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Block diagram of the simplified transceiver considered for baseband modeling of the Tx modulated spur and Tx-IMD2 interference
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This article presents an overview of the major trends and challenges involved with the design of multi-band, multi-standard digitally-intensive radio frequency transceivers for next generation mobile communications. In addition, we discuss in detail one aspect of the implementation challenges, namely the occurrence and cancellation of self-interfer...
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... the Tx-IMD2 dis- tortion components at higher frequencies are filtered away by the base band filtering stages while the distortion component around DC will directly interfere with the wanted signal and degrades its SNR. Figure 3 illustrates the block diagram of the transceiver that we consider to derive an equivalent baseband signal model of the addressed modulated spur and IMD2 self-interference. ...
Citations
... When multicast is utilized, an IMT is essential to communicate its information to different MTs in CMC by the information range [63] that can arrive at the MT with the most terrible network disorder. Consequently, the transmitting power consumption of IMT be stated as Thus, the entire consumption of energy of CMC during utilization of MT k due to IMT and can be demonstrated as follows: ...
The Mobile Edge Computing is a novel prototype that was developed recently due to the benefits and expanding nature of electronic data-processing techniques close to broadcasting networks. In this context nowadays the uses of wireless cellular facilities have been increased drastically in quantity of cellular users and estimation tasks of the subscribers may be offloaded to network interface for remote implementation. Therefore, required information, and hence power consumption capacity of the base radio station has enhanced substantially. Additionally, this increases the running cost of the total system and also causes global-warming. So, referring to the base radio station power consumption capacity in Long-Term Evolution (LTE) has been the main impediment for merchants to become eco-friendly and valuable in the competing mobile industry. It needs an innovative process to develop Energy Efficient intercommunication in LTE networks. Significance of this study has involved vast research and a global investigation process. The active energy source assignment, equal load sharing, carrier accumulation and bandgap enlargement is therefore categorized in groups and projected in this study for the methods of energy conservation. Every single procedure has unique advantages and drawbacks, which leads to compromise amongst conservation of energy and additional performance for measuring the problems of research design. This study focuses on the different energy conservation methods for the LTE networks and briefly examines their usefulness through a complete comparative analysis. With the gradually increasing number of wireless customers an optimization problem is employed here to assess the LTE system performance and Energy Consumption Rate.
... Long-Term Evolution, a technology for communications with wireless data and an evolution standard (GSM/UMTS) which is an implemented design by the European Telecommunications Standards Institute (ETSI) [1] [2]. However, The LTE initiative does include active participation from various countries and businesses. ...
... Radio transceivers can operate simultaneously, i.e., sending and receiving the radiofrequency waves [1,19,20]. The time for sending radio waves (Tx) is different from receiving radio waves (Rx) [21]. The existence of a push to talk (PTT) switch on the transceiver radio is a switch for setting the transceiver radio to the receiver or sender position [13,22]. ...
A radio communication system (RCS) based on digital trunking of the digital mobile radio (DMR) type of Tier-III with any of the brands is installed, consisting of mobile radio devices, portable radio devices, repeater devices, devices antenna, and power supply device. The technical specifications for these types of equipment have been approved by institution-owned. This paper describes a radio communication system infrastructure based on a digital trunking RCS for predicting the area coverage for independent or private use. The research contributions of this study include (a) predicting the signal of area coverage of the repeater and radio devices and (b) observing results of communication performance on the DMR Tier-III Trunking radio communication system. Research methods for achieving research objectives, including five main parameters are required connectivity, the DMR application for predicting radio signal area coverage of the repeater system, and observation of the communication performance. Tuning on the repeater system include five conditions, while on radio equipment includes four conditions. Prediction and observation of the coverage area based on seven parameters as input. The simulation results are in the form of a screenshot with an area coverage of 140.938 kilometers. The observation of communication performance through dummy loads in the form of providing types of artificial condition calls. In general, after the research objectives are obtained, it is expected that the system is well connected.
... A popular area in this is to digitally compensate several RF imperfections and RF interferences using DSP methods, e.g. shown in [134,135,136,36,162,38,163] and also, presented in some of our works [173,174,175,135,176,169]. Inspired by this, as a major contribution of this chapter, all-digital cancellation architectures have been developed and demonstrated for the modulated spur and also, for joint modulated spur and IMD2 interference. ...
