Secondary Synchronization Signal Research Articles

A comprehensive study on the synchronization procedure in 5G NR with 3GPP-compliant link-level simulator

The 5G New Radio synchronization procedure is the first step that the user must complete to access the mobile network. It mainly consists of the detection of the primary and secondary synchronization signals (PSS and SSS, respectively) and the decoding of the physical broadcast channel (PBCH). Our goal is to provide a comprehensive study of the synchronization procedure and investigate different techniques and approaches, through the implementation of a 5G New Radio-compliant simulator. Of significant interest is the investigation of impairments such as the fading channel, the frequency offset, and the delay spread. The results are provided in terms of detection probability for the PSS and SSS detection, and in terms of block error rate for the PBCH. From the data collected, there is evidence that choosing M-sequences for the PSS leads to an appreciably robust solution against frequency offset. The structure of the Gold sequences for SSS generation can be exploited to reduce the detection complexity, and different approaches can be chosen to improve reliability against delay spread. Moreover, the polar coding for 5G PBCH outperforms the former 4G coding technique, but they are still sensible to frequency offset. Finally, the simulator functionalities are validated through real captures of 5G signals.

Complexity-Efficient Sidelink Synchronization Signal Detection Scheme for Cellular Vehicle-to-Everything Communication Systems

Synchronization is a challenging issue in vehicle-to-everything (V2X) cellular communication, especially when V2X devices need to directly communicate with each other outside the network coverage area. By adopting the maximum likelihood principle, we propose joint detection of the sidelink secondary synchronization signal (SL-SSS) and carrier frequency offset (CFO) in a V2X system using 5G new radio sidelink. We formulate an effective joint coherent synchronization scheme for cellular V2X applications by decoupling the estimation of the sidelink identity and CFO, which requires a priori knowledge of channel state information. To verify the feasibility of the proposed detection scheme, we derive a simplified implementation of the proposed SL-SSS detector and a closed-form expression for the detection probability. Simulation results demonstrate that the proposed SL-SSS detector exhibits either comparable performance in terms of detection probability or reduced complexity when compared with conventional SL-SSS detectors. Using the proposed method in the cellular V2X system enables V2X devices to achieve robust synchronization with reduced power consumption during the initial synchronization procedure, while also offering valuable insights for designing a simple, efficient sidelink synchronization receiver.

Blockwise Joint Detection of Physical Cell Identity and Carrier Frequency Offset for Narrowband IoT Applications

This paper presents a novel formulation for detecting the secondary synchronization signal in a narrowband Internet of Things communication system. The proposed approach is supported by a noncoherent algorithm that eliminates the need for channel information. A robust joint synchronization scheme is developed by decoupling the estimations of the physical cell identity and the carrier frequency offset. We derive the detection probability of the proposed physical cell identity detector and the mean squared error of the carrier frequency offset estimator, demonstrating their accuracy through simulation results. The performance of the proposed detection scheme is compared with that of existing detection schemes in terms of both estimation accuracy and computational complexity. Experimental results confirm that the proposed synchronization method exhibits superior performance while maintaining relatively lower complexity compared with benchmark methods.

Implementation and analysis of 5G network identification operations at low signal-to-noise ratio

The article investigates the operations of identifying a cellular network and searching for a cell at various signal-to-noise ratios. The estimation of frequency and time displacement, criteria for detecting the primary synchronization signal are presented. The main contribution of this article is the consideration of the step-by-step execution of the 5G cell search procedure in a complex interference environment. The decoding steps of the primary and secondary synchronization signals are being investigated. This is achieved by analyzing the signals at each step of the correlation algorithm for different signal-to-noise ratios. In order to verify the adequacy of the proposed models, a sequence operation for synchronizing 5G mobile networks with base station signals is considered. The dependence the magnitude of the error vector modulus on the signal-to-noise ratio of a physical broadcasting channel is investigated for three different channel profiles without line of sight. As a result of the experiment, the error vector of the physical broadcast channel changes from 55% to 10%, when the signal-to-noise ratio changes from 0 to 20 dB. In the multiple-input multiple-output (MIMO) mode, we received a 3 dB increase in communication energy efficiency. The findings will be useful for 5G system designers to troubleshoot synchronization problems.

