scholarly journals Terahertz band communications as a new frontier for drone networks

2021 ◽  
Vol 2 (7) ◽  
pp. 1-19
Author(s):  
Akhtar Saeed ◽  
Ozgur Gurbuz ◽  
Mustafa Alper Akkas ◽  
Ahmet Ozan Bicen
Keyword(s):  
Interference Management ◽  
Multipath Fading ◽  
Multimedia Data ◽  
Base Stations ◽  
Future Research ◽  
Distributed Monitoring ◽  
Medium Access ◽  
Seamless Connectivity ◽  
Terahertz Band ◽  
Thz Communications

Terahertz band (0.1-10 THz) communications is one of the candidates for 6G systems due to intrinsic massive bandwidth and data rate support. Having demonstrated the significant potential of THz band at various atmospheric altitudes, in this article, we discuss the prospects of THz communications for drone networks, more specifically, for Drone Sensor Networks (DSNs). For 6G non-terrestrial communication scenarios, drones will not only serve as on-demand base-stations, as supporting alternatives or backhauls for the terrestrial base stations, but they will also provide seamless connectivity for distributed monitoring and surveillance applications, which require an ultra-reliable low latency service for carrying multimedia data. THz band sensing will also provide additional sensing capabilities from the sky to THz-enabled DSNs. Presenting this vision, in this paper, we first discuss possible use cases of THz-enabled drone networks considering communication, sensing and localization aspects. Then, for revealing the capacity potential of THz-enabled drone networks, we provide motivating channel capacity results for communication of drones at different altitudes, under ideal channel conditions with no fading and realistic channel with beam misalignment and multipath fading. We further present major challenges pertaining to employing the THz band for DSNs, addressing physical layer issues, followed with spectrum and interference management, medium access control and higher layers and security, while reviewing some prominent solutions. Finally, we highlight future research directions with Artificial Intelligence (AI)/Machine Learning (ML)-based approaches and mobile edge computing.

scholarly journals Error Comparison Based Patching (ECP) for Medium Access Control of Cell-free Massive MIMO Networks in 6G Terahertz Band Communications

2021 ◽  
Author(s):  
Tai-Kuo Woo
Keyword(s):  
Access Control ◽  
Medium Access Control ◽  
Network Architecture ◽  
Massive Mimo ◽  
Scale Up ◽  
Future Internet ◽  
Data Packet ◽  
Base Stations ◽  
Medium Access ◽  
Terahertz Band

Abstract The future Internet is supposed to support a myriad of applications that generate many bursts of multimedia traffic. While the classical cell-based architecture of wireless networks cannot scale up to meet the area traffic capacity and connection density requirements put forth by 6G, Terahertz band for cell-free massive MIMO is regarded as a promising solution. However, the medium access control in Terahertz band communication is significantly different from that of previous generations due to the distinct channel characteristics of Terahertz band. A good match to Terahertz communication is cell-free massive MIMO network architecture, where the antenna beams are located irregularly, coordination among base stations is required to improve the throughput. In this paper, we propose an error comparison based patching where replicated packets transmitted from different access points in various directions (locations) are compared with each other, section by section, based on the degree of consistency between a data packet and its corresponding polling data bits. The error comparison based patching puts together the best sections among replicas of a data packet to form a good one. In the performance evaluation, we demonstrate that the proposed error comparison based patching can significantly improve the percentage of intermittent blocking fading of the data packets in THz band communications for a cell-free massive MIMO network architecture by as high as 80 percent.

scholarly journals Femtocell Network Synchronization

2012 ◽  
pp. 180-198
Author(s):  
Mohammad Hasan ◽  
Rashid Saeed ◽  
Aisha A. Hassan
Keyword(s):  
Interference Management ◽  
Base Stations ◽  
Third Party ◽  
Future Research ◽  
Access Points ◽  
Mobile Operator ◽  
Research Areas ◽  
Indoor Coverage ◽  
Broadband Network ◽  
Problematic Issue

