Xbee for research purpose

Hi. I`m doing research related to ZigBee protocol. Did Xbee product allows user to access to its firmware ?
I need to access to its one of its layer called “MAC layer” and add my own algorithm in it.

If can`t, can someone suggest ZigBee devices that more to research / experimental usage purpose ? TQ

no u can’t

to explore zigbee/zigbee pro you can buy CC2538 TI development kit

cc2538 dongle for sniffer so that all together u can watch zigbee packets and analyze zigbee protocol

u can built HOME AUTOMATION gateway with this hardware if you have BeagleBoneBlack board with you.