ΑΣΥΡΜΑΤΕΣ-ΔΟΡΥΦΟΡΙΚΕΣΕΠΙΚΟΙΝΩΝΙΕΣ

Διδάσκων

Λούβρος Σπυρίδων

Επίκουρος Καθηγητής - ΤΕΣΥΔ

ΔΙΑΛΕΞΗ 7

ΕΠΙΓΕΙΑ ΜΙΚΡΟΚΥΜΑΤΙΚΗ ΖΕΥΞΗ (MW LINK) – ΣΧΕΔΙΑΣΜΟΣ 1ο Μέρος

HopTerminal Terminal

IndoorUnits

IndoorUnits

Terminology

BSC/RNC

The mobile transport networkNetwork evolution

BSC/RNC

Increase capacity

Add sites

The mobile transport networkNetwork evolution

BSC/RNC

Increase capacity

Add sites

Extend SDH rings

The mobile transport networkNetwork evolution

BSC/RNC

Point-to-multipointIncrease capacity

Add sites

Extend SDH rings

The mobile transport networkNetwork evolution

Microwave transmission networks

A microwave transmission network can be considered to consist of fourdifferent subnetworks.

• Traffic network; traffic distribution and traffic related equipment for the transport from BSC/RNC to ”the last site”

• Syncronization network; transport of synchronization signal from BSC/RNC to transmission equipment and radio base stations.

• Management network; for the supervision of every node in the transmission network.

• Radio network; microwave radio communication to carry traffic, synchronization and management.

Microwave systemsMarket Products

Point to Multipoint Radio

Point to Point RadioCapacities per radio hop• MINI-LINK TN R4.0

PDH: 2 - 75xE1, 4 – 80xDS1 SDH/Sonet: up to 4xSTM-1/OC-3Ethernet: up to 600Mbit/sPmp: up to 4 terminals per sector

• MINI-LINK E PDH: 2 – 17xE1, 4 – 16xDS1Ethernet: up to 34Mbit/s (Eth over E3)

• Marconi LH 2.5.4: SDH/Sonet: up to 20xSTM-1/OC-3Ethernet over SDH via OMS 8xx

ΔΙΑΔΙΚΑΣΙΑ ΣΧΕΔΙΑΣΜΟΥ

The prediction cycle (1)

• Free-space loss• Gas attenuation

Link budget

• Rain attenuation• Diffraction – Refraction loss

• Multipath propagation

Quality and Availability

• Interference

”Slow”

”Fast”+

• Obstacle loss• Reflection loss

•BBER •ESR •SESR •UATR

Frequency planningLoss & attenuation Fading prediction

Fade marginObjectivesfulfilled?

No

Yes

Thresholddegradation

Fading probabilityPath loss

Not always presentHave to be predicted

The prediction cycle (2)- influence factors

Link budget

Frequency planningLoss & attenuation Fading prediction

Fade margin

Path lossThresholddegradation

Fading probability

Network topologyFrequency reuseTerrainAntenna propertiesPolarizationModulation ...

HoplengthFrequencyTerrainAntenna heightClimate ...

HoplengthFrequencyPolarizationTerrainClimateAtmosphere ...

Quality and Availability

Diversity improvementObjectivesTx power

Rx thresholdAntenna gainBranching loss

The ITU-R matrix of recommendations

Multip.-Flat

Multip.-Sel.

Rain

Refr.-Diffr.

Fadi

ng

Mec

hani

sms

Frequency arrangement

Fre

quen

cy P

lann

ing

Qua

lity

& A

vaila

bilit

y ITU-T G.821

ITU-T G.826

ITU-T G.827

ITU-T G.828

F.74

6-9

F.74

7-0

P.3

41-5

P.4

53-9

P.5

25-2

P.5

26-1

0P

.527

-3P

.530

-12

P.5

81-2

P.6

76-7

P.8

33-6

P.8

34-6

P.8

35-4

P.8

36-3

P.8

37-5

P.8

38-3

P.8

40-3

P.8

41-4

P.1

057-

2

F.10

93-2

F.55

7-4

F.59

4-4

F.63

4-4

F.69

6-2

F.69

7-2

F.75

1-2

F.38

4-10

F.38

7-10

F.49

7-7

F.59

5-9

F.63

5-6

F.74

8-4

F.10

99-4

P.8

32-2

P.1

407-

3

P.1

510-

0

F.13

30-2

F.16

05-0

F.38

5-9

F.38

6-8

F.63

6-3

F.63

7-3

F.74

9-2

F.38

3-8

F.13

99-1

F.17

03-0

F.16

68-1

F.69

5-0

F.55

6-1

F.75

2-2

P.1

410-

4

Atte

nuat

ion

Loss Atmosph.

