Performance Of Access Networks Research Articles

Improving the security of NOMA cognitive networks

Aiming at the scenario where the eavesdropper try to eavesdrop on the confidential messages of secondary trusted users, two physical-layer network coding (PNC) strategies, namely dual power superposition (PS-PS) encoding strategy and bit-level exclusive-or power superposition (XOR-PS) encoding strategy, are proposed to improve the security performance of cognitive non-orthogonal multiple access (NOMA) networks with the help of the data transmitted by the primary user. Considering the overlay spectrum sharing mechanism and the imperfect successive interference cancellation (SIC) technology, we first derive the closed-form accurate expressions of the outage probability and intercept probability of the secondary network with these two schemes over Rayleigh fading, and also give the asymptotic outage probability in the high signal-to-noise ratio (SNR) regime. Then, the correctness of the theoretical results is verified by simulation. For comparison, we also use the scheme without the assistance of the primary user as the benchmark scheme, which is represented by NPS. Finally, the simulation results show that the security of the proposed PS-PS and XOR-PS schemes is much better than that of the NPS scheme in the case of without reducing the outage performance.

Model order estimation method for user mobility classification in heterogeneous RAN systems

The performance of modern heterogeneous Radio Access Networks (RANs) can be improved by introducing new methods and algorithms for network resource management. In particular, user mobility information can be used to control RAN resources. To determine user mobility, information about the variation of the Signal to Interference + Noise Ratio (SINR) between base stations and users can be collected and analyzed. These data are multi-linear and can be represented as tensors to extract information from them. However, for the tensors decomposition, it is necessary to know the order of the multi-linear model or the rank of the tensors. Inspired by the LaRGE (LineAr Regression of Global Eigenvalues) method, we propose a novel method for the model order estimation of the multi-linear data based on the analysis of the Complimented Global Eigenvalues (CGE) profile. We have denoted our method as Enhanced LaRGE (EnLaRGE). We have compared the EnLaRGE method with the classical methods AIC, MDL and their multi-linear versions, as well as with the M-EFT and N-D EFT methods. EnLaRGE shows good performance for the tensors with small one of the tensors dimensions. EnLaRGE method is implemented for the automatic model order estimation of multi-linear data received from the Network Simulator 3 with RAN Intelligent Controller (RIC). The results show the high precision of the multi-linear model order estimation in comparison with state-of-the-art methods. The estimated model order can be used for user mobility classification and improving heterogeneous RANs performance. This research was funded by Russian Science Foundation, grant number 23-69-10084, 318, https://rscf.ru/project/23-69-10084/

Distributed computing in special purpose wireless telecommunication systems: performance and prospects

The study is devoted to the analysis of the application of distributed computing technologies in wireless telecommunication systems. The paper considers the concept of cloud radio access networks (C-RAN) and their use to improve productivity and reduce costs of communication operators. The logical relationship of mobile devices, cloud wireless network and internal servers is considered, as well as the role of split-TCP-proxy in the distribution of connections and maintenance of constant communication between the user and the internal server of the cloud. It is noted that the dynamic operations of the wireless network cloud, such as topology configuration and data rate distribution, provide better service at the upper layer. The importance of knowing the state of the wireless channel for the successful implementation of operations in C-RAN is emphasized. It is noted that the use of distributed computing in wireless systems can reduce deployment and maintenance costs, providing efficient data transmission and improved performance. The obtained results indicate the possibility of successful use of distributed computing technologies in wireless telecommunication systems. This opens prospects for communication operators to reduce costs and improve the quality of service. The research is relevant in the context of the continuous development of wireless technologies and has the potential for further research and improvement of wireless telecommunication systems. Future work may focus on expanding the scope of research, including a wider range of technologies and algorithms that can be used to optimize the performance of cloud radio access networks. In addition, the impact of using distributed computing technologies on other aspects of wireless systems, such as security, resource management, and scalability, can be considered. Research may also focus on the use of other protocols and algorithms to distribute computing tasks and optimize data transmission.

Measuring Broadband America: A Retrospective on Origins, Achievements, and Challenges

The "Measuring Broadband America" program, run by the United States Federal Communications Commission (FCC), continually measures and releases data on the performance of consumer broadband access networks in the US. This paper presents a retrospective on the program, from its beginnings in 2010 to the present. It also reviews the underlying measurement approaches, philosophies, distinguishing features, and lessons learned over the program's duration thus far. We focus on fixed broadband access since it is the program component with the longest history. We also discuss future directions and challenges.

