Advanced Quantizer Designs for FDD-Based FD-MIMO Systems Using Uniform Planar Arrays

Massive multiple-input multiple-output (MIMO) systems, which utilize a large number of antennas at the base station, are expected to enhance network throughput by enabling improved multiuser MIMO techniques. To deploy many antennas in reasonable form factors, base stations are expected to employ antenna arrays in both horizontal and vertical dimensions, which is known as full-dimension (FD) MIMO. The most popular two-dimensional array is the uniform planar array (UPA), where antennas are placed in a grid pattern. To exploit the full benefit of massive MIMO in frequency division duplexing (FDD), the downlink channel state information (CSI) should be estimated, quantized, and fed back from the receiver to the transmitter. However, it is difficult to accurately quantize the channel in a computationally efficient manner due to the high dimensionality of the massive MIMO channel. In this paper, we develop both narrowband and wideband CSI quantizers for FD-MIMO taking the properties of realistic channels and the UPA into consideration. To improve quantization quality, we focus on not only quantizing dominant radio paths in the channel, but also combining the quantized beams. We also develop a hierarchical beam search approach, which scans both vertical and horizontal domains jointly with moderate computational complexity. Numerical simulations verify that the performance of the proposed quantizers is better than that of previous CSI quantization techniques.Comment: 15 pages, 6 figure

Advanced wireless communications using large numbers of transmit antennas and receive nodes

The concept of deploying a large number of antennas at the base station, often called massive multiple-input multiple-output (MIMO), has drawn considerable interest because of its potential ability to revolutionize current wireless communication systems. Most literature on massive MIMO systems assumes time division duplexing (TDD), although frequency division duplexing (FDD) dominates current cellular systems. Due to the large number of transmit antennas at the base station, currently standardized approaches would require a large percentage of the precious downlink and uplink resources in FDD massive MIMO be used for training signal transmissions and channel state information (CSI) feedback. First, we propose practical open-loop and closed-loop training frameworks to reduce the overhead of the downlink training phase. We then discuss efficient CSI quantization techniques using a trellis search. The proposed CSI quantization techniques can be implemented with a complexity that only grows linearly with the number of transmit antennas while the performance is close to the optimal case. We also analyze distributed reception using a large number of geographically separated nodes, a scenario that may become popular with the emergence of the Internet of Things. For distributed reception, we first propose coded distributed diversity to minimize the symbol error probability at the fusion center when the transmitter is equipped with a single antenna. Then we develop efficient receivers at the fusion center using minimal processing overhead at the receive nodes when the transmitter with multiple transmit antennas sends multiple symbols simultaneously using spatial multiplexing

Розробка комплексної математичної моделі стану каналу багатоантенних систем радіозв’язку

