The iXem Labs have designed a Long Haul Wireless Networks in order to test the manufacturing process of transmitters constructed by assembling IEEE 802.11a / 802.11h radios and used PC parts. Those transmitters can be used either for short range, point-to-multipoint distribution systems or medium and long distance point-to-point backhaul links. In order to define the latter, the concept of MultiKiloMetric link was introduced, as a low cost, IP-based, point-to- point bidirectional radio connection, ranging from 10 km up to 300 km.
The links can be easily assembled by means of a couple of access points, working on unlicensed frequency bandwidths, connected to an external directive or very directive antenna. The system performance is enhanced by increasing the gain, even if the radiated power is kept under a constant limitation. The result is achieved thanks to the rise of directivity: when the radio acts as a transmitter, the power is decreased to maintain the EIRP Equivalent Isotropic Radiated Power (EIRP) limitation, while the higher directivity avoids radiation towards unwanted directions; when the radio acts as a receiver, the higher gain strengthens the received power, while the higher directivity lowers the noise received from interferers.