Backhaul Communication Research Articles

Delay reduction and interference mitigation by resource management for IAB networks

To overcome the increasing demand for high-throughput data services, the 3rd Generation Partnership Project (3GPP) has proposed Integrated Access and Backhaul (IAB) in Release 16 as a scalable and cost-effective alternative to traditional fiber backhaul for 5 G systems. A key feature of IAB is the shared use of the same spectrum band for both access and backhaul communications, which introduces challenges related to interference, delays, capacity sharing, and additional complexity due to the half-duplex constraint. In this paper, we provide an overview of the 3GPP guidelines for IAB resource management and introduce a semi-centralized, heuristic-based resource management policy aimed at jointly enhancing end-to-end delay and minimizing interference in IAB networks, in compliance with 3GPP standards. We conduct a comparative study of our proposed policy against several policies, including the baseline proposed by 3GPP. The evaluation is performed through discrete-event simulations under two types of traffic and varying network loads. The simulation results underline that our semi-centralized resource management policy effectively controls interference, leading to improved network Key Performance indicators (KPIs) like system throughput and end-to-end delay. Specifically, our solution achieves up to an 11% increase in system throughput and a 30% reduction in end-to-end delay compared to the baseline for constant traffic, while for variable traffic, it results in a 16% increase in system throughput and a 26% reduction in end-to-end delay.

Wide band high gain modified-folded-wave-guide slow wave structure for millimeter-wave traveling wave tube amplifier in 6G and beyond back-haul communications

Abstract Millimeter-wave technology is crucial in telecommunications as it enables higher bandwidths and faster data transfer. V-band represents frequencies ranging from 50 to 75 GHz and is used for short-range back-haul communication, defense radar, inter-satellite communications, and space debris detection. Folded waveguide slow-wave structures (FWG-SWS) are an excellent choice for V-band amplifiers due to their wide bandwidths, large gain, and ease of fabrication using modern lithographic processes. This article presents a modified folded waveguide slow-wave structure (MFW-SWS) for V-band traveling wave tube amplifiers (TWTAs) desirable for multi-gigabit 6G and beyond back-haul communications. The MFW slow-wave structure is an FWG-SWS variant that supports an increased RF phase velocity, accommodating additional SWS length for much-improved amplification. The dispersion analysis effectively provides a 15% operational bandwidth ranging from 64–74 GHz with a reduced phase velocity of three-tenths the speed of light apt for enhanced beam-wave interactions. The two-section SWS has independent attenuators designed to provide over 20 dB attenuation throughout the functional bandwidth effortlessly. Additional wave-guide transitions are introduced to achieve the best attenuation characteristics. Along the axis of the SWS, a square beam tunnel is employed to support a 26 kV round electron beam with a beam current of 70 mA. To contain the electron beam within the beam tunnel, this study used a focusing mechanism with a constant magnetic field of 0.25T, which is highly appropriate for miniaturization and large-scale implementation in 6G back-haul towers. Particle-in-cell (PIC) simulations were performed using the CST (Computer Simulation Technology) Studio Suite, and a gain of over 26 dB with an output power of 50 W was successfully attained across the operational bandwidth.

Latency optimized C-RAN in optical backhaul and RF fronthaul architecture for beyond 5G network: A comprehensive survey

The need for high-speed data connection has significantly strained Mobile Network Operators (MNOs) due to an exponential increase in traffic. Numerous innovative technologies have been used to fulfill consumer service needs in capacity, high-speed data, network coverage, and Quality of Service (QoS), but they still require more thought. Because of several advantageous features in terms of resource utilization, service deployment, Capital Expenditure (CAPEX), Operating Expense (OPEX), and network management, the Cloud-based Radio Access Network (C-RAN) has played a significant role in mitigating the issues faced by mobile network operators. However, the C-RAN technology places high demands on the mobile fronthaul network due to the risk of connection interruptions. This article thoroughly analyzes the essential technologies, problems, design, needs, and solutions for effective fronthaul and backhaul communication a fifth-generation (5G) and beyond systems. There have been reviews of optical-based fronthaul and backhaul technologies. This article makes suggestions for ways to make fronthaul and backhaul communication systems more effective by lowering the costs, bandwidth, latency, and power requirements.

