1

PT

P and P

MP

LinksP

TP

and PM

P Links

RF

Links Overview

2

Full D

uplex Com

munications

Full D

uplex Com

munications

ÿ ÿT

wo stations can talk and listen to each other at the sam

eT

wo stations can talk and listen to each other at the sam

etim

e.tim

e.

ÿ ÿT

his requires two separate m

edia.T

his requires two separate m

edia.

ÿ ÿIn the case of a w

ireless link, 2 separate channels areIn the case of a w

ireless link, 2 separate channels arerequired. T

his is referred to as Frequency D

ivision Duplex

required. This is referred to as F

requency Division D

uplex(F

DD

)(F

DD

)Station 1Station 2

Channel 1

Channel 2

TX

RX

TX

RX

3

Half D

uplex Com

munications

Half D

uplex Com

munications

ÿ ÿT

wo stations have to take turns talking and listening.

Tw

o stations have to take turns talking and listening.S

imultaneous com

munications is not possible. R

equiresS

imultaneous com

munications is not possible. R

equireshandshaking.handshaking.

ÿ ÿT

wo stations share a com

mon m

ediaT

wo stations share a com

mon m

edia

ÿ ÿT

his is referred to as time division duplex (T

DD

)T

his is referred to as time division duplex (T

DD

)

Station 1Station 2

Channel 1

TX

RX

TX

RX

4

Advantages of F

DD

Advantages of F

DD

ÿ ÿM

ore efficient data transfer due to lower overhead

More efficient data transfer due to low

er overhead(required for handshaking).(required for handshaking).

ÿ ÿM

ore efficient use of spectrum in high traffic system

sM

ore efficient use of spectrum in high traffic system

s

ÿ ÿM

ost ITU

frequency bands are structured for FD

D.

Most IT

U frequency bands are structured for F

DD

.

ÿ ÿH

alf the data rate for equivalent data transfer as TD

D.

Half the data rate for equivalent data transfer as T

DD

.

ÿ ÿD

oes not have latency issues associated with

Does not have latency issues associated w

ithhandshaking.handshaking.

5

Advantages of T

DD

Advantages of T

DD

ÿ ÿE

asier to coordinate channels than FD

D.

Easier to coordinate channels than F

DD

.

ÿ ÿR

F H

ardware is potentially less com

plicated and thusR

F H

ardware is potentially less com

plicated and thuslow

er cost.low

er cost.

ÿ ÿInstallation m

ay be simpler.

Installation may be sim

pler.

ÿ ÿO

nly one antenna per T/R

Only one antenna per T

/R

ÿ ÿIn low

traffic networks the spectrum

is utilized more

In low traffic netw

orks the spectrum is utilized m

oreefficiently.efficiently.

6

Point to P

oint (PT

P) Links

Point to P

oint (PT

P) Links

ÿ ÿA

point to point link is one station comm

unicating with

A point to point link is one station com

municating w

ithanother station, 1 to 1.another station, 1 to 1.

ÿ ÿB

oth stations are usually similar in data-rate, m

odulationB

oth stations are usually similar in data-rate, m

odulationand overhead form

at.and overhead form

at.

ÿ ÿF

DD

PT

P links do not require m

edia access control which

FD

D P

TP

links do not require media access control w

hichreduces overhead.reduces overhead.

7

Point to P

oint (PT

P) Links

Point to P

oint (PT

P) Links

ÿ ÿF

DD

PT

P links do not require handshaking, this

FD

D P

TP

links do not require handshaking, thism

inimizes latency.

minim

izes latency.

ÿ ÿP

TP

links are usually used in constant bit rateP

TP

links are usually used in constant bit rateapplications, such as synchronous data transport andapplications, such as synchronous data transport andtrunkingtrunking

applications. applications.

ÿ ÿP

TP

links can be built with extra m

argin to deal with fades

PT

P links can be built w

ith extra margin to deal w

ith fadesand other im

pairments.

and other impairm

ents.

8

System

Pow

er LevelsS

ystem P

ower Levels

ÿ ÿP

oint to point link has extra system gain to increase

Point to point link has extra system

gain to increaseavailability.availability.

ÿ ÿLow

probability of interference to or from other stations.

Low probability of interference to or from

other stations.

ÿ ÿP

to P links typically have narrow

beam antennas.

P to P

links typically have narrow beam

antennas.

