Performance evaluation of in-building DAS for high data rate wireless transmission

In wireless systems, providing high data rate services is a major challenge, particularly for mobile terminals (MTs) in multi-floor buildings. The system performance is impaired by path loss, and co-channel interference due to the need to reuse the limited available spectrum. One way to achieve high data rates and better signal quality in this environment is by getting the transmitter and the receiver closer to each other through the use of distributed antenna systems (DASs). DAS reduces the overall transmit power (and hence co-channel interference) and achieves better link reliability by exploiting spatial diversity of multiple antennas. Currently, DASs are designed primarily to provide good coverage in outdoor environments. However, high quality indoor reception and high data rates may not be guaranteed if the system is not deployed within the building. Indoor environments can be very complex, and an insight into the design, and a thorough understanding of the performance of DASs inside the building is required. In this thesis, the performance of an in-building DAS employing frequency reuse is examined, where remote antenna units (RAUs) are deployed on each floor throughout the building and connected to a central unit (CU) where received signals are processea. The impact of co-channel interference on system performance is investigated by using a propagation channel model derived from multi-floor in-building path loss values retrieved from measurement results. System performance is investigated in terms of location-specific spectral efficiency and bit error rate (BER) which are analysed for a range of potential MT locations and various in-building propagation characteristics. The potential benefits of location based antenna selection and deployment options are also investigated. Co-channel interference cancellation where CUs cooperate through joint signal pro- cessing in order to reduce the impact of co-channel interference is considered. Results obtained suggest that the proposed scheme can facilitate better use of the available radio spectrum, and provide high data rates for indoor MTs

Wireless distributed antenna systems in high buildings

In this paper, a distributed antenna system (DAS) is investigated for indoor high data rate wireless transmission in high buildings. In the proposed indoor DAS, radio transmission/ reception within several neighbouring floors is controlled by one central unit (CU) by exploiting the whole system bandwidth. However, the frequency channels can be reused among the CUs which results in co-channel interference. The capacity of the system is analyzed considering direct propagation inside the building and reflection from a nearby building. The impact of several system parameters, such as the position of the user on the floor, the number of remote antenna units (RAUs), the shape of the floor and the position of the RAUs on the performance is discussed