience the features and test the performance of wireless sensor networks. Millennial Net just announced the availability of a developer’s kit for MeshScape GO technology.  MeshScape GO is a pre-configured, ready-to-go product for OEM customers who need to rapidly develop applications based on reliable and scalable wireless sensor network technology.  MeshScape GO does not require a complicated network configuration process or custom development to set up a wireless mesh network.  For OEM customers, the application can simply send and receive payload data to the node via standard UART serial connection and MeshScape GO will take care of the rest of the data delivery.

Based on field-proven MeshScape technology, the developer’s kit comes with 7 nodes of various types to enable OEM customers to quickly experience the features and test the performance of wireless sensor networks.  The kit can be expanded with additional nodes to grow the network size, as needed. Especially, the kit comes with wireless modules that can be directly integrated into end-user products.

So, why have we made such a “developer’s kit” available?  For many OEM applications using wireless sensor network technology, customers need to go through a quick test and evaluation process before committing to a technology.  We believe it is important to provide customers with an easy and hassle-free way to experience the performance and benefits of the MeshScape technology.  MeshScape GO developer’s kit is the perfect vehicle for customers to become familiar with MeshScape technology and to quickly use the technology to begin developing a variety of custom wireless sensor network applications.

For more information, visit http://www.millennialnet.com/msgo.

 

7 Jul

Zigbee and MeshScape

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , , , .

Wireless Sensor Networks (WSNs) emerged in the industry around year 2000 in response to limited functionality offered by traditional forms of point-to-point wireless communications such as Bluetooth™ and Wi-Fi.  WSNs allow wireless devices to participate in self-forming, self-organizing and self-healing networks; that is, devices are able to communicate on multiple paths that blanket an area to enable greater flexibility and robustness.  This breakthrough makes it easier to install and change devices without costly setup and network administration.  While many competing WSNs (for example, Zigbee) operate well in networks of less than 30 nodes or sensors, they lack critical performance characteristics that are required for more challenging applications.  These characteristics include:

• Scalability (i.e. Effective and reliable communication with more than 100s of nodes and many hops in a network)

• Ability to reliably communicate in a dynamic environment (i.e. Efficient and dynamic routing with minimum overhead)

• Low power requirements for operation, including battery operated and power-harvesting routing/gateway nodes

• Full omni-directional multi-hop communication (i.e. Peer-to-Peer communication) with latencies typically measured in milliseconds per hop

Many WSN vendors manufacture Zigbee-based products.  Zigbee was founded in 2003 as the first industry standard for wireless sensor network.  Though Zigbee has had limited commercial success, it may be suitable for small, limited networks (i.e. less than 30 nodes in relatively small area).  Zigbee uses traditional ad-hoc routing protocols such as AODV and DSR.  Although these traditional techniques are good for relatively small sized networks, they have inherent limitations in scalability and reliability.  Zigbee also heavily relies on a flooding (i.e. broadcasting) technique for its path discovery and address assignment process, which consumes a lot of power and makes it very difficult to be adopted for low power applications.  As the result, it is impractical to run Zigbee routing nodes with batteries or power-harvesting technologies.

Despite such inherent technical issues and limited capabilities, Zigbee is perceived as a standard in WSN market today, especially for smart grid and home automation.  Zigbee also claims interoperability as an advantage, although true interoperability among the end-user product level is not yet proven.

MeshScape uses very different approaches to mesh network.  Due to the advanced routing protocol (Decentralized Distributed Dynamic Routing) and low power technology (“Virtually-On™” distributed synchronization) that MeshScape is based on, it can cover more challenging application requirements than can Zigbee.  Decentralized Distributed Dynamic Routing (“D3R”) treats the mesh network like ”fluid flow”, and routing paths are determined dynamically at each hop with the most up-to-date information, instead of using pre-specified paths.  Unlike traditional routing techniques, D3R eliminates the need for an expensive repeated path discovery process in dynamic environments, which enables the network to be highly scalable in real-world deployments.  Since the path is determined smartly in each hop, the packet delivery is much more efficient and dramatically reduces unnecessary waste in network capacity.  The packet delivery is much more reliable since the path is dynamically determined, avoiding disturbance or interference on communication links.

