Monitoring of Electromagnetic Radiation from Cellular Base Stations in Kuwait

Cellular mobile communication technology has grown exponentially in the last decade resulting in large number of base stations in areas at which people are living or working. All over the world, the electromagnetic pollution produced from cellular base stations erected in residential areas and its effect on the environment and human body is a problem that has been concerning the society for many years. This paper, introduces the effects of electromagnetic energy emitted cellular base stations on the biological systems of the human body. The induced electromagnetic fields (EMF), and specific absorption rate (SAR) were calculated in close proximity to cellular mobile base stations. The calculated values of SAR were compared with the most commonly used international limits. The results show that the electromagnetic radiation (EMR) exposure levels at a distance of several meters from the base station towers can cause hazardous effects to the public

The peculiar line-of-sight (LoS) propagation in air-to-ground channel provides both opportunities and challenges for the emerging cellular-connected unmanned aerial vehicle (UAV) communications. On one hand, the LoS channels make more cellular base stations (BSs) visible to a UAV as compared to ground users, which leads to a higher macro-diversity gain as compared to the ground users. On the other hand, the LoS channels also render the UAV to generate/receive more severe uplink/downlink interference to/from the BSs, thus requiring more sophisticated inter-cell interference coordination (ICIC) techniques with more BSs involved. To draw essential insight, this paper studies the uplink transmission from a UAV to cellular BSs. To mitigate the UAV's interference effect, we aim to maximize the sum-rate of the UAV and all ground users in its resulted ICIC region by jointly optimizing the UAV's cell association, resource block (RB) allocation, and transmit power. We first propose a centralized ICIC design that achieves the optimal performance. As the centralized ICIC requires global information of the network and substantial information exchange among an excessively large number of BSs, we further propose a decentralized ICIC scheme of significantly lower complexity and overhead for implementation. Specifically, we divide the cellular BSs into clusters, each with a dedicated cluster head for collecting information from its cluster BSs and exchanging information with the UAV by exploiting the LoS-induced macro-diversity. Numerical results show that the proposed decentralized ICIC scheme achieves a performance close to the optimal centralized design, and also outperforms the traditional ICIC scheme for cellular networks with terrestrial interference only.

Coal and rock dynamic disasters induced by the large-scale deformation and fracture of surrounding coal and rock, have significant impact on the safe and efficient extraction of coal. Effective and accurate early warning is the elementary basis for the efficient and affordable prevention and control of such kind of disasters. Laboratory experiments have demonstrated that EMR signals are generated during the process of deformation and fracturing of coal or rock under various loading conditions. EMR are paroxysmal pulse signals and increase with stress applied; and the higher the load, the larger the EMR signals. The genetic mechanism, characteristics and laws of EMR of coal and rock were studied by laboratory experiments, based on which, an EMR monitoring and warning method has been put forward. Based on the research results and the method, EMR detectors, Model KBD5 and KBD7, have been developed and employed to predict coal and rock dynamic disasters, such as coal and gas outbursts, rockbursts, monitor goaf roof stability, observe pressure of the surrounding rocks, and determine the width of relief areas. Before the occurrence of a coal and rock dynamic disaster, EMR usually has a corresponding precursor. According to the characteristics of the EMR precursor in time and space, it is possible to recognize the dangerous areas of rockbursts around underground openings and thus give early warnings of the dynamic phenomena as well.

Cellular multihop networks have the potential to decrease power consumption, increase coverage and/or enable higher data rates. We propose using in-band transmissions for the connection between a fixed repeating device and the cellular base station. A user connected via the repeater use one frequency band (fq2) for the communication to the repeater and the repeater uses an adjacent frequency band (fq1) for the communication to the base station. There is strong interference in the repeater due to transmitting and receiving on adjacent frequency bands, and strong interference from users connected directly to the base station on fq2. We demonstrate that the method can be used to introduce multihop functionality into a WCDMA FDD cellular system with only small changes. In a pessimistic scenario repeated users can lower their transmit power, but others have to increase their power. The multihop system requires no extra frequency spectrum but it has a small capacity penalty, and it requires a high adjacent channel leakage ratio in the repeaters. The results are reasonable for this pessimistic study and suggest further studies of alternative scenarios to improve the performance