74 GHz Millimeter-Wave Long-Range Channel Measurements for Backhaul Communications: Sounding System and Propagation Characterization

74 GHz Millimeter-Wave Long-Range Channel Measurements for Backhaul Communications: Sounding System and Propagation Characterization

Secure RoF based 5G backhaul communication using semiconductor laser generated optical chaos

Abstract The fifth generation is considered as the revolutionary technology around the world, but this revolution brings many challenges along with it, especially when employ the advance properties such as massive multiple-input–multiple-output (MIMO) antennae, network densification and new spectrum exploration etc. One more challenge which we consider working on is the cost effective, secure backhaul communication system. The connection of massive and large traffic cells with the core network by using backhaul demands extraordinary requirements concerning availability, latency, capacity, cost efficiency and most importantly security. In the present work, we demonstrated the security implementation in 5G backhaul network by securing RoF signal through optical chaos generated by semiconductor laser. RoF signal of 60 GHz is generated in unlicensed band and after chaos masking with chaos, signal is transmitted over optical fiber to analyze the results. Simulations are carried out by using licensed software (Optisystem version 14.0) and results are analyzed by using multiple data rates and fiber lengths. Moreover, analysis of our scheme is carried out by using RZ and NRZ formats and by varying the power of the laser.

Performance Analysis of Multi-Hop Hybrid FSO/mm Wave Communication System for Next-Generation Wireless Networks

Next-generation wireless networks are facing increasing demand for high data rates, low latency, and seamless connectivity. To address these challenges, a multi-hop hybrid communication system integrating Free Space Optics (FSO) and millimeter wave (mm Wave) technologies for backhaul communication is proposed. This system combines the advantages of FSO, such as high bandwidth and low latency, with the robustness and reliability of mm Wave technology. The multi-hop architecture enables the formation of a network of interconnected nodes, providing improved coverage and flexibility. Each node is equipped with FSO and mm Wave transceivers, allowing for seamless handovers and adaptive routing. For the proposed system, analytical formulas for outage probability (OP) and average bit error rate (ABER) are derived and validated using simulations. The Monte Carlo simulations provide evidence of enhanced performance in the proposed Multi-Hop Hybrid FSO/mm Wave (MHFM) system compared to the FSO system.

Valley-conserved topological integrated antenna for 100-Gbps THz 6G wireless.

The topological phase revolutionized wave transport, enabling integrated photonic interconnects with sharp light bending on a chip. However, the persistent challenge of momentum mismatch during intermedium topological mode transitions due to material impedance inconsistency remains. We present a 100-Gbps topological wireless communication link using integrated photonic devices that conserve valley momentum. The valley-conserved silicon topological waveguide antenna achieves a 12.2-dBi gain, constant group delay across a 30-GHz bandwidth and enables active beam steering within a 36° angular range. The complementary metal oxide semiconductor-compatible valley-conserved devices represent a major milestone in hybrid electronic-photonic-based topological wireless communications, enabling terabit-per-second backhaul communication, high throughput, and intermedium transport of information carriers, vital for the future of communication from the sixth to X generation.

A W-Band SPDT Photoconductive Evanescent-Mode Waveguide Switch

This letter presents the design, fabrication, and measurement of a silicon micromachined photoconductive evanescent (EVA)-mode waveguide switch operating in a single-pole double-throw (SPDT) configuration. Two EVA-mode waveguides loaded with silicon posts are placed in a Y configuration with a common feeding waveguide. In the absence of photoexcitation, the dielectric posts and EVA channel exhibit a bandpass filter response that allows low-loss propagation of signals on the order of 2.0 dB at 96.7 GHz. When photoexcited, the low conductive posts and EVA channel yield a very high isolation of 36.5 dB up to 102.4 GHz within <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$W$ </tex-math></inline-formula> -band. The proposed design shows promise for 5G and 6G communication backhaul devices.

