Error Vector Magnitude Values Research Articles

Centralized full-duplex seamless photonic mmW fronthaul link based on phase modulation

We experimentally demonstrate a photonic full-duplex seamless millimeter wave fronthaul link, based on phase modulation, to address the challenges arising from the increased demands on the mobile fronthaul capacity and network densification toward 5G and beyond. The proposed system relies on phase modulation techniques, implemented at both the central office (CO) and remote radio head (RRH), to achieve optical frequency up-conversion of the downlink (DL) signal and optical modulation of the down-converted uplink (UL) signal. Furthermore, our approach includes the frequency down-conversion of the 40 GHz UL signal through an optically generated local oscillator (LO) signal in the RRH, while the laser employed for UL data transmission is situated at the CO, simplifying the remote site’s equipment. An optical waveshaper serves here as a programmable optical filter to provide signals for DL frequency up-conversion, LO generation, and also the optical carrier for UL transmission. In our experimental validation, we have tested our proposed system using 64-quadrature amplitude modulation (64-QAM) for the DL at a frequency of 41 GHz and quadrature phase shift keying (QPSK) for the UL at a frequency of 40 GHz. Notably, our results demonstrate the successful transmission of up to 200 MHz bandwidth for both digital modulation schemes, all while maintaining the error vector magnitude (EVM) well below the specified threshold. Additionally, when employing 5G new radio (NR) orthogonal frequency-division multiplexing (OFDM) signals with the same modulation formats for both links in full-duplex communication, we achieved EVM values as low as 5.2% for the DL and 6.9% for the UL, further highlighting the efficacy and robustness of our proposed solution.

Concurrent M-QAM transmission performance assessment in a combined four SOA-MZIs arrangement

In this paper, the utilization of four semiconductor optical amplifier Mach-Zehnder interferometers (SOA-MZIs) is explored to achieve concurrent M-QAM (M-ary Quadrature Amplitude Modulation) transmission. Utilizing an actively mode-locked laser, we generate pulses with a duration of 0.5 ps at a repetition rate of 20 GHz, serving as our sampling source. The incoming M-QAM signals, spanning various frequencies, undergo down-mixing at the SOA-MZIs combined exit, resulting in diverse output frequencies by respecting the bandpass sampling procedures. The unparalleled simultaneous M-QAM transmission is assessed through critical metrics such as error vector magnitude (EVM) and bit error rate (BER). The SOA-MZI conversion efficiency (CE) exhibits a notable transition, ranging from 90 % at 76 GHz to 68 % at 84 GHz based on 1024-QAM data. The concurrent down-mixed signals showcase EVM values of 3, 2, 1, and 0.25 % for 16-, 64-, 256-, and 1024-QAM, respectively, at the first range of output frequencies. Besides, an exceptional BER value of 93×10−6 is attained at a symbol rate of 0.25 GSymb/s at 84 GHz for the 1024-QAM replica. A comparative analysis reveals that under identical parameter settings, the proposed Gaussian filter expounds lower EVM values compared to the root raised cosine (RRC) filter. These results highlight the success of the novel experimental approach employing SOA-MZIs for simultaneous down-mixing of four M-QAM carriers with varying levels, showcasing outstanding performance outcomes.

Performance amelioration of simultaneous up- and down-mixing contingent on a parallel SOA-MZIs design

The primary focus of this research is the creation of a first-ever experimental investigation for simultaneous up-down mixing based on three parallel semiconductor optical amplifier Mach-Zehnder interferometers (SOA-MZIs). The three mixed signals from the SOA-MZI terminals are coupled together to create a simultaneous up or down-mixed signal using an optical coupler (OC). The identified mixing function makes use of the consequences of cross-gain modulation (XGM) as well as cross-phase modulation (XPM) that have been shown at the SOA-MZI outlets. Furthermore, the performance characterization of the photonic parallel system is examined and assessed in the optical and electrical sectors. The outcomes of our experiment closely resemble those of the simulation. Several measurable factors, including power scaling measurements, optical conversion gain (OCG), power stability, beam quality factor, electrical conversion gain (ECG), and error vector magnitude (EVM), are employed to evaluate the photonic up and down-mixed signals. This three-parallel SOA-MZIs architecture has a wide range of applications involving radio over fiber and optical telecommunications. A 256-QAM (Quadrature Amplitude Modulation) up- and down-mixed signals can have a top bit rate of 64 Gbit/s with excellent EVM values. Additionally, the maximal frequency range of the concurrent up and down-mixed signal is 80 GHz. The ECG also displays significant values for up and down conversion. In the optical domain, the OCG has the highest values of 15 dB for the up-mixed signal and 12 dB for the down-mixed one, with a data input power of −10 dBm. Finally, the simultaneous mixing system tackles an outstanding beam quality factor with M2 measurement of less than 1.3 (M2<1.3).