On the Mathematical Modeling and Optimization for the Energy Efficiency Performance of CSMA-NOMA Random Access Networks With Channel Inversion

The paradigm of upcoming 5G and beyond is the massive machine type communications (mMTC), where a large number of devices automatically operate wireless communications. Due to their automatic and energy-intensive operations, energy efficiency (EE) becomes crucial, but there is a lack of investigation for EE of random access networks, which is the underlying platform for mMTC. In this paper, we focus on the EE of carrier sense multiple access-based non-orthogonal multiple access (NOMA) random access networks. We first construct mathematical models. Instead of investigating all combinations regarding successful decoding events as in previous works, by pivoting around the decoding process of a specific signal, a hidden pattern of NOMA decoding process is unveiled, which can largely decrease analytical complexity. Then, together with this feature, by adopting Markov chain and Q-function approximation, closed-form formulation for EE is derived. Subsequently, to efficiently solve the complicated non-convex EE maximization problem built via the constructed models, we employ an approach that unifies complementary geometric programming (CGP) and difference of convex programming (DCP) to optimize all the controllable parameters at device side, namely, transmission probability, power, and data rate, with a tightest lower bound strategy to guarantee seamless EE improvement and very fast convergence to local optimal points even in the worst case. Simulation experiments verify the accuracy of mathematical models and efficiency of optimization scheme.

Effective capacity analysis of NOMA with transceiver hardware and SIC imperfections

In this paper, we study the performance of the non-orthogonal multiple access (NOMA) networks. By considering two practical factors of residual hardware impairments (RHIs) and imperfect serial interference cancellation (ipSIC), we adopt effective capacity as a metric to characterize the effects of latency on the performance of NOMA networks and derive the analytical expressions of the effective capacity for the near user (NU) and the far user (FU). For further insights, we provide asymptotic analysis by invoking high signal-to-noise ratio (SNR) slope and high SNR power offset. Numerous analytical and simulated results have shown that: (1) The effective capacities of NU and FU are positively proportional to the SNR at low SNR, while at high SNR, the effective capacities approach to the constants; (2) Comparing the two users of the considered NOMA network, the effective capacity of NU shows pronounced advantages under the requirements of low quality of service. (3) RHIs are detrimental to the effective capacities of both NU and FU, especially for the high SNR regime. (4) The effective capacity of NU is limited by ipSIC.

Full duplex C‐RAN: Effects of power control

This paper investigates the performance of cloud radio access networks (C‐RAN) in different power control scenarios in full‐duplex (FD) cellular networks. Results reveal that FD C‐RAN performance drastically reduces with uplink (UL) power control. We proposed a power control scheme in downlink (DL), which uplifts the UL user rate, but at the cost of DL rate. With UL and DL power control, the average rate saturates after a threshold number of base stations (BS) coordination and has little impact on coordinating additional BSs. Besides, the state‐of‐the‐art self‐interference suppression (SI) of 130 dB provides almost equal performance compared to the perfect SI cancelation. Hence co‐channel interference management becomes the bottleneck for FD system design. We used the Matern cluster process (MCP) to model the network.

Performance model for factory automation in 5G networks

The fifth generation (5G) of mobile networks is emerging as a key enabler of modern factory automation (FA) applications that ensure timely and reliable data exchange between network components. Network slicing (NS), which shares an underlying infrastructure with different applications and ensures application isolation, is the key 5G technology to support the diverse quality of service requirements of modern FA applications. In this article, an end-to-end (E2E) NS solution is proposed for FA applications in a 5G network. Regression approaches are used to construct a performance model for each slice to map the service level agreement to the network attributes. Interference coordination approaches for switched beam systems are proposed to optimize radio access network (RAN) performance models. A case study of a non-public network is used to show the proposed NS solution. Simulation result shows that for services with different QoS requirements, different IC approaches should be used as optimization methods. Design prediction using regression approach has been evaluated and shows that the prediction successful rate increases when more existing data are used.

