Unmanned aerial vehicles (UAVs) have recently been widely used in the military and commercial domains. UAVs, especially domain, were initially for gathering intelligence, surveillance, reconnaissance data, sending them to a command center. Their use was then expanded tactical level perform operations with manned platforms. Operating UAV as relay node air has many advantages, including coverage, recovery from disconnection relay, clear communication channel, easy deployment. Thus, UAV-Relay...

Enhanced quality of service (QoS) and resource allocation are important measurements in a mobile communication system. Compared to traditional networks, 6G uses spectrum from 0.3 3 terahertz (THz) millimeter wave (mmWave) 30 300 GHz (GHz), making QoS proper difficult. Unmanned aerial vehicles (UAVs) have garnered attention academia industry because their high mobility, elastic placement, cost-efficiency, easy combination with other systems. Similarly, reconfigurable intelligent surfaces...

Owing to easy deployment extend network coverage, unmanned aerial vehicle (UAV) relay systems have been widely studied. Most UAVs are equipped with wireless local area (WLAN) and use carrier sense multiple access collision avoidance (CSMA/CA) protocol. However, the performance of CSMA/CA is largely degraded in UAV-relay (URNSs), owing collisions caused by contention at each hop. Thus, improving important. Moreover, there additional requirements: designing a lightweight UAV avoiding...

The growth in wireless communication services together with increasing demand has resulted the scarcity of spectrum resources. Many researchers have attempted to address problem by focusing on sharing allow fixed satellite (FSS) coexist other or systems. However, most secondary users are commercial systems, whose characteristics differ from military systems such as tactical data links (TDLs). A TDL requires anti-jamming capability and multiple operations support; thus, TDLs use frequency...

One of the most attractive applications unmanned aerial vehicles (UAVs) is deploying wireless communication systems. We consider a UAV-based low-altitude platform (LAP) to deploy an hotspot provide Wi-Fi coverage without infrastructure and severe shadowing by urban or mountainous terrain. To address performance degradation carrier sense multiple access with collision avoidance (CSMA/CA) increasing packet collisions number clients, we exploit nonorthogonal (NOMA). best authors' knowledge,...

The non-terrestrial networks (NTN) have the potential to enhance military operations in network-centric operational environment (NCOE) through improved communication coverage and connectivity. However, existing NTN cannot satisfy NCOE requirements. To requirements, we propose (M-NTN) architecture a novel spectrum-sharing method for coexistence between Low Earth Orbit (LEO) beams high altitude platforms (HAP) or unmanned aerial vehicles (UAV) cells. M-NTN employ slow frequency hopping (SFH)...

In a wireless network with large propagation delay S-ALOHA(Slotted ALOHA) requires guard time which causes lower normalized throughput. To reduce the in ISA-ALOHA, alignment mechanism was proposed under assumption of estimation. this letter, we propose framed structure is able to estimate by employing coordinator beaconing. The consists period for beaconing and group multiple slots random access. Beacon-based S-ALOHA(BS-ALOHA) can make packets generated during evenly distributed over access...

A terrestrial based communication system cannot guarantee line-of-sight for node mobility and dynamic constraints. To solve problems, airborne relay, the use of unmanned aerial vehicle (UAV) as a relay (RN) has been studied. The RN provides between disconnected networks. However, to best our knowledge, suitable MAC not In two transmission phases are needed: 1) transmitter 2) receiver node. When adapting current 802.11 WLAN contention CSMA/CA increases latency phase. Because increase latency,...

TDL (Tactical Data Link) is a communication technology that can be base technique to allow all platforms used in the battlefield communicate with each other. To operate smoothly, synchronizing network time over necessary. Most TDLs use GPS (Global Positioning System) for synchronization. vulnerable jamming attacks because power of signal low. Link-16 has independent synchronization method. This method performed when new nodes attempt join certain network. Synchronized transmit IEM (Initial...