Live demonstration of an SDN-reconfigurable, FPGA-based TxRx for an analog-IFoF/mmWave radio access network in an MNO’s infrastructure

This paper presents the end-to-end integration of a software defined network (SDN) reconfigurable real-time analog-intermediate frequency-over-fiber (A-IFoF)/millimeter wave (mmWave) layout into a real mobile network operator (MNO) infrastructure. The key part of the presented infrastructure is the fully programmable gateway array (FPGA)-based A-IFoF transceiver (TxRx), equipped with active SDN functionalities based on constant monitoring of the transport link. This layout was successfully evaluated in the physical data management and application layer. Regarding the physical layer performance evaluation, error vector magnitude values of 7.3% were achieved for quadrature phase shift keying waveforms, while the uninterrupted operation of real-time services such as augmented reality/virtual reality applications was enabled by the reactive SDN-based capacity reconfiguration capabilities.

Real-Time Experimental Demonstration of Hybrid FSO/Wireless Transmission Based on Coherent Detection and Delta-Sigma Modulation

For the fronthaul link in the fifth-generation (5G) wireless networks, optical fiber is one of the most widely used medium, owing to its large bandwidth and low transmission loss. However, in some scenarios, especially the dense urban areas, the installation of fiber optic cables is costly and difficult to establish. Alternatively, the free space optical (FSO) link can be installed easily and spans complex terrain. In this context, we propose and experimentally demonstrate a hybrid FSO/Wireless transmission system based on bandpass delta-sigma modulator and real-time coherent transponder. Advantage of the proposed technique is twofold. Firstly, coherent detection is applied to improve the system sensitivity compared to conventional direct detection. Secondly, delta-sigma modulation (DSM) is utilized to greatly simplify the wireless transmitters and to enhance the bandwidth flexibility. Over a 50-m FSO and 1-m wireless link, a 64-QAM wireless signal at 1 GHz with 500 MHz bandwidth is successfully transmitted. With 16 wavelength division multiplexing channels, the total throughput of the system is up to 24 Gb/s. Meanwhile, the error vector magnitude (EVM) of all channels is around 2.68% and 6.51%, which are demonstrated after FSO and FSO/Wireless transmission, respectively. The results meet the requirement of the third-generation partnership project release 15 with EVM value of 8% for 64-QAM. Moreover, sensitivity of the real-time coherent receiver is lower than −48 dBm under the 7% forward error correction limit with bit error rate of 3.8e-3.

Sampling Parallel SOA-MZIs Configuration for All-Optical Simultaneous Frequency Down-Conversion

In this paper, we expound a modulation concept to contrive simultaneous frequency down-conversion based on a three parallel Semiconductor Optical Amplifier Mach-Zehnder Interferometers (SOA-MZIs) link by using a band pass sampling method in a Virtual Photonics Inc. simulator. Each SOA-MZI is deployed to achieve a down-converted signal, which has ten replicas related to the first ten harmonic ranks of the sampling signal, at the SOA-MZI outer port. Then, the admixture of the three down-converted signals yields a sampled signal, which is called a simultaneous down-converted signal that contains thirty different replicas. The positive down-conversion gains with top values are reached with the sampling parallel SOA-MZIs link. Moreover, we evaluated the quality of the parallel SOA-MZIs transmission system over orthogonal frequency division multiplexing (OFDM) complex modulated signals using the error vector magnitude values as a performance index. The utmost bit rate attained is 2 Gbit/s for OFDM modulations.

Hybrid Beamforming in 5G NR Networks Using Multi User Massive MIMO at FR2 Frequency Bands

