UNIVERSIDADE FEDERAL DO CEARÁ CENTRO DE TECNOLOGIA
DEPARTAMENTO DE ENGENHARIA DE TELEINFORMÁTICA
PROGRAMA DE PÓS-GRADUAÇÃO EM ENGENHARIA DE TELEINFORMÁTICA
RAPHAEL BRAGA EVANGELISTA
CAPACITY AND INTERFERENCE ANALYSIS OF LTE MOBILE NETWORK USING LICENSED SHARED ACCESS CONCEPT
CAPACITY AND INTERFERENCE ANALYSIS OF LTE MOBILE NETWORK USING LICENSED SHARED ACCESS CONCEPT
Dissertação apresentada ao Programa de Pós-Graduação em Engenharia de Teleinformática da Universidade Federal do Ceará, como requisito parcial à obtenção do título de mestre em Engenharia de Teleinformática. Área de concentração: Sinais e Sistemas
Orientador: Prof. Dr. Yuri Carvalho Bar-bosa Silva
Coorientador: Dr. Carlos Filipe Moreira e Silva
Dados Internacionais de Catalogação na Publicação Universidade Federal do Ceará
Biblioteca Universitária
Gerada automaticamente pelo módulo Catalog, mediante os dados fornecidos pelo(a) autor(a)
E92c Evangelista, Raphael Braga.
Capacity and Interference Analysis of LTE Mobile Network Using Licensed Shared Access Concept / Raphael Braga Evangelista. – 2017.
73 f. : il. color.
Dissertação (mestrado) – Universidade Federal do Ceará, Centro de Tecnologia, Programa de Pós-Graduação em Engenharia de Teleinformática, Fortaleza, 2017.
Orientação: Prof. Dr. Yuri Carvalho Barbosa Silva. Coorientação: Prof. Dr. Carlos Filipe Moreira e Silva.
1. Acesso Compartilhado Licenciado. 2. Compartilhamento de Espectro. 3. Acesso Dinâmico ao Espectro. 4. Gerenciamento de Espectro. 5. Redes Móveis. I. Título.
CAPACITY AND INTERFERENCE ANALYSIS OF LTE MOBILE NETWORK USING LICENSED SHARED ACCESS CONCEPT
Dissertation presented to the Graduate Program in Teleinformatics Engineering of the Federal University of Ceará, as part of the requirements for obtaining the Master’s Degree title in Teleinformatics Engineering. Concentration area: Signals and Systems.
Approved in: 22/12/2017.
EXAMINATION BOARD
Prof. Dr. Yuri Carvalho Barbosa Silva (Advisor) Federal University of Ceará
Dr. Carlos Filipe Moreira e Silva (Co-advisor) Federal University of Ceará
Prof. Dr. Francisco Rodrigo Porto Cavalcanti Federal University of Ceará
I would like to express my gratitude to everyone who contributed to me during all my master period, giving me strength to overcome any obstacles that appeared during the whole walk-through.
Prof. Yuri Silva who followed my academic growth since I was an undergraduate student, always giving me councils and making himself useful to help me with any necessities I needed.
Carlos Silva for all his help, patience, time, advice, etc. He was one of the main vectors for me to have accomplished this stage of my life, even when he didn’t have much time available, he was always there for me, supporting me.
I want to say thank to my parents, siblings and family in general for their conditional love and support anytime and anywhere.
I also want to thanks all my friends that directly and indirectly helped me during this tough time. Without them it would be impossible.
Last, but not least, I want to express my love and gratitude to God, for his blessings, protection, kindness and generosity. I never stopped believing in your grace.
Fortaleza, December 2017.
“And following our will and wind, we may just go where no one’s been. We’ll ride the spiral to the end and may just go where no one’s been. Spiral out, keep going.”
O problema da “escassez” de espectro pode ser abordado promovendo o uso mais eficiente desse recurso. As técnicas de compartilhamento de espectro, por exemplo, TV White Spaces (TVWS) e Acesso Compartilhado Licenciado (Licensed Shared Access, LSA), são boas soluções para esse problema e já existem esforços de regulação e padronização em todo o mundo. Este trabalho é focado no conceito de Licensed Shared Access (LSA) e é apresentada uma visão geral desta abordagem de Acesso Dinâmico ao Espectro (Dynamic Spectrum Access, DSA). Também é sugerido um possível estudo de caso do emprego deste conceito para o desenvolvimento da indústria de mineração brasileira. Foi implementado um simulador de uma rede Long-Term Evolution (LTE) que emprega o conceito de LSA para obter uma capacidade de rede adicional. Finalmente, é realizada uma análise em termos de capacidade dos usuários secundários e interferência dos usuários primários, como forma de trazer atenção e confiança no setor de Telecomunicações dos benefícios que esse conceito pode trazer consigo.
ABSTRACT
The spectrum “scarcity” problem can be tackled by promoting a more efficient use of this resource. Spectrum sharing techniques, e.g. TV White Spaces (TVWS) and Licensed Shared Access (LSA), are good solutions for this problem and there are already regulation and standardization efforts worldwide. This work is focused on the LSA concept and it presents an overview of this Dynamic Spectrum Access (DSA) approach. It is also envisioned a possible case study of the employment of this concept for the Brazilian mining industry development. A simulator of the LTE network has been designed, which employs the LSA concept in order to get additional network capacity. Finally, an analysis is performed in terms of secondary users’ capacity and primary users’ interference, as a way to bring trust and attention of the Telecommunications sector with regard to the benefits that this concept can provide.