In this paper, we propose a model for energy cooperation between cellular base stations (BSs) with individual hybrid power supplies (including both the conventional grid and renewable energy sources), limited energy storages, and connected by resistive power lines for energy sharing. When the renewable energy profile and energy demand profile at all BSs are deterministic or known ahead of time, we show that the optimal energy cooperation policy for the BSs can be found by solving a linear program. We show the benefits of energy cooperation in this regime. When the renewable energy and demand profiles are stochastic and only causally known at the BSs, we propose an online energy cooperation algorithm and show the optimality properties of this algorithm under certain conditions. Furthermore, the energy-saving performances of the developed offline and online algorithms are compared by simulations, and the effect of the availability of energy state information (ESI) on the performance gains of the BSs' energy cooperation is investigated. Finally, we propose a hybrid algorithm that can incorporate offline information about the energy profiles, but operates in an online manner.

Levels of radiofrequency radiations around two global systems for mobile communication (GSM) base stations located in the vicinity of a residential quarter and workplace complex were measured. The effects of the radiofrequency radiations on albino mice placed in exposure cages and located around the base stations over a six months period were carried out. The levels of radiofrequency (RF) radiations around the base stations were found to be between 488.51mV/m to 625.49mV/m compared to 59 mV/m in control stations. The results of the weight change experiment showed that over the 180 days of observation, there was weight gain in the exposed and control mice groups. Statistical comparisons of mean weight changes between exposed mice and control mice showed that there were no significant (P>0.05) differences between the weight of the test animals. The hematological studies revealed an elevation of white blood cell (WBC) counts in mice exposed to RF radiations compared to control group. There was however no significant (P>0.05) difference between the red blood cell counts in the exposed and control mice. There was also no significant (P>0.05) difference in the hemoglobin and glucose levels in the blood of both exposed and control mice groups. The red blood cells in exposed mice were however found to contain a higher number of macrocytes, poikilocytes, polychromatic cells and fewer target cells than the control mice. Histological studies of the heart and kidney of exposed mice showed only slight tissues deformities in kidneys of exposed mice compared to control. The relevance of these findings in setting radiofrequency radiation exposure guidelines and the need for more studies with widely varying biological parameters is very necessary as Nigeria leaps further into the communication age.

In this paper, common mode (CM) and differential mode (DM) far-field radiation models of a typical digital inverter with cables are built up to predict electromagnetic field strength and analyze field characteristics. The CM current model and its analyses are based on the imbalance difference method. It is found out that the voltage between the drain and the source electrodes of upper transistor is the key equivalent source of electromagnetic interference (EMI). Far-field radiation strength of the digital inverter in free space is predicted by using the asymmetrical antenna radiation method and current loop radiation method. The accuracy of these methods is verified by the CST electromagnetic simulation results in the frequency range from 1 MHz to 400 MHz. Furthermore, the radiation models are improved by using the mirror method, which enables to include the reflection effect of the metal ground plane at the electromagnetic compatibility (EMC) test site. Both the results of measurements in a semi-anechoic chamber and the simulation results confirm the proposed electromagnetic radiation prediction method.

