Sensitivity Analysis of Ambient Backscattering Communications in Heavily Loaded Cellular Networks

The purpose of this article is to evaluate the impact of adjacent cell interference on monostatic ambient backscattering communication (AmBC) systems at LTE and 5G frequencies. In dense urban areas, cellular macro cell and small cell networks are utilised to provide coverage to backscatter devices (BDs) and traditional users. However, due to the close proximity of adjacent cell mobile base stations, a significant amount of interference is noticed in the serving cell during peak hours. Thus, the signal-to-interference ratio (SIR) is much more of a limiting factor than the signal-to-noise ratio (SNR) of the system. Therefore, the SIR needs to be considered in the system design of AmBC systems. AmBC systems utilise ambient signals as the only source of power, so, there is a necessity for good SIR for proper communication with the BD. Therefore, based on the simulations, the area in close proximity to the base station can be utilised for the deployment of the BDs. Furthermore, it is observed that the achievable range of communication reduces by 44 percent in a heavily loaded cell in comparison with an empty cell when the SIR increases by 10 dB.acceptedVersionPeer reviewe

Evaluation of Maximum Range for Backscattering Communications Utilising Ambient FM radio signals

The objective of this article is to evaluate the maximum range of ambient backscattering communications (AmBC). FM radio signals operating at 100 MHz are selected as the ambient signal due to their large communication ranges. The FM radio signals operate in one of the lowest commercially available frequency bands that can be utilized for AmBC. Additionally, due to the extensive deployment of FM radio, this technology is readily available worldwide. Simulations are performed in a rural highway environment to analyse the suitability of FM radio as an ambient signal for backscattering communications. The FM transmitter and receiver antenna are located in approximately the same area representing a monostatic form of operation for backscattering communications. The sensors are located in more or less the line of sight (LOS) of the TX/RX antenna. The FM signal is reflected back from the sensor towards the receiver for detection. The ray-tracing technique and the radar equation are utilized to perform the simulations. Based on the ray-tracing simulations, a distance of 14.5 km was obtained between the TX/RX antenna and the sensor. The achievable distances utilising the radar equation depend significantly on the cross-section of the sensor and different sizes were utilised in the simulations.acceptedVersionPeer reviewe

Maximum Receiver Harvesting Area of Backscatter Signals from Ambient Low-Frequency Mobile Networks

The purpose of this paper is to estimate the maximum achievable range for ambient backscattering communications (AmBC) by utilizing one of the lowest available frequency bands for mobile networks. Long term evolution (LTE) networks operating at 700 MHz (LTE-700, also referred to as LTE band 28) use the frequency division duplexing (FDD) technique for communications and are utilised as the ambient signals to perform the simulations. The simulations are carried out in urban macro-cellular and suburban highway environments. For the simulations, the sensors are placed in the line-of-sight (LOS) path of the LTE-700 transmitter and receiver antenna as this ensures the maximum applicability of the AmBC technology. Two propagation models, the ray tracing approach and the radar equation are leveraged to determine the maximum range of communication when the signal is reflected by the sensor. It is observed from the analysis that distances of a few hundred meters are achievable utilising both propagation models. The size of the sensor has a pivotal role in determining the maximum range of communication while utilising the radar equation. Therefore, a thorough analysis is performed using real-world sensor sizes deployed for the internet of things (IoT) wireless communication.acceptedVersionPeer reviewe

Interference Analysis of Bi-static Backscatter Communication System: Two Backscatter Devices

Ambient backscatter communication (AmBC) systems utilize existing ambient radio frequency (RF) signals to establish an indirect communication link between a transmitter (TX) and a receiver (RX). Backscatter devices (BDs) modulate their useful information on the incoming ambient signal emitted by the TX, as such their range is usually a very short event when only one BD is considered. This paper aims to analyze the impact of the interference generated due to the presence of another BD in a bi-static backscatter communication system. It is observed from the simulation results that the received signal degradation is mostly due to the cross interference of the other BD, which can be mitigated using successive interference cancellation (SIC) techniques. The level of both cross interference and self interference is significant when the interfering BD is located close to the target BD or the receiver. Therefore, AmBC systems can support more than one BD in an environment as long as the BDs are placed more than a wavelength apart from each other and RX.acceptedVersionPeer reviewe

Direct Path Interference Suppression Requirements for Bistatic Backscatter Communication System

The ambient backscatter communication (AmBC) system utilizes the existing ambient RF signals present in the atmosphere for backscattering the signal. One of the challenges for AmBC system is the interference at the receiver module caused by the direct path signal from the ambient source. The purpose of this paper is to study the coverage aspects of the bi-static backscatter communication system in a typical urban environment at sub-1GHz frequencies using simulations in MATLAB. For the simulation, 3rd generation partnership project (3GPP) urban microcellular and international telecommunication union (ITU) device-to-device (D2D) propagation models are used. Moreover, the dynamic range i.e., the difference in the received power level of the direct path and the backscatter path is investigated. For correctly decoding the backscatter signal at the reader, the target value set for the dynamic range is less than 30 dB. This paper studies the importance of direct path interference suppression for the successful deployment of a bi-static backscatter communication system.acceptedVersionPeer reviewe