A Simple and Low-Cost Technique for 5G Conservative Human Exposure Assessment

The purpose of this paper is to introduce a simple, low-cost methodology for estimating a conservative value of the maximum field level that can be radiated by a 5G base station useful for human exposure assessment. The method is based on a Maximum Power Extrapolation (MPE) approach and requires the measurement of a reference quantity associated with the SS-PBCH, such as Primary Synchronization Signal (PSS), Secondary Synchronization Signal (SSS), Physical Broadcast CHannel (PBCH), or PBCH Demodulation Reference Signal (PBCH-DMRS). This step requires a simple spectrum analyzer and allows one to obtain the Resource Element (RE) power of a signal transmitted through broadcast beams. In the second phase, the RE power of the signal transmitted through the traffic beam is estimated using the Cumulative Distribution Function (CDF) of the antenna boost factor obtained from the broadcast and the traffic envelope radiation patterns made available by the base station vendor. The use of the CDF allows us to mitigate the problems related to the exact estimation of the direction of the measurement point with respect to the beam of the 5G antenna. The method is applied to a real 5G communication system, and the result is compared with the value given by other MPE methods proposed in the literature.

Beamforming Based on a SSS Angle Estimation Algorithm for 5G NR Networks

The current 5G-NR standard includes the transmission of multiple synchronization signal blocks (SSBs) in different directions to be exploited in beamforming techniques. However, choosing a pair of these beams leads to performance degradation, mainly for the cases where the transmit and receive beams are not aligned, because it considers that only few fixed directions among wide beams are established. Therefore, in this article, we design a new 3GPP-standard- compliant beam pair selection algorithm based on secondary synchronization signal (SSS) angle estimation (BSAE) that makes use of multiple synchronization signal blocks (SSBs) to maximize the reference signal received power (RSRP) value at the receiver. This optimization is performed using the SSSs present in each SSB to perform channel estimation in the digital domain. Afterwards, the combination of those estimations is used to perform equivalent channel propagation matrix estimation without the analog processing effects. Finally, through the estimated channel propagation matrix, the angle that maximizes the RSRP is determined to compute the most suitable beam. The proposed algorithm was evaluated and compared with a conventional beam pair selection algorithm. Ours has better performance results. Furthermore, the proposed algorithm achieved performance close to the optimal performance, where all channel state information (CSI) is available, emphasizing the interest of the proposed approach for practical 5G mmWave mMIMO implementations.

Time Domain Analysis of NB-IoT Signals

The NB-IoT (NarrowBand-Internet of Things) radio technology is now widely implemented by mobile phone network operators to support the communication of IoT devices such as smart meters, insurance black boxes for cars, network connected waste bins, smart bicycles. In the present work, some LTE800 cells of different mobile phone network operators implementing the NB-IoT technology in the guard band mode have been investigated. The signals, consisting of a PRB (Physical Resource Block) 180 kHz wide, have been analyzed and characterized in the time domain by means of a narrow band instrumental chain equipped with a Rohde & Schwarz FSH8 spectrum analyzer. Time domain analysis allows us to identify, within the transmission frame, the position of the NB-IoT signaling channels such as the Narrowband Reference Signal (NRS), the primary (NPSS) and secondary (NSSS) synchronization signals and the broadcast channel (NPBCH), but, above all, to measure the power received during the transmission of the NRS. This value has been compared with that measured by the NB-IoT decoding module supplied on the same analyzer, in order to verify the equivalence of these measurement methods. This would allow use of a more diffuse and cheaper instrumentation rather than more expensive vector analyzers, currently required to assess electric fields due to the NB-IoT signals through the extrapolation techniques set by Italian CEI 211-7/E technical standard.

Carrier Frequency Offset Estimation in 5G NR: Introducing Gradient Boosting Machines

The Beyond fifth Generation (B5G) communication systems imposed several challenges on radio designers. For example, a machine is required to set up a call at a low Signal-to-Noise Ratio (SNR), as low as -10 dB, in the extended coverage mode. Moreover, only one receive antenna will be available, and virtually no frequency diversity. Such requirements present major challenges to maintaining timing and frequency synchronization. Carrier Frequency Offset (CFO) estimation is at the heart of these challenges. Different ways have been proposed for CFO estimation such as maximum likelihood based on a cyclic prefix. Nevertheless, these methods remain limited in various ways. At the same time, Machine Learning (ML) techniques showed outstanding performance in several wireless communication problems. In this work, we propose an ML-based approach for CFO estimation in OFDM systems. Specifically, we propose a Gradient-Boosting Machine (GBM)-based solution to predict the CFO given the received Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS). Furthermore, we make our dataset available for public access to encourage other researchers to pursue this promising direction. We compare our results with different baseline models (i.e., artificial neural networks and support vector machines). The experimental results show that our model outperforms other baseline models due to its ensemble nature which enables ensemble models to obtain a better generalization behavior.