AbstractThe current Sub 6 GHz band is highly occupied and unable to meet the demands of future wireless data traffic. As the millimeter wave technology is a promising way of enhancing the performance of next-generation wireless networks, it is essential to explore FR2 frequency bands. Massive Multiple-Input Multiple Output (mMIMO) technology has been introduced to improve the capacity and coverage of 5G wireless networks. Hybrid beamforming (HB) is an efficient technique to improve the channel gain and minimize the interference at reasonable complexity. The aim of HB in mMIMO systems is to maximize the sum rate that can approach the fully-digital beamforming system performance. Combination of mMIMO systems, mmWave, and HB techniques achieve higher data rates and cell coverage in 5G wireless networks. It mitigates the hardware complexity, energy consumption, and cost as number of required radio-frequency chains at base station gets minimized. In this paper, we have investigated the performance of a multi user-mMIMO HB system at 28, 39 GHz of FR2 frequency bands as well as at 66 GHz by analyzing the effect of changing variables that include the number of users, transmitting and receiving antennas, and the type of modulation. Simulation results include RMS values of error vector magnitude (EVM) that gives quantitative analysis and receive constellation of the equalized symbols that shows qualitative analysis. EVM is computed for different scenarios and it is used as an indicator of performance to assess the suitable design configuration of mMIMO system.

Power-Over-Fiber in Support of 5G NR Fronthaul: Space Division Multiplexing Versus Wavelength Division Multiplexing

We investigatethe potential of space division multiplexing (SDM) for the power-over-fiber (PWoF) technique, in terms of weakly-coupled multicore fiber (WC-MCF) design and experimental verification. Our simulation results indicate that, the SDM-enabled PWoF scheme is superior to the wavelength division multiplexing (WDM) enabled counterpart, due to the scalability of the energy light delivery and the save of wavelength division multiplexers. Then, we experimentally demonstrate the co-transmission of optically carried fifth generation new radio (5G NR) signals at 1550-nm and the 60-W energy light at 1064-nm over the 1-km weakly-coupled seven-core fiber (WC-7CF) fronthaul link. Since the optical power delivery characteristic per the WC-MCF core is similar to that of the standard single-mode fiber (SSMF), the SDM-enabled PWoF scheme can evenly distribute the high-power energy light into multiple spatial channels, to maximize the efficiency of the optical power transition efficiency (OPTE). Consequently, the total collected optical power of the energy light over the 1-km WC-7CF is 4.6 times higher than that of the 1-km SSMF, mainly due to the insertion loss of the fan-in and fan-out (FIFO) devices. Meanwhile, the error-vector magnitude (EVM) of 1.5-Gbit/s 5G NR signal is 0.28%, when the received electrical signal power is −25 dBm. The EVM value of the co-transmitted 5G NR signal with the 60-W energy light only has a fluctuation of 0.01% over six hours. The SDM-enabled PWoF is useful for the optically powered 5G pico-cells, with the capability of high-speed access and centralized management.

A Dual-Band RF All-Digital Transmitter Based on MPWM Encoding

Radio frequency (RF) all-digital transmitter (ADT) is one of the most attractive techniques in the next-generation RF transceivers, especially in the carrier aggregation and multiband, multistandard transmission scenario. Among the multiband RF ADTs reported in recent years, the delta–sigma modulation (DSM)-based scheme is the most popular. However, implementing multiband DSM-based RF ADT in field-programmable gate array (FPGA) produces problems of high complexity, high resource consumption, limited carrier frequency (CF) agility, and poor indicator performance. To address these problems, a dual-band ADT architecture with mapping-based pulse width modulation (MPWM) method is first presented in this article. In the ADT, the dual-band intermediate frequency (IF) signals are mapped to the RF sequence by a lookup table (LUT), and the CF can be adjusted by updating the LUT values. The operation principle of the ADT is explained, and the noise analysis model of MPWM is given. Furthermore, three optimization methods are presented to improve the performance of ADT. To evaluate the proposed architecture and methods, the ADT is implemented on an FPGA chip, and the resource consumption is relatively low. A dual band of 16- and 64-QAM signals with bandwidth (BW) of 20 MHz is tested with different CF and CF spacings. From 1 to 4.1 GHz, the adjacent channel leakage ratio (ACLR) values are below −43 dBc, and the error vector magnitude (EVM) values are below 3.5%. From 4.1 to 6.15 GHz, the ACLR values are below −40 dBc, and the EVM values are below 5%. The proposed architecture and design methods can be applied to triple-band or other more band ADT.

