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BER performance for QPSK to 4096-QAM at coding rates of 1/3 and 3/4. QPSK = quadrature phase shift keying.
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Fifth-generation (5G) mobile systems are a necessary step toward successfully achieving further increases in data rates. As the use of higher-order quadrature amplitude modulation (QAM) is expected to increase data rates within a limited bandwidth, we propose a method for orthogonal frequency division multiplexing (OFDM)-based 1024- and 4096-QAM tr...
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Context 1
... to 1024-QAM, the SNRs needed to achieve the benchmark BER of 1 × 10 −2 for 4096-QAM are increased by approximately 2 dB, 3 dB, 5 dB, and 5 dB at coding rates of 1/3, 1/2, 2/3, and 3/4, respectively. Figure 9 shows an overall comparison of BERs for QPSK, 16-, 64-, 256-, 1024-, and 4096-QAM at coding rates of 1/3 (blue lines) and 3/4 (red lines). The SNRs required for 4096-QAM at these coding rates are, respectively, 17 dB and 26 dB higher than those required for QPSK. ...
Context 2
... LTE mobile systems use a link adaptation technology that can choose a modulation scheme and coding rates depending on the channel quality, i.e., received SNR or SINR. The results in Figure 9 suggest that if 4096-QAM is used for the "modulation and coding sets (MCS)", 4096-QAM at coding rates of 1/3 or 3/4 can be assigned to a UE at received SINRs of more than 16 dB or 30 dB, respectively. Similarly, 1024-QAM at a coding rate of 1/3 can be assigned to a UE at received SINR of more than 14 dB. ...
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... However, the transition to the era of super-constellation communications, where very high-order modulation designs are employed, requires an accurate characterization of their inherent susceptibility to specific system imperfections. One of the main impairments that can lead to significant performance degradation in super constellations is the presence of phase noise (PN) due to local oscillator instabilities and the lack of accurate channel state information [20]- [22]. This inherent susceptibility to PN distortions can be attributed to the increased number of symbols that are far from the origin in super constellations so that even small PN distortions can lead to symbol detection errors [23]. ...
In the evolving landscape of sixth-generation (6G) wireless networks, which demand ultra high data rates, this study introduces the concept of super constellation communications. Also, we present super amplitude phase shift keying (SAPSK), an innovative modulation technique designed to achieve these ultra high data rate demands. SAPSK is complemented by the generalized polar distance detector (GPD-D), which approximates the optimal maximum likelihood detector in channels with Gaussian phase noise (GPN). By leveraging the decision regions formulated by GPD-D, a tight closed-form approximation for the symbol error probability (SEP) of SAPSK constellations is derived, while a detection algorithm with O(1) time complexity is developed to ensure fast and efficient SAPSK symbol detection. Finally, the theoretical performance of SAPSK and the efficiency of the proposed O(1) algorithm are validated by numerical simulations, highlighting both its superiority in terms of SEP compared to various constellations and its practical advantages in terms of fast and accurate symbol detection.
... threshold loss) and as URLLC's traffic load grows their proposed methods for puncturing increasingly differ from the optimal solution. It is important to note that, as discussed for instance in [21], bit error rate (BER) on OFDM systems follows a threshold-like phenomena with noise and interference. As puncturing increases, such behaviour is expected, highlighting the relevance of finding policies that are well-adjusted to threshold losses. ...
... If the loss due to puncturing penalizes the eMBB user's utility through a convex loss function, the problem turns out to be a convex optimization problem, which has led to numerous and well known solutions [20]. But if the loss penalty is not convex (for example, a threshold penalty, a much more suitable model for the actual wireless communication link [21]), as we mentioned before proposed solutions can grow afar from optimal. In such cases, the optimal policy would have to be found by trying all possible scheduling scenarios, making it impossible to find online. ...
... Other approaches, as [20], formulate optimization problems very similar to our own, and consider convex functions for U and L. They prove that some policies are optimal under certain conditions, notably a proportional fair assignation for eMBB resources and a random assignation for URLLC resources. However, digital communications' performance exhibit a non-convex response to interference, that can be viewed as a threshold penalty: if interference is larger than a certain value, then the message is completely lost [21]. ...
