Using unlicensed radio#frequency spectrum to increase LTE network capacity Текст научной статьи по специальности «Электротехника, электронная техника, информационные технологии»

USING UNLICENSED RADIO-FREQUENCY SPECTRUM TO INCREASE LTE NETWORK CAPACITY

DOI 10.24411/2072-8735-2018-10033

Anton N. Steputin,

The Bonch-Bruevich Saint Petersburg State University of Telecommunications, Saint Petersburg, Russia, steputin@l234G.ru

Al-Ameri Hamed Abdo,

The Bonch-Bruevich Saint Petersburg State University of Telecommunications, Saint Petersburg, Russia, hamedru2008@gmail.com

Keywords: LTE, Wi-Fi, capacity, carrier aggregation, unlicensed spectrum, LAA, LBT, CCA, FBE, LBE.

The subject of the article is the use of unlicensed spectrum bands in the heterogeneous networks LTE as one of the methods for solving a problem of network overloading; reduce data rate and the lack of LTE network resources. The technical requirements and conditions utilizing the radio frequency band in the 5 GHz unlicensed spectrum across the regions is given, as well as a comparison of coexistence mechanisms of various radio access technologies. Special attention is paid to the description of the coexistence between Wi-Fi and LAA schemes on a one radio-frequency channel in the 5 GHz unlicensed spectrum. These mechanisms include new technological solutions for client access organizations, such as FBE, LBE, LBT and CCA. The evaluation of implementation effectiveness of the LAA technology was accomplished. The efficient use of the radio-frequency resources for a coexistence between these two types of radio-access technologies over an unlicensed spectrum is part of ongoing studies.

This article will identify permissible transmission loss depending on the relative loading area, the relationship between LTE+LAA and the capacity for different MIMO modes (on the signal to interference ratio and channel bandwidth). Based on this study, it can be concluded that the progressive implementation of a given technology may solve the problem of shortages regarding mobile network resources in big cities (as a result of continuous traffic growth). It can be observed that the utilization of the radio frequency band in the 5 GHz unlicensed spectrum allows for an increase in the data rate via the network LTE+LAA.

Information about authors:

Anton N. Steputin, PhD, Associate professor, The Bonch-Bruevich Saint Petersburg State University of Telecommunications; CEO, Portal l234G.ru; Author of the book "Mobile communication on the road to 6G", Saint Petersburg, Russia

Al-Ameri Hamed Abdo, Postgraduate student, The Bonch-Bruevich Saint Petersburg State University of Telecommunications, Saint Petersburg, Russia

Для цитирования:

Степутин А.Н., Аль-Амери Х.А. Повышение пропускной способности сетей мобильной связи стандарта LTE при использовании нелицензионного радиочастотного спектра // T-Comm: Телекоммуникации и транспорт. 2018. Том 12. №2. С. 62-69.

For citation:

Steputin A.N., Al-Ameri H.A. (2018). MUsing unlicensed radio-frequency spectrum to increase LTE network capacity. T-Comm, vol. 12, no.2, pр. 62-69.

Introduction

The expected growth of mobile data traffic is related to the implementation of new broadband services and startup wireless communication. The traffic transmitted over the mobile networks is huge and will continue to grow at a rapid pace, Cisco estimates that in 2021, mobile data traffic worldwide is expected to reach 587 exabytes per year (Fig. 1), i.e., seven times more than mobile data traffic worldwide in 2016 [1]. Traffic from wireless and mobile devices will account for two-thirds of the total IP traffic by 2020, as annual subscribers need more bandwidth to transfer large amounts of data. In order to increase the mobile communication network capacity, a number of technological solutions has been defined for the use of the unlicensed spectrum enabling an additional radio-frequency resource [2, 3].