Figure 1 – Frequency Allocation in Brazil. . . 22 Figure 2 – Protection areas in the 3.5 GHz band in Brazil. . . 29 Figure 3 – LSA use case illustration. . . 32 Figure 4 – Relation among the LSA stakeholders for definition of the sharing framework
and the issuing by National Regulatory Authority (NRA) of individual right of use to the LSA licensee(s). . . 33 Figure 5 – Example of a possible LSA system architecture. . . 34 Figure 6 – Example of a possible LSA system architecture for the case study. . . 39 Figure 7 – Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) architecture. 41 Figure 8 – Cordless camera link scenario. . . 44 Figure 9 – Representation of a grid with 19 hexagon cells wrapped around. . . 45 Figure 10 – Representation of a cell for the simulated scenario. Blue dashed arrows
represent signals of interest and red solid arrows represent interfering signals. 46 Figure 11 – A cluster with 19 cells with two LTE User Equipments (UEs) and one cordless
camera link. . . 47 Figure 12 – Emission mask considered for the simulation. . . 48 Figure 13 – Example of an emission mask and interference in a victim receiver in a given
adjacent frequency. Three different bands are considered in the simulator. . 48 Figure 14 – Correlated shadowing inside a cell (values in dB). . . 51 Figure 15 – CDF of secondary users’ average capacity for default parameters case. . . . 56 Figure 16 – CDF of secondary users’ average capacity for default parameters case varying
the interference-to-noise ratio. . . 57 Figure 17 – CDF of secondary users’ average capacity for default parameters case varying
the frequency separation. . . 58 Figure 18 – Average interference on primary users×interference-to-noise ratio for
dif-ferent number of primary users. . . 59 Figure 19 – Average interference on primary users×frequency separation for different
number of primary users. . . 59 Figure 20 – Jain’s index×number of secondary users for different scheduling algorithms. 60 Figure 21 – Average secondary users’ capacity×number of secondary users for different
Figure 22 – Average secondary users’ capacity×interference-to-noise ratio for different number of primary users. . . 62 Figure 23 – Average percentage of LSA switched-on BSs (%)×interference protection
criterion for different number of primary Users. . . 63 Figure 24 – Average secondary users’ capacity×frequency separation for different
num-ber of primary users. . . 64 Figure 25 – Average percentage of LSA switched-on BSs (%)×frequency separation for
Table 1 – Spectrum auction for the 700 MHz band in Brazil. . . 23
Table 2 – Designated bands for ISM applications. . . 24
Table 3 – Designated bands for operation in U-NII devices. . . 24
LIST OF ABBREVIATIONS AND ACRONYMS
1G First Generation 3G Third Generation
3GPP Third Generation Partnership Project 4G Fourth Generation
5G Fifth Generation
Anatel National Telecommunications Agency (Agência Nacional de Telecomunicações) ASA Authorized Shared Access
BILP Binary Integer Linear Programming C-RAN Cloud Radio Access Network CBRS Citizens Broadband Radio Service CDF Cumulative Distribution Function
CEPT European Conference of Postal and Telecommunications (Conférence Européenne des administrations des Postes et des Télécommunications)
CPS Cyber-Physical Systems CR Cognitive Radio
CSI Channel-State Information DSA Dynamic Spectrum Access DSO Digital Switchover
E-UTRAN Evolved UMTS Terrestrial Radio Access Network EC European Commission
ECC Electronic Communications Committee EIRP Effective Isotropic Radiated Power
eNB Evolved NodeB
ENG Electronic News Gathering EPC Evolved Packet Core
ETSI European Telecommunications Standards Institute FCC Federal Communications Commission
FDD Frequency-Division Duplex FIFO First-in-First-out
IEEE Institute of Electrical and Electronics Engineers IMT International Mobile Telecommunications IoT Internet of Things
IoV Internet of Vehicles IP Internet Protocol
ISM Industrial, Scientific and Medical ITU International Telecommunication Union
ITU-R International Telecommunication Union Radio communication sector LC LSA Controller
LR LSA Repository
LSA Licensed Shared Access LTE Long-Term Evolution
LTE-A Long-Term Evolution Advanced M2M Machine-to-Machine
MFCN Mobile/Fixed Communications Networks MIMO Multiple Input Multiple Output
MNO Mobile Network Operator
MR Maximum Rate
NRA National Regulatory Authority OB Outside Broadcasting
Ofcom Office of Communications
OFDMA Orthogonal Frequency Division Multiple Access
OOB Out-of-band
PCAST President’s Council of Advanced Science & Technology PF Proportional Fairness
PMSE Programme Making and Special Events PRB Physical Resource Block
QoE Quality of Experience QoS Quality of Service
RF Radio Frequency
RRC Reconfigurable Radio Systems RSPG Radio Spectrum Policy Group SAB Services Ancillary to Broadcasting SAP Services Ancillary to Programme making SAS Spectrum Access System
SC-FDMA Single Carrier Frequency Division Multiple Access SDR Software Defined Radio
SINR Signal-to-Interference-plus-Noise Ratio SISO Single Input Single Output
SON Self Organizing Networks TC Technical Committee TDD Time-Division Duplex TC Technical Recommendation TTI Transmission Time Interval
TV Television
TVWS TV White Spaces
U-NII Unlicensed National Information Infrastructure
UE User Equipment
UHF Ultra High Frequency
UK United Kingdom
UMTS Universal Mobile Telecommunications System uRLLC Ultra-Reliable and Low-Latency Communications USA United States of America
1 INTRODUCTION . . . 17
1.1 Objectives . . . 18
1.1.1 General Objectives . . . 18
1.1.2 Specific Objectives . . . 18
1.2 Contributions . . . 19
1.3 Scientific production . . . 20
1.4 Thesis organization . . . 20
2 SPECTRUM MANAGEMENT . . . 21
2.1 Traditional Spectrum Management . . . 23
2.2 Spectrum Sharing and Dynamic Spectrum Access. . . 24
2.2.1 Concept and main examples of Dynamic Spectrum Access . . . 25
2.2.1.1 TVWhite Spaces . . . 25
2.2.1.2 Licensed Shared Access . . . 27
2.2.2 Enabler Concepts and Technologies . . . 27
2.2.3 Dynamic Spectrum Access in Brazil . . . 28
3 LICENSED SHARED ACCESS . . . 30
3.1 Definition and use case . . . 31
3.2 LSAplayers and sharing framework . . . 32
3.3 Architecture . . . 33
3.4 Incumbent protection . . . 34
3.5 Regulation and Standardization . . . 35
3.6 LSAcase study in Brazil . . . 36
4 CAPACITY AND INTERFERENCE EVALUATION IN LTE/LSA NET-WORK . . . 40
4.1 LTE overview . . . 40
4.1.1 Long-Term Evolution Advanced (LTE-A) and Carrier Aggregation . . . . 42
4.2 PMSE overview . . . 42
4.3 Scenario Description . . . 44
4.3.1 Primary and secondary users operation . . . 46
4.3.2 Physical Resource Blocks and Resource Allocation . . . 47
4.3.2.2 Maximum Rate . . . 49
4.3.2.3 Proportional Fair . . . 49
4.3.2.4 Jain’s Index . . . 50
4.3.3 Propagation channel considerations . . . 50
4.3.4 Signal-to-Inference-plus-Noise Ratio . . . 51
4.3.5 Adjusted Shannon capacity formula . . . 52
4.3.6 Primary user protection . . . 53
4.4 Simulation Environment . . . 54
4.5 Results . . . 54
5 CONCLUSION AND FUTURE WORK . . . 66
5.1 Acknowledgment . . . 67
1 INTRODUCTION
There is a considerable increase in mobile data traffic. According to forecasts [1], this traffic will grow sevenfold between 2016 and 2021, and it will reach, by the end of 2021, 49 exabytes per month. This extra boom is mainly due to the popularization and proliferation of devices worldwide, like smartphones and tablets, as well as the development of data-hungry applications.
On one hand it is expected that there will be 29 billion connected devices in the whole world by 2022, thanks to the advancements in technology and development of concepts, like Machine-to-Machine (M2M), Internet of Things (IoT), and Internet of Vehicles (IoV), to name a few [2]. On the other hand, applications which demand high data rate, like video streaming and online gaming, are becoming more common. In order to be capable of dealing with this high traffic, the next generation of communication systems, Fifth Generation (5G), predicted to be launched by 2020, expects to provide a capacity increase of one to ten thousandfold compared to the previous generation, Fourth Generation (4G) technology [3]. As a consequence of this, a huge demand on Radio Frequency (RF) spectrum is also expected. However, this natural resource is limited, and currently it is suffering from scarcity. Actually, this is an apparent scarcity, since there are lots of bands (generally high GHz bands) not explored by any service.
The easiest way of trying to solve this “scarcity” problem is to explore the higher frequency bands, in particular cm and mm wave bands, which have a lot of spectrum available [4]. However, this approach does not cover all use cases, since waves in high bands present hostile propagation characteristics, e.g. strong path loss, atmospheric and rain absorption, low diffraction around obstacles, etc; and therefore may not always be compatible with all applications, for example, communications where devices are found in a mobile and very dynamic environment. The massive Multiple Input Multiple Output (MIMO) technique is a very good approach to deal with the propagation characteristics in higher bands. The utilization of large antenna arrays allows a better steering of the signal transmission power towards the direction of interest, enhancing the transmission gain. Furthermore, it allows the interference to be better managed, which also improves the wireless communication in a network [4].