9

System

Pow

er Levels PT

P Links

System

Pow

er Levels PT

P Links

Station 1Station 2

TX

= +

18 dBm

Antenna G

ain 30 dBA

ntenna Gain 30 dB

RX

= -42 dBm

RX

Threshold = -72 dB

m

Path loss = -116 dB

10

Point to M

ultipoint (PM

P) Links

Point to M

ultipoint (PM

P) Links

ÿ ÿO

ne base station comm

unicating with m

ore than oneO

ne base station comm

unicating with m

ore than onesubscriber on shared m

edia.subscriber on shared m

edia.

PRIZ

M 2400

11

Point to M

ultipoint (PM

P) Links

Point to M

ultipoint (PM

P) Links

ÿ ÿD

ownstream

path is from the hub to the sub.

Dow

nstream path is from

the hub to the sub.

ÿ ÿU

pstream path is from

the sub to the hub.U

pstream path is from

the sub to the hub.

ÿ ÿC

an use either FD

D or T

DD

Can use either F

DD

or TD

D

ÿ ÿW

ith many subscribers P

MP

is more econom

ical thanW

ith many subscribers P

MP

is more econom

ical thanP

TP

in both hardware and spectrum

utilization.P

TP

in both hardware and spectrum

utilization.

12

Point to M

ultipoint (PM

P) Links

Point to M

ultipoint (PM

P) Links

ÿ ÿD

ata-rates and modulation tend to be asym

metrical to

Data-rates and m

odulation tend to be asymm

etrical toreflect the the asym

metric flow

of data in this type ofreflect the the asym

metric flow

of data in this type ofsystem

.system

.

ÿ ÿM

edia Access C

ontrol (MA

C) is m

andatory for a PM

PM

edia Access C

ontrol (MA

C) is m

andatory for a PM

Psystem

.system

.

ÿ ÿT

ypically IP based, does not w

ork well for constant bit rate

Typically IP

based, does not work w

ell for constant bit rateapplications.applications.

13

System

Pow

er Levels PM

P Links

System

Pow

er Levels PM

P Links

ÿ ÿIn a point to m

ulti-point system pow

er levels must be

In a point to multi-point system

power levels m

ust becontrolled to prevent self interference.controlled to prevent self interference.

ÿT

he H

ub

TX

has a fixed

ou

tpu

t po

wer.

ÿT

he H

ub

RX

has a fixed

gain

.

ÿT

he S

ub

TX

has a variab

le ou

tpu

t po

wer th

at is con

trolled

by

the R

SL

at the H

ub

RX

.

ÿT

he S

ub

RX

will ad

just its g

ain fo

r pro

per R

SL

.

14

System

Pow

er Level PM

P Links

System

Pow

er Level PM

P Links

HU

B

TX

Pw

r = +18 dBm

RSL

= -72 dB

m

Ant. G

ain = 20 dBi

TX

Pw

r = +6 dBm

RSL

= -60 dB

m

Ant. G

ain = 20 dBiTX

Pw

r = +12 dBm

RSL

= -66 dB

m

Ant. G

ain = 20 dBi

TX

Pw

r = +18 dBm

RSL

= -72 dB

m

Ant. G

ain = 20 dBi

Sub 3

Sub 2

Sub 1

Path loss = -130 dB

Path loss = -124 dB

Path loss = -118 dB

15

System

Pow

er Levels PM

P Links

System

Pow

er Levels PM

P Links

ÿ ÿIf an unlim

ited number of channels are available then self

If an unlimited num

ber of channels are available then selfinterference is not a consideration.interference is not a consideration.

ÿ ÿW

ithin a sector subscribers will not interfere w

ith eachW

ithin a sector subscribers will not interfere w

ith eachother due to T

DM

A.

other due to TD

MA

.

ÿ ÿB

etween S

ectors of the same channel interference can

Betw

een Sectors of the sam

e channel interference canoccur, T

DM

A control no longer applies.

occur, TD

MA

control no longer applies.

ÿ ÿC

o-channel interference occurs due to antenna sideC

o-channel interference occurs due to antenna sidelobes, back lobes, im

properly aimed antennas and

lobes, back lobes, improperly aim

ed antennas andreflections.reflections.

16

System

Pow

er Levels PM

P Links

System

Pow

er Levels PM

P Links

ÿ ÿT

o minim

ize self interference...T

o minim

ize self interference...

