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In recent years model and Digital Pre-Distortion dimension reduction has been widely researched. The oper- ations involved when running DPD are often far less than those needed during the training of the DPD coefficients. The proposed partitioned Least Squares (LS) adaptation allows a selected subset of DPD coefficients to be updated while the remaining coefficients are held constant. This technique allows a more adaptive training procedure, improved interpretability of the important DPD coefficient’s during training and the ability to partition the DPD function into specific groups. The Frisch-Waugh-Lovell (FWL) theorem is exploited to partition the coefficients of a DPD basis function trained using LS regression. The proposed methodology was experimentally validated with a Generalized Memory Polynomial (GMP) DPD function, used to linearize a 5W power amplifier (PA) driven by a 40MHz 5G-NR signal.

As the physical makeup of cellular base-stations evolve into systems with multiple parallel transmission paths the effort involved in modelling these complex systems increases considerably. One task in particular which contributes to signal distortion on each signal path, is the power amplifier. In power amplifier modelling, Recursive Least Squares has been used in the past to train Volterra models with memory terms, however instability can occur when training the model weights. This manuscript provides a computationally efficient technique to detect the onset of instability and subsequently to inform the decision when to stop adaptive training of dynamic nonlinear behavioural models and avoid the onset of instability. This technique is experimentally validated using four different signal modulation schemes.

A key distinction between today's and future networks is the appetite for reliable communication to support emerging critical-communication services. In this paper, we study multi-operator connectivity as a form of redundancy to support the design of reliable networks and investigate its trade-offs. This approach is motivated by 3GPP standardisation initiatives of dual-connectivity and similar techniques in industrial wired networks. We deploy a risk awareness performance metric to assess reliability: this superquantile metric accounts for periods of connectivity shortfalls. Our analysis shows that multi-operator connectivity brings significant reliability gains, in particular when network deployments by different operators exhibit high complementarity in coverage. We also explore the effects of multi-connectivity on spectral efficiency in times of high demand for bandwidth. Our study is based on a real-world dataset comprising signal strength indicators of three mobile operators in Dublin, Ireland.

The adaptive data rate (ADR) algorithm is a key component of the LoRaWAN protocol which controls the performance of a LoRaWAN Network. This modifies the data rate parameter of a device based on the current wireless conditions. In this article, we present substantive enhancements for the End Device and Network Server which reduce the convergence time for LoRaWAN devices to reach their optimal data rate. We extend the LoRaWAN module in ns-3 by adding ADR, enabling the simulation of realistic LoRaWAN networks, and add the implementation of the new enhancements in this module. The simulations show that these modifications can result in a significant reduction of the data rate convergence time for LoRaWAN devices and lead to an increased overall packet delivery rate for the network in a dynamic network environment. Our contributions are a publicly available implementation of ADR in ns-3, an analysis of the original algorithm behavior, and a novel version of the algorithm with enhancements that improve performance in every case while remaining easily integrable into an existing LoRaWAN system.

This paper proposes a new crest factor reduction scheme to reduce instantaneous-to-average power ratio (IAR) resulting decent peak reduction, and adjacent channel leakage ratio (ACLR) reduction, though the error vector magnitude (EVM) is significantly enhanced. In the conventional peak cancellation (CPC) technique, peak regrowth occurs as a result of finite impulse response (FIR) filter windows overlapping. The peak regrowth problem in CPC technique can be compensated, though this will lead to increased computational complexity and degradation in EVM. The proposed algorithm allocates spacing to contiguous peaks to avoid FIR filter windows overlapping. Two types of overlapping are discussed, incremental and decremental. The optimum spacing can be determined from the FIR filter impulse response characteristic. Simulations are carried out with different intra-band non-contiguous carrier aggregated OFDM signals. The results of simulations show between 3 and 10% improvement in EVM performance while maintaining equivalent IAR and ACLR performance. Applying the proposed optimum spacing peak cancellation scheme compared to the conventional peak cancellation technique.

