Creative Connectivity - the site for eHealth, telematics and wireless

ZigBee and the evil radios

March 27th, 2009 |  Published in Wireless Connectivity  |  6 Comments

Ten years ago, Bluetooth, 802.11 and HomeRF were engaged in an acrimonious battle for supremacy over leadership as the short range radio standard.  HomeRF died, and in the following years Bluetooth and 802.11 found their areas of application and now coexist together, to the extent of joining forces in the new Bluetooth 3.0 specification.  Today a new and ferocious fight is taking place for the role of ultra low power radio champion.  This time, there is likely to be just one winner.


In the two main corners of the ring are ZigBee PRO and Bluetooth low energy (previously known as Wibree).  Alongside them, throwing lighter punches, are an array of lesser contenders, including Z-Wave, ANT, Wavenis, and Wireless M-Bus.  What is at stake is the prize of becoming the standard for connecting low power consumer products to the next generation of mobile phones and enabling smart energy devices within the home.


The industry has learnt a lot from the experience it has gained with Bluetooth and 802.11.  One of the first lessons was the need for interoperability between products from different vendors.  Interoperability isn’t something that comes from a specification alone – it needs a rigorous testing regime that ensures that different implementations work with each other and which check that every product entering the market is tested.  802.11 learnt that lesson.  It didn’t have that process until the Wi-Fi Alliance came along to complement the raw 802.11 specification and turn it into the usable experience that has made it successful.  Any new standard will need that from day one.


In practice, interoperability also needs a minimum of three different suppliers who can demonstrate interoperability.  Any less and manufacturers have little real choice of silicon supplier.  That reduces competition and increases risk, which stalls the market growth.  But to support three or more suppliers the market needs to be big.


Depending on its complexity, it costs between $5 million and $10 million to develop a complete radio chip with its associated embedded protocol stack.  If a vendor is going to be able to sell these at a price of $1 – $2, which is what the volume market will demand, then they need to be able to sell tens of millions to make money.  If we demand a minimum of three suppliers to ensure interoperability, that equates to a market of around 100 million devices.  Less than that and there will not be enough profit to support multiple vendors.  That means no interoperability, lower uptake and a declining future for a standard as a proprietary niche.  For the successful contender, the market can grow into shipments of billions, supporting multiple chip vendors and successive rounds of evolution.  It paints a very stark reality – that there will probably be just one such market to emerge of that size.  The winner will take all (or at the very least, the lion’s share).  That’s why the current battle is so heated.


There are two potential opportunities that offer the route to these volumes for ultra low powered radio chips.  It’s unclear which will be the first to emerge.  The first of these is smart energy.  To help limit the amount of power that consumers use in the home, governments are looking to replace utility meters with smart energy meters that have the ability to control domestic goods.  This allows them to be turned off at peak times, or to alert the user to an increased tariff, in the hope that this will modify their behaviour.  Governments around the world are starting to legislate for the introduction of smart meters.  In the UK, the Energy Retailers Association has been more advanced than most in drafting a plan to assess the different wireless technologies and will shortly start field trials.


The second market is for connected health and fitness devices.  Changing demographics are opening up a market for connected health, whether that is for general fitness, long term chronic disease management or assisted living.  Once again, a low power wireless link is seen a key to deployment, connecting devices to mobile phones and home gateways.  The Continua Health Alliance is actively developing standards to help ensure compatibility of data from such devices and is expected to choose a candidate low power radio in the near future.


The standards needed to meet these demands are new.  Unlike existing low power standards such as Bluetooth and the earlier versions of ZigBee, they need to run off coin cell batteries for months or years.  As yet the main contenders are largely untried – they build on existing standards, but the specifications targeting these applications are still at the final stages of development.


In this atmosphere, the political temperature is rising.  There are probably only two serious contenders which have the potential to reach the volumes necessary for success – ZigBee PRO and Bluetooth low energy.  The reason for this is that they are the only two which can claim a route to get to the hundred million mark.  For Bluetooth low energy it should be easy.  One of the clever aspects of the standard is that the Bluetooth low energy technology is incorporated into the next generation of normal Bluetooth chips, so an increasing number of mobile phones will incorporate it for free.  That gives a critical mass of hundreds of millions of handsets that can act as gateways or displays for a new generation of products.  So whether or not the smart energy or Continua Alliance supports it, Bluetooth low energy will gain market traction.


For ZigBee PRO, the base 802.15.4 radio chip is not used just for ZigBee variants, but for a range of other standards, including 6lowPAN, ISA100 and wireless HART.  At the Wireless Congress in Munich last year, a number of chip suppliers estimated that all flavours of ZigBee may account for less than 25% of 802.15.4 usage, so even if ZigBee PRO grows slowly, it can ride on the volume created by other applications.

 802.15.4 Chipset Market


However, that’s not necessarily an advantage, as it only covers the lowest layers of radio silicon and baseband.  Vendors still need to write the protocol stacks for ZigBee PRO and if a semiconductor manufacturer is selling their 802.15.4 chips into multiple markets, they’re less likely to do so, leaving the work to external partners.  In addition, the chips are less likely to be optimised for the requirements of ZigBee PRO, as they will need to cater for a broader range of applications.  That may be bad news for price as well as interoperability, in contrast to the integrated approach of Bluetooth chipset vendors who do the complete job in a single chip.