One of the biggest innovations on 5G and beyond is the support of three different services with particular delay and bandwidth requirements, such as Massive Machine Type Communications (MMTC), enhanced Mobile Broad Band (eMBB) and Ultra-Reliable Low Latency Communications (URLLC). In order to achieve these multiple service requirements, all users have to share resources over the 5G Orthogonal Frequency-Division Multiple Access (OFDMA) frame. One of the strategies proposed by the 5G standard is puncturing, which allows the scheduler to assign eMBB services on a timescale, and on a shorter timescale to preemptively overwrite part of the eMBB assignment when a URLLC user arrives. The optimization of puncturing poses a challenging problem: the optimal allocation depends on traffic arriving over different timescales, which forces the scheduler to make allocation decisions without knowledge of future users’ demands, all while having to satisfy several strong constraints. This kind of multiple timescales optimization with restrictions is also to be found in many interesting problems, such as energy management. We propose a learning mechanism where the system learns offline the optimal allocation according to the network state. This learned estimation is then used online to determine the optimal allocation. Through simulations, we verify that the proposed learning strategy provides results close to the optimal policy, improving state of the art proposals for puncturing schemes.
... The transmitter comprises the encoder, serial-to-parallel converter, IFFT modulator, cyclic prefix insertion and Radio-frequency-Upconverter. The receiver part comprises of Radio-frequency-Downconverter, Serial-to-parallel converter, Cyclic prefix extraction demodulator, Parallel-to-Serial converter, and decoder [7]. ...
In this work, Orthogonal Frequency Division Multiplexing's (OFDM) principles, implementation design or high-level system architecture and application were reviewed. The condition for orthogonality, frequency spacing between consecutive subcarriers (called frequency spacing) was established analytically with practical instance highlighted. The review also covers Fast Fourier Transform (FFT) which serves as a bank of demodulators while Inverse Fast Fourier Transform (IFFT) serves as a bank of modulators in an OFDM system, advancement in OFDM, Quadrature modulation types (Binary Phase Shift Keying, 4-Quadrature Amplitude Modulation, 8-Quadrature Amplitude Modulation, 16-Quadrature Amplitude Modulation, and 64-Quadrature Amplitude Modulation QAM) and spectrum efficiency was also covered. Several technologies that use OFDM were mentioned but attention was given to its usage in Wireless LAN 802.11a.
... Nevertheless, the application areas and/or conditions for these post-64-QAM schemes are currently very limited [33][34][35][36][37]. Furthermore, OFDM-based 4096-QAM has been investigated using link-level simulations for 5G and beyond [38,39]. ...
The use of heterogeneous networks (HetNets) that combine macrocells and picocells in the same coverage is effective in increasing system capacity and improving user throughput. The use of high carrier frequency bands is also expected to help achieving higher data rates because it promises vast amounts of signal bandwidth. Therefore, multiband HetNets with picocells operating at high carrier frequency bands have attracted significant attention with the aim of increasing system capacity and achieving a high user throughput in fifth-generation mobile systems and beyond. In HetNet deployments, a picocell range expansion (CRE) technique that virtually expands the picocell coverage is well known to allow more user equipment (UE) to access the picocell providing a fixed cell selection offset (CSO) for all UE. Thus far, there has not been sufficient research on optimizing the transmission (Tx) power of pico-evolved node Bs (eNBs) operating at high carrier frequency bands in multiband HetNets. In addition, the effects of CRE in multiband HetNets have not been clarified. In this paper, we first investigated the optimal Tx power of pico-eNB in a multiband HetNet combining macrocells operating at 2 GHz and picocells operating at 4.5 GHz band with a wider signal bandwidth using system-level computer simulations. Then, from the user throughput perspective, we investigated the effects of CRE providing a positive CSO for UE using two pico-eNB Tx powers close to the optimal value. Using these results, we discussed how to choose the pico-eNB Tx power when CRE was activated and validated the design method for a multiband HetNet.
... We performed frequency domain equalization (zeroforcing) by using the transmitted pilot subcarriers for the channel estimation. As a result, a BER of 0.01 is recorded by comparing the transmitted and received data bits, when the average received SNR is around 15 dB, which is below the soft-decision forward error correction (SD-FEC) threshold of 1.5 × 10 −2 [39]. As a comparison, a BER of 3.6 × 10 −4 is obtained in the simulation due to the absence of the background reflections. ...
Convergence of communication and sensing is highly desirable for future wireless systems. This paper presents a converged millimeter-wave system using a single orthogonal frequency division multiplexing (OFDM) waveform and proposes a novel method, based on the zero-delay shift for the received echoes, to extend the sensing range beyond the cyclic prefix interval (CPI). Both simulation and proof-of-concept experiments evaluate the performance of the proposed system at 97 GHz. The experiment uses a W-band heterodyne structure to transmit/receive an OFDM waveform featuring 3.9 GHz bandwidth with quadrature amplitude modulation (16-QAM). The proposed approach successfully achieves a range resolution of 0.042 m and a speed resolution of 0.79 m/s with an extended range, which agree well with the simulation. Meanwhile, based on the same OFDM waveform, it also achieves a bit-error-rate (BER) 10−2, below the forward error-correction threshold. Our proposed system is expected to be a significant step forward for future wireless convergence applications.
