Experimental Investigation of Propagation Characteristics and Performance of 2.4-GHz ISM-Band Wireless LAN in Various Indoor Environments

Wireless communication systems are affected by several factors in the indoor environment. The complexity of this environment, however, has hampered the development of methods for analyzing it. Reported here is our investigation of the relationship between the propagation characteristics and performance of a 2.4-GHz ISMband wireless LAN in various indoor environments. Our objective was to develop guidelines for designing ideal indoor environments for wireless LANs. A booth constructed of a ceiling, floor, and wall materials that could be changed was used for our investigation. The transmission loss and delay spread were measured for four environments; they were calculated by using a ray-tracing method to verify the effectiveness of the ray tracing calculation. The throughput and BER characteristics were measured for the same environments. The following results were obtained. (1) The transmission loss and delay spread could be estimated by using this ray tracing method because the deviations between the calculated and measured data were within 5 dB for the transmission loss and within 10 ns for the delay spread. (2) Reflections from the walls caused a serious interference problem: throughput was 0.0 at more than 30% of the positions along the center line of the booth when the walls were constructed of high-reflection-coefficient material. (3) The throughput and BER were closely correlated with the delay spread; the number of positions meeting a certain throughput was estimated by the method based on the delay spread calculated using the ray tracing method. It was within 10% of the number measured. The results obtained can be used to design ideal indoor environments for 2.4-GHz ISM-band LAN systems. key words: propagation characteristic, delay spread, indoor environment, multipath, 2.4-GHz ISM-band wireless LAN, throughput, BER