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a long-term basis 1. However, in some cases, a spectrum owner does not use the resource assigned to him during all the time and in all geographical areas. Despite the fact that this static approach is very robust in the avoidance of harmful interference among services, it leads to the underutilization of spectrum.
Spectrum sharing comes out as a very good option to solve this inefficiency problem, enabling a more dynamic access to the RF spectrum and allowing this resource to be shared in a flexible way. This concept should not be confused with the unlicensed use of spectrum, e.g. Industrial, Scientific and Medical (ISM) applications, where the spectrum in specific bands is shared without the need of license and with services being subject to interference of other services.
There are already two new spectrum management mechanisms which define different generations of the spectrum sharing: the first generation with the TV White Spaces (TVWS) solutions and the second one with the Licensed Shared Access (LSA) scheme; both having their particularities and use cases well defined, which will be seen in a later chapter.
This work is focused on the LSA. This concept is applied to a Long-Term Evolution (LTE) network and an assessment is performed in terms of capacity and interference of the spectrum users.
1.1 Objectives
1.1.1 General Objectives
The main objective of this work is to analyze the potential and the benefits that the employment of LSA can provide to a mobile network. For that, a simulator of an LTE network was designed, to which the concept of LSA is applied. Furthermore, this work intends to present an overview of DSA in the Brazilian regulatory scenario and also to suggest a possible case study of the employment of the LSA concept in Brazil. Such study is expected to bring the attention and trust of the Telecommunications sector, and specifically of Anatel and other Brazilian stakeholders, to LSA and the benefits it could provide.
1.1.2 Specific Objectives
The specific objectives of this work are:
• To present an overview of the situation of DSA in the Brazilian regulatory scenario, specially for LSA;
• To present a case study of the application of the LSA concept in the development of the mining industry sector;
• To analyze the capacity gain of an LTE network brought by the employment of the LSA concept;
• To analyze the interference in cordless camera services coming from an LTE network employing the LSA concept;
• To analyze the impact in terms of capacity (secondary users) and interference (primary users) due to the variation of different parameters:
– The separation between the operating frequency of the LSA band used by the sec-ondary users, and the operating frequency of the primary ones;
– The interference protection criteria of the primary user receivers; – Scheduling algorithms used;
– Number of primary users; – Number of secondary users.
• To present an approach of primary users interference protection.
1.2 Contributions
In the literature, there are few practical studies regarding LSA employment in an LTE network on physical layer. What it is mainly found are field tests regarding coexistence and feasibility of this spectrum sharing concept.
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1.3 Scientific production
EVANGELISTA, R. B. et al. TV White Spaces and Licensed Shared Access applied to the Brazilian context. In: 12th EAI International Conference on Cognitive Radio Oriented Wireless
Networks. [S.l.: s.n.], 2017.
NASCIMENTO, M. F. S. do et al. TV White Spaces for digital inclusions in Brazil. Revista de
Tecnologia da Informação e Comunicação, v. 6, n. 2, p. 6–15, out. 2016. ISSN 2237-5104. EVANGELISTA, R. B., SILVA, C.F.M. e, NASCIMENTO, M. F. S. do, Gerenciamento de Espectro Eletromagnético. In: CAVALCANTI, F.R.P. et al. Sistemas de Telefonia Celular. Elsevier, 2018 [to be published].
1.4 Thesis organization
2 SPECTRUM MANAGEMENT
The radio waves are used in different wireless communication systems. In the commercial sector, they can be seen in mobile communications networks and radio broadcasting, in the public sector, they are used to support the national defense, aviation, emergency services, etc [6].
Since the air is a medium shared by all the services, the spectrum needs to be managed in order to avoid that the harmful interference from different spectrum owners becomes excessive. If two systems transmit a signal at the same time, at the same frequency and sufficiently close to each other, generally the services provided by them will be compromised by the interference of each other. In some cases, “sufficiently close” means dozens or hundreds of meters. Furthermore, even if the users transmit at adjacent frequencies, they can still suffer interference from each other, because part of the transmit signal “leaks” to adjacent and alternate bands, arising from modulation process, intermodulation products, frequency conversion products, etc.
In order to manage the spectrum, each country creates national norms to regulate the generation and transmission of radio waves. For a proper spectrum management, the manager gives to each user the right to transmit in a given frequency and in a given geographical area, generally in the form of a license. The granting of these licenses must guarantee that no excessive interference might be caused to other licensed users. In practice, this can be a very challenging task, because it demands an accurate study of the physical and legislative environment of a given region.
The main objective of spectrum management is to maximize this resource, so the society can benefit from the gains that a greater availability of RF spectrum brings with it, e.g. improvement of services and availability of new ones; and simultaneously guaranteeing that the interference between different users remains stable and manageable. Figure 1 represents the frequency allocation in Brazil for different kinds of services.