Simultaneous Up-Conversion Based on a Co- &amp; Counter-Directions SOA-MZI Sampling Mixer with Standard &amp; Differential Modulation Modes

Simulation and experimental performance analyses of simultaneous up-converted signals, for the first time, were investigated utilizing a semiconductor optical amplifier Mach–Zehnder interferometer (SOA-MZI) sampling mixer in co- and counter-directions for standard and differential modulation modes. An optical pulse source at a sampling frequency of fs = 15.6 GHz was used as a sampling signal. The IF signal channels carrying quadrature phase shift keying (QPSK) data at frequencies fm were up-converted at different mixing frequencies up to 195.5 GHz. Using the Virtual Photonics Inc. (VPI) simulator, we realized mixed QPSK signals and studied their characteristics through a conversion gain and an error vector magnitude (EVM). Simulations of up mixing operated in a frequency range up to 158 GHz. For the standard modulation in the co-direction, the conversion gain decreased from 43.3 dB at the mixing frequency of 16.6 GHz to 21.8 dB at 157 GHz for the first channel and from 43 dB at 17.6 GHz to 21 dB at 158 GHz for the second channel. The use of the differential modulation principle improved the conversion gain by about 10 dB at 195.5 GHz compared to standard modulations in co- and counter-directions. The EVM reached, respectively, 15.5 and 17.5% for the differential modulation in both configurations, at the bit rate of 100 Gbit/s at 195.5 GHz. The benefit provided by the differential modulation was that EVM values were shifted by 20% for all channels in both configurations at 100 Gbit/s. In the real measurement, we confirmed that co-directional conversion exhibited a better performance than the counter-directional operation. In addition, the real mixed signal exhibited lower efficiency and quality in comparison with simulated signals due to the sensitivity of the receiver.

Passive beamformer based remote beamforming scheme for radio-over-fiber systems: Experimental demonstration using 28-GHz band reflectarray

This paper proposes and experimentally demonstrates a passive beamformer based remote beamforming scheme for millimeter-wave band radio-over-fiber systems. The proposed scheme can control the beam direction of remote radio units (RRUs) from the central station (CS); it yields extremely simple RRUs for flexible and cost-effective deployment. The proposed scheme sets a passive beamformer such as beamforming network, reflector, or lens in the RRU and different wavelengths are assigned to each input port of the passive beamformer. This configuration offers remote beam switching by just carrier wavelength switching at CS. Multi-beam operation can be also realized simply by using multiple wavelengths simultaneously. Experiments on a 28 GHz band reflectarray are conducted. The feasibility of remote beam switching by wavelength switching is confirmed. 5G signal transmission over 20 km of single-mode fiber and 6.3 m air link is successfully achieved with error vector magnitude values of 2.71–3.55%, which satisfies the 3GPP requirements of 8%.

Numerical analysis of UFMC and FBMC in wavelength conversion for radio over fiber systems using semiconductor optical amplifier

The 5G networks promise to use advanced access techniques and modulation formats to achieve new requirements of the huge number of users such as higher data, high speed, and low latency. Millimeter-wave (MMW) signal and new modulation schemes such as universal filtered multicarrier (UFMC) and filtered bank multicarrier (FBMC) are playing a fundamental role to accomplish these requirements. UFMC and FBMC are classified under multicarrier modulation formats which are considered as a suitable modulation scheme in 5G and replacing a well-known modulation format of filtered orthogonal frequency division multiplexing (OFDM) which was used in 4G. This interest in using UFMC and FBMC in 5G wireless systems is the reduction of out-of-band (OOB) spectrum in UFMC and reduction of sidelobe suppression in FBMC. The contribution of this paper is to propose a model of wavelength conversion using a semiconductor optical amplifier (SOA) for both schemes UFMC and FBMC- off-set quadrature amplitude (OQAM). In addition, we analyze and compare their performance in terms of bit error rate (BER) and error vector magnitude (EVM) for a wavelength conversion application. Finally, we investigate the main disadvantage of OFDM which is the high Peak to Average Power Ratio (PAPR) for both schemes, and compare between them. Photonic switching of a 4 Gbps 16-QAM UFMC and FBMC-OQAM signal centered at 50 GHz is performed. The optical single-sideband (OSSB) signal is generated with 18.85 dB of sideband suppression ratio (SSR). The results show that the best values of BER and EVM can be obtained when the injection current (IC) is 0.7–0.9A. For converted signal using FBMC-OQAM, it has power penalty ∼ 2.5 dB at BER threshold 1 × 10-3and has also ∼ 2 dB power penalty compared to the UFMC scheme at EVM threshold 5.6%. In addition, the wavelength switching system with FBMC and UFMC modulation schemes achieves the same PAPR.