A Grouping Algorithm for Random Access Networks and Supermartingale Evaluation

Wireless communications play a critical role in the applications of Internet of Things (IoT). The Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) is a well-proven wireless random access protocol. A crucial factor affecting the performance of random access networks is “hidden node collision,” which incurs performance degradation and lower resource utilization. Grouping is an efficient strategy for hidden node avoidance. In current IoT networks, the terminals usually have different traffic load, so load balance should be considered when grouping algorithm is designed. To mitigate hidden nodes and achieve load balance simultaneously, we propose a grouping algorithm based on the game theory. By introducing the supermartingale theory, the delay performance of the completed groups is analyzed. Simulations prove that the proposed algorithm alleviates collision, balances traffic, and promotes the efficient guarantee for Quality of Service (QoS).

Simulating an LTE Network Using OMNeT++

Abstract: Long Term Evolution emerged from the previous 3GPP system known as the Universal Mobile Telecommunication System. This technology is an entire IP-based network that provides an IP-based mobile content called the Evolved Packet Core. The main goals of LTE are to increase data rates, provide lower latency on the Radio Access Network, improve bandwidth and optimal performance. The LTE architecture combines a new basic channel called eNodeB with a single core called the Evolved Packet Core that provides access to both voice and IP data resources. Long Term Evolution (LTE) talks about a promising new invention that gives broadband internet access to the universe. Therefore, many test groups are trying to simplify their show. Shockingly, from now on, apparently, there are no open source simulation systems, which can be used to emulate high-density user platforms like India, which are unrestricted. Lack of a standard reference system for use by assessment students and researchers is a loss. To overcome this, we came up with a project that not only imitates LTE but can also be used to replicate any OFDM package programs such as LTE pro advanced, and was launched to provide a comprehensive presentation of the LTE environment. Our simulation project has been contemplated to reproduce uplink and downlink editing methods in multi-cell / multi-user environments, considering customer portability, radio asset development, reusable strategies, flexible balance and coding module, and various ideas that work best for aspiring students. researchers. Using simulation software and framework,After researching many simulation software we concluded that OMNet ++ would be the best suit for our project. We have used the Inet 4.3 framework in the required modules.

A Novel Physics-Based Channel Model for Reconfigurable Intelligent Surface-Assisted Multi-User Communication Systems

The reconfigurable intelligent surface (RIS) is one of the promising technologies contributing to the next generation smart radio environment. A novel physics-based RIS channel model is proposed. In the model, the signal reflected through the scatters and the RIS elements are jointly studied as multipath components of the overall received envelope. This novel strategy simplifies the mathematical structure of the channel gain and is able to compactly derive the distribution of the overall channel. For the case of continuous phase shifts, the distribution depends on the number of elements of the RIS and the observing direction of the receiver. For the case of discrete phase shifts, the distribution further depends on the number of phase quantization levels. The scaling law of the average received power is obtained from the scale factor of the distribution. For the application scenarios where RIS functions as an anomalous reflector, we investigate the performance of single RIS-assisted multiple access networks for time-division multiple access (TDMA), frequency-division multiple access (FDMA), and non-orthogonal multiple access (NOMA). Closed-form expressions for the outage probability of the proposed channel model are derived. It is proved that a constant diversity order exists, which is independent of the number of RIS elements. Simulation results are presented to confirm that the proposed model applies effectively to the element-based RISs.

Evaluation of Received Signal Power Level and Throughput Depending on Distance to Transmitter in Testbed for Automotive WLAN IEEE 802.11ac Communication Network

Abstract WLAN IEEE 802.11ac is one of the wireless network technologies that can be used for ITS (Intelligent Transport Systems) needs, in particular for providing vehicle passengers with access to the data transmission network. To evaluate the performance of such automotive wireless access networks, it is necessary to perform experimental measurements. By conducting the throughput measurements in WLAN-based automotive communications testbed, it has been observed that the throughput of the communication channel decreases and the received signal becomes weaker as the vehicle moves away from the wireless access point. The aim of the research is to verify theoretically whether there is a correlation between the received signal power level and the throughput of the communication channel depending on the distance to the transmitter. To calculate the received signal power depending on the distance to the transmitter, a log-normal signal propagation model can be used, which takes into account random signal fluctuations that are described by the Nakagami distribution. Further, based on the obtained results, Shannon’s theorem can be used to calculate the maximum theoretical throughput of the communication channel. The analysis of the obtained results shows that a correlation exists between the received signal power level and the throughput of the communication channel depending on the distance to the transmitter. The performed theoretical calculations justify the experimentally obtained results.