MeshScape also uses patented “Virtually-On™” technology to reduce power consumption for routing nodes and gateway nodes.  Each node sleeps and wakes up based on a distributed/localized synchronization mechanism which enables it to run on very low power but still makes the network highly scalable and responsive.  The application does not even perceive when the node is sleeping.  From the perspective of the application, the node appears to always be up and running, making it suitable for applications that require event-based data transmission with low latency while running on low power.  The Virtually-On technique is applied to any node in the network, including the gateway (or coordinator/network manager) node.  This means that even the gateway node can practically run with batteries or power-harvesting techniques.

Furthermore, MeshScape provides many additional high-end features such as omni-directional communication – any node can talk to any other node without going through the gateway; dynamic multi-network joining – a node can be part of multiple networks and change the associations dynamically; and dynamic subnet formation – subnets or clusters can be formed, merged and dispersed dynamically.  MeshScape also provides very flexible and easy-to-use API functions for application integration.

In summary, there may be a good place in the market for Zigbee technology for applications with relatively small-sized networks with limited capabilities requiring interoperability .  For other applications that do not necessarily require interoperability with other vendors, but do need high-end features for more challenging requirements such as a large-sized network, higher reliability, low power, and ultimate flexibility, MeshScape is the right choice.

Detailed technical comparison of MeshScape and Zigbee can be found in MeshScape vs. Zigbee Comparison Chart.

For more information about important requirements of wireless sensor networks, visit “Good Wireless Sensor Network?”

1 Jul

Turning “Old and Busted” Buildings into “Green” Buildings

Posted by Dr. Sokwoo Rhee in Energy Management. Tagged: , , .

In addition to wireless sensor network technology, Millennial Net is also a leading provider of wireless energy management solutions.  One of our missions is to provide technical solutions to enable energy savings and the elimination of energy waste in buildings.  The challenge in converting existing or older buildings into “green” buildings is finding a cost-effective solution that is also minimally invasive.  Especially, a great number of existing buildings in the US still use pneumatic heating controls. Most of these pneumatic buildings are hard to retrofit to energy efficient building.

Millennial Net’s new Wi-Stat IIIp is the first digital wireless pneumatic thermostat that completely revolutionizes pneumatic systems controls using solid state valve technology.  It replaces mechanical Bi-Metal elements with an advanced Piezo-based solid state valve for much more accurate and reliable pneumatic controls, and it allows complete over-the-air programming, continuous remote monitoring and wireless control.  Significant numbers of buildings around the world are still relying on pneumatic HVAC (Heating, Ventilation and Air-Conditioning) systems.  The Wi-Stat IIIp can transform those “old and busted” pneumatic buildings into energy-efficient and smart “green” buildings without costly renovations, wiring, or removal of entire systems.  Since there are no moving parts in the Wi-Stat IIIp, thanks to its solid state technology, it is more reliable, faster, and more precise than traditional pneumatic thermostats using mechanical valves.  Wi-Stat IIIp can be easily integrated into existing building automation systems via BACnet/IP or Mobus, or can be controlled by Millennial Net’s hosted Energy Management software, “Wi-EMS”. Furthermore, using Millennial Net’s MeshScape wireless mesh network technology, this product can remotely monitor and control energy consumption of pneumatic-controlled buildings and eliminate wasted energy. For more information, please visit here.

Millennial Net's Wireless Pneumatic Thermostat Wi-Stat IIIp

The Wi-Stat IIIp – the first of its kind in the market – is a very economical way to upgrade old pneumatic buildings to “green” buildings.  It has already been installed by major customers.  For example, GE Capital has used Millennial Net technology to retrofit multiple commercial buildings, achieving savings up to 50%. See more details from GE Capital here.

Update : See the article and video showing how Tyngsborough High School is using Millennial Net’s EMS to be come “Green”.

30 Jun

Good Wireless Sensor Network?

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , , , , .

Many people believe that if a good wireless sensor node is built with a good radio, a good wireless sensor network can be built. Although a good sensor node/radio is an important part of the whole wireless sensor network, this is not whole story. The characteristics of a “good” sensor network include: scalability, reliability, responsiveness, mobility, and power efficiency.

A “sensor node” is just a very small part of the wireless sensor network. There are more important design challenges that go into making a network “good.” To build a good wireless sensor network, all of the above factors must work in harmony. The challenge is that this harmony can be difficult to achieve. The complex inter-relationships between these factors is a balance; if these factors are not managed well, the network can suffer from overhead that negates its applicability in the real world.

A. Scalability

Scalability refers to the ability of the network to grow, in terms of the number of nodes, without excessive overhead. This is an important real-world requirement where networks must support more than the small handful of nodes typical in a pilot implementation.

This is due to the network overhead that comes with the increased size of the network. In ad hoc networks, the network is formed without any predetermined topology or shape. Therefore, any node wishing to communicate with other nodes should generate more packets than its data packets – i.e. “control packets” or “network overhead.” As the size of the network grows, more control packets will be needed to find and keep the routing paths. Moreover, as the network size increases, there is higher chance that communication links get broken in communication paths, which will end up with creating more control packets. In a small network, the amount of control packets is almost negligible. But when the network size starts increasing, the overhead increases rapidly. Since the available overall bandwidth is limited, the increase of overhead results in the decrease of usable bandwidth for data transmission. As the network size grows further, there will be very small amount of bandwidth left for application data transmission.

B. Reliability

Reliability is the ability of the network to ensure reliable data transmission in a state of continuous change of network structure. Typically there is an inverse relationship between scalability and reliability in ad hoc wireless networks; as the number of nodes in the network increases, the more difficult it becomes to ensure reliability.

This scalability characteristics of ad hoc networks described above imposes an interesting question on the reliability of the network. Since an ad hoc network is designed to automatically adapt itself to a changing environment or interference, it will issue more control packets when it faces dynamics. More dynamics in the environment will increase the number of control packets and, at some point, the network cannot sustain the amount of overhead caused by the dynamics, which will result in less reliability of data transmission. This breaking point will show up earlier in a large-sized network. So, network scalability and reliability are closely coupled and typically they act against each other.

C. Responsiveness (and Latency)

Responsiveness is the ability of the network to quickly adapt itself to changes in topology. To achieve high responsiveness, an ad hoc network should issue and exchange more control packets, which will naturally result in less scalability and less reliability. In general, the latency of packet delivery in dynamic environment decreases in the network with high responsiveness.

D. Mobility

Mobility refers to the ability of the network to handle mobile nodes and changeable data paths. Generally, a wireless sensor network that includes a number of mobile nodes should have high responsiveness to deal with the mobility. So, it is not easy to design a large scale and highly mobile wireless sensor network.

E. Power Efficiency

Power efficiency – the ability of the network to operate at extremely low power levels – also plays an important role in this complex equation. A typical method for designing a low-power wireless sensor network is to reduce the duty cycle of each node. The drawback is that as the wireless sensor node stays longer in sleep mode to save power, there is less chance that the node can communicate with its neighbors. This will decrease the network responsiveness and may also lower reliability due to the lack of the exchange of control packets and delays in packet delivery. In addition, a more complicated synchronization technique will be necessary to keep more nodes in low duty cycle, which may also affect scalability.

F. Managing the Design Tradeoffs

The complex issue of managing these tradeoffs comes down to how the communication overhead can be minimized while maintaining the network reliability and responsiveness. As explained above, there are many conflicting factors involved in the design of wireless sensor networks, and there are always tradeoffs. When choosing a wireless sensor network for an application, careful consideration of the balance of these factors within the context of the needs of the application is critical.

See Millennial Net‘s MeshScape technology as a good example.

27 Jun

High Performance Wireless Sensor Network

Posted by Dr. Sokwoo Rhee in Networks of Devices. Tagged: , , , .