22 Figure1 –Frequenc yAllocation inBrazil. 3 kHz 9,000 14,000 19,950 20,050 30 kHz 30 kHz 70,000 90,000 110,000 130,000 160,000 190,000 285,000 300 kHz 300 kHz 315,000 325,000 405,000 415,000 490,000 510,000 525,000 535,000 1.605,000 1.625,000 1.705,000 1.800,000 1.850,000 2.000.000 2.065,000 2.107,000 2.170,000 2.173,500 2.190,500 2.194,000 2.300,000 2.495,000 2.501,000 2.502,000 2.505,000 2.850,000 3.000 kHz R 3 MHz 3,025 3,155 3,200 3,400 3,500 3,800 4,000 4,063 4,438 4,650 4,700 4,750 4,995 5,003 5,005 5,060 5,250 5,450 5,680 5,730 5,900 6,200 6,525 6,685 6,765 7,000 7,100 7,200 7,300 7,350 7,400 7,450 8,100 8,195 8,815 8,965 9,040 9,400 9,900 9,995 10,003 10,005 10,100 10,138 10,150 11,175 11,275 11,400 11,600 12,100 12,230 13,200 13,260 13,360 13,410 13,570 13,870 14,000 14,250 14,350 14,990 15,005 15,010 15,100 15,800 16,360 17,410 17,480 17,900 17,970 18,030 18,052 18,068 18,168 18,780 18,900 19,020 19,680 19,800 19,990 19,995 20,010 21,000 21,450 21,850 21,870 21,924 22,000 22,855 23,200 23,350 24,000 24,890 24,990 25,005 25,010 25,070 25,210 25,550 25,670 26,100 26,175 27,500 28,000 29,700 30 MHz R ex c.A e. R R OR R OR R OR R OR R R S S OR S R R 30 MHz 30,005 30,010 37,500 38,250 39,986 40,020 40,980 41,015 50,000 54,000 72,000 73,000 74,600 74,800 75,200 75,400 76,000 88,000 108,000 117,975 136,000 137,000 137,025 137,175 137,825 138,000 143,600 143,650 144,000 146,000 148,000 149,900 150,050 156,000 156,7625 156,8375 157,450 160,600 160,975 161,475 162,050 174,000 216,000 220,000 225,000 235,000 267,000 300 MHz S S S S S S R S S S S S S S 300 MHz 315,000 322,000 328,600 335,400 363,100 363,275 378,700 378,875 387,000 399,900 400,050 400,150 401,000 402,000 403,000 406,000 406,100 410,000 420,000 430,000 432,000 438,000 440,000 450,000 455,000 456,000 459,000 460,000 470,000 608,000 614,000 698,000 806,000 890,000 902,000 907,500 915,000 928,000 942,000 952,500 960,000 1.164,000 1.215,000 1.240,000 1.300,000 1.350,000 1.400,000 1.427,000 1.429,000 1.452,000 1.492,000 1.518,000 1.525,000 1.530,000 1.559,000 1.610,000 1.610,600 1.613,800 1.626,500 1.660,000 1.660,500 1.668,000 1.668,400 1.670,000 1.675,000 1.690,000 1.700,000 1.706,000 1.710,000 1.930,000 1.970,000 1.980,000 2.025,000 2.110,000 2.120,000 2.160,000 2.200,000 2.290,000 2.300,000 2.450,000 2.483,500 2.500,000 2.520,000 2.655,000 2.690,000 2.700,000 2.900,000 3.000 MHz S S S S s S S S S S S S S S S S S S S S S S S S S S S S S S S s S S S S T V C A N A IS 3 8 a 5 1 S S 3 GHz 3,100 3,300 3,400 3,600 3,800 4,200 4,400 4,500 4,800 4,910 4,940 4,990 5,000 5,010 5,030 5,091 5,151 5,250 5,255 5,350 5,460 5,470 5,570 5,650 5,725 5,830 5,850 5,925 6,700 7,075 7,145 7,235 7,250 7,300 7,425 7,750 7,850 7,900 7,975 8,025 8,175 8,400 8,500 8,550 8,650 8,750 8,850 9,000 9,200 9,300 9,500 9,800 10,000 10,450 10,500 10,550 10,600 10,680 10,700 11,700 12,200 12,500 12,700 12,750 13,250 13,400 13,750 14,000 14,400 14,470 14,500 14,800 15,350 15,400 15,430 15,630 15,700 16,600 17,100 17,200 17,300 17,700 17,800 18,100 18,400 18,600 18,800 19,300 19,700 20,100 20,200 21,200 21,800 22,400 22,500 22,550 23,000 23,600 24,000 24,050 24,250 24,450 24,650 24,750 25,250 25,500 27,000 27,500 28,500 29,100 29,500 30 GHz S s S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S 30 GHz 31,000 31,300 31,500 31,800 32,000 32,300 33,000 33,400 34,200 34,700 35,200 35,500 36,000 37,000 37,500 38,000 39,500 40,000 40,500 41,000 42,500 43,500 47,000 47,200 50,200 50,400 51,400 52,600 54,250 55,780 56,900 57,000 58,200 59,000 59,300 64,000 65,000 66,000 71,000 74,000 76,000 77,500 78,000 79,000 81,000 84,000 86,000 92,000 94,000 94,100 95,000 100,000 102,000 105,000 109,500 111,800 114,250 116,000 119,980 122,250 123,000 130,000 134,000 136,000 141,000 148,500 151,500 155,500 158,500 164,000 167,000 174,500 174,800 182,000 185,000 190,000 191,800 200,000 202,000 209,000 217,000 226,000 231,500 232,000 235,000 238,000 240,000 241,000 248,000 250,000 252,000 265,000 275,000 300 GHz S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S S V H F
U H F
S H F E H F S L E G E NDA : E X P LO R A Ç Ã O D A T E R R A P O R S A T É LIT E V L F L F M F
H F
S O S R ad io fa rol S exc.Ae. Exc. Aé Exc. Aé S exc.Ae. exc.Ae. 13 ,5 63 -1 3,5 67 M H z - A p lic aç õ es In d u st ria is , C ie n tíf ic as e M éd ic as (IS M ) 6,7 65 -6 ,7 95 M H z - A p lic aç õ es In d u st ria is , C ie n tíf ic as e M éd ic as (IS M ) ex c.A é SOS Exc. Aé R Exc. Aé S OR OR R ex c.Ae ex c.A é S OR S S 26 ,9 57 -2 7,2 83 M H z - A p lic aç õ es In d u st ria is , C ie n tíf ic as e M éd ic as (IS M ) S S S S exc. A é. S S S S S S S exc.Ae. S S S S S S S s s S S S S S S S S S S S S S exc.Ae. S exc.Ae. S Exc. Aé S S S S A TR IB U IÇ ÃO D A U N IÃ O IN TE R N AC IO N A L S Exc. Aé Exc. Aé S S S S S S S S 24 4-24 6G H z - A p lic aç õ es In d u st ria is , C ie n tíf ic as e M éd ic as (IS M ) D E TE LEC O M U N IC A Ç Õ E S . S S S S S S S S S S S S S S S 24 -2 4,2 5G H z - A p lic aç õ es In d u st ria is , C ie n tíf ic as e M éd ic as (IS M ) 27 5 GH
z A
1 .0 00 G H z NÃ O TE M S S S exc.Ae. S S S S 90 2-92 8M H z - A p lic aç õ es In d u st ria is , C ie n tíf ic as e M éd ic as (IS M ) S S S S Exc. Aé Exc. Aé Exc. Aé S R ad io fa ro l A e. T V C A N A IS 2 a 4 R Á D IO O M 50 0k H z - F re q ü ên cia In te rn ac io n al d e C h am ad a e S o co rr o - R ad io te le g ra fia 2.1 82 k H z - F re q ü ên cia In te rn ac io n al d e C h am ad a e S o co rr o - R ad io te le fo n ia S S exc. A e. T V C A N A IS 1 4 a 3 6 exc. A e.
exc.
ATRIBUIÇÃ
O D
E FAIXAS D
E FREQUÊNCIAS NO B
Table 1 – Spectrum auction for the 700 MHz band in Brazil.
Lot Frequency range (MHz)a Minimum Bidb Winner Bidb
1 738–748 + 793–803 1928 Claro 1947
2 718–728 + 773–783 1928 TIM 1947
3 728–738 + 783–793 1928 Vivo 1928
4 708–718 + 763–773 1893 Not acquired –
5 708–718 + 763–773c 29.6 Algar 29.6
6 708–718 + 763–773c 5.3 Not acquired –
a10 MHz for each link direction, uplink and downlink, respectively. bValue in millions of reais (Brazilian currency).
cDespite the repeated frequency ranges, they were defined for different areas.
2.1 Traditional Spectrum Management
The traditional way radio spectrum is managed in most countries is by two ap-proaches: command-and-control and commons.
In the command-and-control approach, the frequency bands are licensed to users authorized by the government. The main spectrum allocation method is the spectrum auctions, which are performed by the government. In these auctions, the eligible services (e.g. radio or Television (TV) service) are specified for that particular frequency band. Any user/company which provides the specified service and is interested in the use of the auctioned band can offer the amount of money that it is willing to pay to the government to obtain the license. The government selects the winner, which is allowed to use the frequency band under the rules and regulations defined by the government and also during the time it determines [7]. For the sake of curiosity, Table 1 shows an example of a spectrum auction that happened in Brazil [8].
The great advantage of this approach is its robustness regarding harmful interferences, since only the licensed users are allowed to utilize a given frequency band. However, this approach brings with it inefficiency in spectrum utilization, because an authorized user can not utilize the whole spectrum all the time and in all the areas it is licensed to.
In the commons approach, any user has the right to access the spectrum without need of a license (license-exempt). The use of spectrum is regulated by protocols and technical standards. The main characteristic of this approach is the absence of interference protection [9].
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Table 2 – Designated bands for ISM applications.