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m

2016

37

2017

2018

2019

2020

2021

Fig. I. Global mobile data traffic from 2016 to 2021 (in exabytes per month)

The use of unlicensed spectrum in the 5GHz band

The main purpose of the use of the unlicensed span spectrum in the 5GHz band is to obtain the additional radio-frequency resources for the LTF network. Moreover, the access to an unlicensed spectrum is unlimited, where different devices SRD (Short Range Dcvice) including Wi-Fi and radar dcvices work [2]. At the World Radiocommunication Conference (WCC03) the following frequency bands 5150 — 5350 MHz and 5470 -5725 MHz have been identified in the first stage for WAS (Wireless Access Systems) including the RLAN (Radio Local Area Networks) (Fig. 2) [4].

The coexistence of different types of radio access technologies - such as LTF. and Wi-Fi, plus the use of channel access mechanisms - is essential for an amicable/concordant coexistence, the minimization of mutual interference and performance improvement. In the case of Wi-Fi systems across different regions, e.g. Europe, Japan, the United States, and other parts of the world, DFS (dynamic frequency selection), along with TPC (transmit power control) and uniform channel loading schemes have been utilized in the 5 GHz unlicensed spectrum to mitigate interference to previously existing spectrum allocations in the same band for radar operation, as shown in Table 1.

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The technical requirements and conditions utilizing the radio frequency band in the 5 GHz unlicensed spectrum across the regions is given in Table 1.

Table 1

Requirements across the regions in the 5 GHz unlicensed spectrum

Frequency, MHz 5150-5250 5250-5350 5470-5725 5725-5875

Maximum FIRP, mW 200 1000 1000 25

Maximum spcctral densities, mW /MHz 10 50 50 -

Maximum TX power. Emission mask

Russia Coexistence mechanism LBT LBT & DFS/TPC - LBT

locations Indoor - Indoor/ Outdoor

Additional requirements Duty cycle equals 0.1 %, Antenna height < 5 meters.

Europe Coexistence mechanism LBT LBT & DFS/TPC -

locations Indoor Indoor/Outdoor

USA Coexistence mechanism - DFS/TPC -

locations Indoor Indoor/Outdoor

Additional requirements FCC Part 15.247. 15.401-407

China Cocxistcnce mechanism - DFS/TPC - -

locations Indoor - Indoor/ Outdoor

Japan Coexistence mechanism LBT LBT & DFS/TPC -

locations Indoor Indoor/ Outdoor -

Additional requirements Maximum burst length (4 ms), Maximum antenna pain

Korea Coexistence mechanism - DFS/TPC DFS/TPC (5470-5670) MHz -

Locations Indoor Indoor/Outdoor

Additional requirements Maximum anienna gain

* Channels within the frequency band 5850-5925 MHz share with Short Range Devices (SRD) including Wi-Fi networks * E1RP - equivalent isotropically radiated power, mW

5150 5150 5470 5725 W25 5375 Frtqucnci , MHz

Fig. 2. Unlicensed spectrum in the 5GHz band in different regions

Technical considerations for the Implementation of LAA

In 3GPP release 13 are introduced two technologies LWA (LTF. & WLAN Aggregation) and LAA (Licensed Assisted Access) as solutions for utilize the unlicensed spectrum for LTE network. LWA technology requires aggregate LTE and WLAN at the packet data convergence protocol layer, allowing uplink traffic to be carried on LTE and downlink on both LTE and WLAN. The principle of LAA operation hinge on the aggregation of a primary channel (licensed carrier), with one or more secondary channels (unlicensed carriers in 5GHz band) established via an LAA node [5].

By contrast, PCell (primary cell) on licensed spectrum aggregated with SCell (secondary cell) on unlicensed spectrum (Fig, 3). PCell serves to transmit the user data and the service information, i 1 owe ver, the CC (component carriers) in unlicensed bands is utilized as additional (secondary) cell exclusively for transmission user data [6].

ft™))

I nlicritsrd *|* i II ni'

Fig, 3. Licensed assisted access

It must be noted that the technology eLAA {enhanced LAA) described in release 14 allows for an aggregation oflicensed and unlicensed spectrum bands for the primary and secondary channel [2|.