Wireless mesh networks enable numerous embedded applications to be independent of the issues of wiring costs and physical constraints. At the same time, the unique nature of the wireless mesh networks requires many fundamental challenges to be addressed. Among them, robustness and the scalability are the most important issues that need to be addressed. In typical wireless mesh network systems, these two factors generally go against each other due to the self-adjusting and non-hierarchical nature of the networks. For example, as the number of nodes increases, the robustness of network becomes harder to guarantee. On the other hand, to make the network more robust, smaller sized networks are preferred. When the issue of network responsiveness is added on top of these two issues, the equation becomes even more complicated.

Using the wireless mesh networking technology, hundreds or thousands of sensors and actuators can be placed without any wiring constraints. Due to the ad hoc nature of wireless mesh networks, the sensor nodes form a network automatically with minimal human intervention. The network is maintained autonomously, healing itself if any damage occurs to the network. The wireless mesh network is reliable and robust because the network “learns” based on its own changes or problems in the topology and adapts itself to the situation very quickly, even at the individual packet-transmission level. In essence, a wireless mesh network does not assume any predefined topology or placement. The network is designed to adapt itself to them at the initialization, and keep adapting itself continuously.

Much of the technology development in the wireless sensor networking field comes out of the traditional static networking industry (i.e. DSDV, DSR, AODV) that is based on a relatively static environment and stable links. Most of the existing traditional wireless sensor networking technologies such as Zigbee, are based on these assumptions. As a result, these technologies are challenged to address all of the above-named requirements to the level required for production purposes. By contrast, the approach of Persistent Dynamic Routing (PDR) used by MeshScape comes out of the sensor research field that presumes an unstable, rapidly changing environment.

Throughout the next several posts, I will discuss about several important factors that determine the performance of the wireless sensor network. In most cases, these factors have a conflicting impact on each other so that trade-off decisions are unavoidable in network design. Among those factors, scalability, reliability, responsiveness, mobility, and power efficiency will be discussed more in detail. In addition, the advantage of Persistent Dynamic Routing will be discussed and finally, the concept of increasing capacity to improve scalability will be introduced along with several techniques to achieve this.

23 Jun

Getting Connected

Posted by Dr. Sokwoo Rhee in Announcements. Tagged: , , .

We recently set up more channels that you can communicate with us more actively.

Follow us in Twitter – @Millennial_Net Follow Millennial_Net on Twitter

Follow us in Facebook – http://on.fb.me/meVDxK

Follow us in LinkedIn – http://linkd.in/joDeJ7

We believe getting connected to the world is as important as getting devices connected.

23 Jun

Best Application of a Wireless Sensor Network: Millennial Net

Posted by Dr. Sokwoo Rhee in Announcements, Energy Management.

During this week’s wireless sensor networks and RTLS conference in Munich, Germany, IDTechEx Media Group awarded Millennial Net the Best Application of WSN Award for its MeshScape®Wireless Energy Management Solution. The awards honored the most exciting new products and technology developments for WSN, RFID and Energy Harvesting on display at the WSN & RTLS Summit Europe 2011 conference in Munich. Millennial Net received its award for the best implementation of WSN technology.  Judges reviewed the return on investment and value for a user that implemented the system, and how the user overcame hurdles in implementing the technology.

As an example of a case study, GE Capital uses Millennial Net technology to retrofit multiple commercial buildings in their portfolio with Meshscape Wireless Energy Management System varying in sizes from 46,000 to 130,000 sq. ft.  Due to the Millennial Net system being based on wireless communication, the set up time was significantly reduced and most of the equipment was installed during business hours without disrupting tenant operations. One of the installations improved energy savings by 33% and the other is projected to provide 50% over previous years. Lisa Coca, the company’s global sustainability leader said “Millennial Net provides a wireless sensor network-based EMS.  It centralizes management of HVAC systems, giving tenants more transparency and control over their energy consumption to reduce costs.”

More details at http://bit.ly/kDu21v

23 Jun

New World of Connected Devices

Posted by Dr. Sokwoo Rhee in Announcements, Networks of Devices. Tagged: .

It is exciting to start a new blog about the new world of connected devices! Millennial Net has been in business of wireless sensor networks and ubiquitous computing for more than a decade, and we would like to discuss with everyone in the world about the future of connected devices.

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