In today’s world, the mobile phone has become an indispensable device for the global consumer market. To meet the rapid and continuous demand for higher data rates coupled with the severe global spectral shortage, the carrier aggregation (CA) feature has been deployed by the 4G/5G cellular industry. This enables carrier providers to combine several fragmented spectrums into a single wide spectrum in order to en- hance the data rate significantly. To support the CA feature, the user equipment (UE) has to implement multiple integrated transmitters and receivers on a single chip by keeping the cost, area, and power as low as possible. In addition, to cope with the ever-increasing CA combinations, the industry is driving towards low-cost radio fre- quency (RF)-front end solutions containing cheap duplex filters with limited isolation capability. This results in a leakage of the own transmit (TX) signal as well as other so- called blocker signals into the receiver. The simultaneous presence of multiple clocks along with the strong blockers raises several internal and external cross-talk issues in the system leading to various interference scenarios that desensitize the receiver.
This thesis fundamentally targets two interference problems, namely: the modulated spur interference; and the second-order intermodulation distortion (IMD2) inter- ference. Modulated spurs are generated due to the mixing of the leaked TX signal by an unwanted spur in the CA receiver. The resulting modulated spur may exhibit in-phase and quadrature-phase (IQ) imbalance, and directly interfere with the wanted signal in the receive (RX) baseband. On the other hand, the IMD2 interference is produced due to the non-linearity of the receiver driven by the strong blocker signals, like the leaked TX signal. To mitigate those two interferences, in this thesis, all-digital based and mixed-signal based cancellation architectures are proposed and investigated in detail.
In the all-digital architecture, all blocks are implemented fully digitally, which leads to a highly flexible and scalable solution. However, all-digital techniques may lead to complex solutions due to the required accurate interference channel estimation. In contrast, in the mixed-signal schemes the reference signal, which is sensed by an Auxiliary (Aux.) receiver, already contains the distortions introduced by the interference channel. This simplifies the digital cancellation significantly. The modulated spur interference including IQ imbalance is compensated by the proposed widely-linear (WL)-least mean squares (LMS) adaptive filter structure. In addition, to overcome the performance lim- itation by the Aux. receiver IQ imbalance, a novel enhanced WL architecture for the modulated spur cancellation is proposed and studied.
Furthermore, a mixer-detuning based IMD2 cancellation architecture is proposed to mitigate the IMD2 interference induced by multiple unknown blocker signals in the receiver. This architecture uniquely exploits the non-linear nature of the receiver to construct an IMD2 reference signal for the digital cancellation. A key advantage of this architecture compared to the all-digital and the other mixed-signal schemes is, that it does not need to know the nature and frequency location of the typically unknown blocker signals.
As a proof-of-concept, the presented interference cancellation architectures are studied and compared to each other by extensive simulations and measured data from a radio frequency integrated circuit (RFIC) transceiver chip. It is shown, that the pro- posed architectures significantly suppress the target interferences and improve the re- ceiver performance accordingly.
... While there exist analog interference mitigation techniques, they mainly target full duplex operation and therefore are not covered in this paper. The other techniques can be categorized into mixed-signal [1]- [4] and digital [5]- [8] approaches. Both architectures typically include an adaptive algorithm, which according to a system level analysis is a major building block for sufficient cancellation performance [9]. ...
... Another approach to increase the system's power efficiency is to utilize the advantages of integrated circuitry based on digital building blocks [12]. One promising concept is the radio frequency digital-to-analog converter (RF-DAC), which shifts the circuit complexity for wireless transmitters further to the digital domain, reducing the number of required active and passive components [13], [14]. RF-DACs combine the functionality of a DAC and an upconversion mixer in a single circuit, allowing an efficient implementation on a monolithic die and leveraging the benefits of scaled CMOS technology with increased usage of fast and programmable digital blocks. ...
This article presents a novel digital predistortion (DPD) approach to compensate for nonlinear dynamic distortions caused by the supply network of capacitive radio frequency digital-to-analog converters (RF-DACs). The developed DPD concept recreates the voltage distortion on the RF-DAC's supply network and modulates the input signal such that the effects on the output signal of the RF-DAC are canceled. In contrast to conventional DPD approaches such as pruned Volterra series or memory polynomials, the complexity of the proposed concept is reduced to a feasible level, allowing for implementation in integrated circuits. Furthermore, the derived DPD model allows to use linear estimation algorithms for coefficient training. The presented DPD is demonstrated by measurements of two different capacitive RF-DAC designs and compared with conventional DPD approaches. EVM and adjacent channel power ratio (ACPR) can be improved by up to 6 and 7 dB, respectively, outperforming conventional approaches.