Free-space

Reflection

Obstacle

Rain

ITU-RRecommendations

Transmisson project overviewNominal planning - So far nothing is confirmed.

Planned Links

Transmisson project overviewSite acqusition – find the sites

Siteacquisition

Legalaccess • Find and acquire suitable sites

• Site acquisition report • Legal Permits granted • Signed lease contract

Main Activities:

Questions to be answered like:Is there from microwave transmission point of view free line of sight in desiered direction(s)

or has the transmission network topology to be redisigned because of no line of sight?

Transmisson project overviewRealized transmission planning

• Realized Transmission Plan• Network Management System Plan

Main Activities:Transmission

planning

Realized transmission plan

Sites are found, the microwave transmission network topology perhaps redisigned. Detailed microwave planning to meet Quality and Availability objectives, losses, antenna height, frequency planning...

Transmisson project overviewRealized transmission planning

Planned Links Confirmed Links

Transmisson project overviewCivil works

• Civil Work Detailed Design• Site Constructions

Civilworks

Main Activities:

Transmisson project overviewTransmission design and engineering

Transmissiondesign andengineering

Site InstallationDocument

• Site Installation DocumentMain Activities:

expected RF input level, transmitter output power, frequency, antenna size(s) and mounting height(s).

Transmisson project overviewSite integration

Acceptance Test Document

Site integration • Acceptance acc. to contract

Main Activities:

Are the Q&A objectives met? How to test?

ΕΦΑΡΜΟΓΗ

Σχεδιασμός μικροκυματικής ζεύξης κοντινής απόστασης – Short Haul MW Link Design

ΔΙΚΤΥΟ ΜΕΤΑΔΟΣΗΣ (Transmission Network)ΚΙΝΗΤΗΣ ΤΗΛΕΦΩΝΙΑΣ

Τοπολογίες δικτυου

Network Topologies

• Chain • Star• Tree• Ring• Combinations

Chain topology

: BTS Site

: BTS Site connected to BSC (nodal point)

+ Low concentration of equipment at nodal point

- High capacity near nodal point• One link failure affects many

sites• Extended bandwidth

(Time slot grooming, aggregation?)

Rural area commonly. Noise limited

Star topology

: BTS Site: BTS Site connected to BSC

+ Independent paths• Link failure is limited

- Line-of-sight- High concentration of

equipment at nodal point• Require enough space to install

antennas• Interference problems

Dense area commonly. Interference limited.

Tree topolgy

1+1 hop for protection: BTS Site

: BTS Site connected to BSC

+ Line of sight+ Short paths (compared to

Star)• Require smaller antennas

+ Frequency reuse- Availability

• One link failure affects many sites- High capacity near nodal

point• Difficult to expand

(grooming, aggregation?)

Dense area commonly. Interference and noise limited.

Ring topology

: BTS Site

: BTS Site connected to BSC

+ Availability • There is an alternative path

- Line of sight• Every site to be connected with

two other sites- Equipment cost

• MINI-LINK TN, E1 SNCP protectionor Digital Cross Connector required

- High traffic capacity• Require high band width

Network topology

How do I plan the Transmission Network?

: BTS

: BSC or intercity transfer point

Network topologyΥπό φυσιολογικές συνθήκες το δίκτυο χωρίζεται σε διαφορετικές ομάδες Βάσει τοπικού σχεδιασμού. Συνήθως σχεδιάζουμε βάσει clusters

Cluster Solution

• Common topology solution, this is a very common and easy solution touse this.

• A cluster size with less than 25 GSM BTS per cluster is an Ericssonrecommended based on required transmission capacity to the cluster.

• To minimize the number of cascade hops the hub site in each clustershall be positioned in the centre of it.

Network topology

Cluster 4

Cluster 3

Cluster 2Cluster 1

Cluster Solution• Common topology solution.• A cluster size with

10-25 BTS/cluster is common.(GSM)

: BTS

: BSC or Intercity transfer point

BSC

Network topology

BSC

Cluster 4

Cluster 3

Cluster 2Cluster 1

Connection between Cluster – BSC• Protected 1+1 hop is required.• Radios operating in lower

frequency bands are normally used.

• Dimension the links with spare capacity for future expansion

• Each cluster can be connected to a cross-connector node to minimise required link capacity, (grooming) towards BSC.