An Access Network Selection Algorithm for Terrestrial-Satellite Networks Based on a QoS Guarantee

Considering the communication requirements of different monitoring services and the performance of different access networks, to ensure the quality of service and reliability of sensor networks, we propose an access network selection algorithm based on a quality-of-service (QoS) guarantee. According to the service requirements, the attributes that affect the terminal access options are determined. Then, utility functions are designed for normalizing the attribute values of the network. In addition, we construct a weight calculation model that combines subjective and objective factors. Finally, the algorithm calculates the relative closeness between each pair of networks by the technique for order preference by similarity to an ideal solution (TOPSIS) and sorts the candidate networks to obtain the best candidate network of each monitoring terminal to access. Simulation results show that the proposed algorithm can effectively meet the communication needs of different monitoring services, ensures network reliability, and can improve the utilization rate of network resources.

A QoS-Aware Dynamic Bandwidth Allocation Algorithm for Passive Optical Networks with Non-Zero Laser Tuning Time

The deployment of new 5G services and future demands for 6G make it necessary to increase the performance of access networks. This challenge has prompted the development of new standardization proposals for Passive Optical access Networks (PONs) that offer greater bandwidth, greater reach and a higher rate of aggregation of users per fiber, being Time- and Wavelength-Division Multiplexing (TWDM) a promising technological solution for increasing the capacity by up to 40 Gbps by using several wavelengths. This solution introduces tunable transceivers into the Optical Network Units (ONUs) for switching from one wavelength to the other, thus addressing the ever-increasing bandwidth demands in residential broadband and mobile fronthaul networks based on Fiber to the Home (FTTH) technology. This adds complexity and sources of inefficiency, such as the laser tuning time (LTT) delay, which is often ignored when evaluating the performance of Dynamic Bandwidth Allocation (DBA) mechanisms. We present a novel DBA algorithm that dynamically handles the allocation of bandwidth and switches the ONUs’ lasers from one wavelength to the other while taking LTT into consideration. To optimize the packet delay, we introduce a scheduling mechanism that follows the Longest Processing Time first (LPT) scheduling discipline, which is implemented over the Interleaved Polling with Adaptive Cycle Time (IPACT) DBA. We also provide quality of service (QoS) differentiation by introducing the Max-Min Weighted Fair Share Queuing principle (WFQ) into the algorithm. The performance of our algorithm is evaluated through simulations against the original IPACT algorithm, which we have extended to support multi-wavelengths. With the introduction of LPT, we obtain an improved performance of up to 73% reduction in queue delay over IPACT while achieving QoS differentiation with WFQ.

Large Intelligent Surface-Assisted Nonorthogonal Multiple Access for 6G Networks: Performance Analysis

Large intelligent surface (LIS) has recently emerged as a potential enabling technology for 6G networks, offering extended coverage and enhanced energy and spectral efficiency. In this work, motivated by its promising potentials, we investigate the error rate performance of LIS-assisted nonorthogonal multiple access (NOMA) networks. Specifically, we consider a downlink NOMA system, in which data transmission between a base station (BS) and L NOMA users is assisted by an LIS comprising M reflective elements (REs). First, we derive the probability density function (PDF) of the end-to-end wireless fading channels between the BS and NOMA users. Then, by leveraging the obtained results, we derive an approximate expression for the pairwise error probability (PEP) of NOMA users under the assumption of imperfect successive interference cancellation. Furthermore, accurate expressions for the PEP for M = 1 and large M values ( M > 10) are presented in closed-form. To gain further insights into the system performance, an asymptotic expression for PEP in high signal-to-noise ratio regime, asymptotic diversity order, and tight union bound on the bit error rate are provided. Finally, numerical and simulation results are presented to validate the derived mathematical results.

Performance analysis of a hybrid optical CDMA/DWDM system against inter-symbol interference and four wave mixing

This paper reports the implementation and theoretical model for analyzing an optical CDMA/DWDM hybrid system to reduce two major problems, the Inter-Symbol Interference (ISI) and the Four-Wave Mixing (FWM) effects and improve the performance of optical subscriber access networks by using Zero Cross-Correlation (ZCC) optical codes, which helps to reduce the effect of the Multiple Access Interference (MAI). A squeezing method is used in the proposed hybrid system to completely suppress the ISI. In this method, the sequence interval of the signature code is squeezed into a duration of less than one-bit. The hybrid system is capable of accommodating 120 optical CDMA users carried by only 10 DWDM wavelengths spaced by 0.2 ​nm with 60 ​Gb/s/wavelength transmitted over 105.075 ​km of optical fiber. The result shows that the optimum interval of the code sequence is a quarter (i.e., 25%) of the bit duration. Moreover, the results reveal that the CDMA technology based on the spread spectrum is capable of increasing the nonlinear tolerance of the proposed hybrid system as the energy of bits is distributed over the chip sequence code. Also, the number of ones/weight and the positions between them have a significant effect on the performance of the proposed hybrid system.