HK Electric's AMI journey to a full deployment of smart meter and Advanced Metering Infrastructure (AMI)

Going from traditional electro-mechanical meters to smart meters connected with Advanced Metering Infrastructure (AMI) is a significant undertaking for any utility. It may seem simple to change out a single meter but once you scale that up to your entire meter population, it begins to get complicated very quickly. There are many things that need to be considered from the type of meters to use; in what order they will be deployed and by whom; how to keep your customers informed; how to design and deploy the AMI network; how to setup the communication backhaul; what computer systems will be required; how many different computer environments do you need; how will the AMI system integrate with the existing systems; where does the data need to go; data security and many, many other considerations. After addressing the “how” and “what“, you also need to deal with the “when” and fit everything neatly into a viable schedule. HK Electric started a full smart meter and AMI deployment in 2019 with a target for completion in 2025. Prior to the commencement, there was already significant groundwork that had to be done in preparation for a full rollout. This paper will describe the journey from the initial planning and technical trials to the full-steam meter deployment that will allow HK Electric to reach its goal in 2025.

On the Performance of Multihop THz Wireless System Over Mixed Channel Fading With Shadowing and Antenna Misalignment

The existing relay-assisted terahertz (THz) wireless system is limited to dual-hop transmission with pointing errors and short-term fading without considering the shadowing effect. This paper analyzes the performance of a multihop-assisted backhaul communication mixed with an access link under the shadowed fading with antenna misalignment errors. We derive novel probability density and distribution functions of the signal-to-noise ratio (SNR) of the multihop link employing channel-assisted (CA) and fixed-gain (FG) amplify-and-forward (AF) relaying for each hop by considering independent but not identically distributed (i.ni.d) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\alpha $ </tex-math></inline-formula> - <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> fading channel with pointing errors. We present analytical expressions for the outage probability and average bit-error-rate (ABER) and develop asymptotic analysis in high SNR regime to derive the diversity order for both CA-multihop and FG-multihop backhaul links. We use the derived results of the multihop systems to analyze the statistical performance of the integrated backhaul-access relaying for both uplink and downlink transmission considering the generalized- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K$ </tex-math></inline-formula> shadowed fading model in the access link. We also present exact and asymptotic expressions of the outage probability for the considered mixed system. We perform computer simulations to provide design and deployment aspects of employing multiple relays to enhance THz wireless transmissions.

60 GHz RF module with beam-steering optimization algorithm for high data rate access and backhaul communications

This paper presents an 802.11ad-based radio frequency module for high data rate fixed wireless access and backhaul communications. The transceiver chip is manufactured in SiGe BiCMOS technology covering 57–71 GHz, providing 16 RX and 16 TX paths with combined output power of more than 20 dBm. The chip is packaged using embedded wafer-level BGA technology of the size 12.6times 12.6times 0.8~{text{ mm }}^3 and employs advanced dielectric materials with 2 metallic redistribution layers. The package integrates the transceiver chip with RX and TX high gain PCB antenna arrays, allowing effective isotropic radiated power (EIRP) of more than 40 dBm. Beam steering is achieved in ± 50^{circ } by the transceiver through providing appropriate weights to the antenna arrays. The paper presents generation of beamforming lookup table along with optimization of the power distribution to the array. This optimization results in flattening of the EIRP over the whole beam-steering range and frequency bandwidth. The module allows for data rates up to 10 Gbps by employing full-channel 128 QAM and half-channel 256 QAM single-carrier modulation.