Complexity-Efficient Coherent Physical Cell Identity Detection Method for Cellular IoT Systems

Narrowband Internet of Things (NB-IoT) is one of the low-power wide-area network technologies that aim to support enormous connection, deep coverage, low power consumption, and low cost. Therefore, low cost of implementation and maintenance is one of the key challenges of NB-IoT terminals. This paper presents a low-complexity formulation for narrowband secondary synchronization signal (NSSS) detection in the NB-IoT system, supported by a coherent algorithm that requires a priori knowledge of the channel. By exploiting a symmetric conjugate feature of the NSSS sequence, a joint physical cell ID and radio frame number detection method with low complexity is proposed for coherent detection. The probability of erroneous detection of the presented NSSS detection method is computed, and the analytical model is verified by means of simulation. Numerical experiments will demonstrate that the proposed detection scheme remarkably reduces the computational complexity with almost the same detection ability compared to the existing detection scheme.

Balanced-Offset Joint Acquisition of Physical Cell Identity and Radio Frame Number for NB-IoT Communication Systems

This article proposes a reduced complexity synchronization signal detection scheme in a narrowband Internet of Things (NB-IoT) system. By detecting the narrowband secondary synchronization signal (NSSS), both physical cell ID (PCID) and radio frame number (RFN) are jointly obtained during the initial cell search procedure in NB-IoT. To facilitate reduced complexity joint detection of the PCID and RFN, we propose an NSSS subcarrier grouping method by balancing the phase offset among NSSS subcarriers. The advantages and drawbacks of the proposed joint detector are presented by comparing the conventional joint detector in terms of performance and complexity. The probability of detection failure of the proposed detector is theoretically derived, which is further validated by means of simulation results. Both analytical results and simulations show that the proposed solution significantly decreases the computational burden with negligible performance loss, compared to the conventional detectors.

Indoor Positioning with CNN and Path-Loss Model Based on Multivariable Fingerprints in 5G Mobile Communication System.

Many application scenarios require indoor positioning in fifth generation (5G) mobile communication systems in recent years. However, non-line of sight and multipath propagation lead to poor accuracy in a traditionally received signal strength-based fingerprints positioning system. In this paper, we propose a positioning method employing multivariable fingerprints (MVF) composed of measurements based on secondary synchronization signals (SSS). In the fingerprint matching, we use MVF to train the convolutional neural network (CNN) location classification model. Moreover, we utilize MVF to train the path-loss model, which indicates the relationship between the distance and the measurement. Then, a hybrid positioning model combining CNN and path-loss model is proposed to optimize the overall positioning accuracy. Experimental results show that all three positioning algorithms based on machine learning with MVF achieve accuracy improvement compared with that of Reference Signal Receiving Power (RSRP)-only fingerprint. CNN achieves best performance among three positioning algorithms in two experimental environments. The average positioning error of hybrid positioning model is 1.47 m, which achieves 9.26% accuracy improvement compared with that of CNN alone.

5G NR 기지국의 전자파 노출량 평가 방법 제안

The proliferation of 5G new radio (NR) base stations (gNBs) worldwide sheds light on electromagnetic field (EMF) measurements of gNB to assess human exposure. Over-the-air (OTA) measurement of gNBs is mandatory because 5G NR uses an active array antenna. Furthermore, it is well known that 5G NR provides various types of services such as enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (MTC). Therefore, in the case of 5G NR gNB, a reliable method of EMF measurement for each gNB is required because the traffic information varies greatly depending on the services provided, and many gNBs are installed in a hotspot area. Thus, EMF measurements involve the selection of the synchronization signal/physical broadcast channel (SS/PBCH) block, which is “always-on” and does not depend on traffic signals. In this study, we analyze the methods used to measure EMF for 5G NR, which involve the application of instruments such as a dedicated NR decoder or spectrum analyzer. Consequently, we assert that EMF measurement methods should be classified and implemented according to their evaluation purposes. In addition, we propose that the compliance for installing gNBs should be measured by using a dedicated NR decorder based on a secondary synchronization signal (SSS) that can not only increase the reliability of the measurement but also accurately measure the EMF exposure for each gNB.