... If the average energy of the constellation diagram of QAM remains constant, the symbols are required to be very near to one another that causes QAM less immunity to channel variations. The high order modulation schemes need high SINR to precisely demodulate transmitted signals because high order modulation schemes such as QAM are more exposed to noise, interference, non-linear distortion and multipath fading [33] thus causing high BER. The distortion, attenuation and noise effects of fading channels on a 64-QAM signal are more catastrophic in comparison to a 16-QAM signal due to more symbol points in a constellation diagram which are very close to each other thus causing high BER. ...
A growing trend has been observed in recent research in wireless communication systems. However, several limitations still exist, such as packet loss, limited bandwidth and inefficient use of available bandwidth that needs further investigation and research. In light of the above limitations, this paper uses adaptive modulation under various parameters, such as signal to interference plus noise ratio (SINR), and communication channel’s distances. The primary goal is to minimize bit error rate (BER), improve throughput and utilize the available bandwidth efficiently. Additionally, the impact of Additive White Gaussian Noise (AWGN), Rayleigh and Rician fading channels on the performance of various modulation schemes are also studied. The simulation results demonstrate that our proposed technique optimally improves the BER and spectral efficiency in the long-range communication as compared to the fixed modulation schemes under the co-channel interference of surrounding base stations. The results indicate that the performance of fixed modulation schemes is suitable only either at high SINR and low distance or at low SINR and high distance values. Moreover, on the other hand, its performance was suboptimal in the entire wireless communication channel due to high distortion and attenuation. Lastly, we also noted that BER performance in the AWGN channel is better than Rayleigh and Rician channels with Rayleigh channel exhibiting poor performance than the Rician channel.
... Owing to the low-quality factor of capacitors at mm-wave, as well as flicker noise, the phase noise of the complementary metal-oxide-semiconductor (CMOS) voltage-controlled oscillator (VCO) is very poor and its power consumption is quite high. Therefore, instead of implementing a mm-wave phase locked loop (PLL), numerous combined two-stage structures of subsampling PLL (SSPLL) or injection-locked PLL (ILPLL) and following frequency multiplier have been preferably researched and published as the best solutions of mm-wave synthesizers [1]- [4]. Both architectures of SSPLL [ Fig. 1(b)] and ILPLL [ Fig. 1(c)] are modified from the charge-pump PLL (CPPLL) as shown in Fig. 1(a) with a common concept of improving the in-band phase noise by removing the frequency divider N in the feedback path. ...
This article presents 16-times frequency multiplier composing of two four-times frequency multipliers (quadrupler) in cascade connection. The proposed topology is new structure of tuned-frequency multiplier (TFM) for better harmonic rejection ratio (HRR) with wide frequency range and low power consumption. For accomplishing reliable output frequency band of 16–28 GHz, the whole band is divided into 64 subsidiary frequency bands by applying 6-bits digitally controlled capacitor-bank of
LC
-tuned tank. The proposed quadrupler is consisted of a harmonic generator (HG) and a cascode
LC
-tuned buffer. The proposed HG topology is based on double balanced mixer (DBM). Unlike typical mixer bias, the bottom differential pair devices of the proposed HG are C-class biased to generate more desired the fourth order harmonic. In addition, to reduce power consumption and frequency conversion gain variations for the whole target frequency band, negative-
$g_{m}$
differential pair is added in parallel to enhance the equivalent parasitic parallel resistance of the HG
LC
-tank while keep it from oscillation. Great efforts have been contributed to minimize process variation effects by simple but relatively accurate capacitance calibration. Furthermore, each
LC
-tuned tank output amplitude is regulated by a loop to maintain same output swing for the best optimization of specifications such as power consumption and HRR. The proposed 16-times multiplier is fabricated on 65-nm complementary metal–oxide–semiconductor (CMOS) process and successfully tested. Chip die size 0.7 mm
<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>
excluding input/output (I/O) pads and average power consumption is only 6 mW for 16–28 GHz frequency band. Also, negligible phase noise degradation is achieved.
... QAM is a specific modulation types: Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK). Furthermore, 4G and 5G wireless mobile communication systems have been developed based on increasing the capacity and data rates of these systems and enhancement the throughput of users and provide low latency [7][8][9]. The multimedia data of wireless mobile communication system such as speech, video, image and its rate increasing are very important issue. ...