Because of its integration into handsets, Bluetooth low energy is assured of success in reaching critical mass.  In contrast, ZigBee PRO needs to win the approval of key industries if it is to survive.  At a recent conference a spokesman for one of the major chip companies behind the ZigBee PRO healthcare profile let slip the fact that if it failed to win Continua approval, his company would probably kill their ZigBee PRO healthcare development effort.  Other proponents within the ZigBee PRO camp are openly talking of the competition with “evil radios” as they ramp up the level of rhetoric (and give this piece its title).  That smacks of an increasing level of desperation, but then again, ZigBee needs this approval far more than Bluetooth.


What is clear is that the smart energy and healthcare bodies need to make sure that they base their decisions on hard facts.  The adoption of a radio standard will have a long term bearing on the performance and availability of desperately needed products.  That choice needs to be firmly based on technical merit, not bestowed as an act of charity.


The next few months should be interesting.  The support of major handset suppliers will ensure that Bluetooth low energy has a future.  If that argument of volume and associated development resource wins the day and Bluetooth low energy is selected for healthcare and smart energy, then 2009 could be a painful year for many of the other aspiring low power radio standards.




I am afraid I have had to disable comments on this post, as someone has been bombarding it with spam.  It’s sad to think that someone in the technical community is unable to cope with honest debate.  I am sure that their action is neither appreciated nor endorsed by the majority of those working on ZigBee.



#1 NETWORKING-THE.INFO | on 03.28.09 at 12:24 am

[…] Go here to see the original:  ZigBee and the immorality radios […]

#2 Akiba on 03.28.09 at 6:06 am

Hi Nick.
Great post. I’ve watched Zigbee go up against Z-Wave in home automation, 802.11 and proprietary protocols in smart metering, and RF4CE in remote control specs. 6LoWPAN is still at odds with the Zigbee camp as well, but I think they should work together.

Looks like going up against Bluetooth is the next battle Zigbee is going to have to face. The points you made were really good and I’m looking forward to seeing how this battle will end.

FYI, I linked to your post on my newsfeed at my blog.

FreakLabs Open Source Zigbee Project

#3 WSN Observatoin on 04.01.09 at 10:52 pm

Hi Nick,

I totally agree with your judge on Zigbee. Zigbee is more desperate than BT LE for sure to get industry approval.

Zigbee will likely win Continua approval on both LP-LAN and LP-PAN, according to my feeling in last week’s Continua summit. The Zigbee members have done a pretty good job controlling the main positions along the Continua standard selection process, from use case, end to end architecture, to the dedicated low power radio task group. You can find many attendees of Continua meetings actually sitting on Zigbee org chart.

Not fair to other technologies. But they do not break the law of Continua to turn it into Zigbee friendly.

WSN Observation

#4 WSN Buzz » Only “Evil Radios” Have Products on 04.07.09 at 8:56 am

[…] Evangelist Nick Hunn posted “Zigbee and the evil Radio “, analyzing the competition between Bluetooth Low Energy (BT LE) and Zigbee for the crown of […]

#5 Chris Downey on 04.21.09 at 10:13 pm

Good article. Aren’t there fundamental differences between Zigbee Pro and LP-BT with regards to the Mesh and the number of clients the PAN can support?

#6 Nick on 04.22.09 at 5:06 am

There are, and it’s very important for users to understand the capabilities of different radio standards to decide which best matches their application. It’s far too common to find people fixating on the PR headline features and forgetting what is actually important for their specific need.

Mesh regularly comes up in this context and ZigBee PRO is the only widely supported mesh standard. So if mesh is vital that’s the way to go. However, I’ve come across very few applications that need mesh. What most applications need are features like low cost, robustness, ease of installation, interoperability and power consumption. Bluetooth low energy scores rather better than ZigBee PRO on all of these points. It doesn’t support mesh, but allows expandable star networks, which is adequate for most use cases.

In terms of number of clients, Bluetooth low energy can have as many as you want. The theoretical limit is just over 2 billion, so it’s largely academic. You’ll run out of RAM long before you get there.

I’m in the process of writing a book about short range wireless, concentrating on the real world issues that designers need to understand when they make their choice of radio and how best to apply that choice. My experience over the last ten years is that too many users get blinded by features they don’t need, resulting in a less than optimum radio choice. If you need mesh, that’s fine; but make sure that you aren’t using it just because it’s there. That’s the route to adding unnecessary cost and complexity. And that applies to every wireless standard. They’re all different and you need to take time in the design process to ensure that your choice is the correct one.

About Creative Connectivity

Creative Connectivity is Nick Hunn's blog on aspects and applications of wireless connectivity. Having worked with wireless for over twenty years I've seen the best and worst of it and despair at how little of its potential is exploited.

I hope that's about to change, as the demands of healthcare, energy and transport apply pressure to use wireless more intelligently for consumer health devices, smart metering and telematics. These are my views on the subject - please let me know yours.

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