Performance evaluation of coordinated multipoint at Millimeter wave frequencies

Current cellular technologies operate in the microwave frequencies below 6 GHz. The spectrum below 6 GHz has become congested due to the various technologies that use this frequency band. This has led to a shortage in spectrum. The millimeter wave (mmWave) band offers a solution to the spectrum shortage and thus has been suggested by researchers as a technology enabling the fifth generation (5G) of cellular communications. There are large bandwidths available within the mmWave band which enables high throughput for end users. Coordinated multipoint (CoMP) is a technology that uses the coordination between two or more base stations. As a result subscribes enjoy higher throughput values. In addition, an improvement in the spectral efficiency is also achieved. The performance of systems utilizing CoMP at mmWave frequencies is evaluated in this thesis. The simulation environment is considered in order to reflect the dense urban environment where 5G is the most likely to be deployed. Various scenarios for the coordination between cells from one or more base stations are formulated. The simulations for these CoMP scenarios are carried out at 2.1 GHz and 28 GHz frequencies with the channel bandwidth of 20 MHz. The bandwidth is increased ten times to 200 MHz and the evaluation of the system performance is carried out in order to offer a comparison as to how CoMP scenarios perform at different bandwidths at mmWave frequencies. Parameters such as received signal strength, signal-to-interference-plus-noise-ratio (SINR), spectral efficiency, area spectral efficiency and throughput are calculated. An analysis of the system performance is carried out based on these parameters. The results indicate that the use of mmWave frequencies improves the performance of the system by improving the throughput when 200 MHz is the bandwidth used. However, the spectral efficiency decreases when the same bandwidth is used. CoMP improves the system performance with the increase in the number of coordinating points. The scenario where the most number of sectors coordinate provides the best SINR, throughput and spectral efficiency among the scenarios considered. The use of CoMP at mmWaves provides high throughput for users. The locations of the evolved NodeBs (eNBs) in practical deployments can be different in comparison with the simulation environment, which may change the performance of the systems

Performance Evaluation of Ambient Backscattering Communication (AmBC) in Outdoor Environments

The demand for wireless communications surged in the past decade due to the massive number of devices requiring a connection to the internet. Although traditional wired communications provide a much more reliable connection, utilizing wires in specific deployment scenarios is improbable. The Internet of Things wireless communication is a concept where interrelated and interlinked devices and objects are connected to each other and the internet to collect information and respond intelligently to the end users. These “things” are deployed at a variety of locations with the objective of providing support for various use cases. Furthermore, the Internet of Things is envisioned to integrate everyday objects into the connected ecosystem. This has led to a significant increase in the amount of energy that will be required to power up these devices. Modern battery technology involves the movement of electrons between the positive and negative electrodes. Thus, lithium-ion batteries need to be replaced as they degrade over time. However, different deployment scenarios of the Internet of Things render the regular maintenance of these devices impossible. Therefore, newer technologies need to be identified in order to provide energy and power to such devices. Ambient backscattering communication utilizes ambient radio frequency signals to establish connection links between the transmitter, receiver, and backscatter devices. Radio frequency signals can originate from a variety of sources such as television and radio broadcasts, Wi-Fi signals, and cellular signals to name a few. Additionally, in ambient backscattering communication, the backscatter devices are able to harvest energy from the ambient signals and utilize them as the source of power for the backscatter devices. This thesis focuses on the coverage, capacity, and interference aspects of ambient backscattering communication pertaining to different outdoor deployment scenarios. The main contributions to this thesis can be divided into three main parts. Firstly, an analysis to determine the maximum coverage of ambient backscattering communication systems (operating in the mono-static and bi-static modes) was performed utilizing ambient FM radio signals. It was observed that in the bi-static mode of operation, about 44 dB (from the path loss) remained for the propagation of the signal between the backscatter device (located 30 km from the TX) and the RX. Additionally, in the mono-static mode of operation, the backscatter device could be located 14.5 km away utilizing the free space path loss equation. The achievable distance reduces with the decrease in the cross-section of the backscatter device. Secondly, cellular signals were utilized to evaluate the achievable range of communication of mono-static ambient backscattering communication systems. It was observed that utilizing ambient Long-Term Evolution (LTE) signals (operating at a carrier frequency of 700MHz) a communication link between the TX/RX and the backscatter device located a few hundred meters apart could be established. Additionally, an analysis was carried out to determine the applicability of 5G signals for ambient backscattering communication systems in the outdoor macro cell and small cell environments. It was concluded that very short-range communication distances could be established between the TX/RX and the backscatter device at 5G frequencies, especially at the millimeter-wave carrier frequency of 26 GHz. The achievable range of communication was heavily dependent on the cross-section of the backscatter device and the additional loss. Furthermore, a study was carried out to determine the impact of the cell load and the adjacent cell interference on the coverage of mono-static ambient backscattering communication systems. It was observed that there was a 44 percent decrease in the coverage in a heavily loaded cellular network in comparison with an unloaded network. Finally, bi-static AmBC systems were studied utilizing sub-1 GHz ambient signals. It was observed that only the carrier frequency of 200MHz was suitable for bi-static ambient backscattering communication. Subsequently, the need for the suppression of the direct path signal from the legacy source was studied and some interference suppression techniques were proposed. In addition, the impact caused by the presence of a second backscatter device in the environment was studied. It was observed that the second backscatter device caused the most interference when it was located close to the original backscatter device or the RX. The impact of the second backscatter device could be alleviated by positioning it one wavelength meter away from the first backscatter device or the RX