<p>This thesis considers the analysis of current and future cellular communication systems. The main focus is on multiuser multiple-input multiple-output (MU-MIMO) antenna systems. The goal of this work is to characterize the achievable spectral efficiency of MU-MIMO systems, as well as to analyze the performance of practical, linear MU-MIMO transceiver structures in heterogeneous propagation environments. The analytical derivations in this thesis are based on the mathematical theory of finite and large dimensional random matrices. A collection of new general random matrix theory results, which permit efficient numerical evaluation are derived. With downlink regularized zero-forcing (RZF) processing at a cellular base station (BS), a general framework for the analysis of the expected (average) signal-to-interference-plus-noise-ratio (SINR) and ergodic sum spectral efficiency is developed for uncorrelated and semi-correlated Rayleigh fading, as well as uncorrelated Ricean fading propagation channels. In contrast to existing results, the presented analyses are extremely general, applicable to single-cellular, multi-cellular, as well as distributed antenna systems. These systems could consist of arbitrary numbers of transmit and receive antennas, link signal-to-noise-ratios (SNRs), equal and unequal transmit correlation structures, and line-of-sight (LoS) levels, respectively. Numerical results are presented for single-cellular, as well as for two-tier multi-cellular systems demonstrating the impact of novel BS coordination strategies to suppress dominant inter-cellular interference. With dominant LoS directions in the propagation channel, the instantaneous downlink zero-forcing (ZF) SNR of a given terminal is analyzed. The ZF SNR is shown to be approximated by a gamma distribution for any number of transmit and receive antennas, link SNRs, and LoS levels. Furthermore, for moderately sized MU-MIMO systems, simplified instantaneous and ergodic sum spectral efficiency analyses are presented with RZF, ZF and matched-filter (MF) transmission on the downlink, and minimum-mean-squared-error, ZF and maximum-ratio combining (MRC) on the uplink, respectively. The simple nature of the derived expressions lead to the discovery of several valuable system level insights as a function of the contributing network parameters. Numerical results are presented for conventional and moderate MU-MIMO systems. Considering downlink semi-correlated Rayleigh fading channels with spatial correlation at the BS, it is mathematically proven that common correlation patterns for each terminal predicts lower ergodic sum spectral efficiencies in comparison to terminal specific correlation patterns. Closed-form approximations for the expected SINR and ergodic sum spectral efficiency are derived for both MF and ZF precoding, demonstrating the sensitivity of unequal correlation structures on the expected signal, interference and noise powers, respectively. The presented numerical results provide a cautionary tale of the impact of unequal correlation patterns on MU-MIMO performance and the importance of modeling this phenomenon. Finally, an approximate uplink performance analysis of large MU-MIMO systems with MRC and space-constrained uniform linear antenna arrays (ULA) is presented for semi-correlated Ricean fading channels. A space-constrained channel model is proposed, encapsulating the effects of unequal receive spatial correlation, unequal LoS levels, and unequal link gains for each terminal. The per-terminal and cell-wide ergodic sum spectral efficiencies are characterized and numerous practical special cases are presented. A limiting analysis of the ergodic per-terminal and cell-wide spectral efficiencies is also carried out, as the number of BS antennas grow without bound with a finite number of terminals and fixed physical dimensions of the ULA. Numerical results demonstrate the impact of space-constrained ULAs on the MU-MIMO system performance with variation in the LoS levels, correlation structures, physical array dimensions, and system size, respectively.</p>

In this paper, a spectrum sharing protocol is proposed for device-to-device (D2D) communication overlaying cellular networks. Specifically, the protocol allows the D2D users to communicate bi-directionally with each other while assisting the two-way communication between the cellular base station (BS) and the cellular user (CU) over the same time and frequency resources. The achievable rate region of the sum-rate of the D2D transmissions versus that of the cellular transmissions is evaluated. The Pareto boundary of the region is found by optimizing the transmit power at BS and CU as well as the power splitting factor at the relay D2D node. We find through numerical results that the proposed two-way protocol with power control at the BS and CU is effective to improve the sum rate for both the D2D and cellular communication.

Owing to the nature of battery-operated sensors, the residual energy of their battery should be considered when a sink node collects sensory data from them. If a sink attempts to collect data from a sensor that does not have sufficient residual energy to transmit data, the utilization of wireless communication resources may be degraded. However, requiring a periodic residual energy report of the sensors considerably reduces the energy efficiency of them. Consequently, the sink node must be able to estimate the residual energy of the sensors without additional information exchange before attempting to collect data. To tackle this problem, we propose a data collection scheme for mobile sinks in cellular Internet-of-things (IoT) networks. The scheme consists of two phases. In the first phase, the mobile sink estimates the residual energy of the surrounding sensors. To reduce the complexity, we design a state diagram composed of three states based on the Markov chain of the sensor. The sink node calculates the communicable likelihood of each sensor based on the state diagram and collects data from the sensor with the highest likelihood. In the second phase, a cellular base station (BS) selects the appropriate mobile sink to improve the signal-to-interference-plus-noise ratio (SINR) of the signal from a cellular user. Each sink node delivers the bidding price to the BS based on the likelihoods of the sensors. The BS determines an appropriate sink node to allocate resources based on the received bidding prices. Moreover, we show the performance of the proposed method in terms of SINR and IoT network utilization through simulation.