LAA may utilize the FDD (Frequency Division Duplex) or the TDD (Time Division Duplex) in the primary and secondary channels. The scheduling of traffic over the secondary channel is a function of the type of traffic, such as latency sensitivity, mobility speeds, and traffic load optimization. For the implementation of the LAA technology (Fig. 4), there are 4 scenarios considered within release 13 [7]. In addition to implementation of the LTE+LAA new LTE mobile devices capable of operation in the unlicensed spectrum and have mechanisms for fair spectrum sharing between users are required.

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Fig. 4. Deployment Scenarios of LAA

It is necessary to emphasize thai the utilization of the unlicensed spectrum as an additional frequency band - due to the fact that it has been a random and rapidly changing electromagnetic environment - could not guarantee high QoS (Quality of Service): system capacity and latency. In addition, the special measures are needed to reduce conflict with other radioeleclronic devices working in the same band. In release 13

the following mechanisms in (Table I) as a means to resolve conflicts were specified [8j:

• LBT (Listen Before Talk);

■ DTX (Discontinuous Transmission Mode);

■ DFS (Dynamic Frequency Selection);

■ TPC (Transmit Power Control)

Requirements for LBT coexistence mechanism

The type of interference mitigation and fair coexistence mechanisms vary with markets and regional regulatory regimes. These schemes utilize the concept of an adaptive on/off transmission, based on channel utilization measurements. This concept is the foundational LBT scheme (a basic requirement in Europe and Japan) for optima! interaction between the LAA and Wi-Fi devices work in unlicensed spectrum. The LBT scheme utilizes CCA (clear channel access) oriented channel availability sensing, which performs adaptive transmission based on a variable time-scale that spans L10 milliseconds [9].

Energy Detection (ED) applied in conjunction with the CCA procedure to enable an effective coexistence scheme between LTE and Wi-Fi while minimizing the performance impacts as a result of resource sharing over unlicensed spectrum. Energy detection provides an indication of whether a channel is available or busy. If the detected energy levels are below the threshold, the channel is deemed to be clear and an LAA node is permitted to transmit. Otherwise, the LAA node continues to monitor the energy levels, until the channel is deemed to be clear, and establishes a random backoff. This enables a commencement of transmission after the channel is clear for a minimum duration. An example of this process is illustrated in Fig. 5 [&J,

LMCCATHpmu mriluiti >t idit

CCA

LM CCA ttpMJ IfiA CCA nttltl mHfi um aï buiy rodlu m bi IHle

WI-FI CCA ttiwti mrfum « bdty

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Fig. 5. LTE Licensed-Assisted Access (LAA) and Wi-Fi coexistence

Basically, the LBT mechanism - in terms of the clear channel assessment (CCA) - is classified into two types of a time domain: Frame Based Equipment (EBE) and Load Based Equipment (LBE). As illustrated in Fig. 6, the assumption of FBE, eNB or UE performs the CCA every fixed frame period, and the data transmission can only be started when it is decided to clear the channel. Meanwhile, the burst of the transmission is limited to a maximum value (channel occupancy time) so as to keep the balance of channel access with other neighboring nodes. On the other hand, LBT with LBE makes the eNB or UE assess the channel only when the data arrives at the buffer (Fig. 7).

The European technical requirements for the coexistence mechanism LBT were provided in Table 2 [9].

Both DFS and LBT schemes are largely classified as listen before talk schemes for managing the coexistence of heterogeneous radio-access technologies over unlicensed spectrum. These and other enabling adaptations in the MAC and PHY layers, including new measurements, transmit power control, channel occupancy, etc., are envisioned with respect to specifications for LAA (Rel-13).