A Multi-Cluster-Based Distributed CDD Scheme for Asynchronous Joint Transmissions in Local and Private Wireless Networks

In this paper, a multiple cluster-based transmission diversity scheme is proposed for asynchronous joint transmissions (JT) in private networks. The use of multiple clusters or small cells is adopted to reduce the transmission distance to users thereby increasing data-rates and reducing latency. To further increase the spectral efficiency and achieve flexible spatial degrees of freedom, we consider that a distributed remote radio unit system (dRRUS) is installed in each of the clusters. A key characteristic of deploying the dRRUS in private networks is the associated multipath-rich and asynchronous delay propagation environment. Therefore, we consider asynchronous multiple signal reception at the remote radio units and propose an intersymbol interference free distributed cyclic delay diversity (dCDD) scheme for JT to achieve the full transmit diversity gain without requiring full channel state information of the private network. The spectral efficiency of the proposed dCDD-based JT is analyzed by deriving a new closed-form expression, and then compared with link-level simulations for non-identically distributed frequency selective fading over the entire network. Due to its distributed structure, the dRRUS relies on backhaul communications between the private network server and cluster master (CM), which is the main backhaul connection, and between the CM to remote radio units, which are the secondary backhaul connections. Thus, it is important for us to investigate the impact of reliability of main and secondary backhaul connections on the system. Our results show that the resulting composite backhaul connections can be accurately modeled by our proposed product of independent Bernoulli processes.

Record-Low Thermal Boundary Resistance between Diamond and GaN-on-SiC for Enabling Radiofrequency Device Cooling.

The implementation of 5G-and-beyond networks requires faster, high-performance, and power-efficient semiconductor devices, which are only possible with materials that can support higher frequencies. Gallium nitride (GaN) power amplifiers are essential for 5G-and-beyond technologies since they provide the desired combination of high frequency and high power. These applications along with terrestrial hub and backhaul communications at high power output can present severe heat removal challenges. The cooling of GaN devices with diamond as the heat spreader has gained significant momentum since device self-heating limits GaN's performance. However, one of the significant challenges in integrating polycrystalline diamond on GaN devices is maintaining the device performance while achieving a low diamond/GaN channel thermal boundary resistance. In this study, we achieved a record-low thermal boundary resistance of around 3.1 ± 0.7 m2 K/GW at the diamond/Si3N4/GaN interface, which is the closest to theoretical prediction to date. The diamond was integrated within ∼1 nm of the GaN channel layer without degrading the channel's electrical behavior. Furthermore, we successfully minimized the residual stress in the diamond layer, enabling more isotropic polycrystalline diamond growth on GaN with thicknesses >2 μm and a ∼1.9 μm lateral grain size. More isotropic grains can spread the heat in both vertical and lateral directions efficiently. Using transient thermoreflectance, the thermal conductivity of the grains was measured to be 638 ± 48 W/m K, which when combined with the record-low thermal boundary resistance makes it a leading-edge achievement.

Substrate-Integrated-Waveguide-Fed Wideband Filtering Antenna for Millimeter-Wave Applications

In this article, a wideband filtering antenna based on substrate integrated waveguide (SIW) structure for millimeter-wave (mm-wave) applications is proposed and studied. The proposed antenna is developed using multilayer printed circuit board (PCB) technology. It consists of an SIW feeding structure with a coupling slot, differential-fed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L$ </tex-math></inline-formula> -shaped probes as well as radiating patches. Such architecture provides wide impedance bandwidth along with good filtering characteristic in the lower stopband. Simultaneously, by introducing a pair of open slots on the individual radiating patch as well as two shorting loops on top of the coupling slot, good filtering response in the upper stopband is obtained. The suppression level in the lower stopband is then further improved by introducing a pair of shorted stubs in the coupling slot region. The proposed filtering antenna features no extra filtering circuits, but has wide bandwidth as well as low profile. To verify the proposed structure and design philosophy, antenna array prototypes have been designed, fabricated, and measured. It achieves a 29% bandwidth from 23.5 to 31.5 GHz. Good agreement is achieved between simulated and experimental results. The proposed antenna array is particularly suitable to be applied in 5G (the fifth generation) mm-wave backhaul communications.