The complex mathematical model of the state of the channel of multi-antenna radio communication systems is developed. The model takes into account: the effect of intentional noise and signal fading, the number of receiving antennas, Doppler effect, correlation coefficient, speed and direction of the receiver and the transmitter, intersymbol interference, phase jitter and inclination of the constellation matrix. Simulation of the state of the channel of multi-antenna radio communication systems is carried out for each individual antenna channel, after which a generalized estimate is formed at the output. The development of the proposed integrated mathematical model is due to the need to improve the accuracy of the description of the channel state of multi-antenna radio communication systems with an acceptable computational complexity. The proposed model allows to improve the accuracy of the description of the state of the channel of multi-antenna radio communication systems by taking into account additional destabilizing factors, thereby increasing the accuracy of the channel state assessment. I would like to note that at the same time there is an increase in the computational complexity at the level of 5-7% due to an increase in the number of evaluated indicators. The mentioned complex mathematical model should be used in radio stations with a programmable architecture to increase their noise immunity by increasing the accuracy of the evaluation of the characteristics of the receiving and transmitting path relative to the state of the channel. The research of the correlation between antennas of multi-antenna radio communication systems was conducted. The results show that in the presence of a line of sight between the receiver and the transmitter, the signal correlation is high and therefore a small increase is expected from the use of several antennas, and in the absence of line of sight conditions, the signal correlation is lowРазработана комплексная математическая модель состояния канала многоантенных систем радиосвязи. Модель учитывает: влияние преднамеренных помех и замираний сигнала, количество приемных антенн, эффект Доплера, коэффициент корреляции, скорости и направление движения приемника и передатчика, межсимвольную интерференцию, фазовый джиттер и наклон констеляционной матрицы. Моделирование состояния канала многоантенных систем радиосвязи проведено для каждого антенного канала, после чего на выходе формируется обобщенная оценка. Разработка предложенной комплексной математической модели обусловлена необходимостью повышения точности описания состояния канала многоантенных систем радиосвязи с приемлемой вычислительной сложностью. Предложенная модель позволяет повысить точность описания состояния канала многоантенных систем радиосвязи за счет учёта дополнительных дестабилизирующих факторов, тем самым повысить точность оценки состояния канала. Хотелось бы отметить, что при этом отмечается увеличение вычислительной сложности на уровне 5–7 % за счет увеличения количества показателей, которые оцениваются. Указанную комплексную математическую модель целесообразно использовать в радиостанциях с программируемой архитектурой для повышения их помехозащищенности за счет повышения точности оценивания характеристик приёмо-передающего тракта относительно состояния канала. Проведено изучение корреляции между антеннами многоантенных систем радиосвязи. Результаты показывают, что при наличии прямой видимости между приемником и передатчиком корреляция сигнала высока и поэтому ожидается небольшой прирост от использования нескольких антенн, а при отсутствии условий прямой видимости корреляция сигнала низкаяРозроблено комплексну математичну модель стану каналу багатоантенних систем радіозв’язку. Модель враховує: вплив навмисних завад та завмирань сигналу, кількість приймальних антен, ефект Допплера, коефіцієнт кореляції, швидкості та напрямок руху приймача та передавача, міжсимвольну інтерференцію, фазовий джитер та нахил констеляційної матриці. Моделювання стану каналу багатоантенних систем радіозв’язку проведено для кожного окремого антенного каналу, після чого на виході формується узагальнена оцінка. Розробка запропонованої комплексної математичної моделі обумовлена необхідністю підвищення точності опису стану каналу багатоантенних систем радіозв’язку з прийнятною обчислювальною складністю. Запропонована модель дозволяє підвищити точність опису стану каналу багатоантенних систем радіозв’язку за рахунок врахування додаткових дестабілізуючих факторів, тим самим підвищити точність оцінювання стану каналу. Хотілося б зазначити, що при цьому відмічається збільшення обчислювальної складності на рівні 5–7 % за рахунок збільшення кількості показників, що оцінюються. Зазначену комплексну математичну модель доцільно використовувати в радіостанціях з програмованою архітектурою для підвищення їх завадозахищеності за рахунок підвищення точності оцінювання характеристик приймально-передавального тракту щодо стану каналу. Проведено вивчення кореляції між антенами багатоантенних систем радіозв’язку. Результати показують, що за наявності прямої видимості між приймачем та передавачем кореляція сигналу є високою і тому очікується невеликий приріст від використання декількох антен, а при відсутності умов прямої видимості кореляція сигналу низьк

Розробка комплексної математичної моделі стану каналу багатоантенних систем радіозв’язку