Table 2

Technical requirements for LBT mechanisms

Parameter Technical requirements

Types of coexistence mechanism LBF. (Load Based Equipment) FBE (Frame Based Equipment)

Clear Channel Assessment Time (CCAT) Minimum 20 ps

Number of Clear Channel with Enhanced CCA (N) N s [1, q] where q is a fixed backoff scaler selected from 4 to 32 -

Fixed timing frame - Channel occupancy time + wait period

Channel occupancy time (CoT) <(l3/32)*q ms Minimum = 1 ms, Maximum = 10 ms

WaiL period N* time interval - CCA Minimum 5% of channel occupancy time

Short control signal lengths Maximum duty cycle equals 5% within monitoring period 50 ms

Energy detection threshold CCA < -73 dBm /MHz (EIRP = 23 dBm) = -73 dBm /MHz + 23 dBm - PH (dBm) (with different values ofElRP, PH)

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Comparison of LTE and Wi-Fi technologies

The design differences between the LTE and the Wi-Fi suite of radio access technologies, in terms of the PHY/MAC (physical and medium access control) layer protocols, procedures, and standards, together with the absence of any specifications for mutual interference mitigation capabilities, underscore the need for the establishment of such capabilities in a heterogeneous radio-access sharing of unlicensed spectrum resources.

In the case of Wi-Fi systems, there is no power control mechanism, and when a channel is accesscd the transmission occurs at the maximum available power. On the other hand, in the case of LTE systems, transmissions occur every subframe (1 millisecond interval), which potentially blocks Wi-Fi systems in physical proximity that are attempting to gain access to shared, unlicensed spectrum resources.

In order to enhance the effectiveness of the LTE and Wi-Fi sharing systems operation scenarios utilize elCIC (enhanced Inter-cell Interference Coordination). The elCIC proposes enhancement of techniques for inter-system interference reduction due to the usage ABS (Almost Blank Subframes) allowing low power nodes to use these subframes at the cell edge.

However, LTE+LAA node turn user services off in ail the ABS subframes, which allows avoid or reduce the impact of interference on common resources of the unlicensed spectrum. In addition to the ABS, to promote an intelligent coexistence an adaptive channel sensing within Wi-Fi systems must be harvested, and the use of SINR (Signal to Interference plus Noise Ratio) oriented power control within LTE systems. Examples of LTE / Wi-Fi comparison are given in Table 3.

Table 3

Comparison of performance LTE and Wi-Fi

LTE Wi-Fi

Subcarriers spacing, kHz ¡5 312.5

Number of subcarriers 1200 56

The efficiency of the system (FDD) (15 kHz * 1200)/ 20 MHz = 0.9 (312.5 kHz* 56)/ 20 MHz = 0.875

Symbol duration, ps 66.7 3,2

Cyclic prefix 4.7 us 800 ns (400 ns)

The efficiency of the system (TDD) 66.7 / (66.7+4,7) = 0.934 3.2 /(3.2 + 0.8) = 0.8 3.2 / (3,2 + 0.4) = 0.889

The overall efficiency 0.9* 0.934 = 0.841 0.875 * 0.8 = 0.7 0.875 * 0.889 = 0.778

Fig. 7. Operation mode of FBE-based LBT

The simulation results of these LTE/Wi-Fi coexistence strategies and efficiency calculations that use the radio frequency spectrum, as examined in figure 8, have shown that LTE system performance exceeds that of Wi-Fi systems, where LTE system allows to get peak data rates 8-15% greater than Wi-Fi systems. Furthermore, when calculating the maximum acceptable line losses according to Fig. 9, the energy budget of the LTE channel becomes better than the Wi-Fi channel by -14 dB.

i 110 MHz.

i

Carrier 1 Cirjw / Carrier 3 Carrier 4 Carriers

Fig. 10.1mra-band carrier aggregation of 5 * 20 MHz component carriers

1 t __pLTE ■ Wi-Fi

UUI

The efficiency ofthe The efficiency of the The overall efficiency system (TDD) system (TDD)

Fig. 8. Comparison of performance LTE and Wi-Fi (Capacity)

Relative Loading Area

Fig. 9. Dependence of the acceptable transmission loss on relative loading area

Moreover, a variety of considerations affect a harmonious coexistence of LTE and Wi-Fi systems, such as the spatial distribution of heterogeneous radio access technology nodes, environmental topologies (e.g. structural layout of indoor and outdoor environments, etc.), antenna configurations, transmission power levels, etc [6].