Frequency range Central Frequency 13 553 to 13 567 kHz 13 560 kHz 26 957 to 27 283 kHz 27 120 kHz 40.66 to 40.70 MHz 40.68 MHz
902 to 928 MHz 915 MHz
2400 to 2500 MHz 2450 MHz 5725 to 5875 MHz 5800 MHz 24 to 24.25 GHz 24.125 GHz
Table 3 – Designated bands for operation in U-NII devices. Band Frequency range U-NII-1 5.150 to 5.250 GHz U-NII-2A 5.250 to 5.350 GHz U-NII-2B 5.350 to 5.470 GHz U-NII-2C 5.470 to 5.725 GHz
networks [9].
Another example of band for unlicensed use of spectrum is the Unlicensed National Information Infrastructure (U-NII) bands, defined by the Federal Communications Commission (FCC). These bands are designated for fixed or mobile communications that use broadband digital modulation techniques and provide high transmission rates. Examples of U-NII bands are presented in Table 3 [10].
2.2 Spectrum Sharing and Dynamic Spectrum Access
The crucial issue related to the traditional spectrum management is its lack of flexibility, which leads to an inefficiency in the use of this resource. Among the limitations of the traditional approach, it can be mentioned [7]:
• The user licensed to use the spectrum can’t be changed and, therefore, if there is an underutilization of this resource, it can’t be reallocated to another service that needs it;
• The granularity of spectrum use is fixed. This means that a frequency band granted to a given service has a fixed size. This leads to some limitations, for instance, in certain cases it may be necessary a shorter frequency band, just for use in a special scenario, e.g. a supplementary band for a mobile operator to provide its traffic in areas with high density of subscribers;
use previously mentioned), and, therefore, if a service is underutilizing or even not utilizing its allocated spectrum in a given area or time, unlicensed users are not allowed to use this resource in an opportunistic fashion, what would enable a higher efficiency in spectrum use.
To solve the problems due to the traditional spectrum management, more dynamic approaches have emerged, which use new technologies and concepts that enable more flexibility in spectrum access. DSA and spectrum sharing are two concepts very important in this matter.
2.2.1 Concept and main examples of Dynamic Spectrum Access
Spectrum sharing has different meanings. For a National Regulatory Authority (NRA), it means to provide more spectrum for a service without interfering or bringing harm to the existing users of that resource.
The focus of this work is on DSA, where the sharing is organized among users and depends on demands of systems that share the resources, with the allocations changing with time in a dynamic manner. This branch of spectrum sharing should not be confused with the co-existence concept, where the shared spectrum is provided in a fixed or static manner, in a way that there is no interference among users using the same or adjacent spectrum [11].
The main problem that comes with the DSA employment is the interference that new users (also called secondary users) of the spectrum can bring to the original users (or primary users) of this resource. For the traditional case where a service has an exclusive license to the spectrum, the unwanted emissions that can cause interference in other services in the same or adjacent bands are regulated through spectral masks, which are generally harmonized across the world regions. For DSA, there is a sharing of spectrum in different radio technologies, then some limits should be established regarding the transmit power and/or the sharing distance, so that one service does not cause interference to the others and vice-versa, compromising the communication.
Two examples of spectrum sharing techniques are TVWS and LSA.
2.2.1.1 TVWhite Spaces
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good propagation characteristics. They emerge as a by-product of the Digital Switchover (DSO), also known as the digital television transition; a process in which analog TV broadcasting is replaced by the digital one. The DSO has been successfully completed in various countries and it is still in progress in some others. In Brazil, for example, the Ministry of Communications established in 2014 a DSO plan, starting in 2015 and gradually to be implemented until December 2018 [12].
The basic principle of TVWS consists of allowing unlicensed, secondary users to access spectrum at specific geographic locations and/or during specific time intervals, not inter-fering with terrestrial TV transmission or reception, or any other primary service. Importantly, the TVWS regulations require White Space Devices (WSDs) to obtain authorization before they can transmit, and require those devices to cease operation when they are located within protected areas [13].
Since waves at the frequency range of TVWS have good propagation characteristics, the application of this concept is more envisioned for use cases where there is a need for wireless coverage extension. For example, TVWS can be used to improve the coverage of a 4G network of a mobile operator in rural locations.
The potential uses of TVWS are still being considered by the industry and regulatory bodies, because there are still uncertainties about what sort of TVWS availability is realistic, and the amount of TVWS spectrum available can change significantly from one country to another [14]. Many countries have studied the use of TVWS, but only two of them currently have a proper regulation model that permits the license-exempt use of TVWS: the United States of America (USA) with FCC, and the United Kingdom (UK) with Office of Communications (Ofcom).
The extension of spectrum occupancy of TVWS has opened up a new dimension for a variety of potential applications. The merit of TVWS exploitation is to provide innovative applications not fully supported by existing technologies, and to offer resource expansion to existing applications for enhanced performance [15]. One company that has begun developing rural broadband equipment using TVWS is Carlson Wireless Technologies 1from USA. The
company has more than a decade of experience in developing effective rural solutions. These wireless radios can provide broadband data rate over much larger distances than the existing Wireless Fidelity (Wi-Fi) routers, and in December 2013, FCC approved its commercial and
unlicensed use in the USA.
2.2.1.2 Licensed Shared Access
While TVWS is considered a technology of the first generation of spectrum sharing, LSA is the key example of a concept of the next generation [3]. Since the main topic of this work is LSA, the concept is seen with further details in the next chapter.
2.2.2 Enabler Concepts and Technologies
DSA enables the efficient use of the spectrum, however it brings with it some challenges for its proper operation. Such challenges can be overcome by the following concepts and technologies:
• Software Defined Radio (SDR) is a radio frequency transmitter or receiver which employs a technology that allows the radio frequency operational parameters (e.g. operating frequency, type of modulation and transmission power) to be configured or modified via software [16];
• Cognitive Radio (CR) is a radio frequency system which employs a technology that allows the system to obtain knowledge about the operational and geographic environment and to adjust dynamically and autonomously its operational parameters and protocols according to the acquired knowledge, so to achieve predefined objectives and learn with the obtained results [16];
• Spectrum Sensing involves incorporating spectrum scanners in network nodes. They sweep the radio frequency energy in a given channel to verify its availability. In order for an equipment to utilize a certain channel, it should be considered available by these scanners [15];
• Geolocation Database (GLDB) is a database with location maps of free available channels for different frequency bands, along with allowed transmission power for secondary use. In this approach, the secondary devices obtain the available channels through a GLDB query. In order for this concept to be reasonable, it is necessary to constantly update the channel availability information at the database.
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The CR allows the spectrum sensing, so the spectrum sharing is possible without harming primary users. The GLDB concept can be combined with spectrum sensing to bring more reliability and robustness in the available channel detection.
2.2.3 Dynamic Spectrum Access in Brazil
One way to increase the provision of wireless broadband in general is the employ-ment of techniques or technologies to allow the RF spectrum to be used more dynamically and efficiently, so a broader range of stakeholders could have access to and explore wireless broadband. Either TVWS or LSA are very good tools for reaching this efficiency and dynamism of spectrum use.
At the moment, it seems that Anatel is particularly interested in fostering the devel-opment of telecommunications/broadband in rural and remote areas. This can be attested in the Anatel regulatory agenda, which indicates a movement towards the regulation of the use of TVWS for the development of broadband of Brazilian rural areas, as a regulatory impact analysis on the use of white spaces in VHF and UHF bands is expected to happen by the second semester of 2018 [17].
