As it was mentioned before ZigBee standard is the most direct competition for currently developed WBAN standard. It is even more direct as ZigBee is based on previous version of 802.15.4 (from 2003). Since that time a lot has changed thus a new standard is developed.
In this post I will try to answer a question if we should be afraid that success of new implementation will be crippled by ZigBee older brother.
At first it’s important to show how ZigBee is related to its root 802.15.4. As the old 802.15.4 is focused only on mac layer and physical media specification, ZigBee was developed to build on top of that a fully operational network system with necessary functions e.x. security and encryption. This relation can be described in few points:
- 802.15.4 (2006) was designed to allow point to point energy sufficient communication
- ZigBee adds on top of that more services: star topology routing, encryption, application services
- ZigBee creates semi-centralized network. It allows only end devices to sleep (to reduce power but keep the main node waiting for communication)
In case of new version of 802.15.4 the focus was broadened to include this parts as well in the basic standard. Also the additional options for physical layer were defined to allow even better adaptation of final solution to the application.
A table and short description is shown to illustrate differences between both standards.
|Physical medium||Narrow band||Narrow band, UWB, HBC|
|Bands||~900MHz||~900Mhz, 3-10Ghz, 16Mhz, 27MHz|
|Bitrate||20,40,250kbps||Upto 100mbps (with UWB)|
|Typical application||Mostly industrial, building monitoring||Sensor nodes in WBAN applications|
|Complexity||Low||Very low (with HBC)|
We can see that a new standard has a lot of advantages over ZigBee –mostly it’s better suited for short distance communication on the body surface. It can’t be forgotten that with use of UWB, as it was already shown, new standard is more suited for medical applications:
- Low interference with medical equipment
- Lowest possible effect on living tissue
Thus even with so many common roots, these both standards are quite different. It’s possible that with introduction of new 802.15.4 standard, ZigBee will be adapted to be compatible with new version, or the new version finally will add some way of interoperability with ZigBee. That would help to answer the question of who will win in this confrontation. Unfortunately at this stage of standard development it’s hard to determine how it will end.