LTE+LAA carrier aggregation enhancement

Carrier aggregation (CA) allow mobile network operators (MNO) to combine multiple component carriers (CCs) across the available spectrum to create a wider bandwidth channel for increasing the network data throughput and overall capacity. CA enables the MNO to enhance data rates and can be utilized to aggregate licensed and unlicensed carrier spectrum as well in the downlink, uplink, or both [2].

LTE-Advanced Pro as of 3GPP release 13 (Rel-13) allows the aggregation of a maximum of 32 component carriers with up to 20 MHz bandwidth each. In addition, the enhanced carrier aggregation support aggregation of frequency division duplexing (FDD) as well as time division duplexing (TDD). Therefore, the total channel bandwidth can reach 1 DO MHz. Fig. 10 shows the example ofthe aggregation of five component carriers within the same frequency band in a contiguous way.

As none of these service providers owns a continuous spectrum of 100 MHz, three different modes of carrier aggregation exist within LTE-Advanced: intra band contiguous, intraband non-contiguous and interband carrier aggregation. Fig. 11 illustrates the example ofthe aggregation of three component carriers reside in different frequency bands.

Band A Band B

Carier 1 Carrier 2 Carrier 3

Physically, the possible increase data rates ( >in) in LTE can be justified by the following formula:

where, Cr~ coding rate; / - transport block size is measured in

bits (bit); Nimmq ~ number of the transmission and receiving

antenna. Figure 12a presents the relationship between data rate of MIMO system and channel bandwidth. Results of the calculations are presented in the Table 4.

Channel bandwidth (MHz) 1.4 3 5 10 15 20

Number of subcarriers 72 150 300 600 900 1200

Maximum number of resource blocks 6 15 25 50 75 100

Modulation and Coding Scheme Index 28

Modulation type 64 QAM

Transport Block Size Index. / 26

Transport Block Size (bit) 4392 11064 18336 36696 55056 75376

Maximum peak downlink data rales in LTE (Mbps) SISO 4.2 10.6 17.S 35.1 52.5 71.9

MIMO (2*2) 8.4 21.1 35.1 70.1 105.1 143.8

MIMO (4*4) 16.8 42.2 70.1 140,1 210.1 287.5

Maximum peak downlink dala rates in LTE+LAA (Mbps) MIMO (4*4) 33.5 84,4 139.9 280.1 420.1 575.1

Fig. 11. Inter-band carricr aggregation of 3 * 20 MHz component carriers

Table 4

Maximum peak downlink data rates in LTE+LAA

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SISO MIMCXÏ'ÏI MIMO(4*4)

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1 300

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100

0

1,4 3 5 10 15

Channel bandwidth (MHz)

(a) Peak download data raie in LTE ft)

UMO( LAA MMO(4*1)

20

1j< 3 5 10 15

Channel band-width (MHzJ

Evaluating the effectiveness deployment of LAA technology

The evaluation of implementation effectiveness of the LAA technology can be achieved by the utilization of the radio frequency band in the 5 GHz unlicensed spectrum. Physically, the possible increase LTE capacity can be justified by Shannon's following capacity formula:

C = f *log3(l+-§)> N

!t can be seen that where C is located the channel capacity is measured in megabits per second (Mbps); while the f channel

bandwidth is measured in megahertz (MHz); and the A signal

N

to interference ratio is expressed in decibels (dB). The effective capacity of a multiple-input multiple-output (MiMO) is determined by the following formula:

C = A/*f,*log2(l+|r)'

N

Where M is stated represents the number of the transmission and receiving antenna [10]. The relationship between the capacity of the MIMO system and channel bandwidth is illustrated in Fig. 13.

