Electromagnetic compatibility research of non-standard LTE-1800 TDD Base stations for Railway

applications and Base stations LTE-1800 FDD

Prof. Dr. Valery Tikhvinskiy1,2, Dr. Sergey Terentiev3, Dr. Mikhail Shelkovnokov3,

Dr. Evgeniy Devyatkin2

1 (Affiliation): Radio Research & Development Institute (NIIR), Moscow, Russian Federation,2 (Affiliation): Moscow Technical University of Communications and Informatics (MTUCI), Moscow, Russian Federation3 (Affiliation): OJSC GlobalInformService (GIS) 1

Regulation Actuality. The band 1710-1885 MHz is allocated by the Radio

Regulations to the mobile service on a worldwide basis and can be allocated

by national communications administrations for use by any radio

technologies included in the IMT family as LTE technology.

A part of this frequency band 1785-1805 MHz is allocated by the

Russian Communications Administration for the construction technological

communication network of LTE standard with time-duplex mode (hereinafter

LTE-1800 TDD) for railway transport.

Technological Actuality. Technological Actuality. It is defined by lack of Technical requirements of 3GPP to

the Spectrum mask of LTE TDD transmitter signal for non-standard frequency band 1785-1805 MHz and

needs of Railway mobile network coexistence in adjacent bands to LTE-1800 FDD band network (n3).

Actuality of EMC Study for LTE-1800 Networks

coexistence

E-UTRA

Operating Band

Uplink (UL) operating band

BS receive

UE transmit

Downlink (DL) operating band

BS transmit

UE receive

Duplex Mode

FUL_low – FUL_high FDL_low – FDL_high

3 1710 MHz – 1785 MHz 1805 MHz – 1880 MHz FDD

4 1710 MHz – 1755 MHz 2110 MHz – 2155 MHz FDD

This frequency band 1785-1805 MHz is not part of the frequency bands standardized

by the 3GPP Partnership Project for LTE networks with TDD duplex mode.

2

Task of LTE FDD with LTE TDD coexistence

The task of spectrum sharing use ensuring between LTE FDD and LTE TDD

networks in adjacent frequency bands was solved for LTE FDD and LTE TDD

network in the 2.6 GHz band were determined by ECC Report 119 and under

conditions for networks operation with frequency spacing of adjacent channels of 5

MHz.

The Russian communications administration has established 5 MHz frequency

spacing requirement to provide an EMC between technological railway network of

LTE-1800 TDD (1785-1805 MHz) and traditional mobile networks of LTE-1800 FDD

(Band 3). The frequency guard intervals (1785-1790 MHz and 1780-1805 MHz)

were established, which do not allow the use of Railway LTE-1800 TDD network for

the transmission and reception of radio signals efficiently.

Therefore, the development of requirements for spectrum edge mask (SEM) and

permissible level of out-of-band emissions (OOB) for LTE-1800 TDD base station

transmitters of railway networks are relevant issues of EMC research, as well as

development of norms of spatial and territorial separation (STS) between these LTE-

1800 TDD with non-standard frequency bands and standard base stations LTE-1800

FDD (Band 3).

+

3

EMC-scenarios for study of LTE-1800 TDD and

LTE-1800 FDD network sharing

b) BS and UE Transmitters LTE-1800 FDD network as source

harmful interferences

A) BS and UE Transmitters LTE-1800 TDD network as source harmful interferences

EMC-scenarios of these research can be divided into two groups

depending on whether the BS (eNB) or UE is source of harmful interference

(aggressor) as is shown in Figures A) and B).

The first group of these scenarios includes EMC- scenarios in

which the transmitting devices of the LTE-1800 TDD railway communication

network are the source of harmful interferences (Fig. a). The second group

includes EMC-scenarios in which the transmitters (TX UE and TX eNB)

LTE-1800 FDD are the sources of harmful interference (Fig. b).

The most difficult scenarios for providing EMC of LTE networks and

developing norms STS are scenarios with indices 1.1.1 and 2.2.2 for

mutual influences of LTE-1800 TDD and LTE-1800 FDD base stations.

These scenarios for EMC assessment and development of norms STS

are determined by the values of acceptable levels of unwanted

emissions. These levels characterize BS or UE transmitters emissions

in outside of BS or UE spectrum bands, which interfere with operation

of receivers BS and UE of other networks. In these scenarios are two

types of unwanted emissions: out-of-band and spurious emissions. The

requirements for these types of transmitter emissions of eNB base

stations are established in Technical Specification 3GPP TS 36.104 and

in ITU-R Recommendation SM.329. 4

RX UE

E-UTRA Band 3

(victim)TX eNB

(agressor)

Guard

Band 5

MHz

OOB/spurious

emission

TX UE

(agressor)RX eNB

E-UTRA Band 3

(victim) Guard

Band 5

MHz

Time

Frequency

Scenario

1.1.1

Scenario

1.1.2

Scenario

1.2.1

Scenario

1.2.2

OOB/spurious

emission

TX eNB

E-UTRA Band 3

(agressor)RX UE

(victim)

Guard

Band 5

MHz

OOB/spurious

emission

RX eNB

(victim)TX UE

E-UTRA Band 3

(agressor) Guard

Band 5

MHz

Time

Frequency

Scenario

2.1.1

Scenario

2.1.2

Scenario

2.2.1

Scenario

2.2.2

OOB/spurious

emission

OOB/spurious

emission

OOB/spurious

emission

Conditions of EMC providing for LTE-1800 FDD radio

access networks

3GPP Technical Specifications for LTE-1800 FDD BS (Band 3) are

established requirements for level of unwanted (spurious) emissions.

