Secondary spectrum usage in TV white space

Currently, the use of TV frequencies is exclusively license based with the area not covered by licensed TV transmitters being known as TV white space. In TV white space, the spectrum can be reused by a secondary user. This thesis studies how the TV white space can be used by a cellular system. The study addresses the problems of how the access to the spectrum is arranged, how the spectrum usage is constrained and how much capacity a secondary system will have. The access to TV white space can be arranged by using spectrum sensing or a geolocation database. This spectrum sensing relies on the performance of the signal detection algorithm. The detector has to operate in a fading environment where it should identify very low signal levels. In this thesis, the detector performance in a slow and fast fading environment is modeled. The model indicates that for a sufficiently long measurement time the impact of the fast fading can be averaged out. Unfortunately, simple single antenna-based detectors are not able to operate at a low enough signal-to-noise level. We propose a novel multi antenna-based detection algorithm that is specially designed to operate in a fading environment. TV white space is characterized by the amount of spectrum available for secondary usage. Because of the signal detection errors, a system using the sensing-based access is not able to use the entire available spectrum. This dissertation provides a method for estimating the spectrum utilization efficiency. The method illustrates how the detection error level affects the amount of available spectrum. One of the central questions studied in this thesis is how to describe the interference generated by the secondary transmitters. In the conventional model, the interference is computed as the sum of the interfering powers from individual transmitters. An alternative approach, pursued here, is to characterize the transmitter by its transmission power density per area. With such a model, the interference computation is done by integrating over the secondary system deployment area. The proposed method simplifies the interference estimation process. In data communication systems the spectrum attractiveness depends on the data rate the system can provide. Within the scope of this work, the achievable data rate is computed for a cellular system. Such computation is described as an optimization problem. The solution to this problem is found by searching for the optimal power allocation among the cochannels and the adjacent channels of a nearby TV transmitter

Zero-Energy-Device for 6G: First Real-Time Backscatter Communication thanks to the Detection of Pilots from an Ambient Commercial Cellular Network

Ambient backscatter communication technology (AmBC) and a novel device category called zero-energy devices (ZED) have recently emerged as potential components for the forthcoming 6th generation (6G) networks. A ZED communicates with a smartphone without emitting additional radio waves, by backscattering ambient waves from base stations. Thanks to its very low consumption, a ZED powers itself by harvesting ambient light energy. However, the time variations of data traffic in cellular networks prevents AmBC to work properly. Recent works have demonstrated experimentally that a backscatter device could be detected by listening only ambient pilot signals (which are steady) instead of the whole ambient signal (which is bursty) of 4G. However, these experiments were run with a 4G base station emulator and a bulky energy greedy backscatter device. In this paper, for the first time, we demonstrate real-time AmBC on the field, with Orange commercial 4G network as ambient source and Orange Zero-Energy Device.Comment: 3 pages, 7 figures , 6Get202

Latency-Aware Power Management in Software-Defined Radios

| openaire: EC/H2020/815191/EU//PriMO-5GCloud computing provides benefits in terms of equipment consolidation and power savings from higher utilization for virtualizable software. Cellular communication software faces challenges in cloud computing platforms. BSs create a specific load profile that differs from traditional cloud service loads. Cellular communication system implementations have real-time deadlines with fixed, periodic latency requirements. In this paper, we assess the suitability of an unmodified Ubuntu Linux OS running on a commodity server to operate latency-critical software using a 4G LTE BS software-defined radio implementation. Scaling of the CPU clock frequency is shown to be feasible without excessive impact on the platform's ability to meet the 4 ms processing delay requirement imposed by the LTE standard. Measurements show the relationship between the processor's operating frequency and the number of missed subframe processing deadlines to be nonlinear. The results obtained also indicate that a high computational capacity does not suffice to ensure satisfactory operation since fronthaul processing overhead can limit achievable performance. Use of offload-capable network interface cards is studied as a potential remedy.Peer reviewe

Multi-bounce Effect: an Overlooked Aspect in Analysis of Ambient Backscatter Networks

Peer reviewe

Performance Evaluation of Switched Beam Antenna with Different Configurations at 28 GHz

| openaire: EC/H2020/815191/EU//PriMO-5GThe main target of this paper is to evaluate the performance of a switched beam antenna in a macro-cellular environment at 28 GHz frequency. Another objective of this study is to compare the performance of a cellular system equipped with 7-beams switched beam antenna with conventional system implemented with wide 65◦ horizontal HPBW antenna. A campaign of 3D ray tracing simulations was carried out by using realistic 3D building data. Performance metrics considered for this study are RX level, SINR, system spectral efficiency, and the relative gain. Different configurations of 7-beams antenna is studied and the advantages and the disadvantages of considered configurations are highlighted in this paper. It is learned from the acquired results that an optimal configuration of 7-beams antenna can provide upto only 209.72 % of relative gain with respect to a traditional 3-sector site deployment. However, the relative performance gain of a 7-beam antenna can be negative under certain circumstances.Peer reviewe

DAS and UDN Solutions for Indoor Coverage at Millimeter Wave (mmWave) Frequencies

| openaire: EC/H2020/815191/EU//PriMO-5GThe future 5th Generation (5G) wireless networks are expected to support a variety of bandwidth hungry applications. Millimeter wave (mmWave) communications, and Ultra Dense Network (UDN) deployment along with smart Distributed Antenna System (DAS) can be considered as a tempting solution for cellular networks. The aim of this paper is to analyze the performance of different UDN and DAS configurations in an indoor environment i.e. real university office building at 3.5 GHz, 28 GHz, and 60 GHz frequency. System performance is analyzed by performing ray launching simulations using a three dimensional floor plan. The obtained results show the incapability of basic indoor solution in providing the ubiquitous Quality of Service (QoS) in an indoor environment at higher frequencies. Simulation results shows that it is inevitable to have a dedicated indoor network with UDN or DAS configuration to provide homogeneous coverage in an indoor condition. It is found that despite of more interference the UDN deployment providesa higher system capacity compared with DAS due to more number of cells. However, the gain of cell densification saturates with the increasing number of cells.Peer reviewe