(b) Peak download data rate in LTE+LAA Fig. 12. The relationship between peak data rate ofLTE network and channel bandwidth

The LTE+LAA data rate increases significantly with the number of the transmission and receiving antenna Nmmq increasing, Channel bandwidth: when the channel bandwidth is wider, the LTE+LAA capacity is greater. The LTE+LAA data rate equals 575.1 Mbps (for MIMO 4*4, W„+f =40Mfe), at

the same time the LTE data rate without using LAA technology (for MIMO 4*4, f^ = 2QMHz) equals 287.5 Mbps only. Fig. 12b

presents the relationship between LTE+LAA data rate of MIMO system and channel bandwidth. Results of the calculations are presented in the Table 4.

It is important to note that the LAA technology support the enhancements for higher-order CA scenarios (up to 32 component carriers). In addition, the maximum number of component carriers has been constrained by the necessary synchronization of the transmission traffic in the PCell (primary cell) and SCell (secondary cell), an increasing complexity of decoding and of raising the payload size of the PUCCH (physical uplink control channel).

This implies that the overload impact on the PCell on the uplink increases with the volume of mobile devices served. Furthermore the higher-order CA induced PUCCH overhead adversely impacts system performance, as well as for mobile devices that are not operating in the CA mode.

It should be underlined that the utilization of PUCCH on the SCell (secondary cell) is an integral aspect of the CA configuration enhancements for higher-order CA scenarios, while balancing the preservation of efficiency and minimizing the number of different control and signaling formats. As part of these enhancements, improvements in the HARQACK feedback and channel state information (CSI) lead to feedback transported over a single UL carrier are envisioned [6].

g 400

LTE+LAA (SISQ) —w— LTE+LAA (MIMO 2*2)

—LTE * LAA ( MIMO 4"4 ) ■ - LTE+LAA (MIMO E'5)

SNR [dB]

Fig, 13. LTE throughput for different MIMO modes

A further increase capacity system can be accomplished via the aggregation of a LTE licensed carrier with one or more unlicensed carriers in 5GHz band. In order to assess the LTE capacity using the LAA technology, we will calculate LTE+LAA system capacity regarding the SINR (Signal to interference Ratio) (Fig. 14) by the following formula:

C=A/*(W,f+fJ*Iogia+^>'

jV

where w( represents the channel bandwidth in the 5 GHz

unlicensed spectrum (MHz).

The LTE+LAA capacity is greater according to Fig. 13 and 14, due to the fact that it utilizes the aggregation of a LTE licensed carrier with one or more unlicensed carriers in 5GHz band. However, the LTE+LAA capacity increases significantly w ith the number of transmissions and receiving antenna increasing, channel bandwidth and the SINR increasing. The LTE+LAA capacity equals 796.1 Mbps (for MIMO 4*4,

W, + f =40MHz and S1NR = 20 dB), at the same time the LTE

capacity without using LAA technology {for M1MO 4*4,f = 20MHz, SINR = 20 dB) equals 388.6 Mbps only.

y

-■-LTE (SISO)

—•— LTElMiWO 4"4)

—LTEtM«Moe-e) -•"LTE+CM [SfâO) -^■'LTE+LAA iMlMO 4'4) -4--LTE+LAA I Ml WO a48)

U

1000 ja eoo

SNR JdB]

Fig. 14. LTE+LAA Throughput for different MIMO modes

Conclusions

The most promising technology for increasing LTE capacity network is LAA technology. The possible solutions for the problems of network overloading and reducing data rate in the heterogeneous networks LTE which show the advantage of LAA technology were analyzed in article. The unlicensed spectrum is utilized as an additional cell exclusively for transmission user data and is unable to guarantee a high quality of service (QoS) in connection with the possibility of free access to unlicensed spectrum. The coexistence between Wi-Fi and LAA schemes on a one radio-frequency channel in the 5 GHz unlicensed spectrum was described. These mechanisms include new technological solutions for client access organizations, such as FBE, LBE, LBT and CCA.