Conditions of EMC providing are included:

1. The level of unwanted (spurious) emissions from co-located base station

transmitters in the frequency band of receiver (any from consider receivers)

had to no more than 3GPP requirement to these type emission in the

measurement range of 100 kHz.

2. The interference signal level from co-located TX eNB had to no more than

the set value of the receiver selectivity requirements given in 3GPP Technical

Specifications.

Levels of spurious emissions for LTE-1800 FDD BS (Band 3)

In Result of our study we proposed to provide EMC with the aim of

eliminating the effect of unwanted emissions by following measures:

•have use inter-band filters in Receiver (RX) eNB (Band 3) which

attenuate unwanted emissions in the frequency band 1790-1800

MHz to the level of minus 49 dBm (in the measurement band 1 MHz);

•have use the spectrum signal mask of TX eNB LTE-1800 TDD in the

frequency band 1785-1805 MHz as shown on Figure right (yellow).

Spectrum signal mask of TX eNB LTE-1800 TDD

10 MHz 10 MHz

Frequency

Operating band

unwanted

emissions

Spurious

emissions

Level of unwanted emission measured in 1 MHz bandwidth, dBm

-30

-13

Channel BW

-14dBm, Measurement

bandwidth = 30kHz

-26dBm, Measurement bandwidth = 30kHz

f_offset=1,

015MHz

f_offset=1,5MHz

-13dBm, Measurement

bandwidth = 1MHz

1805

MHz

1785

MHz

f_offset=0,

215MHz

-30dBm, Measurement bandwidth = 1MHz

(36.104, Table 6.6.4.1.2.1-1: BS Spurious

emissions limits, Category B)

f_offset=10,5MHz

1790

MHz

1800

MHz

Total TX Power =

43/46 dBm

-49dBm, Measurement bandwidth = 1MHz

(36.104, Table 6.6.4.3.1-1: BS Spurious emissions limits for E-UTRA BS

for co-existence with systems operating in other frequency bands)-52dBm, Measurement

bandwidth = 1MHz (36.104,

Table 6.6.4.3.1-1)

Definition and providing of norms of spatial and

territorial separation for LTE base stations

Depending on power level of spurious emissions from base station transmitters, the required values of territorial separation

may be:

• 10-40 meters provided that inter-band filters are used at eNB LTE-1800 TDD for railway communications and eNB

LTE-1800 FDD (Band 3) base stations, which is feasible in Urban and Dense Urban areas;

• 50-230 meters for the frequency range 1790-1795 MHz without the use of inter-band filters at base stations eNB

LTE-1800 TDD and eNB LTE-1800 FDD (Band 3), which is acceptable in urban areas and rural areas;

• 250-1000 meters for frequency band 1795-1800 MHz without the use of inter-band filters at base stations eNB LTE-

1800 TDD for railway communications and eNB LTE-1800 FDD (Band 3), which is permissible only in rural areas.

As radio propagation models for predicting the path loss

coefficient LCL [dB] for mobile communications is usually used

Okamura-Hata, COST231-Hata and COST231- Walfisch-

Ikegami empirical models.

To study EMC scenarios 1.1.1 and 2.2.2 under consideration, it

can be considered more better to use the COST231-Walfisch-

Ikegami model, which is designed to calculate a signal level in

small cells with radiuses from 0.02 to 5 km subject to flat earth

surface. In scope of a solved task conditions for providing EMC

can be considered as some restrictions on eNB permissible

placement from each other not exceeding limits of line of sight

(LOS).

Conclusions

1.The research results showed that for the joint use of base stations eNB LTE-1800

TDD for railway communications with a non-standard frequency range and eNB LTE-

1800 FDD (Band 3) and ensure EMC, it is necessary to limit unwanted emission

levels through use of inter-band filters and due to utilization developed spectrum

signal mask for eNB LTE-1800 TDD.

2.The utilization of inter-band filters changes the requirements of norms of spatial

and territorial separation for the considered base stations depending on the relative

orientation of antennas beam and urban conditions (Urban and Dense Urban) or

rural areas (Rural).

3. Calculating values required for territorial separation may be:

• 10-40 meters (inter-band filters, in Urban and Dense Urban areas);

• 50-230 meters (for frequency band 1790-1795 MHz, without inter-band

filters, in Urban areas and Rural areas);

• 250-1000 meters (for frequency band 1795-1800 MHz, without inter-band

filters, only in rural areas).

4.To completely eliminate the influence of interference from the eNB LTE 1800 TDD

for railway communications and eNB FDD-LTE (Band 3), territorial separation norms

have to be 650-2700 meters, which is difficult to do in urban areas and rural areas.

THANK YOU FOR ATTENTION!

2019