The complex mathematical model of the state of the channel of multi-antenna radio communication systems is developed. The model takes into account: the effect of intentional noise and signal fading, the number of receiving antennas, Doppler effect, correlation coefficient, speed and direction of the receiver and the transmitter, intersymbol interference, phase jitter and inclination of the constellation matrix. Simulation of the state of the channel of multi-antenna radio communication systems is carried out for each individual antenna channel, after which a generalized estimate is formed at the output. The development of the proposed integrated mathematical model is due to the need to improve the accuracy of the description of the channel state of multi-antenna radio communication systems with an acceptable computational complexity. The proposed model allows to improve the accuracy of the description of the state of the channel of multi-antenna radio communication systems by taking into account additional destabilizing factors, thereby increasing the accuracy of the channel state assessment. I would like to note that at the same time there is an increase in the computational complexity at the level of 5-7% due to an increase in the number of evaluated indicators. The mentioned complex mathematical model should be used in radio stations with a programmable architecture to increase their noise immunity by increasing the accuracy of the evaluation of the characteristics of the receiving and transmitting path relative to the state of the channel. The research of the correlation between antennas of multi-antenna radio communication systems was conducted. The results show that in the presence of a line of sight between the receiver and the transmitter, the signal correlation is high and therefore a small increase is expected from the use of several antennas, and in the absence of line of sight conditions, the signal correlation is lowРазработана комплексная математическая модель состояния канала многоантенных систем радиосвязи. Модель учитывает: влияние преднамеренных помех и замираний сигнала, количество приемных антенн, эффект Доплера, коэффициент корреляции, скорости и направление движения приемника и передатчика, межсимвольную интерференцию, фазовый джиттер и наклон констеляционной матрицы. Моделирование состояния канала многоантенных систем радиосвязи проведено для каждого антенного канала, после чего на выходе формируется обобщенная оценка. Разработка предложенной комплексной математической модели обусловлена необходимостью повышения точности описания состояния канала многоантенных систем радиосвязи с приемлемой вычислительной сложностью. Предложенная модель позволяет повысить точность описания состояния канала многоантенных систем радиосвязи за счет учёта дополнительных дестабилизирующих факторов, тем самым повысить точность оценки состояния канала. Хотелось бы отметить, что при этом отмечается увеличение вычислительной сложности на уровне 5–7 % за счет увеличения количества показателей, которые оцениваются. Указанную комплексную математическую модель целесообразно использовать в радиостанциях с программируемой архитектурой для повышения их помехозащищенности за счет повышения точности оценивания характеристик приёмо-передающего тракта относительно состояния канала. Проведено изучение корреляции между антеннами многоантенных систем радиосвязи. Результаты показывают, что при наличии прямой видимости между приемником и передатчиком корреляция сигнала высока и поэтому ожидается небольшой прирост от использования нескольких антенн, а при отсутствии условий прямой видимости корреляция сигнала низкаяРозроблено комплексну математичну модель стану каналу багатоантенних систем радіозв’язку. Модель враховує: вплив навмисних завад та завмирань сигналу, кількість приймальних антен, ефект Допплера, коефіцієнт кореляції, швидкості та напрямок руху приймача та передавача, міжсимвольну інтерференцію, фазовий джитер та нахил констеляційної матриці. Моделювання стану каналу багатоантенних систем радіозв’язку проведено для кожного окремого антенного каналу, після чого на виході формується узагальнена оцінка. Розробка запропонованої комплексної математичної моделі обумовлена необхідністю підвищення точності опису стану каналу багатоантенних систем радіозв’язку з прийнятною обчислювальною складністю. Запропонована модель дозволяє підвищити точність опису стану каналу багатоантенних систем радіозв’язку за рахунок врахування додаткових дестабілізуючих факторів, тим самим підвищити точність оцінювання стану каналу. Хотілося б зазначити, що при цьому відмічається збільшення обчислювальної складності на рівні 5–7 % за рахунок збільшення кількості показників, що оцінюються. Зазначену комплексну математичну модель доцільно використовувати в радіостанціях з програмованою архітектурою для підвищення їх завадозахищеності за рахунок підвищення точності оцінювання характеристик приймально-передавального тракту щодо стану каналу. Проведено вивчення кореляції між антенами багатоантенних систем радіозв’язку. Результати показують, що за наявності прямої видимості між приймачем та передавачем кореляція сигналу є високою і тому очікується невеликий приріст від використання декількох антен, а при відсутності умов прямої видимості кореляція сигналу низьк