In this paper, a novel outphasing power amplifier (PA) based on class-E amplifiers with shunt capacitances and shunt filters is proposed. The new design provides high drain efficiency for both peak and back-off power levels. A mathematical model for the class-E power amplifier with shunt capacitance and shunt filter is presented. The proposed model enables derivation of load circuit parameters that provide optimum drain efficiency for the peak and back-off power levels using closed form mathematical expressions. Based on this model, an outphasing power amplifier is designed and subsequently implemented using microstrip transmission lines and a GaN HEMT devices. The fabricated power amplifier prototype is optimized for 2.14 GHz and provides drain efficiency of over 60% for back-off power levels up to 8.5 dB. The amplifier demonstrates a 44.3% drain efficiency for 64QAM OFDM modulated signal with 20 MHz bandwidth. Adjacent channel leakage ratio (ACLR) of −39.5 dB and error vector magnitude (EVM) of 0.9 % were achieved after the application of a memory polynomial linearization algorithm.

Orthogonal frequency division multiplexing (OFDM) has become an indispensable part of waveform generation in wideband digital communication since its first appearance in digital audio broadcasting (DAB) in Europe in 1980s, and it is indeed in use. As has been seen, the OFDM based waveforms work well with time division duplex operation in new radio (NR) systems in 5G systems, supporting delay-sensitive applications, high spectral efficiency, massive multiple input multiple output (MIMO) compatibility, and ever-larger bandwidth signals, which has demonstrated successful commercial implementation for 5G downlinks and uplinks up to 256-QAM modulation schemes. However, the OFDM waveforms suffer from high peak to average power ratio (PAPR), which is not desired by system designers as they want RF power amplifiers (PAs) to operate with high efficiency. Although NR offers some options for maintaining the efficiency and spectral demand, such as cyclic prefix based (CP-OFDM), and discrete Fourier transform spread based (DFT-S-OFDM) schemes, which have limiting effects on PAPR, the PAPR is still as high as 13 dB. This value increases when the bandwidth is increased. Moreover, in LTE-Advance and 5G systems, in order to increase the bandwidth, and data-rate, carrier aggregation technology is used which increases the PAPR the same way that bandwidth increment does; therefore, it is essential to employ PAPR reduction in signal processing stage before passing the signal to PA. In this paper, we investigate the performance of an innovative peak shrinking and interpolation (PSI) technique for reducing peak to average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) based signals at waveform generation stage. The main idea behind the PSI technique is to extract high peaks, scale them down, and interpolate them back into the signal. It is shown that PSI technique is a possible candidate for reducing PAPR without compromising on computational complexity, compatibl

Next generation wireless communications such as 5G are expected to feature wide channel bandwidths on the order of hundreds of MHz. As bandwidths increase, circuit impairments caused by frequency dependent behaviour such as ripple and tilt in gain and group delay become more significant. PAPR of OFDM signals also increase with increasing number of subcarriers. Transmitter circuit characterisation for the wide-band frequency response is needed to pre-compensate the signal to be transmitted. In this article, we propose a novel scheme which uses the circuit characteristics combined with the channel response to generate the keys for encrypting signals to provide an additional tier of security at the physical layer. The modulated constellation of the signal of interest is encrypted by dispersing its phases in addition to encrypting the bits using Diffie Hellman scheme. It is also shown that the method is able to reduce the PAPR of OFDM signals. This scheme is experimentally validated from end-to-end on a millimetre wave wireless link at 28.9 GHz demonstrating security against a well-positioned eavesdropper and a reduction of PAPR by 3.5 dB in a 2048 point OFDM signal with 1664 active QPSK modulated sub-carriers.

The next generation of mobile networks will bring an appetite for reliable communication, which enables emerging critical-communication services. In this paper, we present network sharing between operators as a way to provide increased reliability while using the already existing mobile network infrastructure. Our results indicate that network sharing significantly improves network performance during periods of connectivity shortfalls, benefiting the design of reliable networks. Our conclusions are drawn from a real-world dataset of signal quality indicators for three mobile operators in Dublin, Ireland.

Next generation wireless communication systems such as 5G will feature a step increase in the speed of wireless data transmission. This requires using RF signals of wider bandwidths along with higher order modulation schemes. Such signals are subjected to frequency and power dependent impairments such as gain compression, amplitude ripple and tilt, group-delay and AM-PM conversion as they traverse through the transmitter’s hardware blocks. This paper introduces a novel calibration scheme that applies a specially designed wideband 64- QAM modulated stimulus and uses the captured response to evaluate the impairments within the transmitter’s RF chain. The needed pre-compensation is applied in a single iteration. This technique is intended for use with Doherty, Outphasing and MIMO type applications. Presented technique was experimentally validated using signal bandwidths up to 100 MHz for both weakly and strongly nonlinear systems.

