CT0173en.001( Overview).ppt

1 © NOKIA CTDF 0173 / 20.9.1999 / Sanjiva Sabanayagam

Welcome to

FlexiHopper Course


OverviewOverview

• Power supply unit

• Modem board includes:

• microprocessor environment

• digital signal processing (RATS ASIC and two CIAD ASICs)

• analog signal processing (TX and RX antialiasing filters)

• analog measurements

• Single cable interface (COBRA)

• AD/DA conversion

• IF unit

• Microwave unit


FlexiHopper Block Diagram

Indoor Unit

.

.

.

C I

uP 302 x 2

MUX ASICLineInter-face

CICI DC/DC

Pow

Q1/LMP

FlexBusFlexBus

Single-cable

DSP ASIC

uP 302

DC/DC

C I

2M

Outdoor Unit

TX/RX filt.LNA

Duplex

HPA

LO

IQ-MOD

LO Ant

MIX

MWUPLL

AGC+filt.

IF-LO

IQ-demod.

Modem IF-parts MWU

Power/CI

2...16x2M

( Cable Interface)


Nokia FlexiHopper Outdoor Unit - Mechanical ConstructionOutdoor Unit - Mechanical Construction


Customer Specs (not guaranteed)Customer Specs (not guaranteed)• Programmable capacities 2x2, 4x2, 8x2 and 16x2

• Modulation method Pii/4-DQPSK

• Input power < 25W

• Flexbus: Single cable for power and data.

• Channel Spacing for 2*16 E1- 28 MHz

FrequencyGHz

IF frequencyMHz

Nominal TXpower/dBm

Treshold2x2Mbittypical/dBm




13 266 19 -90 -87 -84 -81

15 420728644

19 -90 -87 -84 -81

18 1010 16 -90 -87 -84 -81

23 12321008

16 -89 -86 -83 -80

26 1008 16 -89 -86 -83 -80

38 1260 16 -86 -86 -83 -80


MP

OUTINOUTINOUT INOUTIN

LMP PWR _ + Q1 Q2 FB1FB2

Flexihopper Radio Link Family FeaturesFlexihopper Radio Link Family Features

• Software download• Selectable interleaving (off, 2-depth, 4-depth)• Forward error correction ( FEC)• MTBF estimation 290 000 hours• Fading margin measurement • Temperature range - 40ºC to + 55ºC• Size W x H x D 210mm x 230mm x 80mm - 165mm• Weight without antenna and alignment app. 3.5 to 4.5 kg• ALCQ or adaptive level control with quality measure• Controlled by Node manager, Q1 or service terminal emulator


FEC ( FEC ( Forward Error CorrectionForward Error Correction) & Interleving ) & Interleving • Nokia FlexiHopper radios use forward error correction (FEC) and interleaving to

improve signal quality.

• The FEC is continuously on and the interleaving is selectable between off, 2-depth, and 4-depth modes.

• The forward error correction uses Reed-Solomon coding (RS(63,59)). The code uses 4 redundancy symbols for every 59 data symbols, so the redundancy of the coding is 6.4%. Together with interleaving also errors of burst type can be corrected. Maximum error correction effectiveness is achieved with 4-depth interleaving.

• When the interleaving is in use, transmission delay increases slightly .This is normally not a problem, but in long chains of radio-links the delay cumulates, and it might be necessary to turn the interleaving off. Acceptable delay for a chain of links should be determined in transmission planning stage and the interleaving status set accordingly.

• Recommended " Interleaving to be OFF in Condition"


Automatic fading margin measurementAutomatic fading margin measurement

• During the commissioning of a microwave radio, it is possible to measure the fading margin of the radio hop.

• Traditionally this has required much work and additional hardware, such as RF (radio frequency) attenuators.

• In Nokia FlexiHopper, the fading margin measurement is automatic and can be started simply by using software.


ALCQ( ALCQ( Adaptive Level Control with Quality Measure)Adaptive Level Control with Quality Measure)

• ALCQ is a method for automatic transmit power control. This feature enables the radio transmitter to increase or decrease the transmit power automatically, according to the response received from the other end of the hop. This approach achieves more efficient utilization of radio frequencies than the constant level approach.

• The controlled use of transmit power reduces interference between systems, which in turn allows tighter packing of radio links within the same geographical area or at network star points.

• The maximum transmission power is set with Hopper Manager. When ALCQ is in use, the radio always tries to transmit at minimum power. If the fading increases rapidly (multipath fading), the radio reacts immediately by increasing the power, but not higher than the set maximum value. After the fading conditions resume to normal, the power is gradually decreased. ALCQ also reacts to slow changes in fading conditions by gradually increasing the transmission power.


Automatic Fading Margin Measurement

STATION 1 STATION 2

CONTROL CONTROL

DUPLEXFILTER

DUPLEXFILTER

TRAN

SMIT

TER

TRAN

SMIT

TER

REC

EIVE

R

REC

EIVE

R

MAIN SIGNAL

CONTROLS

Prx/dBm

Pdet/dBPsig,det

Pthni,detPth,detPni,detPn,det

Pn Pni

Pthn

Pthn

i

Psig

ACTUALFADE MARGIN

CT0173en.001( Overview).ppt

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