making tetra compliant with fcc rules - · pdf filebackground tetra is an standard defined by...

Making TETRA compliant with FCC rules

Jose M. Martin

Executive Vice President & Chief Operating Officer

PowerTrunk Inc.

One Platform, Multiple Technologies: TETRA, P25, WiMAX

The Hilton, New York City

17 June 2010

Background

TETRA is an standard defined by ETSI (European

Telecommunication Standards Institute), a private

association subject to the French law.

TETRA’s Air Interface (including the physical layer) is defined

by ETSI EN 300 392-2 (trunked mode operation) and by ETSI

EN 300 396-2 (direct mode operation).

The RF TETRA signal does not meet several mandatory

requirements described by FCC 47 CFR 90.

Applicable FCC requirements (not met by TETRA)

Mask B (equipment with audio low pass filter). As

defined by FCC 47 CFR § 2.1049 § 90.210.

Occupied bandwidth < 20 KHz1. As defined by FCC

47 CFR § 2.1049 & 90.209.

1Mean powers radiated below the lower and above the upper frequency

limits shall be each equal or less than 0.5 % of the total mean power radiated

by a given emission.

Possible modifications to meet FCC rules

Modulation type: π/4-DQPSK1

Symbol rate: 18 Ksymbol/s1

Modulation filter: root raised cosine (RRC)

filter with roll-off factor α=0.352

1Modifying any of the first two would involve

losing interoperability with standard equipment. 2The roll-off factor can be changed within a

range of values while interoperability is kept.

TETRA square raised cosine spectrum

TfforfG

Tf

Tfor

TffG

TfforfG

2

10)(

2

1

2

1

*2

1**2sin1*5.0)(

2

11)(

Where:

α: roll-off factor (0.35 is the standard value)

T: symbol duration (55.55 microseconds is the standard value)

Occupied bandwidth vs. roll-off value

Roll-off factor (α) RRC Modulation Filter

Occupied Bandwidth (KHz) (as defined FCC 47 CFR § 2.1049) with Square Windowed version RRC filter1

Occupied Bandwidth (KHz) (as defined FCC 47 CFR § 2.1049) with

Hamming Windowed version RRC filter 0.05 18.703 19.969 0.1 19.055 20.250

0.15 19.406 20.602 0.2 19.758 20.953

0.25 20.250 21.445 0.3 20.742 21.867

0.35 (TETRA standard)

21.305 22.359

0.4 21.938 22.922 0.45 22.570 23.484 0.5 23.273 24.680

1Practical implementation of square windowed RRC filter is

contemplated by ETSI EN 300 392-2.

TETRA 0.35 and 0.2 vs. Mask B (theoretical)

TETRA 0.35 and 0.2 spectrum (practical)

Blue: 0.35

Yellow: 0.2

TETRA 0.35 vs. Mask B (lab)

FAIL

TETRA 0.2 vs. Mask B (lab)

PASS

Frequency Band (MHz) Rule / Limit TETRA

Standard TETRA 0.2

410-430

Occupied Bandwidth

FCC Part 90: 20KHz No pass 1 Pass 1

RSS-119: 20KHz No pass 1 Pass 1

Emission Mask

FCC Part 90 with Audio LPF: Mask B No pass 1 Pass 1

FCC Part 90 without Audio LPF: Mask C No pass 1 Pass 1

RSS-119: Mask C No pass 1 Pass 1

450-470

Occupied Bandwidth



Emission Mask


FCC Part 90 without Audio LPF: Mask C No pass 1 Pass 1

RSS-119: Mask C No pass 1 Pass 1

806-809 /

851-854

Occupied Bandwidth



Emission Mask


FCC Part 90 without Audio LPF: Mask H No pass 1 No pass 1

RSS-119: Mask G No pass 2 Pass 2

809-824 /

854-869

Occupied Bandwidth



Emission Mask


FCC Part 90 without Audio LPF: Mask G No pass 2 Pass 2

RSS-119: Mask G No pass 2 Pass 2

Frequency sub-bands vs.

FCC & IC applicable

rules

TETRA 0.2 performance issues (1)

Increment of peak to average ratio (PAR)

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8

Peak power/Mean power (PAR) (dB)

CCDF for PI/4 QPSK modulation with RRC filter.

1e-007

1e-005

.001

.1

Pro

ba

bili

ty

ALPHA=0.1

ALPHA=0.2

ALPHA=0.3

ALPHA=0.35

∆PAR ≈ +1.3 dB

Involving the 1 dB

compression point P1dB

for the amplifier is

increased.

State-of-the-art RF

hardware is compliant.


Increment of inter-symbol interference (ISI)

Lab tests have shown

that the quality of

the reception stays

within the limits

defined by ETSI EN

300 392-2 and EN

300 396-2 0 40000 80000 111111

Time (ns)

Eye pattern with PI_4 QPSK modulation

-40

-20

0

20

40ALPHA=0.2

RC filter

0 20000 40000 60000 80000 100000

Time (ns)

Eye pattern with PI_4 QPSK modulation

-40

-20

0

20

40ALPHA=0.35

RC filter

Eye Patterns TETRA 0.35 and 0.2


Field tests have shown no operational loss of performance1

0.35 0.2 1Source: PowerTrunk (BC Hydro trials in Vancouver area)

TETRA 0.35 and TETRA 0.2 interoperability

TETRA

network

TETRA 0.35 TETRA 0.21

1TETRA 0.2 equipment can pass 100 % of the TETRA Interoperability

Profile (TIP) tests as defined by the TETRA Association, interoperating

with standard equipment from all vendors.

Find TIPs at www.tetra-association.com

0.35 or 0.2

TMO TMO

DMO

http://www.tetra-association.com/



Frequently Asked Questions (1)

Is the PowerTrunk-T TETRA implementation really TETRA ?

YES, because it is interoperable with standard TETRA

equipment. The modification of the roll-off factor is not of a

different nature from that of many implementation decisions.

Did PowerTrunk-T receive type acceptance from the FCC and

Industry Canada ? YES

Does the modification involve HW changes ? NO. The

equipment can be re-flashed with the standard software at

any time.

Frequently Asked Questions (2)

Should the FCC grant the waiver requested by the TETRA

Association so that TETRA 0.35 can be accepted in the United

States ? YES, because TETRA has been deployed in more than

100 countries and no interference has been reported so far

(in many cases coexisting with P25 and other technologies).

TETRA 0.2 is available now, but using the same software than

in the rest of the world is a very desirable goal.

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