Design and evaluation of 2.3 Tb/s (23 ch. × 100 Gb/s) multi-carrier WDM optical transmission systems

Multilevel phase modulation formats with coherent detection enable a new generation of high speed optical transport platform. We demonstrate 23 × 100 Gbps (2.3 Tb/s) WDM Optical systems employing multicarrier generation concept. Three lasers are used to generate 23 sub-carriers using multicarrier generator at transmitter section. Each sub-carrier transmits at a transmission rate of 100 Gbps using polarization division multiplexed quadrature phase shift keying (PDM-QPSK) modulation format with spacing of 25 GHz between sub carriers. The analysis is carried out for 23 × 100 Gb/s (2.3 Tb/s) PDM-QPSK WDM optical systems with ultra large area fiber (ULAF), standard single mode fiber (SSMF) and large effective area fiber (LEAF) at transmission reach from 600 to 5000 km. Coherent detection with DSP is used for all the systems at receiving end. Systems are verified with parameters like symbol error rate, error vector magnitude (EVM) and Q-factor using analytical and simulation results. Improvement of 1.66 dB to 3.21 dB and 2.08 dB to 4.63 dB is noted in Q-factor for system with ULAF in comparison with system using SSMF and LEAF respectively over 600 km to 5000 km transmission reach. EVM values are found 2.24% to 2.68% and 2.68% to 12.43% lower in system with ULAF than system with SSMF and LEAF respectively. Log of estimated symbol error is observed less for system with ULAF than systems with SSMF and LEAF fibers, respectively, at transmission distance of 5000 km. The results clearly show that WDM optical system with ULAF fiber gives better performance.

Intersymbol Interference and Equalization for Large 5G Phased Arrays With Wide Scan Angles

Intersymbol interference (ISI) is introduced in a phased array when the beam is scanned. The cause of the ISI is demonstrated and its dependence on the phased array dimensions, scan angle, and symbol rate is derived. A mathematical model is created to simulate the ISI effects on transmitted (or received) symbols, and an equalizer model is introduced and achieves near-perfect equalization of the ISI. Also, for wideband signals, it is shown that large phased arrays result in amplitude modulation versus frequency. The effect of ISI on the error vector magnitude (EVM) is simulated using complex modulated signals, and the EVM before and after equalization is compared, using an adaptive 17-tap linear equalizer implemented in MATLAB. The results show that ISI in large phased arrays can be equalized regardless of the modulation, bandwidth, scan angle, and symbol rate. The EVM of 16-, 64-, and 256-quadrature amplitude modulation (QAM) signals is measured for a 256-element array in the transmit mode. The measurements verify the derivations, eliminating ISI and resulting in low EVM values after equalization. The effect of array tapering on EVM is also presented, and the results show no difference in the EVM for uniform and tapered excitations.

A Multimode 5–6 GHz FD/HD/FDD Quadrature Balanced CMOS Front End With Transmit–Receive Cross-Modulation Distortion Correction

We introduce a multimode and wideband quadrature balanced CMOS RF front end (RFFE) supporting full-duplex (FD), half-duplex (HD), and frequency-division duplex (FDD) operation at the 5-6 GHz band. The proposed RFFE is enhanced by nonlinear digital algorithms that maintain optimal performance at high transmit (Tx) power levels. A theoretical model of the transmit-receive (TR) cross-modulation (CM) distortion mechanism stemming from instantaneous variations in the power amplifiers (PAs) output impedance is laid out and verified in simulation and measurement. A 2-D digital postdistortion (2-D DPoD) algorithm that utilizes the known baseband Tx signal and the downconverted distorted Rx signal is proposed to linearize the CM-distorted Rx signal, in conjunction with wideband digital RF and baseband cancellation of the Tx self-interference at the receiver input and 1-D digital predistortion to linearize the Tx signal. The system was characterized in simultaneous TR operation using 802.11ac VHT Wi-Fi signals at 10 dBm average Tx power. In the FD mode using 20 MHz signals, TR isolation of 66 dB was achieved, and the 2-D DPoD corrected Rx error vector magnitude (EVM) by 11 dB to a value of -33 dB. In the FDD mode with 800 MHz frequency separation, 14 dB improvement was demonstrated in Rx EVM with 2-D DPoD to the levels of -35 and -31 dB for 20 and 160 MHz signals, respectively. Similar EVM values were measured in the HD Rx mode at -40 dBm average Rx power, along with Rx insertion loss lower than 1 dB without using a TR switch.

100-GHz FrOFDM-Based Serial-to-Parallel Converter and QPSK Modulation Format Applicability

A novel fractional orthogonal frequency division multiplexing (FrOFDM)-based 100-GHz serial-to-parallel (S-P) converter is experimentally demonstrated. A 10-GHz sinusoidally modulated Nyquist-optical time division multiplexing serial signal, with 100-GHz repetition rate, is optically restored after S-P conversion. In addition, the performances for quadrature phase shift keying (QPSK) modulation have been numerically evaluated. Also in this case, the error vector magnitude values and the constellation map of 100-GHz QPSK serial signals demonstrate a successful S-P conversion.