Centralized and Distributed Algorithms for Energy and Spectrum Efficient User Association in Small Cell Networks

Macro base stations are overlaid by small cells to satisfy the demands of user equipment in heterogeneous networks. To provide wide coverage, some small cells are not directly connected to macro base stations and thus backhaul connections are required to connect small cells to macro base stations. Millimeter wave backhauls which have high bandwidths are preferred for small cell backhaul communication, since they can increase the capacity of network considerably. In this context, association of user equipment to base stations becomes challenging due to the backhaul architecture. Considering environmental concerns, energy efficiency is a vital criterion in designing user association algorithms. In this paper, we study the user association problem aiming at the maximization of energy efficiency given a specific spectral efficiency target. We develop centralized and distributed user association algorithms based on sequentially minimizing the power consumption. Finally, we evaluate the performance of the proposed algorithms under two scenarios and show that they achieve higher energy efficiency compared to the existing algorithms in the literature, while maintaining high spectral efficiency and backhaul load balancing.

Application of Cybertwin for Offloading in Mobile Multiaccess Edge Computing for 6G Networks

Multiaccess edge computing is an essential technology that academia and industry have recognized as fundamental for the future of the Internet of Things. Current research on the subject utilizes virtual machines as the intermediary between end devices and cloud servers. However, recently a new framework was proposed that utilizes Cybertwins instead of virtual machines for the same function. Such framework comes with a myriad of advantages but, most importantly, in this case, it includes a control plane capable of enabling cooperation between the Cybertwins. In this article, we present a mathematical model of the total service delay of a Cybertwin-based multiaccess edge computing system that includes user mobility, migration of virtual servers, multiple physical servers at different network tiers, fronthaul and backhaul communication, processing, and content request/caching. We also propose algorithms for guiding the operation of Cybertwins and the control plane in a multiaccess edge computing scenario. Finally, a performance analysis between Cybertwin and a virtual machine-based scheme is offered. Simulations show that Cybertwin brings significant improvement for the assumed scenario in the form of a faster overall service due to the higher cooperation. The models and simulations here were designed with the characteristics of future networks, beyond the current 5G, in mind, making them likely relevant for future networks, where multiaccess edge computing and the Internet of Things should play an even more important role.

Field Trial on 5G New Radio Over Satellite

5G New Radio (NR) is the 3rd Generation Partnership Project (3GPP) radio access technology for the next generation mobile communications network. A major evolution of 5G constitutes the integration of non-terrestrial networks including geostationary and low Earth orbit satellites. The seamless integration of satellites in the terrestrial mobile network requires significant adaptations within the radio access network and the development of new features in the core network to cope with the specific satellite channel characteristics. To date, the 5G control and data plane has been standardized to handle only continuous backhaul communication between the network components. However, a mobile satellite enabled next generation Node B (gNB) located in a vehicle or in a moving aerial platform needs to be able to handle frequent backhaul outages of various duration as well as longer signal delays as opposed to short terrestrial connections via fiber. In this paper, we report the results of an over-the-air (OTA) field trial comprising a mobile edge node connected to the 5G standalone core network components over a geostationary satellite. We analyze Transmission Control Protocol (TCP) acceleration and GPRS Tunneling Protocol (GTP)/TCP/Internet Protocol (IP) header compression features through the GTP. Moreover, the influence of short and long interruptions in the communication between the edge node and the central components on the entire system performance is investigated. The header compression and TCP acceleration modules were implemented on the satellite modems and are now part of the protocol stack of these devices. The results show up to 12% higher data rates for the 5G user equipment (UE), on a 1.5 MHz single carrier return link compared to deactivated TCP acceleration and header compression. We increased the data rate by 20% on the 4.5 MHz DVB-S2X forward link between the UE and 5G core. Moreover, our measurements reveal that even satellite-enabled gNB mobility is possible with the current Release 15 standard. After a short outage of the satellite connection due to shadowing, the UE can successfully re-establish the user plane connection to the core network. Our results will facilitate the full integration of satellite components in 5G through open and standard solutions.