ÿU

se min

imu

m n

ecessary hu

b T

X p

ow

er to reach

farthest o

ut

sub

scriber.

ÿK

eep farth

est ou

t sub

scribers in

center o

f beam

if po

ssible.

ÿC

arefully ad

just elevatio

n an

gle to

give g

oo

d sig

nal to

farthest o

ut su

bscrib

ers wh

ile still pro

vidin

g u

seable sig

nal

to clo

se in S

ub

s.

ÿM

ake sure S

ub

anten

nas are p

oin

ted co

rrectly, use elevatio

nb

rackets if necessary.

ÿU

se maxim

um

nu

mb

er of ch

ann

els that is p

ractical.

ÿA

ll links sh

ou

ld b

e LO

S, avo

id reflectio

ns an

d o

bstru

ction

s.

17

Media A

ccess Control

Media A

ccess Control

ÿ ÿT

he M

AC

is imp

lemen

ted b

y the h

ub

mo

dem

and

con

trols

Th

e MA

C is im

plem

ented

by th

e hu

b m

od

em an

d co

ntro

lsaccess o

f the su

bscrib

er mo

dem

s to th

e shared

chan

nel. S

pike

access of th

e sub

scriber m

od

ems to

the sh

ared ch

ann

el. Sp

ikeu

ses the D

OC

SIS

(IEE

E 802.14) M

AC

.u

ses the D

OC

SIS

(IEE

E 802.14) M

AC

.

ÿ ÿE

ach S

ub

scriber is assig

ned

on

e or m

ore exclu

sive time slo

ts inE

ach S

ub

scriber is assig

ned

on

e or m

ore exclu

sive time slo

ts inw

hich

they m

ay transm

it data. T

his is referred

to as tim

e do

main

wh

ich th

ey may tran

smit d

ata. Th

is is referred to

as time d

om

ainm

ultip

le access (TD

MA

).m

ultip

le access (TD

MA

).

ÿ ÿT

he H

ub

mo

dem

adju

sts the p

ow

er level of th

e Su

b T

X.

Th

e Hu

b m

od

em ad

justs th

e po

wer level o

f the S

ub

TX

.

ÿ ÿT

he H

ub

mo

dem

synch

ron

izes all sub

s with

the H

ub

and

Th

e Hu

b m

od

em syn

chro

nizes all su

bs w

ith th

e Hu

b an

deq

ualizes p

ath d

elay.eq

ualizes p

ath d

elay.

18

Media A

ccess Control

Media A

ccess Control

ÿ ÿT

he MA

C provides a m

eans for new subscribers to join

The M

AC

provides a means for new

subscribers to jointhe netw

ork.the netw

ork.

ÿ ÿT

he MA

C also provides for equitable sharing of bandw

idthT

he MA

C also provides for equitable sharing of bandw

idthand arbitrating contention am

ong subscribers.and arbitrating contention am

ong subscribers.

ÿ ÿT

he MA

C m

ust assure that all similarly provisioned

The M

AC

must assure that all sim

ilarly provisionedsubscribers have sim

ilar quality of service regardless ofsubscribers have sim

ilar quality of service regardless oftheir location.their location.

19

Bro

adband W

irele

ss E

xam

ple

Bro

adband W

irele

ss E

xam

ple

q qT

ransceiverT

ransceiver

q qM

odulation Techniques

Modulation T

echniques

q qP

ath Analysis

Path A

nalysis

q qA

mplifier P

arameters

Am

plifier Param

eters

q qF

ilter Types

Filter T

ypes

q qF

ilter Technologies

Filter T

echnologies

q qP

LL and Attenuators

PLL and A

ttenuators

20

Tra

nsceiv

er D

esig

n O

utlin

eT

ransceiv

er D

esig

n O

utlin

e

qO

verview

qF

un

ction

ality

qV

ersion

s

qD

esign

Featu

res

qB

asic RF

Co

ncep

ts

21

Key R

F P

ara

mete

rs fo

r Wire

less

Key R

F P

ara

mete

rs fo

r Wire

less

Syste

ms

Syste

ms

•A

ntenna•

Gain

•Sidelobe L

evel

•T

ransceiver•

Frequency Accuracy

•Spurious R

esponse (Regulatory A

gency)•

RM

S Phase Error

•O

utput Power

•M

odem•

Data rates

•R

equired Signal to Noise

•Spurious R

esponse (Regulatory A

gency)