As the physical makeup of cellular basestations evolve into systems with multiple parallel transmission paths the effort involved in modelling these complex systems increases considerably. One task in particular which contributes to signal distortion on each signal path, is the power amplifier. In power amplifier (PA) modelling, Recursive Least Squares (RLS) has been used in the past to train Volterra models with memory terms. The Volterra model is widely used for modelling of PAs. In this paper we present a comparison of the stability performance for a PA model during training for various model memory lengths, model orders of non linearity and signal sample rates. This examination provides a technique to avoid instability occurring during the adaptive training of dynamic nonlinear behavioural models.

A new technique for the estimation of coupling between array elements in MIMO transceivers is presented. The estimation method is founded on subsequent transmission and over-the-air (OTA) reception between the array elements, when the transmitter’s characteristics are unknown. The method enables accurate on-line characterization of the behavior of the array in terms of coupling for a complete system with PAs and antennas connected. The method is validated via OTA measurements on a four-element array in a MIMO transmitter configuration. The results demonstrate that the estimated couplings with the proposed technique are similar to the ones obtained from S-parameter measurements with deviations reflecting the operation with antennas and PAs connected. The proposed intra-array coupling estimation facilitates practical OTA measurement-based modeling and linearization of MIMO transmitters.

In this paper, we present a novel and effective linearization technique for nonlinear phased array antennas. For large phased arrays, linearization of the array using a single digital predistortion (DPD) is inevitable since one digital path is upconverted and feeds several RF transmission paths, each of which is connected to a power amplifier (PA) and an antenna element. However, a critical issue is that the PA characteristics can vary considerably within an array. Thus, linearizing individual PAs with one DPD is rather challenging. We formulate and solve an optimization problem that corresponds to jointly minimizing the maximum residuals between the input to the array and the output of individual PAs. We demonstrate that the proposed technique outperforms state-of-the-art linearization solutions while retaining the linear gain of the array.

In modern radio frequency (RF) transceivers the power amplifier (PA) is a central component in terms of power consumption. Achieving efficient performance in this component results in the PA output signal becoming distorted. Linearisation can be performed using techniques such as Digital Pre-Distortion (DPD). The pre-distorter operation of a DPD system involves the constant computation of a distorted signal to ensure linear operation of the nonlinear power amplifier. In this work a novel polynomial evaluation scheme is proposed to optimise the pre-distorter operation within a DPD system. Improvements to latency and hardware requirements are possible with new techniques. Validation of the proposed design was conducted using FPGA implementations and compared to incumbent pipelined solutions for both low latency and hardware efficiency. The proposed method indicated hardware savings of 67.8%, while operating 58.7% faster, compared to an existing implementation.

This work proposes a concise standalone model for Chireix power combiner. The model is based on the analysis of the nonlinear behaviour of a Chireix power combiner under amplitude imbalance. The generalised equations for input impedance of Chireix combiner branches excited by signals with different amplitudes have been derived. The results predicted by the model were validated using both commercial high frequency circuit simulations and experimentally measured results. As a result the proposed model serves two purposes. For one it can be used directly in a larger circuit simulation to predict the performance of an outphasing power amplifier. It can also be used as the basis for a linearization strategy for outphasing power amplifiers.

Power amplifiers are widely employed electronic devices in various fields such as mobile networks and radio frequency (RF) transceivers. To achieve efficient operations, power amplifiers can often suffer from nonlinearity problems. This problem can be mitigated through the use of linearization techniques, such as digital predistortion, regarded as the most promising solution to power amplifier linearization. Behavioural modeling is a substantial part of the digital predistortion, responsible for acquiring the coefficients that are necessary to linearize the power amplifier. A Complex Reduced Non-Uniform Generalized Memory Polynomial model was proposed to reach comparable performance of accuracy as Memory Polynomial Model with reduced complexities. The proposed model was tested with a 5MHz LTE signal measured at the input and output of a Doherty PA under different conditions of nonlinearities, memory effects and attenuations as well as PA working powers. It can be observed that the proposed model shows superior accuracy at low complexities, when the PA has higher levels of nonlinearity and memory depth while still maintaining low complexities. Over 60% of coefficients reduction could be reached at the same level of accuracy compared to the MP model.

