We often get asked about wireless CCTV as people understandably are looking for an easy to install solution. However we have to understand the technologies available and the limitations.
Generally options are limited and we'd always recommend wired over wireless CCTV, unless you really need to use it as a wired camera connection is always a more reliable one. (Of course if you are looking to position cameras at great distances apart it may be your only option with these specialist wireless transmitters which do work very well in line of sight).
If you must go wireless around the house/business you will need to look at IP cameras and kits as the HD over coax methods must be wired. Even if going down this route you must still provide power to each of the cameras, using a wire.
In terms of options we do now have a stand alone kit which works well enough although going through 2 solid external thickness walls will be pushing it's limits: hikvision-hilook-wireless-2mp-system-ik-4142b-mhw.html
There are otherwise very few IP cameras with wireless (wifi) built into them that lock on to your router and these suffer from the same limitations, with the performance and reliability being down to your wifi signal strength and building layout. So these solutions are not recommended for larger properties with thick walls but can work well enough if positioned within good signal strength.
However you could run any non wireless IP camera or kit without long wire runs by using home plugs/powerline adapters. Home plugs use your mains electrical wiring to bridge the connection between the plugs and are generally more reliable and less complex than relying on wifi technologies, although again a wired connection is always best if possible. These have been used to good effect on larger properties although the electrical wiring needs to be in good shape and everything running off the same meter/fuse board using the following reccomended homeplugs:
This Solwise Homeplug has POE built into it so you could link it to a camera via a single short cable run (cat 5) while providing it with power at the same time (as if plugged directly into the NVR):
Then one of these could be used back at the NVR, at another socket to receive the camera signals (up to 8):
Please note that homeplugs do have their limitations as they do depend on decent electrical wiring at your property but in most instances you should not have a problem, as long as they are all running off the same main fusebox/meter.
The following provides some examples of the attenuation values of common office construction:
o Plasterboard wall: 3dB
o Office window: 3dB
o Cinder block wall: 4dB
o Glass wall with metal frame: 6dB
o Metal door: 6dB
o Metal door in brick wall: 12.4dB