Temitope Alade

Uplink Spectral Efficiency Analysis of In-Building Distributed Antenna Systems

Providing high data rate wireless transmissions has been difficult in indoor environments, particularly in multi-floor buildings. One way to achieve high data rate wireless transmissions is to reduce the radio transmission distance between the transmitter and the receiver by using distributed antenna systems (DASs) and employing frequency reuse. However, due to the reuse of the limited available spectrum, co-channel interference can severely degrade system capacity. In this paper, the uplink spectral efficiency of an in-building DAS with frequency reuse is studied, where remote antenna units (RAUs) deployed on each floor throughout the building are connected to a central unit (CU) where received signals are processed. The impact of co-channel interference on system performance is investigated by using a propagation channel model derived from multi-floor, in-building measurement results. The proposed scheme exploits the penetration loss of the signal through the floors, resulting in frequency reuse in spatially separated floors, which increases system spectral efficiency and also reduces co-channel interference. A comparative analysis with conventional co-located antenna deployment at the floor center is provided. Location based RAU selection and deployment options are investigated. System performance is evaluated in terms of location-specific spectral efficiency for a range of potential mobile terminal (MT) locations and various in-building propagation characteristics.

Uplink Co-Channel Interference Analysis and Cancellation in Femtocell Based Distributed Antenna System

In wireless systems, coverage and capacity is a major challenge especially in high buildings. The need to reuse the limited available spectrum results in cochannel interference. Cochannel interference is a very critical factor affecting system performance. It limits the uplink coverage and capacity of wireless networks such as femtocells. Joint processing of the received signal among cochannel receivers has recently been shown to be very beneficial from an interference cancellation point of view. This paper proposes a femtocell based distributed antenna system (DAS) for uplink transmission in high buildings where distributed antenna units deployed on each floor of the building are connected to femto base stations (BS). The femto BSs can cooperate through joint signal processing for all cells in order to estimate the received signal, reduce cochannel interference introduced by frequency reuse among the femtocells and maintain high spectral efficiency. Analysis and numerical results show remarkable gains especially when interference cancellation is employed at each cooperative femto BS, leading to many more simultaneous users being supported on the same frequency and resulting in large capacity increase when compared with the traditional system with no interference cancellation technique.

Spectral Efficiency Analysis of Distributed Antenna System for In-Building Wireless Communication

Indoor mobile communication systems are expected to provide significantly higher data rates and coverage than that offered by the conventional microcell system. However, the system performance is impaired by co-channel interference due to the need to reuse the limited available spectrum. To mitigate the effect of co-channel interference in this environment, distributed antenna systems (DASs) can be used to reduces the overall transmit power (and hence co-channel interference) by shortening the radio transmission distance between the transmitter and the receiver. In this paper, the impacts of DAS on uplink transmission in high-rise buildings is investigated, where remote antenna units (RAUs) are deployed on each floor throughout the building and connected to a central unit (CU) where received signals are processed. The performance of the system is analysed using a propagation channel model derived from multi-floor in-building path loss values retrieved from measurement data. For different system parameters, the average spectral efficiency is computed for a given maximum required BER, and parameters which yield the maximum spectral efficiency are identified. Numerical results obtained suggest that the proposed scheme can facilitate better use of the available radio spectrum, and provide higher data rates for indoor MTs.

Joint Signal Processing in Femtocell Based Distributed Antenna Systems in High Buildings

In wireless systems, coverage and capacity is a major challenge especially in high buildings. The system performance is impaired by cochannel interference created due to the need to reuse the limited available spectrum in nearby floors. Each base station (BS) does not only receives signals from the desired user but also from cochannel interferers in the neighbouring floors, thereby limiting the coverage and capacity of the indoor networks. Joint processing of the received signal among cochannel receivers has drawn considerable attention in recent years due to its enormous benefits from an interference cancellation point of view. This paper proposes and investigates the uplink of a femtocell based distributed antenna systems (DAS) in high buildings where remote antenna units deployed (RAU) on each floor of the building are connected to femto BS. The femto BSs can cooperate through joint signal processing for all femtocells in order to estimate the received signal, reduce cochannel interference introduced by frequency reuse among the femtocells and maintain high spectral efficiency. Investigation and numerical results show remarkable gains especially when interference cancellation is employed at each cooperative femto BS, resulting in large capacity increase when compared with the traditional system with no interference cancellation technique.

Performance Analysis of Distributed Antenna System for High Building Wireless Communication

In wireless systems, coverage and capacity is a major challenge especially in high buildings. The system performance is impaired by co-channel interference due to the need to reuse the limited available spectrum in neighbouring floors. In this environment, distributed antenna systems (DASs) can provide adequate coverage and high speed data services in the presence of multipath fading and co-channel interference by optimally combining the same signal from several antennas. This paper proposes a DAS for uplink transmission in high-rise buildings; where remote antenna units (RAUs) are deployed on each floor so as to reduce the access distance while at the same time exploiting spatial diversity. The RAUs are connected to a central unit (CU) where received signals are processed. To analyse the bit error rate (BER) performance of the system with diversity reception, Nakagami/Rayleigh fading channel is assumed for different building geometries and a propagation channel model for in-building propagation is developed based on multiple floor in-building path loss values retrieved from measurement data. This model accounts for the propagation between different floors and ceilings and includes possible reflections from surrounding buildings. The effects of different numbers of receive antennas per floor and deployment conditions are investigated. Numerical results indicate that the proposed scheme provides improved BER performance, leading to many more simultaneous users being supported on the same frequency in high buildings when compared with a system with a single antenna per floor.