In this paper, we propose a novel wideband wireless transmission scheme with spatially combined frequency interleaved transmitters of narrower bandwidths. The proposed technique enables development of seamless scalable bandwidth transmitters for next generation wireless and satellite communications with potential to reuse legacy hardware. The scheme is experimentally validated at Ka Band with instantaneous modulation bandwidths up to 400 MHz achieving transmission bit rates up to 2.039Gbps.

This paper discusses topic of high Peak to Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) based signals. An innovative technique is proposed to reduce PAPR without compromising Error Vector Mapping (EVM). The proposed technique is named Peak Shrinking and Interpolating (PSI), and results show no more than 1% EVM when the technique is operated. The hardware resource consumption of PSI technique is analyzed and compared with the simplest Crest Factor Reduction (CFR) technique known as Clipping and Filtering (CF). This analysis, together with EVM performance, and PAPR reduction performance indicates that PSI technique can be an outstanding scheme for existing and future technologies such as Long-Term Evolution (LTE) and 5th Generation of cellular mobile communications (5G), resulting in more efficient Power Amplifier (PA) operation.

Modern wireless communication systems employ wideband modulated RF carriers to communicate the data of interest between the nodes in the network. The security of communications has been conventionally addressed in the data link layers through scrambling and data encryption schemes. These schemes however do not secure the air interface parameters such as modulation scheme and leave them susceptible to eavesdropping and interception by man-in-the-middle platforms. Physical layer security schemes such as directional modulation, DFT S OFDM and RF fingerprinting have been proposed. In this paper, we propose a novel physical layer encryption scheme based on the spectral profile of the intended modulated signal through deliberately introduced constellation distortion to conceal the modulation scheme. The scheme uses a dispersive filter in the modulator with unique group delay profiles unknown to the eavesdropper. The appropriate inverse filter is employed in the authorized receivers to recover the original modulated basebands for demodulation.

Next generation wireless communication systems such as fifth generation mobile communications and high throughput satellites have promised a step increase in the rate at which digital data can be transmitted. This requires wideband modulators consisting of high speed digital to analogue converters and RF upconverters to generate the wideband signal of interest. In this paper we demonstrate a scheme to generate a wide bandwidth modulated signal by bandwidth interleaving multiple modulators of narrower bandwidths. The proposed scheme is experimentally validated with measured results on an 8PSK signals of symbol rate 80 MSPS with modulation characteristics in accordance with DVB-S2 standard.

Modern wireless communication equipment such as outphasing power amplifiers or systems like massive-MIMO rely heavily on transmission of complex wideband modulated radio frequency signals on parallel signal paths. As these signal bandwidths increase, wireless transmitters are more susceptible to amplitude and phase distortions across frequency. We propose a novel method to quantify the complex signal distortions in each transmit path and a technique to pre-compensate the transmitter over a wide bandwidth of interest. This work has been experimentally validated with measured results on two separate RF test benches using signal bandwidths up to 100 MHz. An outphasing power amplifier bench for WCDMA at S band requiring 4 signal paths and a satellite uplink modulator using 8- PSK at Ku band requiring two signal paths were tested in the experimental validation. Further, it is also validated that this method requires only one iteration to calibrate a set of parallel RF signal paths.

Peak to Average Power Ratio (PAR or PAPR) is one of the most challenging issues in the operation of Orthogonal Frequency Division Multiplexing (OFDM) for multicarrier signals used in Fourth and Fifth Generation of broadband cellular network technology (4G and 5G). There are numerous PAPR reduction or also recognized as Crest Factor Reduction (CFR) techniques, for instance Clipping, Coding, Dummy Sequence Insertion (DSI), Tone Reservation, Active Constellation Sequence (ACE), Partial Transmit Sequence (PTS), and Selective Mapping (SLM) schemes. Among these methods, SLM-based techniques are very attractive solutions due to their good performance without additional out-of-band radiations or in-band distortions. This study demonstrates a performance analysis of an SLM-based method combined with adding randomly generated dummy sequences to power-free subcarriers. Simulation results show that the PAPR of the OFDM based signal can be reduced efficiently by using adequate number of dummies and tolerable number of iterations, and that is a potential scheme for 4G and 5G

New wireless technologies have been developed in recent years which enable applications that require the transmission of small amounts of data over long distances in an energy efficient manner. One of these technologies, LoRaWAN, includes a server-initiated communication mode named Class B which provides a deterministic latency for downlink communications. In this paper, we model Class B of LoRaWAN in ns-3 to explore the limits of scale at which this form of bi-directional communication remains feasible in large networks. The simulation results show that the principle restriction on scalability is caused by the duty cycle limits that the gateway must adhere to. In addition, we identify a limitation in the protocol which in certain configurations allows a gateway node to block the future transmission of its own beacon frames. Our contributions are the development of the first implementation and simulation of LoRaWAN Class B in ns-3, and an evaluation of the scalability limits of Class B.