The results show that implementation effectiveness of the LAA technology is related to the increase of data rates in LTE network; an improvement in network capacity and the

minimization of mutual interference with the coexistence of different types of radio access technologies. All those factors contribute to the offloading of LTE technology through unlicensed spectrum (5 GHz) more attractive to mobile operators.

References

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ПОВЫШЕНИЕ ПРОПУСКНОЙ СПОСОБНОСТИ СЕТЕЙ МОБИЛЬНОЙ СВЯЗИ СТАНДАРТА LTE ПРИ ИСПОЛЬЗОВАНИИ НЕЛИЦЕНЗИОННОГО РАДИОЧАСТОТНОГО СПЕКТРА

Степутин Антон Николаевич, Санкт-Петербургский государственный университет телекоммуникаций им. проф. М. А. Бонч-Бруевича, Санкт-Петербург, Россия, steputin@1234G.ru Аль-Амери Хамед Абдо, Санкт-Петербургский государственный университет телекоммуникаций им. проф. М. А. Бонч-Бруевича, Санкт-Петербург, Россия, hamedru2008@gmail.com

Аннотация

Исследованы вопросы повышения пропускной способности сетей LTE путем использования нелицензионного радиочастотного спектра в диапазоне 5 ГГц как один из способов решения проблемы перегрузки базовых станций, снижения скорости передачи данных и нехватки ресурсов гетерогенных сетей стандарта LTE. Представлены технические требования и условия использования нелицензионного спектра в диапазоне 5 ГГц в разных регионах мира. Приведено сравнение механизмов организации доступа к каналу при совместной работе различных технологий радиодоступа в диапазоне 5 ГГц: FBE (Frame Based Equipment) и LBE (Load Based Equipment). Особое внимание уделено описанию совместной работы LTE+LAA и Wi-Fi на одном канале в диапазоне 5 ГГц, где в структуру сети LTE+LAA включены такие новые технологические решения для организации доступа, как FBE, LBE, LBT и CCA. Выполнена оценка эффективности внедрения технологии LAA. В рамках моделирования процесса совместного существования LTE / Wi-Fi представлены результаты расчетов эффективности использования частотного ресурса для сетей LTE и Wi-Fi в отдельности, зависимость максимально допустимых потерь на линии относительно загрузки соты, результаты расчетов скорости передачи данных без применения технологии LAA, зависимость пропускной способности сети LTE от количества антенн и зависимость пропускной способности LTE+LAA от отношения сигнал/шум и ширины канала. На основании проведенного исследования можно сделать вывод о том, что постепенное внедрение данной технологии позволяет успешно справляться с проблемами перегрузки базовых станций и нехватки ресурсов сетей мобильного оператора в крупных городах из-за постоянного роста трафика. Показано, что использование нелицензионного радиочастотного спектра в диапазоне 5 ГГц в сети LTE+LAA значительно увеличивает скорость передачи данных.

Ключевые слова: LTE, Wi-Fi, пропускная способность, агрегация частот, нелицензионный спектр, LAA, LBT, CCA, FBE, LBE. Литература

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Информация об авторах:

Степутин Антон Николаевич, к.т.н., доцент кафедры "Радиосвязи и вещания" Санкт-Петербургского государственного университета телекоммуникаций им. проф. М.А. Бонч-Бруевича; руководитель проекта 1234G.ru; председатель Оргкомитета Международного съезда TELECOMTREND "Технологии мобильной и беспроводной связи. Тренды и перспективы"; автор книги "Мобильная связь на пути к 6G", Санкт-Петербург, Россия.

Аль-Амери Хамед Абдо, Аспирант кафедры "Радиосвязи и вещания" Санкт-Петербургского государственного университета телекоммуникаций им. проф. М. А. Бонч-Бруевича, Санкт-Петербург, Россия