The capacity-achieving coding scheme for the multiple-input multiple-output (MIMO) broadcast channel is dirty-paper coding. With this type of transmission scheme the optimal number of active users that receive data and the optimal power allocation strategy are highly dependent on the structure of the channel matrix and on the total transmit power available. In the context of packet-data access with adaptive transmission where mobile users are equipped with a single receive antenna and the base station has multiple transmit antennas, we study the optimal number of active users and the optimal power allocation. In the particular case of two transmit antennas, we prove that the optimal number of active users can be a non-monotonic function of the total transmit power. Thus not only the number of users that should optimally be served simultaneously depends on the user channel vectors but also on the power available at the base station transmitter. The expected complexity of optimal scheduling algorithms is thus very high. Yet we then prove that at most as many users as the number of transmit antennas are allocated a large amount of power asymptotically in the high-power region in order to achieve the sum-capacity. Simulations confirm that constraining the number of active users to be no more than the number of transmit antennas incurs only a marginal loss in spectral efficiency. Based on these observations, we propose low-complexity scheduling algorithms with sub-optimal transmission schemes that can approach the sum-capacity of the MIMO broadcast channel by taking advantage of multiuser diversity. The suitability of known antenna selection algorithms is also demonstrated. We consider the cases of complete and partial channel knowledge at the transmitter. We provide simulation results to illustrate our conclusions.

This paper investigates the performance of current downlink power allocation mechanisms for soft handoff in CDMA systems, including the equal power allocation (EPA), quality balancing power allocation (QBPA), site selection diversity transmission (SSDT), and link proportional power allocation (LPPA). We evaluate the outage performance of these power allocation schemes from the perspectives of base station transmission power limit and power control error. Traditionally, the SSDT scheme has been viewed as the optimal solution for downlink handoff from the standpoint of power efficiency. The SSDT scheme selects the best base station from the active set to transmit downlink signals to the user. However, we find that SSDT is very sensitive to power control error as the user is at the cell boundary. Thus, with consideration of both base station power shortage and transmission control errors, LPPA exhibits the lowest outage probability when the system load is not heavy, while SSDT is the best choice only in the case of heavy traffic load.

The new MIMO schemes commonly referred to as spatial modulations (SM) use the index of the transmit (resp. the receive) antenna to transmit additional data and hereby increase the spectral efficiency of digital communication systems. Most of proposed SM schemes allow for simultaneously transmitting two types of symbols, the classical IQ-symbols of a M-order modulation, and a spatial information related to the index of the transmit or targeted receive antenna(s). In this paper, we propose a complete uplink and downlink transmission system between a Base Station and a Connected Device for Internet-of-Things application based on SM. We thus concentrate on SM schemes only conveying spatial information for both downlink (from a base station to a connected device) and uplink (from a connected device to a base station) transmissions and leading to low complexity at the device. For the downlink we propose the use of an existing receive SM, the ERASK that is an extension of a very simple receive spatial modulation known as RASK (Receive Antenna Shift Keying) which aims at increasing the spectral efficiency. For the uplink, we firstly propose a new scheme which analogy with ERASK is highlighted. Both ERASK and ESSK can be efficiently used in the global system while keeping very low complexity at the device side. All complexity is reported at the base station with pre-processing function used to concentrate the signal energy towards the device targeted antenna(s). The channel estimation is also only needed at the base station for pre-processing of the ERASK and detection process of the ESSK.

A resource allocation algorithm for orthogonal frequency division multiple access-based and infrastructure-based relay networks is introduced in this paper. The algorithm is applied in the downlink of a single cell. Channel state information is exploited at the transmitting base station (BS) and at the transmitting relay stations (RSs). The algorithm coordinates the allocation of subcarriers, bits, and power distributed over the BS and RSs. The goal of the resource allocation algorithm is that the sum rate in a cell is maximized. Simultaneously, each subscriber station (SS) achieves a requested data rate called minimum data rate, and a tolerated bit error probability is ensured on each link. Simulation results show that a sum rate in a cell is achieved which is near to an upper bound introduced in the paper. Even if the sum of the minimum data rates of all SSs is large, the proposed algorithm offers the minimum data rate nearly as reliable as the upper bound. Additionally, simulation results show that the proposed algorithm achieves a superior sum rate compared to the sum rate of other resource allocation algorithms.

As the mobile telecommunication systems are tremendously growing allover the world then the numbers of handheld and base stations are also rapidly growing and it became very popular to see these base stations distributed everywhere in the neighborhood and on roof tops which has caused a considerable amount of panic to the public in Palestine concerning wither the radiated electromagnetic field from these base stations may cause any health effect or hazard. This paper focuses on the radiated electromagnetic energy from some typical mobile base stations around the city of Nablus. The exposure levels due to these stations were measured and compared to some international standard guidelines like ICNIRP and FCC to see if it meets these standards, this is in order to answer some of the public fear and concern. The results are presented and some comments are made on the other sources of electromagnetic radiation in the 200 kHz to 3 GHz range.