LPWAN technologies are defined by their focus on extended coverage while maintaining energy efficiency, at the expense of data throughput. In this research we enable the analysis of LoRa, a key LPWAN technology, in terms of energy efficiency. We perform real-world measurements of a standard LoRa chip and use the results to develop an energy consumption module in ns-3. Our contributions are an analysis of the energy consumption of different states in a LoRa transmission by the SX1272, the LoRa transceiver that is used in most common LoRaWAN devices, beyond what is provided in the datasheet, and an energy consumption module for use in three of the LoRaWAN ns-3 modules described in research, enabling more accurate energy consumption analysis of LoRa-based systems.

In this paper, we revisit the fundamental problem of computing MIMO capacity under per-antenna power constraint (PAPC). Unlike the sum power constraint counterpart which likely admits water-filling-like solutions, MIMO capacity with PAPC has been largely studied under the framework of generic convex optimization. The two main shortcomings of these approaches are (i) their complexity scales quickly with the problem size, which is not appealing for large-scale antenna systems, and/or (ii) their convergence properties are sensitive to the problem data. As a starting point, we first consider a single user MIMO scenario and propose two provably-convergent iterative algorithms to find its capacity, the first method based on fixedpoint iteration and the other based on alternating optimization and minimax duality. In particular, the two proposed methods can leverage the water-filling algorithm in each iteration and converge faster, compared to current methods. We then extend the proposed solutions to multiuser MIMO systems with dirty paper coding (DPC) based transmission strategies. In this regard, capacity regions of Gaussian broadcast channels with PAPC are also computed using closed-form expressions. Numerical results are provided to demonstrate the outperformance of the proposed solutions over existing approaches.

Because of its lack of feedback process and the simplicity of its searching algorithm, conventional selected mapping(CSLM)is an efficient peak-to-average power ratio (PAPR)reduction technique in orthogonal frequency division multiplexing systems compared to the present techniques such as partial transmit sequence and active constellation extension. The requirement for large numbers of inverse fast Fourier transform (IFFT) blocks to provide desired PAPR reduction performance is introduced as the most significant draw back of the CSLM. This paper uses the special structure of anN-point radix-II IFFT in the CSLM and proposes a low complexity method to reduce the redundant calculations with almost the same PAPR reduction, bit-error rate, and power spectral density performances as those of the CSLM. The simulation results show that the computational complexity is reduced by at least 46.8% compared to that of the CSLM with approximately the same PAPR performance.

The widespread deployment of IEEE 802.11 has made it an attractive target for potential attackers. The latest IEEE 802.11 standard has introduced encryption and authentication protocols that primarily address the issues of confidentiality and access control. However, improving network availability in the presence of misbehaving stations has not been addressed in the standard. Existing research addresses the problem of detecting misbehavior in scenarios without overlapping cells. However, in real scenarios cells overlap, resulting in a challenging environment for detecting misbehavior. The contribution of this paper is the presentation and evaluation of a new method for detecting misbehavior in this environment. This method is based on an objective function that uses a broad range of symptoms. Simulationresultsindicatethatthisnewapproachisverysensitive to misbehaving stations in ultra dense networks.

This paper presents an efficient approach to computing the capacity of multiple-input multiple-output (MIMO) channels under multiple linear transmit covariance constraints (LTCCs). LTCCs are general enough to include several special types of power constraints as special cases such as the sum power constraint (SPC), per-antenna power constraint (PAPC), or a combination thereof. Despite its importance and generality, most of the existing literature considers either SPC or PAPC independently. Efficient solutions to the computation of the MIMO capacity with a combination of SPC and PAPC have been recently reported, but were only dedicated to multipleinput single-output (MISO) systems. For the general case of LTCCs, we propose a low-complexity semi-closed-form approach tothecomputationoftheMIMOcapacity.Specifically,amodified minimax duality is first invoked to transform the considered problem in the broadcast channel into an equivalent minimax problem in the dual multiple access channel. Then alternating optimization and concave-convex procedure are utilized to derive water-filling-based algorithms to find a saddle point of the minimax problem. This is different from the state-of-the-art solutions to the considered problem, which are based on interiorpoint or subgradient methods. Analytical and numerical results are provided to demonstrate the effectiveness of the proposed low-complexity solution under various MIMO scenarios.