... These concepts are summarized under the term self-interference cancellation (SIC). We concentrate on two approaches, namely digital interference cancellation (DIC) [2]- [5] and mixedsignal interference cancellation (MSIC) [6]- [9]. Both architectures typically include an adaptive algorithm. ...
... The Aux path has less stringent requirements in terms of sensitivity, linearity and resolution compared to a main LTE Rx chain and thus can use a simplified analog design. However, effects such as in-phase and quadrature (I/Q) imbalance in the Aux receiver can limit the overall cancellation performance [2] and make it necessary to alleviate these limitations by employing enhancement mechanisms, such as described in [10], [11]. ...
... In the last few years, wireless sensor networks (WSNs) gained a lot of research interest from the research community due to its dynamic nature and wide range of applications [1,2]. A WSN comprises tiny smart devices called micro-sensors with limited memory, storage, processing, and battery resources. ...
Nowadays, the integration of Wireless Sensor Networks (WSN) and the Internet of Things (IoT) provides a great concern for the research community for enabling advanced services. An IoT network may comprise a large number of heterogeneous smart devices for gathering and forwarding huge data. Such diverse networks raise several research questions, such as processing, storage, and management of massive data. Furthermore, IoT devices have restricted constraints and expose to a variety of malicious network attacks. This paper presents a Secure Sensor Cloud Architecture (SASC) for IoT applications to improve network scalability with efficient data processing and security. The proposed architecture comprises two main phases. Firstly, network nodes are grouped using unsupervised machine learning and exploit weighted-based centroid vectors for the development of intelligent systems. Secondly, the proposed architecture makes the use of sensor-cloud infrastructure for boundless storage and consistent service delivery. Furthermore, the sensor-cloud infrastructure is protected against malicious nodes by using a mathematically unbreakable one-time pad (OTP) encryption scheme to provide data security. To evaluate the performance of the proposed architecture, different simulation experiments are conducted using Network Simulator (NS3). It has been observed through experimental results that the proposed architecture outperforms other
state-of-the-art approaches in terms of network lifetime, packet drop ratio, energy consumption, and transmission overhead.
... If the application enables the usage of digital signal processors instead of dedicated hardware elements, even online reprogrammability is possible. The increased flexibility of DIM compared with other mitigation techniques may outweigh its inferior cancellation performance and reliability [70]. ...
This article presents a comprehensive survey of the literature on self-interference (SI) in long-term evolution advanced (LTE-A) and fifth-generation (5G) new radio transceivers and should serve the reader as a guide and starting point for further work on SI management. Current trends in cellular transceiver designs are discussed, and reasons why new technologies, such as carrier aggregation, cause potential sensitivity degradation due to self-interfering signals are highlighted. The survey provides an overview of the most common interference mechanisms and continues with a taxonomy on SI mitigation architectures by comparing the strengths and weaknesses of various techniques.
... The other category of blind concepts applies blind source separation (BSS) techniques, which however suffer from high computational effort [19]. In the context of interference cancellation [20], [21], I/Q imbalance calibration plays a role, too. Mixed signal solutions employ an auxiliary receiver with less stringent requirements than a normal receiver, which often leads to designs, where low IRR is even more an issue [22], [23]. ...
Direct-conversion transceivers are the predominating architecture in current mobile communication systems. Despite many advantages, this topology suffers from unavoidable mismatches in the analog part, which causes imbalance between the in-phase and quadrature (I/Q) component. In this paper, we present a novel fully digital, blind I/Q imbalance compensation algorithm that features extremely low computational complexity and high compensation performance for a wide range of input signal types. Different to many state-of-the-art compensation schemes, the approach is not based on a gradient descent optimization and does not require any global feedback. This simplifies the implementation at high data rates and reduces the configuration effort to a minimum. For comparison, we examine an existing method of moment-based estimator with similar properties, for which we also provide the detailed insights beyond available literature. For both algorithms, we provide a rigorous mathematical analysis, which is supported by simulations with a focus on various long-term evolution (LTE) signal types. In addition, hardware architectures, including field-programmable gate array (FPGA) verification, are presented for both algorithms.