Reconfigurable Receiver Front-Ends for Advanced Telecommunication Technologies

The exponential growth of converging technologies, including augmented reality, autonomous vehicles, machine-to-machine and machine-to-human interactions, biomedical and environmental sensory systems, and artificial intelligence, is driving the need for robust infrastructural systems capable of handling vast data volumes between end users and service providers. This demand has prompted a significant evolution in wireless communication, with 5G and subsequent generations requiring exponentially improved spectral and energy efficiency compared to their predecessors. Achieving this entails intricate strategies such as advanced digital modulations, broader channel bandwidths, complex spectrum sharing, and carrier aggregation scenarios. A particularly challenging aspect arises in the form of non-contiguous aggregation of up to six carrier components across the frequency range 1 (FR1). This necessitates receiver front-ends to effectively reject out-of-band (OOB) interferences while maintaining high-performance in-band (IB) operation. Reconfigurability becomes pivotal in such dynamic environments, where frequency resource allocation, signal strength, and interference levels continuously change. Software-defined radios (SDRs) and cognitive radios (CRs) emerge as solutions, with direct RF-sampling receivers offering a suitable architecture in which the frequency translation is entirely performed in digital domain to avoid analog mixing issues. Moreover, direct RF- sampling receivers facilitate spectrum observation, which is crucial to identify free zones, and detect interferences. Acoustic and distributed filters offer impressive dynamic range and sharp roll off characteristics, but their bulkiness and lack of electronic adjustment capabilities limit their practicality. Active filters, on the other hand, present opportunities for integration in advanced CMOS technology, addressing size constraints and providing versatile programmability. However, concerns about power consumption, noise generation, and linearity in active filters require careful consideration.This thesis primarily focuses on the design and implementation of a low-voltage, low-power RFFE tailored for direct sampling receivers in 5G FR1 applications. The RFFE consists of a balun low-noise amplifier (LNA), a Q-enhanced filter, and a programmable gain amplifier (PGA). The balun-LNA employs noise cancellation, current reuse, and gm boosting for wideband gain and input impedance matching. Leveraging FD-SOI technology allows for programmable gain and linearity via body biasing. The LNA's operational state ranges between high-performance and high-tolerance modes, which are apt for sensitivityand blocking tests, respectively. The Q-enhanced filter adopts noise-cancelling, current-reuse, and programmable Gm-cells to realize a fourth-order response using two resonators. The fourth-order filter response is achieved by subtracting the individual response of these resonators. Compared to cascaded and magnetically coupled fourth-order filters, this technique maintains the large dynamic range of second-order resonators. Fabricated in 22-nm FD-SOI technology, the RFFE achieves 1%-40% fractional bandwidth (FBW) adjustability from 1.7 GHz to 6.4 GHz, 4.6 dB noise figure (NF) and an OOB third-order intermodulation intercept point (IIP3) of 22 dBm. Furthermore, concerning the implementation uncertainties and potential variations of temperature and supply voltage, design margins have been considered and a hybrid calibration scheme is introduced. A combination of on-chip and off-chip calibration based on noise response is employed to effectively adjust the quality factors, Gm-cells, and resonance frequencies, ensuring desired bandpass response. To optimize and accelerate the calibration process, a reinforcement learning (RL) agent is used.Anticipating future trends, the concept of the Q-enhanced filter extends to a multiple-mode filter for 6G upper mid-band applications. Covering the frequency range from 8 to 20 GHz, this RFFE can be configured as a fourth-order dual-band filter, two bandpass filters (BPFs) with an OOB notch, or a BPF with an IB notch. In cognitive radios, the filter’s transmission zeros can be positioned with respect to the carrier frequencies of interfering signals to yield over 50 dB blocker rejection

In-band-full-duplex integrated access and backhaul enabled next generation wireless networks