Group-Wise Sidelink Synchronization Signal and Carrier Frequency Offset Detection Method for D2D-Based NR-V2X Systems

This article proposes an effective joint sidelink secondary synchronization signal (S-SSS) and carrier frequency offset (CFO) detection method for device-to-device-based new radio vehicle-to-everything networks. In order to improve the S-SSS and CFO detection performance, the proposed method uses a group-by-group correlation between four consecutive sidelink synchronization signals. The benefits and drawbacks of the proposed detection scheme are presented, and a theoretical analysis is derived, which is further discussed by means of simulation results. Both analytical results and simulations show that the proposed solution attains an improved detection performance using a group-wise correlation with slightly increased complexity, compared to existing detection algorithms.

FPGA Implementation of 5G NR Primary and Secondary Synchronization

The 5G communication systems are widely established for high-speed data processing to meet users demands. The 5G New Radio (NR) communications comprise a network of ultra-low latency, high processing speeds, high throughput and rapid synchronization with a time frame of 10 ms. Synchronization between User Equipment (UE) and 5G base station known as gNB is a fundamental procedure in a cellular system and it is performed by a synchronization signal. In 5G NR system, Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS) are used to detect the best serving base station with the help of a cell search procedure. The paper aims to determine the Physical Cell Identity (PCI) by using primary synchronization and secondary synchronization blocks. The PSS and SSS detection for finding PCI is implemented on Zynq-7000 series Field Programmable Gate Arrays (FPGA) board. FPGA are reconfigurable devices and easy to design complex circuits at high frequencies. The proposed architecture employs Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS) detection aims with high speed and low power consumption. The synchronization blocks have been designed and the synthesized design block is implemented on the Zynq-7000 series Zed board with a maximum operating clock frequency of 1 GHz.

RESEARCH OF THE PROCEDURE OF INITIAL ACCESS TO THE FIFTH GENERATION COMMUNICATION NETWORK

Traditional mobile networks have bandwidth and infrastructure limitations. Each base station has a limited number of users and data capacity. 5G technology uses advanced technologies, such as massive MIMO and beamforming, to increase data rates and spectrum efficiency. These features, and the large number of small cells, allow many 5G users to receive low latency and high traffic without overloading the base station. Small cells work the same way as regular cells, but use new technology and millimetre waves (5G New Radio). Low-power base stations can be easily deployed. Cell search is a procedure by which the user equipment (UE) obtains time and frequency synchronization with the base station and decodes the cell ID of the mobile device. System information is broadcast information that is periodically transmitted by the base station on the downlink. This is very important information for the mobile device (UE) needed to connect to the base station (gNB). The UE reads system information to determine the location of mobile devices when turned on, to select and re-select a cell. System information provides the following information: system frame number, system bandwidth, PLMN, mobile subscriber selection and redial thresholds, etc., required to access the network. Physical Cell ID (PCI) is used to distinguish mobile devices in the network radio communication. PLMN (Public land Mobile Network) – mobile network service area. Is a set of all mobile devices of one cellular network operator. The UE scans the bandwidth in the sync raster. The synchronization raster indicates the frequency positions of the synchronization unit that can be used by the UE to detect the system when there is no explicit indication of the position of the synchronization unit. In the next step, the UE decodes the primary and secondary synchronization signals to obtain the Physical Cell ID (PCI) and the DMRS PBCH. The base station transmits SSB packets that contain one SSB per beam. The beam direction changes for each SSB transmission. The following steps are performed to complete the synchronization procedure. The UE selects the preferred beam and decodes the PBCH MIB information, such as SFN, SSB index, raster offset, default DL numerology, RMSI configuration, DM-RS location, and cell prohibition information. If the cell is not locked, the UE attempts to decode the physical downlink control channels (PDCCH) to obtain the frequency location of the PDSCH resources. A study of the model of restoring the synchronization of symbols and frames in the QPSK system, caused by a variable synchronization error. A study of the formation of the radio channel at the physical level.

