$4.50 wifi modules are in 1M quantity. You also have to add a CPU to make the wifi modules work – they depend on the cell phone’s CPU to do a lot of work.

The 802.15.4 chips are self-contained – CPU, radio, ram, flash, etc. Add a PCB antenna, crystal and a power source and you’re done. 802.15.4 would be under $3 at that quantity.

Wifi would displace 802.15.4 if cheaper solutions were available. Right now it’s just too expensive to put it into every light switch. ZeroG wifi modules are a step in the right direction but they are still too expensive.

There is a problem with formatting in my earlier post. So, I’m posting again.

The cost projections on Wi-Fi vs Zigbee are wrong. Wi-Fi modules inside today’s mobile phones come for less than $4.5 (refer to teardowns e.g,. from isuppli)

Below is a comparison of Wi-Fi and Zigbee on various metrics that should be useful:

1. Technology Penetration into Home Products – 2009 (USA)
   Wi-Fi: >35% Zigbee: <1%

2. “Number of Certified Products (2009 October)
   Source: Wi-Fi Forum Website and Zigbee Forum Website”
   Wi-Fi: 6356 Zigbee: <30

3. Band (most used)
   Wi-Fi: 2.4-2.5GHz Zigbee: 2.4-2.5GHz

4. Effective Bandwidth / Channel Spacing (most used)
   Wi-Fi: 20MHz / 25MHz Zigbee: 3MHz / 5MHz

5. Tolerance of Interference:
   Wi-Fi: Good. Wider-bandwidth Spreadspectrum Zigbee: Bad. Narrower-bandwidth Spreadspectrum

6. Tolerance of Multipath – RMS Delay spreads (Implementation dependent)
   Wi-Fi: “150ns RMS @ 54Mbps, 500ns RMS @ 1Mbps” Zigbee: 500ns RMS @ 250kbps

7. MAC/PHY Security:
   Wi-Fi: WPA/WPA2/CCX are Industry Tested Zigbee: MAC layer security Not available. Relies on Higher layer Security

8. Cost Of solutions:
   Wi-Fi: Steadily reducing over years. Single-antenna, Zero-Host, Wi-Fi Chipsets are available today for ~$5 & self-contained modules for ~$10 (including TCP/IP)
   Zigbee: Not known

9: Number of Vendors
Wi-Fi: Many Zigbee: Few

10: Data-rate (Max/Typ/Min)
Wi-Fi (b/g): 54Mbps / 36Mbps / 1Mbps
Zigbee: 250kbps alone (Ref: 802.15.4-2006 Section 6.5)

11: Receiver Sensitivity (at Max/Typ/Min data-rates) – Implementation dependent
Wi-Fi (54/36 and 1Mbps) -75dBm / -81dBm / -98dBm
Zigbee (250Kbps) -98dBm

12: Max Packet Length supported
Wi-Fi: 4KBytes (b/g), 64KBytes (n) Zigbee: 127 bytes

13: IP Layer can be directly ported over the MAC?
Wi-Fi: Yes Zigbee: Needs additional layer – 6LowPAN

14: Peak Rx Current @ 3.3V (min/max values for typical implementations in the market)
Wi-Fi: 100 – 200mA Zigbee: 60 – 100mA

15: Peak Tx Current @ 3.3V for 20dBm Tx Power (min/max values for typical implementations in the market)
Wi-Fi: 250 – 350mA Zigbee: 250 – 350mA

16: Shutdown current (min/max values for typical low-power implementations available today)
Wi-Fi: 1 – 5uA Zigbee: 1 – 5uA

17: Energy Efficiency of Reception @ highest datarate (using max values for current consumption)
Wi-Fi: 15nJ / bit Zigbee: 1320nJ/bit

18: Energy Efficiency of Reception @ lowest datarate (using max values for current consumption)
Wi-Fi: 825nJ / bit Zigbee: 1320nJ/bit

19: Does the PHY have error correction coding
Wi-Fi: Yes Zigbee: No

20: Certification for Peer to Peer Low-power operation available?
Wi-Fi: “Yes(Wi-Fi Direct)” Zigbee: Yes

Hope this is useful

Thanks
Partha

To @Marty and @Ksenia, I agree that WiMAX and proprietary standards for WAN and zigbee for the home have their own set of issues.

To Denise from Tropos, I didn’t mean to imply that Tropos “abandoned selling its products to municipalities,” just that the company is now heavily targeting the smart grid market, and muni WiFi was a term that was hot to use several years ago, but now isn’t. I’ll cross out “former,” as I can see how it is confusing. I’d also like to add that from the perspective of watching the market for muni WiFi products boom and bust between about 2005 to 2007, I think the muni WiFi industry has clearly not reached the potential that many had expected. But yes, Im sure there is some business and revenue still being done in that area.

Tropos has been selling products to municipal utilities for more than 5 years providing backhaul for smart meters (and several other smart grid applications such as power quality monitoring, outage management, SCADA, and substation security). When I refer to smart meters, I’m including those used for water, gas and electric. We estimate our networks are being used to read over 600,000 meters today with approximately 60% of those being AMI (two-way communications).

You cited interference as a major problem with Wi-Fi. While the criticism is valid for Wi-Fi generically, it frankly doesn’t even make our top-five list of technical challenges due to technological advances we have made to our products. Finally, we agree that security is an important consideration for networks supporting critical infrastructure, and Tropos sets itself apart from other Wi-Fi vendors with FIPS 140-2 certification and NERC CIP compliance and has implemented a multi-tiered security architecture to provide customers with the stringent security needs of critical infrastructure communications.

To learn more about Tropos’ Smart Grid and Smart City solutions, please visit http://www.tropos.com.

For more info on energy management visit ~ Titan Energy http://bit.ly/vfQkc

Thanks!