In sixth generation (6G) wireless networks, the severe traffic congestion in the microwave frequencies motivates the exploration of the large available bandwidth in the millimetre-wave (mmWave) frequencies to achieve higher network capacity and data rate. Since large-scale antenna arrays and dense base station deployment are required, the hybrid beamforming architecture and the recently proposed integrated access and backhaul (IAB) networks become potential candidates for providing cost and hardware-friendly techniques for 6G wireless networks. In addition, in-band-full-duplex (IBFD) has been recently paid much more research attention since it can make the transmission and reception occur in the same time and frequency band, which nearly doubles the communication spectral efficiency (SE) compared with state-of-the-art half-duplex (HD) systems. Since 6G will explore sensing as its new capability, future wireless networks can go far beyond communications. Motivated by this, the development of integrated sensing and communications (ISAC) systems, where radar and communication systems share the same spectrum resources and hardware, has become one of the major goals in 6G. This PhD thesis focuses on the design and analysis of IBFD-IAB wireless networks in the frequency range 2 (FR2) band (≥ 24.250 GHz) at mmWave frequencies for the potential use in 6G. Firstly, we develop a novel design for the single-cell FR2-IBFD-IAB networks with subarray-based hybrid beamforming, which can enhance the SE and coverage while reducing the latency. The radio frequency (RF) beamformers are obtained via RF codebooks given by a modified matrix-wise Linde-Buzo-Gray (LBG) algorithm. The self-interference (SI) is cancelled in three stages, where the first stage of antenna isolation is assumed to be successfully deployed. The second stage consists of the optical domain-based RF cancellation, where cancellers are connected with the RF chain pairs. The third stage is comprised of the digital cancellation via successive interference cancellation followed by minimum mean-squared error (MSE) baseband receiver. Multiuser interference in the access link is cancelled by zero-forcing at the IAB-node transmitter. The proposed codebook algorithm avoids undesirable low-rank behaviour, while the proposed staged-SI cancellation (SIC) shows satisfactory cancellation performance in the wideband IBFD scenario. However, the system performance can be affected by the hardware impairments (HWI) and RF effective channel estimation errors. Secondly, we study an FR2-IBFD-ISAC-IAB network for vehicle-to-everything communications, where the IAB-node acts as a roadside unit performing sensing and communication simultaneously (i.e., at the same time and frequency band). The SI due to the IBFD operation will be cancelled in the propagation, analogue, and digital domains; only the residual SI (RSI) is reserved for performance analysis. Considering the subarray-based hybrid beamforming structure, including HWI and RF effective SI channel estimation error, the unscented Kalman filter is used for tracking multiple vehicles in the studied scenario. The proposed system shows an enhanced SE compared with the HD system, and the tracking MSEs averaged across all vehicles of each state parameter are close to their posterior Cramér-Rao lower bounds. Thirdly, we analyse the performance of the multi-cell wideband single-hop backhaul FR2-IBFD-IAB networks by using stochastic geometry analysis. We model the wired-connected next generation NodeBs (gNBs) as the Matérn hard-core point process (MHCPP) to meet the real-world deployment requirement and reduce the cost caused by wired connection in the network. We first derive association probabilities that reflect how likely the typical user-equipment is served by a gNB or an IAB-node based on the maximum long-term averaged biased-received-desired-signal power criteria. Further, by leveraging the composite Gamma-Lognormal distribution, we derive results for the signal to interference plus noise ratio coverage, capacity with outage, and ergodic capacity of the network. In order to assess the impact of noise, we consider the sidelobe gain on inter-cell interference links and the analogue to digital converter quantization noise. Compared with the HD transmission, the designated system shows an enhanced capacity when the SIC operates successfully. We also study how the power bias and density ratio of the IAB-node to gNB, and the hard-core distance can affect system performance. Overall, this thesis aims to contribute to the research efforts of shaping the 6G wireless networks by designing and analysing the FR2-IBFD-IAB inspired networks in the FR2 band at mmWave frequencies that will be potentially used in 6G for both communication only and ISAC scenarios