"A 900-MHz system will be more easily able to broadcast through a multifloor house, but a 2.4-GHz system will have a longer range (if unobstructed)" - isn't it so that lower frequencies can penetrate longer distances without obstructions? And higher frequencies are better in short distances? If they get interupted they can easily replace the "damaged" data with new ones since it's high frequence(ability to transver more information in the same time).