Presently, femtocell technology is emerging for cellular wireless networks, which have rapidly engrossed the cellular industry. The main advantage of femtocell to the mobile operators is a reduction of cost and an improvement of the signal quality in indoor coverage, which is also considered a possible path to the Fixed–Mobile Convergence (FMC) goal. Femtocell extends network coverage and delivers high-quality mobile services inside residential and business buildings through broadband networks (i.e. ADSL). Femtocell Access Points (FAP) or Home Base Stations (HBS) are intended to serve small number of users (i.e. 4 users) and cover about 30-square meters, similar to existing WiFi access points. However, femtocell introduces new challenges to the telecom industries in terms of handoff between femto and microcells, interference management, localization, and synchronization. Among all of these challenges, synchronization is considered as the cornerstone for the femtocells to function properly. The problematic issue in femtocell synchronization is that all the data and control traffic travels through an IP broadband network. The IP broadband network is usually owned and managed by a third party and not by the mobile operator which can complicate the synchronization. Unsynchronized FAPs may cause harmful interference and wrong handover dictions. In this chapter, the authors investigate and overview the current femtocell synchronization techniques and make comparisons between them. Possible improvements and recommendations for each method have been identified. Future research areas and open issues are also discussed.

scholarly journals A Reinforcement Learning Approach for Interference Management in Heterogeneous Wireless Networks

2021 ◽  
Vol 15 (12) ◽  
pp. 65
Author(s):  
Akindele Segun Afolabi ◽  
Shehu Ahmed ◽  
Olubunmi Adewale Akinola
Keyword(s):  
Reinforcement Learning ◽  
Power Level ◽  
Heterogeneous Wireless Networks ◽  
Interference Management ◽  
Base Station ◽  
User Equipment ◽  
Base Stations ◽  
Multi Agent Systems ◽  
Q Learning ◽  
Macro Cell

<span lang="EN-US">Due to the increased demand for scarce wireless bandwidth, it has become insufficient to serve the network user equipment using macrocell base stations only. Network densification through the addition of low power nodes (picocell) to conventional high power nodes addresses the bandwidth dearth issue, but unfortunately introduces unwanted interference into the network which causes a reduction in throughput. This paper developed a reinforcement learning model that assisted in coordinating interference in a heterogeneous network comprising macro-cell and pico-cell base stations. The learning mechanism was derived based on Q-learning, which consisted of agent, state, action, and reward. The base station was modeled as the agent, while the state represented the condition of the user equipment in terms of Signal to Interference Plus Noise Ratio. The action was represented by the transmission power level and the reward was given in terms of throughput. Simulation results showed that the proposed Q-learning scheme improved the performances of average user equipment throughput in the network. In particular, </span><span lang="EN-US">multi-agent systems with a normal learning rate increased the throughput of associated user equipment by a whooping 212.5% compared to a macrocell-only scheme.</span>

scholarly journals Investigation of sub-carrier multiplexed fiber optic link supporting WLAN and WCDMA

2021 ◽  
Author(s):  
Roland M. C. Yuen
Keyword(s):  
Access Control ◽  
Medium Access Control ◽  
Mobile Communication ◽  
Fiber Optic ◽  
Multipath Fading ◽  
Numerical Results ◽  
Optical Noise ◽  
Medium Access ◽  
Air Interface ◽  
Nonlinear Distortions

In this thesis, an optical fiber based radio access architecture that simultaneously provides services of the wireless local area network (WLAN) and the third generation (3G) mobile communication system is investigated. The sub-carrier multiplexed (SCM) technique of the fiber optic system is considered. The SCM architecture does not require frequency conversion and plays an important role enabling the WLAN to complement the cellular mobile communication systems so that the user can have both services as needed. In the SCM architecture, the two mediums that signals propagate are the air interface and the radio over fiber (ROF) link. In the air interface, the signal experience path loss and multipath fading that have effect on the system performance. The ROF link introduces nonlinear distortions and optical noise. The uplink and downlink analysis are performed in this thesis considering all the impairments from the air interface and the ROF link. Thereafter, numerical results are generated for both the uplink and downlink to illustrate the performance of the SCM architecture. The analysis identifies the interdependent relationship of the WLAN and the WCDMA system. The numerical results graphically illustrate such interdependent relationship. In the downlink, a 5 km ROF link operating at optimal power can support a WCDMA system with 1 km radius of coverage that has 26 dB of signal to distortion and noise ratio (SDNR); and a WLAN system with 400 m radius of coverage that has 27 dB of SDNR. The throughput of IEEE 802.11 WLAN depends on the medium access control. Hence, the medium access control is investigated and the throughput expression is modified to adapt to the SCM architecture where signals travel extra distance in a fiber.