Implementation of 5G NR Primary and Secondary Synchronization

The 5th generation cellular communication system (5G) is oriented towards a new generation of cell conversation device. Similar to all cellular broadband for highly reliable communique with networks consisting of very low latency, synchronization within the respective time frame and frequency domain plays an essential role by allowing the user devices (UE) to acquire data accordingly and transfer it. The paper gives an overview of the 5G signal receiving systems framework required to obtain a physical mobile identification. The physical alerts anticipated with the aid of the 3GPP (third Generation Partnership Project) 5G New Radio specification for synchronization and cellular seek in 5th-era Wi-Fi broadband get entry to structures is provided in this paper. The statistics required to determine the 5G NR physical layer that is carried with the aid of. Secondary Synchronization Signal (SSS) and Primary Synchronization Signal. Subsequently, this paper affords implementation of low power, High speed Synchronization signal detection in Xilinx Kintex FPGA. An excessive-Performance Synchronization Signal detection is derived.

Physical Cell ID Detection Using Joint Estimation of Frequency Offset and SSS Sequence for NR Initial Access

This paper proposes a physical-layer cell identity (PCID) detection method that employs joint estimation of a frequency offset and the secondary synchronization signal (SSS) sequence for the 5G new radio (NR) initial access with beamforming transmission at a base station. Computer simulation results show that by using the PCID detection method with the proposed joint estimation, an almost identical PCID detection probability to the primary synchronization signal (PSS) detection probability is achieved for an average received signal-to-noise ratio (SNR) of higher than approximately -5 dB. The results suggest that the residual frequency offset is compensated to a sufficiently low level leading to accurate SSS sequence estimation. The results also show that by using the PCID detection method, high PCID detection probabilities of greater than 90% and 50% are achieved at the carrier frequencies of 30 GHz and 50 GHz, respectively, at the average received SNR of 0 dB at the frequency stability for a local oscillator in a set of user equipment of 3 ppm.

Complexity-Effective Sequential Detection of Synchronization Signal for Cellular Narrowband IoT Communication Systems

Narrowband Internet of Things (NB-IoT) is one of the most promising low-power wide-area technologies to support low cost, massive connection, deep coverage, and low-power consumption. This article proposes a complexity-effective narrowband secondary synchronization signal (NSSS) detection scheme for the cellular NB-IoT communication system. By taking advantage of the NSSS sequence, the search space of NSSS hypotheses is reduced by decoupling the detection of complementary Walsh sequence and Zadoff-Chu sequence in a sequential manner. Such a detection strategy allows reduced-complexity NSSS detection in the NB-IoT system. Both numerical and simulation results are presented to verify the effectiveness of the proposed NSSS detection scheme. The simulation results show that the proposed NSSS detector achieves a considerable complexity reduction at the cost of some performance degradation, compared to the conventional NSSS detector.

Complexity Effective Sequential Detection of Secondary Synchronization Signal for 5G New Radio Communication Systems

In this article, a complexity-effective secondary synchronization signal (SSS) detection scheme is presented for fifth-generation (5G) new radio (NR) communication systems, which uses a gold sequence for SSS generation by multiplying two different m-sequences. By taking advantage of good autocorrelation property between cyclic-shifted versions of m-sequence, the search space of SSS hypothesis testing is reduced by decoupling the detection of two m-sequences. The combination of such a sequential strategy with maximum likelihood detection criterion facilitates low-complexity and reliable SSS detection in the 5G NR system. Both numerical and simulation results are presented to justify the effectiveness of the proposed detection scheme. It is demonstrated from presented results that the proposed SSS detector achieves a considerable complexity reduction while incurring slight performance loss, compared to existing SSS detectors.

Effective Joint Detection of Synchronization Signal, Duplex Mode, and Frequency Offset for LTE Machine-Type Communications

In this article, a complexity effective and robust cell search method is proposed for machine-type communication in a long-term evolution system. The correlation between the primary synchronization signal (PSS) and secondary synchronization signal (SSS) in the frequency domain is exploited to remove the effect of channel fading distortion and symbol timing offset. This design facilitates robust synchronization of the carrier frequency offset, sector ID, and duplex mode without performing hypothesis testing on SSS candidates, followed by the detection of group ID. Both theoretical and experimental results are presented to justify the effectiveness of the proposed cell search scheme. The simulation results show that the proposed method achieves robust and reduced-complexity cell search when there are nonnegligible residual symbol timing error and frequency-selective fading distortion, compared to existing methods.