Intra-volume, centralised array concept for improved public-safety communications

The author report on the testing and measurements of an intra-volume centralised array concept suitable for public-safety communications in buildings. The centralised array concept refers to the use of several small communication devices that are arbitrarily placed in an area and hence create a real-time communication network. The overall concept is to use randomly located (or arbitrarily placed) wireless devices in a coordinated manner in order to increase the radio-frequency signal level otherwise at unreachable locations. In a typical ad-hoc network, the transmission range of any communication link in that path is limited. We seek to extend the radio-frequency coverage within the array volume by using two or more nodes as elements of a phased array. The measurement results presented here, collected in real-world environments, along with simulations based on real-world data demonstrate that the centralised array technique can provide useful gain, up to 10 dB with only four elements. Both the measurements and simulations also indicate a typical gain of 2 to 6 dB, using only two elements. Analysis of the phase indicates a phase alignment of ±45° achieves within 1 dB of the maximum gain.