Design of power and resource management in OFDMA networks using sleep mode selection technique

This paper considers the consumption of power and resource metrics in small cell networks, which are enabled through the Sleep Mode Selection (SLS) function in Orthogonal Frequency Division Multiple Access (OFDMA) system. The proposed technique considers heterogeneous networks and operates under two different schemes that includes power management using SLS and resource management using a deactivation algorithm. Further, the limitation of low power consumption schemes leads to degradation of network performance in Orthogonal Frequency Division Multiple Access (OFDMA) networks. Hence, to improve the performance, a Semi-Markov SLS (SMD-SLS) decision making process is utilized in the present study. The performance is again improved with spectrum reuse maximization, where a small cell deactivation strategy identifies well the cells in sleep modes condition and eliminates them optimally for improved spectrum reuse. The performance is evaluated for the conventional non-sleeping mode cells and a benchmark technique. The results validates the performance of proposed model against improved resource and power management.

Bit Error Rate for NOMA Network

This letter examines the bit error rate (BER) performance of downlink non-orthogonal multiple access networks for binary phase-shift keying modulation. Exact BER expression is derived for each user in closed-form under additive white Gaussian noise and Rayleigh fading channels in perfect and imperfect successive interference cancellation (SIC) cases. Next, in perfect SIC case, the asymptotic BER expression in a high signal-to-noise ratio (SNR) region is obtained to express the behavior of the network with diversity and array gains. On the other hand, in imperfect SIC case, the upper bound for BER is attained, and at high SNR values, the BER reveals an error floor, and hence a zero diversity gain is achieved. Then, a feasible range of power allocation coefficients is found such that a good BER performance can be provided for each user. Finally, through simulations and software-defined radio-based real-time tests, analytical results are validated.

Delay and Stability Analysis of Connection-Based Slotted-Aloha

In recent years, connection-based slotted-Aloha (CS-Aloha) has been proposed to improve the performance of random access networks. In this protocol, each node attempts to send a request to the access point (AP) before packet transmission. Once this attempt is successful, the node can transmit up to M packets to the AP. Previous works indicated that the CS-Aloha can achieve a higher throughput than the classical slotted Aloha (S-Aloha), if M is large enough. However, the impact of M on the delay performance and stability is still unknown. To solve this problem, we model each node of the CS-Aloha as a vacation queueing system with limited service discipline, where we consider each batch of packet transmissions as a busy period, and the attempt process between two successive busy periods as a vacation period. We derive the delay distribution, which is turned out to be a geometric distribution. From this result, we further obtain the mean delay, the delay jitter, and the bounded delay region. Our analysis shows that increasing M can accelerate the clean-up of the buffer in each node and thus decrease the attempt rate, which can reduce the average time needed by a node to make a successful attempt. As a result, a large M can decrease the mean delay and the delay jitter, and enlarge the bounded delay region. Also, we obtain the condition to achieve the minimum mean delay under different values of M .

Security Analysis of Multi-Antenna NOMA Networks Under I/Q Imbalance

This paper investigates the reliability and security performance of the downlink non-orthogonal multiple access (NOMA) networks over Nakagami-m fading channels, where the base station (BS) aims to communicate with multi-antenna NOMA users in the presence of a multi-antenna eavesdropper. To be more practical, a detrimental factor at both transmitter and receiver is considered, namely in-phase and quadrature-phase imbalance (IQI). To further improve the reliability and security of the considered networks, the selection combining (SC) algorithm at the receiver is taken into account. More specifically, the exact analytical expressions for the outage probability (OP) and the intercept probability (IP) are derived in closed-form. To obtain a better understanding of the influence for the IQI parameters on the system performance, the asymptotic behaviors for the outage probabilities (OPs) in the high signal-to-noise ratio (SNR) region are analyzed. Based on the asymptotic results, the diversity order of the considered system are obtained and discussed. The numerical results are presented to verify the validity of the theoretical analysis.