Connected slots antenna array feeding a high-gain lens for wide-angle beam-steering applications

AbstractThis paper presents a 60 GHz connected slots linear-phased array feeding a high-gain semi-symmetric lens antenna. This design provides high gain, broadband, and beam-steering capabilities for gigabit rate access and backhaul communications. The connected slots antenna array (CSAA) is excited at 16× equidistant points which not only yields spatial power combining but also allows the progressive phase changes to steer the beam in ±45° in azimuth plane. To characterize the CSAA-fed lens antenna, four different power splitters are fabricated which steer the main beam in 0, 15, 30, and 45°. The lens is designed in a way to overcome the scan loss and get comparatively higher gain when beam is steered away from the broadside. The measured results show 25.4 dBi maximum gain with 3 dB gain bandwidth covering the full band 57–66 GHz whereas 3 dB beam-steering range is ±45° for all frequencies. Besides, the half power beamwidth is 6 and 10° in elevation (E-plane) and azimuth plane (H-plane), respectively.

Wideband MIMO antenna for SCADA Wireless Communication Backhaul Application

A wideband multiple-input-multiple-output (MIMO) antenna system with common elements suitable for SCADA wireless communication backhaul application which is operating frequency of 0.85-2.6GHz that can cover global system for mobile communication (GSM) 900MHz and 1.8GHz, The Universal Mobile Telecommunication System (UMTS) 2GHz, Wi-Fi (2.4GHz) and Long Term Evolution (LTE) 2.6GHz is proposed. The proposed MIMO antenna system consists of four microstrip feedline with common radiating element and a frame shaped ground plane. A single port antenna also was designed and presented in this paper to show the process to design wideband MIMO antenna structure. The radiator of the MIMO antenna system is designed as the shape of modified rectangle with straight line at each corner to enhance the bandwidth frequency. To improve the isolation between ports, the ground plane is modified by inserting four L-slots in each corner to reduce mutual coupling. For an antenna efficiency of more than 60%, the simulated reflection coefficients are below -10dB for all ports at expected frequency. Simulated isolation is achieved greater than -10dB by using a modified ground plane. Also, a low envelope correlation coefficient (ECC) less than 0.1 and polarization diversity gain of about 10dB with the orthogonal mode of linear polarization and omnidirectional pattern during the analysis of the radiation characteristic are achieved. Therefore, the proposed design can be used for SCADA wireless communication backhaul application.

LPWAN-based hybrid backhaul communication for intelligent transportation systems: architecture and performance evaluation

Increased number of the vehicles on the streets around the world has led to several problems including traffic congestion, emissions, and huge fuel consumption in many regions. With advances in wireless and traffic technologies, the Intelligent Transportation System (ITS) has been introduced as a viable solution for solving these problems by implementing more efficient use of the current infrastructures. In this paper, the possibility of using cellular-based Low-Power Wide-Area Network (LPWAN) communications, LTE-M and NB-IoT, for ITS applications has been investigated. LTE-M and NB-IoT are designed to provide long range, low power and low cost communication infrastructures and can be a promising option which has the potential to be employed immediately in real systems. In this paper, we have proposed an architecture to employ the LPWAN as a backhaul infrastructure for ITS and to understand the feasibility of the proposed model, two applications with low and high delay requirements have been examined: road traffic monitoring and emergency vehicle management. Then, the performance of using LTE-M and NB-IoT for providing backhaul communication infrastructure has been evaluated in a realistic simulation environment and compared for these two scenarios in terms of end-to-end latency per user. Simulation of Urban MObility has been used for realistic traffic generation and a Python-based program has been developed for evaluation of the communication system. The simulation results demonstrate the feasibility of using LPWAN for ITS backhaul infrastructure mostly in favor of the LTE-M over NB-IoT.