Downlink distributed antenna systems in indoor high building femtocell environments

Over the last decade high data rate wireless transmission has gained considerable attention in hot spot areas, including high buildings. It has been demonstrated that distributed antenna systems (DASs) improve the performance of the indoor environment by providing spatial diversity and covering dead spots. In this paper, indoor wireless communications have been studied together with a femtocell based DAS. In this DAS, a femtocell managed by a central unit (CU) is deployed to cover several neighbouring floors, which compose a floor-bank. Since the radio spectrum becomes limited and expensive, the spectrum should be reused among different floor-banks. The performance of downlink DAS transmission is analysed in terms of bit error rate (BER) in the presence of co-channel interference from other floor-banks. Numerical results show that when decreasing the number of floors in a floor-bank, the BER performance degrades due to the strong co-channel interference. The number of floors in a floor-bank has a significant effect on the BER performance in high buildings.