In Brazil, there is still no ongoing regulatory actions related to LSA, but there is already research regarding the application of this concept in the Brazilian scenario. In [18] there is a spectrum sharing proposal based on the LSA concept with its specificities, in order for it to be more appropriate to the Brazilian reality. The candidate frequency bands for LSA in Brazil are: 1.4 GHz (L-Band), 2.7 GHz (2500 to 2690 MHz) and 3.5 GHz (3565 to 3650 MHz). In the same reference, there is also an analysis of the protection areas in the whole Brazil territory in the 3.5 GHz band, for which the Fixed Satellite Service (FSS) is the main incumbent in the country. Figure 2 shows the protection areas for co-channel operation (red circles) and adjacent-channel operation (blue circles).
Figure 2 – Protection areas in the 3.5 GHz band in Brazil.
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3 LICENSED SHARED ACCESS
With the previously mentioned apparent spectrum scarcity problem, the USA Presi-dent’s Council of Advanced Science & Technology (PCAST) reported [19] the urgency within the wireless industry for new alternatives to overcome this spectrum crisis. The spectrum sharing concept was highlighted as an excellent option, with potential to unlock a considerable amount of spectrum to different systems and services with different spectrum needs and dynamics. In Europe, at the same period, the European Commission (EC)’s advisory group Radio Spectrum Policy Group (RSPG) also shows itself interested in the spectrum sharing concept, specifically in LSA as a complementary spectrum tool to deal with the increasing demand for mobile data traffic. The RSPG opinion stated that “To meet the growing demand for spectrum the industry and administrations are under pressure to introduce new technologies and regulatory mechanisms to optimize the use of the limited frequency resources. In this context, the promotion of the shared use of radio spectrum resources is a valuable means to offer additional spectrum access to broadband communications, for license exempt but also licensed usage, which is a new paradigm referred to as Licensed Shared Access.” [20].
These documents show high-level policy drivers efforts towards a spectrum sharing concept, and specifically LSA. However, in order for the spectrum sharing concept to be deployed in commercial services, a close cooperation between business, policy and technology domains is necessary, mainly because the application of this concept means several radio systems operating in the same band and/or at the same time, fact that can weaken the stakeholders’ trust, once this can be translated into interference between systems and therefore compromise their service provision. This thinking can create a certain fear in the adoption of the sharing approach, instead of exclusive long duration licensing, where the interference is well-known, managed and the Quality of Service (QoS) is guaranteed.
Therefore, it can be observed that only a subset of researches regarding spectrum sharing has entered into the regulatory and business domain. One clear example of this, it is the research on spectrum sensing through the application of cognitive radio to deal with interference issues [11]. Despite that, there is also the TVWS concept, which was supported by NRAs and standardization bodies, mainly in USA [21] and UK [22]. In [23], it is possible to see an example of a product commercially available off-the-shelf, which applies the TVWS solution to deliver wireless broadband connection to costumers in non-line-of-sight and rural locations.
and Spectrum Access System (SAS) [25] from the USA. Both concepts are very similar, however SAS is based on a three-tier model, introducing three different levels of priority (LSA has two tiers: incumbent and LSA licensee), and, more notable than this, the sensing is mandatory in SAS system for determination of incumbent usage information. The FCC considers the Citizens Broadband Radio Service (CBRS) 3.5 GHz band for sharing through the SAS system, which in the USA is used by military radar and FSS services [3].
As the focus of this work is LSA, this is the only concept that is deepened here. Further details regarding SAS can be seen in [26].
3.1 Definition and use case
LSA is a new complementary licensing method that enables the spectrum allocated to an incumbent, which is underutilized, to be shared in time, frequency and space with other services (called LSA licensee), such as Mobile Network Operators (MNOs). The differential of this spectrum sharing concept is that the conditions, similar to the exclusive licensing, assure the rights of use for both incumbent and LSA licensee, and therefore QoS can be guaranteed in both services.
The major use case for the LSA concept is the “Bandwidth Expansion for Mobile Network Operator” defined by the European Telecommunications Standards Institute (ETSI) in [27]. In this use case, an MNO operating LTE in a licensed band already assigned to it, can apply for an individual authorization through the concept of LSA, which enables the MNO to use RF frequencies within the 2300 to 2400 MHz band (Third Generation Partnership Project (3GPP) LTE Band 40) and expand its total bandwidth through carrier aggregation mechanisms. Figure 3 illustrates this principle.
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Figure 3 – LSA use case illustration.
Licensed
Spectrum LSA Spectrum
Source: Created by the Author
3.2 LSAplayers and sharing framework
The main players in the LSA approach are the incumbent, the NRA and the LSA licensee. According to the LSA concept [24], the spectrum sharing is allowed in a binary basis, in this sense, both incumbent and LSA licensee have exclusive individual access to a spectrum at a given time and location. The NRA is responsible for the identification of LSA spectrum to be licensed and definition of the sharing framework [24].
The sharing framework is a set of sharing rules which will cause changes, if any, in the spectrum use by the incumbent (in time, frequency and/or space) and defines the possible available spectrum for access by the LSA licensee under LSA regime with its corresponding technical and operational conditions [28].
right of use to the LSA licensee, so the latter is able to use the additional spectrum. Figure 4 summarizes this relation among the stakeholders.
Figure 4 – Relation among the LSA stakeholders for definition of the sharing framework and the issuing by NRA of individual right of use to the LSA licensee(s).
Incumbent(s) LSA Licensee(s)
NRA De✁nition
of sharing framework
Individual right of use
Source: Created by the Author
3.3 Architecture
The LSA architecture introduces two logical entities, the LSA Controller (LC) and the LSA Repository (LR) [29]. These two entities are necessary to support the dynamic access to the LSA spectrum and to guarantee the incumbent rights and interference free operation.
The LR plays the role of a database. Its main functions are the following [29]:
• the entry and storage of information regarding incumbent’s spectrum use and protection requirements;
• transmission to LCs of availability information;
• reception and storage of acknowledgement information received from the LCs; • support the NRA to monitor operation of the LSA system;
• it guarantees that the LSA system works according to the sharing framework.
The LC is an entity located within the LSA licensee’s domain. Its key functions are the following [29]:
• provides to the LSA licensee the spectrum resource availability information from the LR; • allows that acknowledgment information is exchanged between LSA licensee and LR; • supports the mapping of availability information into appropriate radio configurations by
interacting with the licensee’s network management system.
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activity and its protection against interference. According to information senta priorifrom the incumbents regarding spectrum usage and protection requirements to the LR, the latter assesses the availability of LSA spectrum over space and time. The LC can either grant access or request to vacate channels to LSA licensees based on the LR information gathered through an interface between both entities defined in [29]. The LR is located outside the LSA licensee network and it can serve multiple networks. Differently, the LC is considered as part of a specific network.
Figure 5 – Example of a possible LSA system architecture.
Incumbent 1
Incumbent 2
Incumbent 3 LSA
Repository
LSA Controller
Mobile Network Management
System Licensed Spectrum LSA Spectrum LSA
Repository
Source: Created by the Author
3.4 Incumbent protection
European countries can be found in [30]. In Brazil, the same kind of consultation can be performed at Anatel’s Interactive systems [31].
According to the information related to incumbent’s location and protection criteria, exclusion and protection zones can be defined to protect the incumbent from harmful interference. These zones are typically defined as circles of few kilometers with center being the victim sites. It was also defined another kind of zone called restriction zone. The definition of each type of zone is the following [32]:
• Exclusion Zone: a geographical area defined for a frequency range and time period, within which interferers are not allowed to have active radio transmitters;
• Protection Zone: a geographical area defined for a frequency range and time period, where victim receivers will not be subject to harmful interference from interferers;
• Restriction Zone: a geographical area defined for a frequency range and time period, where LSA licensees are allowed to have active radio transmitters under certain restrictive conditions.