22

(0000) (0001) (0010) (0000) (0001) (0010)

(0011) (0011)

(0100) (0101) (0110) (0111)(0100) (0101) (0110) (0111)

(1000) (1001) (1010) (1011)(1000) (1001) (1010) (1011)

(1100) (1101) (1110) (1100) (1101) (1110) (1111)

(1111)

(00) (00)

(01) (10)(01) (10)

(11)

(11)

Modula

tion T

echniq

ues

Modula

tion T

echniq

ues

BP

SK

QP

SK

16QA

M

(0) (1)(0) (1)

23

Modula

tion W

ith N

ois

eM

odula

tion W

ith N

ois

e

BP

SK

QP

SK

16QA

M

24

Manufacturer:

SP

IKE

Technologies

Path Length

15.0 m

i.

Subscriber S

tation B

ase Station

Transm

it Frequency

3.550G

Hz

Transm

it Frequency

3.450G

Hz

Antenna T

ransmit G

ain19.0

dBi

Antenna T

ransmit G

ain20.0

dBi

Antenna R

eceive Gain

19.0dB

i A

ntenna Receive G

ain19.6

dBi

IF B

andwidth

6.000M

Hz

IF B

andwidth

6.000M

Hz

Receiver N

oise Figure

6.5dB

Receiver N

oise Figure

5.5dB

UP

LIN

K D

OW

NL

INK

Subscriber U

nit Tx O

utput25.0

dBm

Base T

ransmitter O

utput27.0

dBm

Output B

ackoff5.0

dB O

utput Backoff

5.0dB

Subscriber T

ransmit P

ower

20.0dB

m B

ase Transm

it Pow

er22.0

dBm

Back-off to B

alance Path

0.0dB

Back-off to B

alance Path

0.0dB

Tx F

ilter Loss0.0

dB T

x Filter Loss

0.0dB

Transm

ission Line Loss1.0

dB T

ransmission Line Loss

1.2dB

Tx D

uplexer Loss0.0

dB T

x Duplexer Loss

1.5dB

Subscriber T

x Antenna G

ain19.0

dBi

Base T

x Antenna G

ain20.0

dBi

Subscriber E

IRP

(dBm

)38.0

dBm

Base E

IRP

(dBm

)39.3

dBm

Subscriber A

verage EIR

P (W

atts)6.3

W B

ase Average E

IRP

(Watts)

8.5 W

Subscriber M

ax EIR

P (W

atts)20.0

W B

ase Max E

IRP

(Watts)

26.9 W

Up Link P

ath Loss131.1

dB D

own Link P

ath Loss130.9

dB

Base R

x Antenna G

ain19.6

dBi

Subscriber R

x Antenna G

ain19.0

dBi

Transm

ission Line Loss1.0

dBi

Transm

ission Line Loss1.2

dB

Base R

x Signal Level

-74.5dB

m S

ub Rx S

ignal Level-73.8

dBm

Therm

al Noise P

ower

-102.1dB

m T

hermal N

oise Pow

er-100.8

dBm

Req

uired

C/N

(Lan

City)

25.0dB

Req

uired

C/N

(Lan

City)

25.0dB

Final M

argin2.6

dB F

inal Margin

2.0dB

Dow

nlink Limited B

y:0.6

dB

Usab

le Marg

in:

2.0d

B

PR

IZM

3500 RF

PA

TH

AN

AL

YS

IS

25

Receive

LN

AG

ain

10 MH

zR

eferenceO

scillator

IF

Transm

it

BPF

SAW

SP

A

LD

1

Analog

Atten

Gain

BPF

Ceram

ic

Analog

Atten

Transceiver Block DiagramTransceiver Block Diagram

Digital

Atten

Digital

Atten

PLL

#1

PLL

#2

External

Reference

BPF

Helical

Gain

BPF

Ceram

ic

MC

U &

Control

Loop

Loop

Loop

Loop

BPF

Ceram

icB

PFC

eramic

DUPLEXER

Res.

Coup.

