For internal circulation of BSNL only

E2-E3

E &WS

Radio MODEM

For internal circulation of BSNL only

WELCOME

• This is a presentation for the E2-E3 E&WS

Module for the Topic: Radio MODEM

• Eligibility: Those who have got the Upgradation

to from E2 to E3.

• This presentation is last updated on 26-3-2011.

• You can also visit the Digital library of BSNL to

see this topic.

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RADIO MODEM

Long distance connectivity to medium and large

enterprise customers.

It is to establish private networks facilitating

internal communications like office data, inter

office information from various units spread

across the country.

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Limitations of legacy L/L

Local leads are more suitable for speed below

2Mbps.

Copper has speed and distance limitations.

Laying of OFC is not possible.

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Features of RADIO MODEMS

These links work on the wireless principle

based on line of sight operation.

It comprises of Transmitter-Receiver on both

sides with necessary interface for feeding in &

out.

This system uses free band (2GHz).

These systems are low cost.

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Features contd…

Data transmission is in the form of Ethernet on the

system.

Interface for interconnection: V.35 to Ethernet

convertors

Data speeds: Upto 4MBPS (supports speeds upto 10

MBPS.)

Distance range: upto 10 kms, but extendable,

depends on LOS and option taken

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Features contd…

Antenna height: a. BSNL End: Either exchange or

BTS tower is used to give maximum height as per

need. The needed height is decided by survey

calculations. It also depends on the height of antenna

at customer site. This varies from case to case.

b. Customer end: Roof top or any structure available.

If height needed is more and no structure is available,

a tripod type mast is erected for the antenna. It is

available in lengths upto 20 metres. Normally the

antenna height at customer end varies from 3m to

20m.

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FEATURES OF RADIO MODEM

RADWIN MAKE (M/s SM CREATIVE)

FREQU: ISM BAND 2.4 GHz AND 5.8GHz

DATA TRANS: ETHERNET

INTEFACE: V35 TO ETHERNET

SPEED: UPTO 10MBPS (4MBPS AT

PRESENT)

DISTANCE: UPTO 10 KM

ANTENNA HT: ROOF TOP/ 3M TO 20M

POWER: 230V AC

COST: APPROX. 1.5LAKHS

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FEATURES contd…

MODULATION: 1. FHSS 2. DSSS

Tx POWER LIMITS: 1 WATT EIRP

PEAK POWER DENSITY: NOT MORE THAN 8 dB

FREQUENCY RANGE: 2400 MHz TO 2483.5 MHz

5725 MHz TO 5825 MHz

5. PROVISION FOR 1+1 S/B MODE

6. ORDER WIRE FACILITY CAN BE PROVIDED.

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ADVANTAGES

1.OVERCOMES LIMITATIONS OF COPPER

2.SPEED UPTO SEVERAL MBPS

3.WORKS BEYOND 20KM

4.MORE RELIABLE THAN COPPER

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Functional & Technical Requirements

of Radio Modem Equipment

• Data Rates : The modem shall support one or more of

the following data rates.

• i) 64 Kbps

• ii) 128 Kbps

• iii) 256 Kbps

• iv) 512 Kbps

• v) 2048 Kbps (E1)

• vi) 2 *2048 Kbps (2xE1)

• vii) 4 *2048 Kbps (4xE1)

• viii) 8 *2048 Kbps (8xE1)

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Functional & Technical Requirements

of Radio Modem Equipment

• Digital Line Interface: The modem interface shall

be either hardware configurable (e.g. DIP

Switches) or software configurable (e.g. AT

commands) to act as Data Communication

Equipment (DCE) or Data Terminal Equipment

(DTE) as per the requirements.

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Functional & Technical Requirements of

Radio Modem Equipment

• Digital Interfaces:

• V.35 / V.36 (ISO – 2593) 34 pin physical

connector.

• V.11 (ISO – 4902) 37 pin physical connector

• V.36/V.35/V.II (ISO – 2110) 25 pin physical

connector

• G.703 Co-directional interface at 64 Kbps with

ISO-2110 connector

• G.703 physical interface with ISO 2110

connector with 120 Ohm balanced for 2048

Kbps. ITU-T recommendation G.703

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Modulation

The radio modems shall conform to one of the

following modulation:

i) Frequency Hopping Spread Spectrum (FHSS)

ii) Direct Sequence Spread Spectrum (DSSS)

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Frequency Hopping Spread

Spectrum (FHSS)

FHSS modulation shall make use of at least 75

well defined, non-overlapping channels of

hopping positions separated by the channel

bandwidth as measured at 20 dB below peak

power.

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FHSS

The maximum 20 dB bandwidth of hopping channel is 1

MHz.

The average time of occupancy on any frequency shall

not be greater than 0.4 seconds within a 30 seconds

period.

The system shall hop to channel frequencies that are

selected at the system hopping rate from a pseudo

randomly ordered list of hopping frequencies.

Each frequency must be used equally on the average by

each transmitter. The system receivers shall have shift

frequencies in synchronization with the transmitted

signals.

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Direct Sequence Spread Spectrum

(DSSS)

Direct Sequence Spread Spectrum (DSSS)modulation is a form of modulation in which bothdata to be transmitted and known codesequence are combined and used to directlymodulate a carrier.

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Transmitter parameter limits

1. Effective radiated power: For FHSS andDSSS : The maximum peak output powershall not exceed 1 watt effective isotropicradiated power (EIRP).2. Peak power density: For DSSS, the peakpower spectral density shall not be greaterthan 8 dBm in any 3 kHz band during anytime interval of continuous transmission. Forthe hybrid system the power densityrequirement shall comply for the directsequence operation with the frequencyhopping turned off.

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Processing Gain

The ratio in dB of the signal-to-noise ratio with thesystem spreading code turned off to the signal-to-noise ratio with the system spreading code turnedon.The processing gain represents the improvement tothe received signal-to-noise ratio after filtering to theinformation bandwidth from the spreading /dispreading function.The processing gain of a DSSS shall be at least 10dB.Hybrid systems that employ a combination of bothdirect sequence and frequency hopping modulationtechniques shall achieve a processing gain of atleast 17 dB from the combined techniques.

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Frequency range

The frequency range of the radio modem shalllie within one of the following band:i) 2400 MHz to 2483.5 MHz (FL>2400 MHz andFH < 2483.5 MHz)ii) 5725 MHz to 5825 MHz (FL>5725 MHz andFH < 5825 MHz)

For internal circulation of BSNL only

Field strength of emissions

(Specified at a distance of 3 meters.)

Fundamental

Frequency

Field Strength

fundamental

(millivolts/meter)

Field Strength of

Harmonics

(microvolts/meter)

2400 – 2483.5 MHz 50 500

5725 – 5825 MHz 50 500

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Spurious emissions limits for

receivers

Narrowband

30 MHz – 1000 MHz -57 dBm

Above 1 GHz – 12.75 GHz - 47 dBm

Wideband

30 MHz – 1000 MHz -107 dBm/Hz

Above 1 GHz – 12.75 GHz - 97 dBm/Hz

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Alarm Indications

a) Transmit power failure

b) Receive power below threshold

c) Radio sync loss

d) Power up

e) DTE input loss

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Diagnostics

i) Local loop back test

ii) Remote loop back test

iii) Loop back to remove end

iv) Receive power level determination

v) Receive power signal quality determination

vi) Quasi random sequence generator

vii) Data output failure

viii) System log capability for alarms and test

results

ix) Local & remote monitoring

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