3.5 Regulation and Standardization
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incumbents (e.g. PMSE and telemetry services) and also example of implementation of the scenarios. Another report is more focused on studying just the PMSE use case and guidelines for implementation of the sharing framework [32].
Despite the fact that the LSA concept was developed for the European context and its application is a national matter, for this and any innovation to scale and succeed is essential a global spectrum harmonization. It is possible to observe some studies of the International Telecommunication Union Radio communication sector (ITU-R) considering LSA [38, 39, 40].
The responsible for the standardization activities of LSA is ETSI with its Techni-cal Committee (TC) Reconfigurable Radio Systems (RRC), after EC issued a standardization mandate on RRC [41]. In its first Technical Recommendation (TC) [27], the LSA concept is introduced in high level with its key use case, operational features, functions and performance requirements. The system requirements are specified in [42] and the system architecture and high level procedures are described in [29]. The last completed specification addresses information elements and protocols for interface between LR and LC [43].
3.6 LSAcase study in Brazil
Some examples of case studies for employment of the LSA concept to the Brazilian scenario can be devised, taking advantage of the flexibility and accessibility in spectrum access provided by the LSA concept to improve important activities or sectors.
Brazil is very rich in natural resources, holding a very large mineral repository. The Brazilian mining industry has a great importance worldwide, producing and exporting high quality ores, which makes mining a very important activity for the Brazilian economy. Brazil is very well ranked in the world for different minerals regarding its production and reserves. Forecasts show excellent perspectives for this economic activity for the next decades [44].
The importance of the mining industry makes the development of this activity crucial for Brazilian economy growth. In the current globalized world, to face competition, the industry must be in constant development so that the productivity is maximized. The Industry 4.0 is the concept used for the following industrial revolution that is about to happen and which was defined in Germany, one of the world top competitive manufacturing industries. This concept is expected to improve the “industrial processes involved in manufacturing, engineering, material usage and supply chain and life cycle management” [45].
been called the smart factory, which is a factory that assists people and machines in performing their tasks through the awareness of the physical and virtual world. This awareness is allowed thanks to a network compatible equipment called Cyber-Physical Systems (CPS) supplied with sensors and actuators, which monitor physical industrial processes, helping to decentralize decisions. In the smart factories, these CPSs are interconnected using the concept of IoT, so the industry is a network of automated machines and people, with the possibility of some activities being controlled remotely by the latter [46].
Regarding the automation process envisioned by Industry 4.0, the wireless factory automation is recently drawing more interest than the wired one, since the former presents attractive advantages, e.g. low installation and maintenance cost, higher flexibility.
One main challenge of wireless factory automation is its requirements regarding communications latency and reliability. Industrial applications like packaging machines need very strict requirements (latency less than 1 ms and block error probability around 10−8 or
10−9) [47]. Such services with very rigorous requirements, mainly in respect to latency and
reliability, were defined by International Telecommunication Union (ITU) as Ultra-Reliable and Low-Latency Communications (uRLLC) [48].
In recent years, there were some advances in wireless technologies for factory applications, e.g. WirelessHART, ISA 100.11a, Industrial WLAN [49]. However, these solutions together with other proprietary ones operate mostly on unlicensed spectrum, and, hence, there are no QoS guarantees, since there is interference from other services using the shared band.
The employment of the Industry 4.0 concept to the mining industry in Brazil is a process that needs to occur in order to keep this sector competitive in the world market [50], and the application of the LSA framework concept is a good approach to address the challenges mentioned previously. The LSA band would be made available to the mining companies with QoS guarantees, since this is a key feature of the exclusive licensing basis of this concept. Despite that, this solution facilitates the granting of spectrum license to the companies, in comparison with the traditional bidding process, which happens not so often and has quite expensive bids.
The flexibility of LSA is another advantage for this case study. The definition of the sharing framework by the stakeholders facilitates that the conditions of the parts are met. For example, a mining company would require the spectrum just for a specific part of the country, for a certain time and with a particular bandwidth size.
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be considered carefully, since the interference management is made using data that is present at the LSA repository (e.g., incumbent location, maximum Effective Isotropic Radiated Power (EIRP)) together with a propagation model. Since the mining sites are very particular, with a irregular relief and big depressions, the propagation model is very different from the ones already studied and available in the literature. Therefore, it represents a critical part for which a certain importance must be given.
Using this approach, all the stakeholders are contemplated. The financial investment of the mining company would be addressed to the incumbent. The LSA licensee would have the access to the licensed spectrum with the QoS guarantees that it needs. The advantage for Anatel would be a more efficient use of the spectrum, alleviating, in this sense, the spectrum “scarcity” problem.
Figure 6 depicts a possible architecture for the described case study. The FSS is considered the incumbent user, sharing its 3.5 GHz band through the LSA concept. Anatel manages a database with the spectrum access information according to the information provided by FSS. A mining company contacts Anatel for new spectrum access. Anatel checks its database and grants spectrum access to the mining company. The mining company is free to use the LSA spectrum for its smart factory.
Regarding the financial exchange that could occur, the FSS receives money from Anatel for making the spectrum of the former (or part of it) available to be exploited through the LSA concept. Finally, a mining company pays directly Anatel for additional spectrum, without the need to take part of spectrum auctions.
Figure 6 – Example of a possible LSA system architecture for the case study.
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4 CAPACITY AND INTERFERENCE EVALUATION IN LTE/LSA NETWORK
For the assessment of an LTE network on which the concept of LSA is applied, a simulator at the physical layer level was developed. The next sections make an overview of LTE/PMSE and describe the scenario considered in the simulator, as well as concept and parameters used. Finally, the obtained results are presented and analyzed.
4.1 LTE overview
The cellular networks are currently at the 4G, evolving since the First Generation (1G) with growing data rates both in downlink and uplink, thanks to the development of new technologies. The LTE was launched as a project in 2004 by 3GPP as result of the redesign of both radio and core network of the Third Generation (3G) technology, Universal Mobile Telecommunications System (UMTS) [51].
LTE is sometimes considered a 3.9G system [52], since the term 4G remains unde-fined. ITU has developed a framework of standards (International Mobile Telecommunications (IMT) system) for mobile telephony, in order to support the development of standards for global mobile communications. It has started with the IMT-2000, also referred as 3G, and evolving for the next generation of standards, known as IMT-Advanced, with improved technical and operational criteria, for instance, the target throughput for IMT-Advanced is 100 Mb/s in a high mobility environment and 1 Gb/s in a stationary environment. It is seen further in this chapter that LTE does not satisfy this and other technical requirements set by 3GPP for IMT-Advanced systems. Since the term 4G is usually applied by mobile operators to the IMT-Advanced technologies, 3.9G is also used to refer to LTE and other evolved 3G technologies [53].
3GPP standards are organized as releases and the first standard of this group related to LTE is the release 8. The main objective of LTE is to provide high throughput, low latency and all-Internet Protocol (IP) radio access network optimized to support flexible bandwidth.
The LTE network architecture is simpler than the one of 3G networks. This is due to the elimination of circuit-switched services, eliminating the mobile switching center. This architecture is divided into radio network and core network.
between eNBs is made through the X2 interface. The base stations are also connected to the core network, which is called Evolved Packet Core (EPC)1 through the S1 interface. Finally,
the communication between eNB and UE is made wirelessly by the Uu interface. Figure 7 summarizes the E-UTRAN architecture just described [54].