RSSI

26

Am

plifie

rs - C

ritical P

ara

mete

rsA

mplifie

rs - C

ritical P

ara

mete

rs

•G

ain / S

tability

•L

inearity / O

utp

ut 3rd

Ord

er Intercep

tP

oin

t ( OIP

3 )

•O

utp

ut P

ow

er / 1dB

Co

mp

ression

Po

int

qN

oise F

igu

re

27

“ “Ideal

Ideal” ” A

mplifie

r Gain

Am

plifie

r Gain

Linear Gain Amplifier

1 10 100

1000

10000

100000

0.010.1

110

1001000

Pin (milliwatts)

Pout (milliwatts)

Linear Gain Amplifier

0 10 20 30 40 50 60

-30-20

-100

1020

3040

Pin (dBm)

Pout (dBm)

28

Actu

al A

mplifie

r Perfo

rmance

Actu

al A

mplifie

r Perfo

rmance

F1 F

22515.0 2515.1

F1-D

2514.9

Frequency (M

Hz)

F1

+D

2515.2F

2-F

10.1

F2

+F

15030.2

29

Mixers

Mixers

•M

ixers are the key component for F

requency Conversion

•C

an be used for either Up or D

own C

onversion

•T

he output response is actually: N L

O +

M R

F

RF

IN

Radio F

requency ( RF

)

IF IN

( IF ) Interm

ediate Frequency = L

O + R

F

X35.75 M

Hz

LO IN

384.25 MH

zL

ocal Oscillator

420 MH

z( 360 M

Hz )

30

Filte

r Types

Filte

r Types

Amplitude

fo

Frequency

qB

and

Pass

qL

ow

Pass

qH

igh

Pass

qB

and

Sto

p

qD

iplexer

31

Filte

r Technolo

gie

sFilte

r Technolo

gie

s

Type

Advantages

Disadvantages

- Lum

ped Elem

entSm

all size, Low

costL

ow F

req Lim

it

- Microstrip/Stripline

Planar, H

igh Repeatability

Large in Size

- Ceram

icSm

all size, Low

Cost

Low

Freq L

imit

- Cavity

High Q

High C

ost, Large

- SAW

High R

ejection "in Close"

High L

oss ( Surface A

coustic Wave )

32

Transceiver Block Diagram

Receive

Receive

LN

AG

ain

10 MH

zR

eferenceO

scillator

IF IF

Transm

itT

ransmit

BPF

SAW

SP

A

Analog

Atten

Gain

BPF

Ceram

ic

Analog

Atten

Digital

Atten

Digital

Atten

PLL

#1

PLL

#2

External

External

Reference

Reference

BPF

Helical

Gain

BPF

Ceram

ic

Loop

Loop

Loop

Loop

BPF

Ceram

icB

PFC

eramic

DUPLEXER

Res.

Coup.

RSSI

PL

L1a &

2a

PL

L1b &

2b

•Phase L

ocked Loops ( P

LL

s ) -Stabilize the VC

Os to a R

eference Oscillator

33

Basic

Phase L

ocked L

oop

Basic

Phase L

ocked L

oop

XL

oopF

ilter

Vtune

Output

Div by N

Div by R

~Reference

Oscillator

10 MH

zP

hase C

omparator

V3.0 O

nly

Div by 4

Prescaler

PL

L C

hipV

CO

34

Base

Station

SU

r = 1000 ft

Pr =

-53 dBm

Loss =

-90 dB

SU

r = 1 m

ileP

r = -67 dB

mL

oss = -104 dB

SU

r = 6 m

ileP

r = -83 dB

mL

oss = -120 dB

ER

P=5W

•Subscriber R

eceive power estim

ated and measured at installation

•M

odem P

ower C

ontrol will com

pensate for approx +15 dB

of signal variation

•Sam

e attenuator setting used on Transm

it side

•B

ase Station will receive pow

er at same level from

all Subscribers

•Subscriber R

eceive power estim

ated and measured at installation

•M

odem P

ower C

ontrol will com

pensate for approx +15 dB

of signal variation

•Sam

e attenuator setting used on Transm

it side

•B

ase Station will receive pow

er at same level from

all Subscribers

System Pow

er ControlSystem

Power Control

35

•Digital A

ttenuators

•C

oarse gain selection

•Step Size / 2dB

•Analog A

ttenuators

•Fine Step Size / < .1 dB

•Fine gain selection and tem

peraturecom

pensation

Varia

ble

Atte

nuato

rsV

aria

ble

Atte

nuato

rs