1mw 802154 XBee - On Chip Antenna - Problem with indoor range

I have 1mw 802154 XBees with on chip (PCB) antenna. It is a unstructured mesh routing research project where the devices are expected to be smallest form factor low power and low cost so I want to be fair and not cheat with xbee pro or whip/dipole antenna.

The documentation seems to say indoors with whip or dipole antenna range is about 30m but less with PCB antenna. Clearly floors/walls will affect this, but in a regular house I have device desk height on ground floor and desk height immediately above on floor 1, distance about 3m, and they ‘appear’ to be out of range. Other similar positionings (eg same distance + wall) are out of range too.

This was unexpected. Assuming good conditions (no metal, interfetence etc) am I still expecting too much?

I have a Texas instruments sniffer (CC2531 USB Dongle) on floor 1 desk, it is very small and also with PCB antenna but it receives all the ground floor packets easily @ approx -69 rssi and floor 1 packets a few inches away @ approx -46 rssi (does -46 sound reasonable?). I have tried different devices instances and orientations, same issue. When I move them closer all is well.

I have power level default (level4 I.e. 1mw ?). Is there some other hardware/software configuration which be affecting this or may help? Can I ‘add’ say a whip antenna to the pcb without changing the actual module?

The XBees were sold together with and already connected to libelium waspmotes (arduino). The libelium advertising said outdoor range for 1mw on chip antenna (non-pro) 100m so I didn’t anticipate 3m and between floors would be a problem. The advertising appears to be wrong though as the digi documentation says only 90m and says 90m is with whip or dipole and says it is significantly less with on chip antenna. With the 1mw on chip non-pro is range as low as this is to be expected? Perhaps I should just try to ensure sufficient density in the network, but if there are any useful configuration actions I can do (eg change channel (I am on 802154 ch11 which looks like its inside WiFi Channel 1, just looked at inssider app 4 aps on wifi ch1 !!)? multiple transmissions on broadcast packets? .etc…?) I would appreciate any configuration advice.

Given the circumstances of my project it may not be possible for me to change the modules plus may not be fair to the intention. Does any one have any advice.

I managed to get communication if I move one device right under the ceiling. That was at 100% battery.

Strangely I find by the time battery level is down around 75 to 80% there is no communication.

If any one has any advice on this or the main question I would really appreciate it.