Integrating Radio-Over-Fiber Communication System and BOTDR Sensor System.

In this paper, we propose and experimentally demonstrate for the first time, the integration of a radio-over-fiber (RoF) communication system and a Brillouin optical time-domain reflectometry (BOTDR) distributed sensor system using a single optical fiber link. In this proof-of-concept integrated system, the communication system is composed of three modulation formats of quadrature phase-shift keying (QPSK), 16-quadrature amplitude modulation (16-QAM) and 64-QAM, which are modulated onto an orthogonal frequency division multiplexing (OFDM) signal. Whereas, the BOTDR sensor system is used for strain and/or temperature monitoring over the fiber distance with a spatial resolution of 5 m using a 25 km single-mode silica fiber. The error vector magnitude (EVM) is analyzed in three modulation formats in the presence of various BOTDR input pump powers. Using QPSK modulation, optimized 18 dBm sensing and 10 dBm data power, the measured EVM values with and without bandpass filter are 3.5% and 14.5%, respectively. The proposed system demonstrates a low temperature measurement error (±0.49 °C at the end of 25 km) and acceptable EVM values, which were within the 3GPP requirements. The proposed integrated system can be effectively applied for practical applications, which significantly reduces the fiber infrastructure cost by effective usage of a single optical fiber link.

Assessment of Transient EMI Impact on LTE Communications Using EVM &amp; PAPR

The brief contact losses between the pantograph and the catenary in high-speed trains create transient interferences, which extend to the frequency bands used by telecommunication systems. This article presents a study of the impact of these transient wideband interferences on LTE communications between the train and a base station. In this study, we set up an experimental test bench, which establishes LTE communication between a communication tester and a USB/LTE dongle in the presence of transient interferences. We analysed the impact of these interferences on the error vector magnitude (EVM) of the received LTE signals and we observed that the EVM evolution does not explain certain communication interruptions. Indeed, interruptions can occur for EVM values significantly inferior to the standard limits. To understand the relationship between the interference characteristics and the communication interruption, we studied the peak to average power ratio (PAPR). Indeed, the PAPR is well suited to analyse transient interferences because it evolves with the amplitude but also with the repetition of the transient. Then, the PAPR measurement can provide a diagnostic assistance to analyse whether along certain railway lines, pantograph-catenary interferences are the cause of the LTE interruptions.

Detecting and Receiving Phase-Modulated Signals With a Rydberg Atom-Based Receiver

Recently, we introduced a Rydberg-atom based mixer capable of detecting and measuring the phase of a radio-frequency field through the electromagnetically induced transparency (EIT) and Autler-Townes (AT) effect. The ability to measure phase with this mixer allows for an atom-based receiver to detect digital modulated communication signals. In this paper, we demonstrate detection and reception of digital modulated signals based on various phase-shift keying approaches. We demonstrate Rydberg atom-based digital reception of binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), and quadrature amplitude (QAM) modulated signals over a 19.626~GHz carrier to transmit and receive a bit stream in cesium vapor. We present measured values of Error Vector Magnitude (EVM, a common communication metric used to assess how accurate a symbol or bit stream is received) as a function of symbol rate for BPSK, QPSK, 16QAM, 32QAM, and 64QAM modulation schemes. These results allow us to discuss the bandwidth of a Rydberg-atom based receiver system.

Analysis on the Definition Consistency Problem of EVM Measurement and its Solution

The definition consistency problem of error vector magnitude (EVM) measurement is analyzed, and a solution using the peak-to-average ratio of the constellation diagram as a correction factor is proposed. Using different vector signal analyzers, the EVM values for 16-quadratic-amplitude modulation (QAM) and 64-QAM digitally modulated signals with certain distortions are measured. Furthermore, the corresponding theoretical EVM values are obtained through numerical simulation and analytical calculation. Comparing these results, it could be found that the definitions of EVM in different instruments are different. The essential reason is the different definition of EVM in the radio broadcast television technical standards and the wireless communication technology standards. This difference will lead to measurement errors and cognitive confusion. In order to solve this problem, a method using the peak-to-average ratio of the constellation diagram as a correction factor is proposed, and the experimental results proved that this solution is effective. At the same time, we strongly recommend the adoption of a unified EVM definition.