... where G ∈ ℂ × is the transmitted matrix which depends on the function 1 √ 2 / . A cyclic prefix (CP) guard interval is added to the OFDM signal to compensate the effects of the channel multi-path delay spread and eliminate the inter-symbol interference (ISI) [3], [9]. At the receiver, after remove CP, the received signal is written by [16]: ...
The security of speech signals have become a very important research issue in mobile wireless communication systems. Encryption and decryption of speech signals for such communication systems have been simulated to utilize the security of it. In this paper, the encrypted speech transmission model has been assumed through orthogonal frequency division multiplexing (OFDM) over a doubly selective fading channel. A two-dimensional (2D) logistic map is used to provide a pseudo-random bit generator (PRBG) and index permutation. The simulation of the proposed system is programmed using MATLAB program version 2019a for 64 QAM and 256 QAM modulation and different speed velocities of 200 km/h and 500 km/h using Hybrid ciphering and scrambling techniques. The simulation results show that the speech signal over an OFDM system has good intelligibility measures and robust against any attack and the signal is decrypted with little effect on the bit error rate.
... In this paper, we focus on the performance evaluation of downlink user throughput. As the use of higher-order QAM is expected to increase data rates within a limited bandwidth, the implementation of 1024-QAM and 4096-QAM has been discussed [26][27][28] for 5G and beyond. However, in the simulations, we use 15 types of MCS indexes up to 256-QAM in the downlink as listed in Table 2, because the application conditions for these post 256-QAM are currently very limited. ...
Heterogeneous networks (HetNets), which are combined with a macrocell and picocell in the same coverage, are expected to further increase the system capacity in fifth-generation mobile systems and beyond. In HetNets, the cell range expansion (CRE) technique plays an important role and can allow more user equipment (UE) to access the picocell, i.e., virtually expand the picocell coverage. However, conventional CRE techniques that provide a fixed cell selection offset (CSO) for all UE may worsen user throughput if UE is forced to connect to the picocell because the received signal-to-interference plus noise ratio of the UE becomes lower. Therefore, we propose a personal picocell scheme using an adaptive control CRE technique to improve user throughput in which different CSOs are assigned to UE to form each optimal picocell for each UE. In this paper, we first describe the aspects and algorithm of the proposed scheme. Then, we show the user throughput for adaptive control CRE in comparison with conventional CRE by using system-level computer simulations for the two types of HetNets, i.e., single-band and multi-band HetNets. In the simulations, we first clarify the optimal parameters of the adaptive control CRE. We then show the average and 5-percentile user throughput of the optimized adaptive control CRE in comparison with that of conventional CRE. From these results, we confirmed that the personal picocell scheme using the adaptive control CRE can improve the 5-percentile user throughput while maintaining the average user throughput compared with that of conventional CRE.
... These increased requirements cannot be fully met with Quadrature Amplitude Modulation (QAM) formats such as 16/64 QAM which have widely been used in WiFi and 4G Long Term Evolution (LTE) applications. A notable feature of 5G will be dense infrastructure networks in which the distance between a base station (BS) and user equipment (UE) is reduced and the link budget is improved, allowing higher order modulation based channels to operate [6]. The 3 rd Generation Partnership Project (3GPP) release 12 started supporting 256 QAM for LTE downlink, and now with release 15, 1024 QAM support has been added. ...
Wireless communication is rapidly evolving to fulfill diverse requirements in a number of application areas. Researchers are experimenting with novel ideas to improve different aspects of communication systems and performance metrics. While computer simulation is the first step to validating these approaches, testing platforms are needed to transform them to implementations for further validation and experimentation. Software Defined Radios (SDR) and System on Chip (SoC) offer a great deal of flexibility and versatility allowing researchers to experiment with wireless algorithms. However there are challenges; noise, channel effects, and synchronization errors have to be dealt with, and measures to mitigate their effects on received symbols should be implemented. Existing research using state of the art SDR platforms has not leveraged the powerful processing capabilities of Field Programmable Gate Arrays (FPGAs) in SoCs for receiver backend operations. In this work, we use high level tools to describe hardware, and automatically synthesize and implement receiver baseband wireless signal processing algorithms for FPGA targets. We demonstrate the ability to use such platforms for real world applications using over the air waveforms. We use Xilinx ZC706, Zedboard, ADI’s FMComms3, and NXP’s BGA7210 variable gain amplifier (VGA) for the experiments presented in this paper. Use cases considered include testing the performance of higher order modulation schemes, adjacent channel interference, power amplifier (PA) gain compression and effects on the bit error rate (BER) performance.
