Hi there,
problem: I have to transmit Wireless over 6 floors. Of course with regular WiFi equipment that’s not possible.
So I thought I could maybe use my XBee modules.
Questions:
Has someone already done this before and would like to share his experience?
Is there maybe an existing solution that does exactly that (and is not too expensive)? Briding Wireless over, lets say, 30 meters (incl. brick walls).
cheers,
F.
The XBee modules use the same frequency as WiFi so you won’t get more range with XBees. Also XBees are intended for low data rates and would be very slow for TCP/IP.
XBee is 802.15.4. The most popular is 2.4GHz ISM where WiFi is. But there’s also 868 and 900MHz versions.
The range with 802.15.4 at 2.4GHz is much, much greater than WiFi 802.11 if both have the same radiated power (including antenna gain). This is because (1) 802.15.4 is a 2MHz wide signal which is 1/10th that of 802.11; (2) the modulation order (bits/Hz/sec) is much lower with 802.15.4 by intent. These enable 802.15.4 to get a good error rate with a much weaker signal (lower signal to noise ratio or SNR), than 802.11.
This is because the intent with 802.15.4 was reliable low data rates at low power whereas 802.11 is trying to be an wireless Ethernet.
In technical terms, 802.11 is too slow or too error laden at received signal levels below -85dBm or so. Most people want the speeds associated with -70 to -80dBm.
Most all 802.15.4 receivers work well at -95 or less.
TCP on 802.15.4 - not advised due to the high overhead of TCP and IP versus the intentionally small data frames in 802.15.4. But if you must - take a look at what the 6LoWPAN group is doing - moving IP packets on 802.15.4. A couple of 802.15.4 vendors support 6LoWPAN.