Realized case of smart antenna in mobile communication systems

Summary form only given. Recently, many spatial signal processing technologies based on plural antennas and signal processing has been studied. It is well known that the technologies, i.e., adaptive array, space division multiple access (SDMA), and multi-input multi-output (MIMO) provide increasing communication quality, spectrum efficiency, and throughput. However, the technologies are not yet almost utilized for the actual product. In order to introduce the spatial signal processing technologies to real commercial products, we have studied and developed them. We consider that a mobile terminal has a limitation of performance of a processor and power consumption. Therefore, we have studied the technologies that do not require heavy performance for a mobile terminal. In this paper, we present results of our research and development: the adaptive array PHS base station, SDMA PHS test bed, MIMO PHS test bed, and adaptive array WLAN test bed. We have carried out field tests for the AA PHS BS in Tokyo. The results of the field test show that the AA PHS BS increases the system traffic by about 11% and reduces interference level as compared with the existing PHS BS. Results of the field test for the SDMA PHS test bed indicate that the SDMA test bed improves the traffic by about 2.4 to 2.7 times, and can coexist with the existing PHS BS. Results of the indoor test for the MIMO PHS test bed indicate that the test bed establishes two stable paths if the MIMO BS antenna distance is larger than 1.0 λ and the MIMO terminal antenna distance is larger than 0.3 λ. We also have developed an adaptive array test bed for the wireless LAN, i.e., IEEE 802.11b. Results of the field test show that the AA-WLAN test bed expands communication distance by 1.9 times, and increases average throughput.