Figure 7 – E-UTRAN architecture.
EU eNB
eNB eNB
X2 X2
X2
Uu
E-UTRAN
EPC S1
Source: Created by the Author
The main design targets of LTE are the following [55]:
• Downlink peak throughput of 100 Mb/s for downlink and 50 Mb/s for uplink over a 20 MHz bandwidth;
• Communication with terminal moving in high speed (up to 500 km h−1);
• Cell coverage of 5 km when performance is met (Otherwise, up to 100 km of coverage); • Scalable bandwidths.
LTE air interface uses Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier Frequency Division Multiple Access (SC-FDMA) as multiple access schemes for downlink and uplink, respectively. It supports both Time-Division Duplex (TDD) and Frequency-Division Duplex (FDD) for link direction separation. Other important concepts introduced in LTE are adaptive link adaptation, time-frequency scheduling and MIMO antenna systems.
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4.1.1 Long-Term Evolution Advanced (LTE-A) and Carrier Aggregation
In order to comply with the IMT-Advanced requirements, 3GPP developed its Release 10 with major features referred as LTE-A. The main objective of the enhancements of LTE-A is cost reduction and throughput improvement in cell edge [52].
Among the new functionalities brought by LTE-A, carrier aggregation is the more relevant for this work.
Carrier aggregation is a simple way to increase the individual throughput by increas-ing the channel bandwidth. This concept does not mean to increase the maximum bandwidth of LTE, 20 MHz, instead it makes possible to aggregate the capacity of several individual carriers. It should be noticed that the carriers that are aggregated don’t necessarily need to be in adjacent bands, actually they can belong to different LTE bands. Further details can be found in [56].
4.2 PMSE overview
PMSE applications, as the name says, can be Programme Making related, for exam-ple, the making of a programme for broadcast, the making of a film, etc; and Special Events related, for example, large cultural, sport, entertainment festival coverages.
PMSE refers to a variety of different services, i.e. SAP/SAB, ENG/OB and ap-plications used in meetings, conferences, cultural and educational activities, trade fairs, local entertainment, sport, religious and other public or private events for perceived real-time presenta-tion of audiovisual informapresenta-tion [57].
The definition of each of those acronyms are the following [57]:
• SAP are related to activities in the making of “programmes”, e.g. film making, adver-tisements, concerts and other activities not initially intended for broadcasting to general public;
• SAB are related to activities of broadcasting industry carried out in the production of their program material;
• ENG is related to the collection of video and/or audio by wireless cameras and/or micro-phones with radio links to the news room and/or to the portable tape or other recorders;
• OB is related to the temporary provision of programme making facilities at the location of on-going news, sport or other events, lasting from a few hours to several weeks.
gen-erally used to refer to the whole variety of services. Similarly, the term ENG/OB is considered. There is a variety of PMSE applications which can be divided in a total of seven categories [57]:
• Radio camera (line-of-sight/non-line-of-sight): Handheld or otherwise mounted camera with integrated or Clip-on transmitter, power pack and antenna for carrying broadcast-quality video together with sound signals over short-ranges line-of-sight/non-line-of-sight;
• Miniature camera/links: Very small transmitter and miniature camera for specialist action shots, e.g. helmet cam, covert assignments, UAV, etc. Can be body worn or covert assignments;
• Portable video link: Small transmitter, for deployment over greater ranges, typically up to 2 km;
• Mobile air-to-ground video link: Video transmission system employing radio transmitter and receivers mounted on helicopters, airships or other aircraft.(includes repeaters and relays);
• Mobile vehicular video link (including ground-to-air): Video transmission system employ-ing radio transmitter mounted in/on motorcycles, racemploy-ing motorbikes, pedal cycles, cars, racing cars or boats. One or both link terminals may be used while moving;
• Temporary point-to-point video links: Temporary link between two points (e.g. part of a link between an OB site and a studio or network terminating point), used for carrying broadcast quality video/audio signals. Link terminals are mounted on tripods, temporary platforms, purpose built vehicles or hydraulic hoists. Two-way links are often required.
For sharing and compatibility studies, these categories can be grouped and reduced to four other categories: cordless camera link, portable video link, mobile video link and temporary point-to-point video links.
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co-channel case, additional interference mitigation mechanisms are necessary for operation in the same area and time.
Cordless camera category includes radio camera (line-of-sight) and radio camera (non-line-of-sight), this service is normally used by a cameraman to transmit video and audio from transmitter in a handheld camera to an outside broadcasting vehicle at short distances (up to 500 m). Characteristics of the cordless camera transmitter and receiver can be found in [57].
Figure 8 depicts an example of the cordless camera link scenario.
Figure 8 – Cordless camera link scenario.
Source: Created by the Author
4.3 Scenario Description
The simulation scenario consists of an LTE network on which the concept of LSA is applied to extend its total network capacity. In this case, the considered primary user is a PMSE application, particularly cordless camera service, and the secondary user is the LTE network itself.
The main goal of the simulator is to perform an LTE resource allocation, considering that an additional band coming through the LSA concept is aggregated to the LTE licensed band. Furthermore, the simulator also outputs capacity results of the secondary users and interference values of primary ones. Hence, the simulation runs at the physical layer level only and higher layer level procedures are neglected.
single omni-directional antenna. A fixed number of LTE UEs (also equipped with a single omni-directional antenna) are distributed randomly over each cell site.
Figure 9 – Representation of a grid with 19 hexagon cells wrapped around.
-4000 -3000 -2000 -1000 0 1000 2000 3000 4000
X-coordinate (meters) -3000 -2000 -1000 0 1000 2000 3000 Y-coordinate (meters)
Grid with Wrap Around
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Source: Created by the Author
It is assumed that in each cell site, there is a fixed number of cordless camera links, composed of transmitter and receiver, which operate in the 2300 to 2400 MHz band. This service agreed in sharing its resources through the LSA concept and expects to be protected against interference coming from LSA licensees.
The representation of a single cell for the described scenario with primary and secondary users is depicted in Figure 10.
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Figure 10 – Representation of a cell for the simulated scenario. Blue dashed arrows represent signals of interest and red solid arrows represent interfering signals.
Source: Created by the Author
4.3.1 Primary and secondary users operation
As it was previously exposed in section 4.2, it is unfeasible to both primary and secondary users coexist in the same band at the same time, hence a separation frequency is considered between the operating frequency of PMSE and the one possibly used by the LTE network through the LSA concept (LSA operating frequency). It is assumed that, when available, the additional LSA bandwidth is aggregated to the LTE network licensed bandwidth through carrier aggregation mechanism, which, for simplicity, is just seen as a summation of bandwidths in the simulator.
Figure 11 – A cluster with 19 cells with two LTE UEs and one cordless camera link.
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Source: Created by the Author
whenever possible. Figure 13 presents these three different bands and an illustration of the emission mask of eNB.
4.3.2 Physical Resource Blocks and Resource Allocation
Only the downlink scenario is simulated, i.e. transmission from eNB to UE, where the LTE technology employs OFDMA technique. OFDMA enables multiple UEs to receive information at the same time in different “subchannels”, which are termed Physical Resource Blocks (PRBs). PRB is a frequency-time block composed of 12 consecutive subcarriers spaced by 15 kHz (total bandwidth of 180 kHz) that lasts for one slot, 0.5 ms.