Recently, radar frequency bands have been considered as promising candidates for cognitive radio (CR) owing to their low utilization. From a temporal access perspective, substantial number of spectral opportunities could be exploited if CR users achieve rotational synchronization with radar. However, the best our knowledge, no research has focused on this issue. In article, we propose scheme between and networks opportunistically band. First, framed structure sensing transmission phases...

Link-16은 가장 널리 사용 중인 전술데이터링크로써 TDMA(Time Division Multiple Access)를 기반으로 동작한다. 안정적이지만 전송 속도가 매우 낮아 전술 메시지, 음성 등 작은 사이즈의 데이터 전송을 지원한다. 그러나 최근 효과중심작전(EBO: Effect-Based Operation)에 대한 관심이 증가하면서, Link-16을 통해 이미지와 같은 상황 인식 정보를 전송하려는 동향이 있다. 이미지는 기존 메시지에 비해 크기가 크기 때문에 Link-16의 Static TDMA가 아닌 별도의 TDMA 스케줄링이 필요하다. 따라서 본 논문에서는 MAC을 진화시킨 Link-16K를 제안하였다. Link-16K는 Link-16과 호환성을 유지한다. 그리고 이미지 효과적으로 지원하기 위해 DTDMA(Dynamic TDMA), 새로운 재전송 방법, 패킹 방법을 포함한다. 제안하는 아이디어의 시뮬레이션 결과를 시간이 단축되었고, 채널 효율성이 높아졌음을...

Link-16 is a widely used tactical data link system for battlefield networks. A key component of network time synchronization. provides two types synchronization methods: global positioning (GPS)-based and GPS-less In particular, requires relay nodes multi-hop However, in Link-16, the are selected statically before begins, which inhibits direct communication from incoming nodes; therefore, fails. this paper, we propose new dynamic node selection scheme Link-16. Thus, all can be dynamically...

Link-16 is a widely used Tactical Data Link (TDL) system and very low rate system, thus, it supports transmission of limited data such as text-based tactical messages voice. Recently, in order to support large amounts imagery, there have been several studies focusing on increasing the by modifying waveform. However, efforts reduce effect propagation delay are also required, time slot includes waste guard time. In particular, which requires number slots, significantly affected Moreover, uses...

In this letter, we propose relay-based positioning in time division multiple access (TDMA) networks, called RPT. Although the concept of is an improvement over performance relative navigation (RelNav), there are two problems to be solved when applying relay a TDMA network. First, measurement errors caused by mobility may degrade user accuracy because references transmit messages at their assigned times TDMA, unlike conventional systems, where all continuously transmit. Second, selection...

Ground tactical networks are often limited in their operations when the line of sight (LOS) is not guaranteed. To overcome this limitation, airborne relay communications using unmanned aerial vehicles (UAVs) a possible solution. In communication, it important to reduce relaying delay because communication extended two-hop unlike conventional environment. paper, we proposed dynamic time-division multiple access (DTDMA) scheme based on time mirroring and allow nodes network effectively. The...

Link-16은 현재 미 공군 및 북대서양 조약기구 (NATO : North Atlantic Treaty Organization)에 의해 운용되고 있는 대표적인 전술데이터링크 (TDL Tactical Data Link)이며 멀티넷 구조를 지원한다. 이러한 환경에서는 Link-16의 단말 노드들이 동시에 전체 대역에서 도약함으로써 작전을 효과적으로 수행할 수 있다. 최근 항공 교통량이 급증함에 따라 이를 수용하기 위해 새로운 시스템을 도입하거나 기존의 확충해야 하며 운용하기 할당되어야 할 주파수 대역이 부족한 상황이다. 해결하기 Link-16에서 사용하는 대역의 재분배 계획이 예정되어 수행되어 운용을 위한 제한될 경우 다중 접속 간섭 발생률이 증가하게 되므로 성능 저하가 일어날 이로 인해 다양한 군사 수행하는데 어려움이 따른다. 따라서 본 논문에서는 부족 현상으로 Link-16 웨이브폼의 성능이 저하되는 문제를 그룹 기반의 도약 방식을 제안하였다. 모의실험을 통해 제안 사용할...