Distributed antenna systems with frequency reuse

Performance of distributed antenna systems (DASs) is investigated for high data rates transmission in high buildings. Downlink transmission is considered, neighbouring floors are grouped together and controlled by a central unit (CU). The spectrum is not reused in the floors controlled by the same CU, however it can be reused among floors belonging to different CUs. Therefore, co-channel interference occurs among CUs. Radio signals can propagate among floors in high buildings and reflections from a nearby buildings can have an effect on the performance. In this paper, the effect of the frequency reuse factor on the channel capacity performance is shown.

The impact of antenna selection and location on the performance of DAS in a multi-storey building

It is well known that providing high data rate wireless mobile services is a major challenge in indoor environments, particularly in multi-storey buildings. One way to achieve high data rate wireless transmissions is to reduce the radio transmission distance between the transmitter and the receiver by using distributed antenna systems (DASs) employing frequency reuse. However, due to the reuse of the limited available frequency spectrum, co-channel interference can severely degrade system performance. In this paper, the uplink performance of an in-building DAS with frequency reuse is studied, where remote antenna units (RAUs) deployed on each floor throughout the building are connected to a central unit (CU) where received signals are processed. The impact of RAU selection and location strategies on the performance of the interference-limited system is analysed by using a propagation channel model derived from multi-floor, in-building measurement results. The proposed scheme exploits the penetration loss of the signal through the floors, resulting in frequency reuse in spatially separated floors, which increases system spectral efficiency and also reduces co-channel interference. RAU location is shown to be a dominant factor influencing the levels of co-channel interference, and consequently, have a major implications on system performance.

In-Building DAS for High Data Rate Indoor Mobile Communication

As well known, providing high data rate wireless mobile services is difficult in indoor environments, particularly in multi-floor buildings. One way to achieve high data rate wireless transmissions is to reduce the radio transmission distance between the transmitter and the receiver by using distributed antenna systems (DASs) employing frequency reuse. However, frequency reuse causes co-channel interference, which is detrimental to system performance. In this paper, the impact of cochannel interference on the achievable uplink spectral efficiency of an in-building wireless communication system employing DAS is examined. In the system, remote antenna units (RAUs) are deployed on each floor throughout the building and connected to a central unit (CU) where received signals are processed. System performance is investigated by using a propagation channel model derived from multi-floor, in-building measurement results. The proposed scheme exploits the penetration loss of the signal through the floors, resulting in frequency reuse in spatially separated floors, which increases system spectral efficiency and also reduces co-channel interference. Location based RAU selection and deployment options are investigated. System performance is evaluated in terms of location-specific spectral efficiency for a range of potential mobile terminal (MT) locations and various in-building propagation characteristics.

Deployment of Distributed Antenna Systems in High Buildings

It has been demonstrated that distributed antenna systems (DASs) improve the transmission performance in indoor environment by reducing the radio transmission distance and providing macro diversity. In this paper, indoor DAS is proposed for high building environments. The objective is to provide high data rate transmission for indoor mobile users. The radio signal in high buildings can propagate through floors, a mathematical channel model is proposed in this work based on measurement results. The spectrum is reused among floors but can not be used in the same floor. Therefore co-channel interference exists between floors using the same frequency. Theoretical analysis is presented based on the mathematical channel model proposed. The performance of the system is evaluated in terms of bit error rate (BER) and the effect of the frequency reuse factor is presented. It is demonstrated as well that the shape of the floor and the deployment of the RAUs have a significant effect on the BER performance.

Downlink Transmission of Distributed Antenna Systems in High Building Environments

Over the last few years 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 covering dead spots. In this paper, the DAS is investigated in high building to provide high data rates for indoor wireless mobile communications by exploiting spatial diversity and reducing radio transmission distance. In the proposed indoor DAS, several neighbouring floors compose a floor-bank and are controlled by one central unit (CU). The spectrum is not reused in a floor-bank, but can be reused among different floor-banks, which causes co-channel interference. In order to analyse the performance of the indoor DAS in high building with the presence of co-channel interference, an accurate propagation model of the interference from other floor is a key requirement. Direct propagation inside the building and reflection from nearby buildings have been considered in the channel model. Based on the theoretical analysis, the impact of several system parameters on the performance is presented in terms of BER. Numerical results indicate that the position of the user in the floor has significant effect on the system performance and the attenuation introduced by the floor separation in high buildings should be taken into consideration during the planning of the number of floor in each floor-bank.