Short range in XBee 802.15.4 network

Hi, I have a problem with range of XBee 802.15.4. I use the two regular XBee boards( not XBee-Pro) to communicate. They can talk each other; however, just within a range of 5-7 meters. I also run a range test but the range is not longer. I dont know the reason.
When I hooked the XBee board to Arduino board to control LEDs, the range is the same.
Is there anyone can help me out?
thank you so much!

Power supply? Antenna type?

I use the series 1, non pro, and they work quite well in and around our home; through walls; upstairs, downstairs…

I am using the USB port from the computer for the Arduino board and Arduino board connect to the XBee with whip antenna. I think the output of the Arduino is around 40mA to 50mA which meets the requirement for the Xbee. Last night, I updated the firmware and changed the channel from the C to 1A. The range was enhanced [:)] . It was 20 meters in light in sigh indoor. But when the transmitter and receiver are separated by walls, the range downs to 7 meters [:((] . Are you using the Arduino for your boards? how long of your xbee network range indoor? do you use extra circuit to avoid the interference with Wi-Fi or other sources? Do you do some noticeable configuration for XBee? thank you very much!

Yes, walls cut the distance. In my house, some walls have metal air ducts, some have masonry/brick, some have foil-backed insulation.

I just did a series of tests at my home with the S2B (not S1, but similar hardware). Using 2 Xbee non-PRO, they seem to have a range of about 1 wall or floor barrier.

‘Distance’ depends on the wall or floor. In some directions, a node 3 meters away had trouble, in others it could be 12 to 15 meters.

Making the coordinator a PRO will have a dramatic impact. It ‘talks louder’ and ‘hears soft responses better’, so the non-PRO will show a surprising increase in performance. In my home, with a PRO coordinator and non-PRO sensors, the entire interior of the house was reachable withotu repeaters.

NOTE: this was just a test - my ‘normal’ S2 (not S1) system has lots of routers and meshes. This test was merely to determine how well 2 non-PRO’s talked in my home.

When using the wire antenna, be sure to extend it away from the board. I’ve seen many XBee modules with the antenna parallel to the board – which is sure to reduce your range considerably!