Heat mapping is important before you deploy a Wi-Fi network so you know what you will be bringing to the installation is exactly what you need, placed where you need it.  Measuring signal after an installation is important too, so you have a quantifiable representation of how the network you installed performed before you turned it over to a production environment.   General Packet works with Ekahau planning and survey software and will be happy to help you plan, design, or survey your Wi-Fi network.