scholarly journals Performance Analysis of Millimeter-Wave UAV Swarm Networks under Blockage Effects

Sensors ◽  
2020 ◽  
Vol 20 (16) ◽  
pp. 4593
Author(s):  
Haejoon Jung ◽  
In-Ho Lee
Keyword(s):  
Millimeter Wave ◽  
Channel Model ◽  
High Mobility ◽  
Base Stations ◽  
Shape Theory ◽  
High Data ◽  
Mobile Cellular ◽  
Seamless Connectivity ◽  
Mobile Cellular Networks ◽  
Uav Swarm

Due to their high mobility, unmanned aerial vehicles (UAVs) can offer better connectivity by complement or replace with the existing terrestrial base stations (BSs) in the mobile cellular networks. In particular, introducing UAV and millimeter wave (mmWave) technologies can better support the future wireless networks with requirements of high data rate, low latency, and seamless connectivity. However, it is widely known that mmWave signals are susceptible to blockages because of their poor diffraction. In this context, we consider macro-diversity achieved by the multiple UAV BSs, which are randomly distributed in a spherical swarm. Using the widely used channel model incorporated with the distance-based random blockage effects, which is proposed based on stochastic geometry and random shape theory, we investigate the outage performance of the mmWave UAV swarm network. Further, based on our analysis, we show how to minimize the outage rate by adjusting various system parameters such as the size of the UAV swarm relative to the distance to the receiver.

scholarly journals Key Technologies for THz Wireless Link by Silicon CMOS Integrated Circuits

Photonics ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 50 ◽  
Author(s):  
Minoru Fujishima
Keyword(s):  
Integrated Circuits ◽  
Silicon Germanium ◽  
Cmos Integrated Circuits ◽  
Future Research ◽  
Wireless Transceivers ◽  
Terahertz Band ◽  
Silicon Integrated Circuits ◽  
Terahertz Communication ◽  
Bicmos Integrated Circuits ◽  
Silicon Cmos

In terahertz-band communication using ultra-high frequencies, compound semiconductors with superior high-frequency performance have been used for research to date. Terahertz communication using the 300 GHz band has nonetheless attracted attention based on the expectation that an unallocated frequency band exceeding 275 GHz can be used for communication in the future. Research into wireless transceivers using BiCMOS integrated circuits with silicon germanium transistors and advanced miniaturized CMOS integrated circuits has increased in this 300 GHz band. In this paper, we will outline the terahertz communication technology using silicon integrated circuits available from mass production, and discuss its applications and future.

scholarly journals Coverage and Energy Efficiency Analysis for Two-Tier Heterogeneous Cellular Networks Based on Matérn Hard-Core Process

2019 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Jie Yang ◽  
Ziyu Pan ◽  
Lihong Guo
Keyword(s):  
Energy Efficiency ◽  
Cellular Networks ◽  
Mutual Exclusion ◽  
Interference Management ◽  
Hard Core ◽  
Approximate Expression ◽  
Base Stations ◽  
Heterogeneous Cellular Networks ◽  
Coverage Analysis ◽  
Management Techniques

Due to the dense deployment of base stations (BSs) in heterogeneous cellular networks (HCNs), the energy efficiency (EE) of HCN has attracted the attention of academia and industry. Considering its mathematical tractability, the Poisson point process (PPP) has been employed to model HCNs and analyze their performance widely. The PPP falls short in modeling the effect of interference management techniques, which typically introduces some form of spatial mutual exclusion among BSs. In PPP, all the nodes are independent from each other. As such, PPP may not be suitable to model networks with interference management techniques, where there exists repulsion among the nodes. Considering this, we adopt the Matérn hard-core process (MHCP) instead of PPP, in which no two nodes can be closer than a repulsion radius from one another. In this paper, we study the coverage performance and EE of a two-tier HCN modelled by Matérn hard-core process (MHCP); we abbreviate this kind of two-tier HCN as MHCP-MHCP. We first derive the approximate expression of coverage probability of MHCP-MHCP by extending the approximate signal to interference ratio analysis based on the PPP (ASAPPP) method to multi-tier HCN. The concrete SIR gain of the MHCP model relative to the PPP model is derived through simulation and data fitting. On the basis of coverage analysis, we derive and formulate the EE of MHCP-MHCP network. Simulation results verify the correctness of our theoretical analysis and show the performance difference between the MHCP-MHCP and PPP modelled network.

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