In this paper, an efficient approach for weighted sum rate maximization (WSRMax) for zero-forcing(ZF)methods with general linear transmit covariance constraints (LTCCs) is proposed. This problem has been extensively studied separately for some special cases such as for sum power or per-antenna power constraints (PAPC). Due to some practical and regulatory requirements, these power constraints alone are not in general sufficient, which motivates the consideration of general LTCCs. On the other hand, the zero-forcing (ZF) is a simple linear precoding technique to mitigate inter-user interference. The problem of WSRMax for ZF methods with LTCCs was studied previously using a gradient descent algorithm with barrier functions, but this method was also shown to converge slowly. To derive an efficient solution to this problem, we first reformulate it as an equivalent minimax problem using Lagrangian duality. The obtained result in fact resembles BC-MAC duality but is specialized for ZF methods. We then combine alternating optimization and concave-convex procedure to efficiently compute a saddle point of the minimax problem. The proposed method is numerically shown to converge very fast and its complexity scales linearly with the number of users.

In this paper, we study the uplink transmission power control problem in ultra dense Wi-Fi networks and propose two novel access point-controlled frameworks, which determines optimum transmit power settings with the intention of maximizing an objective function. NS-3 simulation results show that the proposed centralized approaches reduce starvation among stations and significantly improves the objective function, resulting in improved performance.

This paper proposes an efficient (semi-closed-form) zero-forcing (ZF) precoder design for the weighted sum-rate maximization problem under per-antenna power constraint (PAPC). Existing approaches for this problem are based on either interior-point methods that do not favor-ably scale with the problem size or subgradient methods that are widely known to converge slowly. To address these shortcomings, our proposed method is derived from three elements: minimax duality, alternating optimization (AO), and successive convex approximation (SCA). Specifically,the minimax duality is invoked to transform the considered problem into anequivalent minimax problem, for which we then recruit AO and SCA to finda saddle point, which enables us to take advantages of closed-form expressions and hence achieve fast convergence rate. Moreover, the complexity of the proposed method scales linearly with the number of users, compared to cubically for the standard interior-point methods. We provide an analytical proof for the convergence of the proposed method and numerical results to demonstrate its superior performance over existing approaches.Our proposed method offers a powerful tool to characterize the achievable rate region of ZF schemes under PAPC for massive multiple-input multiple-output

Massive-MIMO and beamforming techniques have long been proposed as a means of increasing cellular network capacity and improving signal to interference ratio performance. The implementation of such systems requires a large number of signal transmission paths. To realize this, a distributed array of power amplifiers (PAs) is likely to be needed. These PAs will possess similar, but unique, characteristics which will alter over time independently due to temperature drift and component ageing. In order to operate all PAs in both a linear and efficient fashion a linearisation technique, such as Digital Pre-Distortion (DPD), must be used. DPD algorithms benefit from reconfigurability, low latency and power efficiency, all traits associated with Field Programmable Gate Arrays (FPGAs). This demonstration shows how an FPGA, specifically a ZYNQ System on a Chip (SoC), can be used in tandem with a transceiver board, the FMCOMMS2, to implement a DPD system.

Behavioral models are intended as high level mathematical descriptions which require less computational effort to simulate behavior compared to physical or circuit level equivalent models. When designed and dimensioned properly they are well suited to concise characterization of power amplifiers under different operating conditions. In this paper we compare the relative performance of several behavioral models for modelling an asymmetric Doherty power amplifier for their use in distributed arrays.

With an increasing interest in backwards compatibility for existing satellites and the emerging satellite markets, wireless transceivers at Ku band are increasing in popularity. This paper presents the design of a four-way digitally driven Doherty amplifier, aimed at applications in Ku-band. Single tone measurements indicate a maximum drain efficiency of 53.4% at a maximum of 19.2 dBm output power. The final output power can readily be adjusted by changing the biasing in each stage accordingly. The N-way Doherty power amplifier was tested with an 800 MHz bandwidth, 64 QAM test signal aimed for future communication signal standards. An analysis of this configuration has also been performed for 2-way, 3-way and 4-way architectures.