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Thursday, May 8, 2008

Any Flaws in the Home Automation Use Cases and Models for Z-Wave and Zigbee?

Though weeks old, this piece of news has kept pushing me to throw out some of my pre-mature thoughts on WSN applications in homes.

The news release is about some top companies teaming up together to study the state and future of smart home. "The smart home is defined as a home where the systems (security, lighting, sensors, heating, air-conditioning, audio-video, etc.) are interconnected to allow the automatic or remote control of the home to save energy and improve comfort, safety and convenience for the homeowner." The ten companies are Whirlpool Corporation, Bell Canada, Cisco, Direct Energy, HP, Legrand, Leviton, Microsoft, Procter & Gamble and Zensys as well as the Z-Wave Alliance.

Whirlpool, Bell Canada, Cisco, HP, Microsoft, P&G and Others Announce Collaboration to Advance the Connected Home Space

It is great to see companies possibly cover the entire value chain and supply chain getting together (to pay for this study). These companies are eagerly looking for answers to get out the "trough of disillusionment" and move to the "slope of enlightenment" of the smart home hype cycle.

Per my personal experiences, the value of the report will largely depend on the design of the survey and I am not positive to any consumer studies based on “what do you think” type of questions on applications still in vapor. If I were these companies, I would just use the report to prove the answers that are already in my mind and challenge those disagree. And the answers in my mind are from my observation on how people live everyday and troubles they have to deal with often. I also trust my own imagination since I know what can be done and how will be done the next.

Here is a rule of thumb: A solution will only prevail if this solution provides values that few others can provide.

Let's take a look of the four potential applications mentioned in this new release to see if they can prevail.

- When the phone rings, the caller ID shows up on a television screen. ---- leave this application to those who watch TV a lot, unless the phone is on top of the TV. Will the phone ring

- The home's temperature can be controlled remotely, allowing the homeowner to save on energy costs by adjusting the home's temperature according to changing weather conditions. ----- Automatic control is cheaper and easier. If you want to make it complex, a hub with complex algorithm receiving temperatures from multiple rooms will do the job per room better than the home owner. Fundamentally those who are currently in the home should control. The homeowner may not know if there are people in home or not.

- Multiple rooms in a home can be video-monitored via the Internet from anywhere in the world ----- good idea, but only when I am the monitor, not the "monitoree". This application has niches such as home based prison, remote managed office etc. This application could also be an alert triggered home security feature, which of course has cheaper alternatives.

- A homeowner can adjust the home's lighting remotely, allowing travelers to give the home a "lived-in" feel ---- Again automatic control is cheaper and easier. And human conversation and pet barking can be simulated automatically. When I am in travel in HongKong, should I remember at noon to turn on the living room light in my home in LA?

Personally, besides energy saving and security, I have not seen any generic applications that meet the rule of no or few alternatives. I am not saying there are no cool applications that will find their own niches. There could be a lot such applications like mentioned above. But they won’t justify the investment by big companies.

To further worsens the business case of Zigbee and Z-wave, have you seen any wireless elements in the above applications? Few and not necessarily required. First there are few popular home applications; and then for the few, the wireless solution is only one of the options.

Let’s analyze a use case to examine in-depth the possible issues for WSN in home. BTW, this is a very popular use case. Either Zigbee or Z-wave makes a flash to show it on their website. The case is to turn on the bedroom light while you are in the garage. Let imagine,

You get out of your car and you want to turn on the bedroom light. (I think I want to turn on my garage light first.) You need to find the remote control (ah, it is a fixed switch on the wall. How about this, your cell phone? So you can operate anywhere) and switch it to ON. (if you use a phone, you need to find the icon among many other controllable items for your bedroom light after your fumbling many pages to locate application menu. Your IQ need to be high enough in order to have a shortened learning curve.) This signal "1" goes to the garage door sensor, then the kitchen light switch, then the living room light and finally it reaches the bed room. (We all own big houses in North America, aren’t' we?) When you get to the bed room, the light is ON already as you expect and you feel so cool. If it is not on (come on, glitches are allowed. It is wireless. We all know that), then you find the switch on the wall (it is always there) and simply you turn it on, though you feel not so cool. Now you run back to the garage, because you have an insurmountable impulse to figure out what goes wrong.

The technology is cool, and you are a nerd!

Ask yourself if you really need to turn on the bedroom light from the garage. (Cool!) Ask yourself again if you want to pay $500 to make it. (Cold!)

Wireless can not guarantee 100% reliable communication. Zigbee and Z-wave both can do mesh to boost the reliability to certain satisfactory degree. For example, if the "1" can not go through from the kitchen to the living room, it will be via another route from the wash room. This sounds much easier than implementation. In reality, for normal consumers without sophisticated equipment, this is a process of trial-and-fail steps unique to every home. You need to be a knowledgeable homeowner. You need to plan the signal path or even the topology. You need to test if signal in bed room can be reliably received in living room. You need to decide if you need a node to perform as coordinator…

However, anyway, whatsoever, you have set up such a network. But you forget, you have to live alone just by yourselves. Why? You get home late, you turn on the bed room light while you are in garage but only find that you beloved the other half is angry that you badly disturb his or her sleep. The bedroom light get confused just as you do when you report to two bosses.

The user interface and psychological issues for home applications is a huge one that has not been studied thoroughly. Basically, to control something out of sight is something uncomfortable for both who control (not sure if it has happened) and those who are in where is under control (not sure what has happened). People tend to see the feedback right away. People tend to deal with situations that are simple and direct, by instinct and no need to learn.

In short, wireless sensor network for home use have the following inherent issues that destine its limit success:
1. wired alternatives exist, cheaper, straight and reliable.
2. complex mesh is required for reliability for "real remote" control, but costly and hard to install
3. Home is a dynamic living area. To control things out-of-sight will cause unease, confusion and many other psychological frustrations.
4. For Zigbee and Z-Wave, who offer over-killed mesh features, direct remote control can be easily taken over by other wireless technologies, simpler and cheaper.

Welcome argument. But my above points have been proven by the low adoptive rate and current situation of both Zigbee and Z-Wave. Zigbee is an infrastructure-oriented protocol (I first heard this term from my friend in Chipcon, now Texas Instrument). You hardly find it in consumer home applications, but it seems get momentum in building automation and AMR (Automatic Meter Reading) where can show-off its strength. Z-Wave is much easier to implement, so you see many home-used remote control applications for light and appliance that do not need an infrastructure, but a simple star or peer to peer network, no more complex than a home Wi-Fi.

1 comment:

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