Requirements for controlling coverage of 2.4-GHz-band wireless LANs by using partitions with absorbing board

For a wireless communication system to work effectively without interferenc e, the electromagnetic environment needs to be controlled. We experimentall y and analytically investigated the requirements for controlling the electr ical field strength and delay spread so as to achieve the best communicatio n without electromagnetic interference in selected regions for a 2.4-GHz-ba nd wireless LAN system. To control the coverage, partitions were placed aro und desks in a test environment and covered on the inside with electromagne tic absorbing board from the top of the desks to the top of the partitions; four indoor environments that combined one of two wall-material types and one of two partition heights were used. The transmission loss and delay spr ead were measured, then calculated using ray tracing to verify the effectiv eness of using ray-tracing calculation. The throughput and BER characterist ics were measured for the same environments to clarify the requirements for controlling the coverage. We found that covered and uncovered regions coul d be created by using partitions with absorbing boards and that the delay s pread must be less than 15 ns and the received-signal must be stronger than -75 dBm for a region to be covered. We verified that the delay spread can be calculated to within 5 ns and the received-signal level can be calculate d to within 5 dB of the measured data by using ray tracing. Therefore, ray tracing can be used to design antenna positions and indoor environments whe re electromagnetic environments are controlled for 2.4-GHz-band wireless LA N systems.