Performance evaluation of coordinated multipoint at Millimeter wave frequencies

Current cellular technologies operate in the microwave frequencies below 6 GHz. The spectrum below 6 GHz has become congested due to the various technologies that use this frequency band. This has led to a shortage in spectrum. The millimeter wave (mmWave) band offers a solution to the spectrum shortage and thus has been suggested by researchers as a technology enabling the fifth generation (5G) of cellular communications. There are large bandwidths available within the mmWave band which enables high throughput for end users. Coordinated multipoint (CoMP) is a technology that uses the coordination between two or more base stations. As a result subscribes enjoy higher throughput values. In addition, an improvement in the spectral efficiency is also achieved. The performance of systems utilizing CoMP at mmWave frequencies is evaluated in this thesis. The simulation environment is considered in order to reflect the dense urban environment where 5G is the most likely to be deployed. Various scenarios for the coordination between cells from one or more base stations are formulated. The simulations for these CoMP scenarios are carried out at 2.1 GHz and 28 GHz frequencies with the channel bandwidth of 20 MHz. The bandwidth is increased ten times to 200 MHz and the evaluation of the system performance is carried out in order to offer a comparison as to how CoMP scenarios perform at different bandwidths at mmWave frequencies. Parameters such as received signal strength, signal-to-interference-plus-noise-ratio (SINR), spectral efficiency, area spectral efficiency and throughput are calculated. An analysis of the system performance is carried out based on these parameters. The results indicate that the use of mmWave frequencies improves the performance of the system by improving the throughput when 200 MHz is the bandwidth used. However, the spectral efficiency decreases when the same bandwidth is used. CoMP improves the system performance with the increase in the number of coordinating points. The scenario where the most number of sectors coordinate provides the best SINR, throughput and spectral efficiency among the scenarios considered. The use of CoMP at mmWaves provides high throughput for users. The locations of the evolved NodeBs (eNBs) in practical deployments can be different in comparison with the simulation environment, which may change the performance of the systems

Assessment of 5G as an ambient signal for outdoor backscattering communications

The aim of this article is to evaluate the applicability of 5G technology as a possible ambient signal for backscattering communications (AmBC). This evaluation considers both urban macro-cellular, small cell as well as rural highway environments. The simulations are performed in outdoor areas including analysis about 5G implementation strategies in different scenarios. Essential aspects of 5G radio network topology such as frequency domain (3.5 GHz and 26 GHz) and antenna locations (offering line-of-sight, LOS) are highlighted and turned to applicability scenarios with AmBC. The LOS scenarios are evaluated to determine the widest applicability area of 5G for AmBC. Typical AmBC applications are studied including collection of data from several sensors to receivers. Evaluation of the applicability of 5G was based on propagation related simulations and calculations utilising the ray tracing technique and the radar equation. The results demonstrate that 5G can be used as an ambient signal for backscattering communications for short ranges for typical sensor sizes. It is also observed that the range of communication is heavily dependent on the the size of the sensor.publishedVersionPeer reviewe

Power Budget for Wide Area Ambient backscattering Communications

The objective of this article is to extend the range of Ambient Backscattering Communications (ABC). The ABC technology is a key enabling technologies for Internet of Things (IoT) wireless communications. A rural open area towards Hanko, Finland is considered for the power budget calculations. FM radio waves are considered as the source of ambient RF waves as the FM radio waves have long communication range and the technology is readily available worldwide. The sensors are placed on a highway at an example distance of 30 km from the FM transmitter. There is a clear line of sight (LOS) connection between the FM transmitter and the sensors. The path loss is determined based on the sensor locations and the losses at the sensor occur due to diffraction and scattering. A power budget is calculated based on these aforementioned key system parameters. It is observed that there is around 44 dB of power margin available after the signal from the FM transmitter is backscattered (at the sensor) and the losses in the system are accounted for. This indicates that the receiver module is able to detect the signal as it is above the minimum reception level threshold for the system. Therefore, the radio waves are able to propagate further after the signal is backscattered at the sensor(s) utilizing the available power margin. Thus, the range of communication can be extended to a wider area.acceptedVersionPeer reviewe