Radio frequency bands

“High” frequency• Easier to get license• Short range• Generally used in

urban areas• Limiting factor: rain

“Low” frequency• Long range• Good resistance to

rain fading• Generally used in

rural areas• Limiting factor:

multipath fading

Example14 frequency bands [GHz]

38322826231815131110

87

6U6L

Frequency plan, sub-bands18GHz band

11/15 1010 17706.5 18009.5 18716.5 19019.5

12/16 1010 17933.5 18236.5 18943.5 19246.5

21/25 340 18580 18670 18948 19910

31/35 1560 17700 18003 19260 19563

Lower sub-bandTx frequency [MHz]

Upper sub-bandTx frequency [MHz]

Sub-bands

Duplex

“CD” [MHz] Loweredge

Loweredge

Upperedge

Upperedge

- - -

- - -

Upper bandLower band

18/15Duplex (1010 MHz)

18/11

17.7

GH

z

19.7

GH

z

Sub-band pair

High bandradio

Low bandradio

TXRX

17755.00 MHz17755.00 MHz

18765.00 MHz18765.00 MHz

TX RX

18/11 18/15

18/15Duplex (1010 MHz)

17.7

GH

z

19.7

GH

z

18/11

Upperedge

Loweredge

UpperedgeLo

wer

sub

-ban

d

Upp

er s

ub-b

and

Loweredge

Lower and upper frequency edge

11/15 1010 17706.5 18009.5 18716.5 19019.5

Lower sub-bandTx frequency [MHz]

Upper sub-bandTx frequency [MHz]

Sub-bands

Duplex

“CD” [MHz] Loweredge

Loweredge

Upperedge

Upperedge

Lowest usable Tx centre frequenciesat channel spacing of 28 and 14MHz

14MHz 28MHz28MHz

17720.50 MHz7MHz 14MHz

17713.50 MHz

14MHz

Lower edge

Channelspacing

AntennasThe largest antennas are mainly used for long range, low frequency trunk links commonly in rural or semi-rural areas.

A single polarized antenna radiats at one polarization at the time. It can be adjusted for either Vertical (default setting) or Horizontal polarization.

The use of Horizontal polarization is commonly due to the necessesity to reduce interference between nearby radio hops using the same or an adjacent radio channel.

A dual polarized antenna has two feeders and radiates simultaneously on both Vertical and Horizontal polarization.

This gives a possibility to doubble the traffic capacity over the radio hop without employing an extra radio channel.

Antennas

Ø = 0.2m

Ø =

0.6

m

Ø =

0.3

m

Short-Haul LINK Point to point antennas directional parabolic antennas available in the following diameters:0.2m (only as single polarized)

0.3m 0.6m

0.9m 1.2m

1.8m 2.4m

3.0m 3.7m

• Single polarization antennasIntegrated radio mounting up to antenna diameter1.8m

• Dual polarization antennasIntegrated radio mounting to 0.3 and 0.6mantennas.

Antenna performanceHPBW: Half Power Beam Width, the angle where the gain is reduced by 3dB.

A standard performance antenna, Std, is without radome and without absorbing material. Its main use is in rural areas with no interference problems. Thereby only the largest antennas at low frequency are available as Std performance. (1.8m is also available as Std perf. at 13GHz).

All diameters of single polarized are available as HP antennas.

Dual polarized antennas are only available as HP antennas.

Standard performance antennas fulfil at least RPE (radiation pattern enveloppe) class 1 defined in ETSI EN 302 217-4-1 V1.1.3 (2004-12).

High performance antennas fulfil at least RPE class 2 defined in ETSI EN 302 217-4-2 V1.2.1 (2006-06). Most even fulfil RPE class 3.

Antenna performance”Standard performance, Std”

”High performance, HP”All diameters single pol.All diameters dual pol.

Absorbing material

Radom

Reduced side-loobs

Gain and HPBWthe same.

Ø: 1.8m, 2.4m, 3.0m, 3.7m @ 6/7/8GHz1.8m @ 13GHzSingle pol.

HP vs Std antennaNext slide is an axample of Radiation Pattern Envelope diagram, RPE diagram, for two single polarized antennas.

In the RPE a Standard antenna is compared to a High Performance antenna.

Solid lines represent Co-polarization (the polarization the antenna is set to) gain and dashed lines represent cross-polarization gain.

It can be seen that for these antennas the HP antenna is somewhat better, reduced side lobs, from 30 degrees and considerably better from 60 degrees. Co-polarization gain in the main beam for the antennas above is 39.3dBi (at mid-band).

Cross-polar discrimination is minimum 30 dB in azimuth over an angle twice the half power beam width (HPBW ~1.7 degree) of the co-polarized main beam and 32dB within the 1 dB co-polarized contour (=“absolute main beam”).

HP vs Std antennaExample 1.8m, 6GHz, RPE diagram.

Gai

n [d

Bi]

Angle of azimuth relative to main beam axis [degrees]

Std ant.HP ant.

Cross polarization gain

StdHP

Co polarization gain

1.8m 6GHz, Standard and High Performance antennas

PolarizationSingle polarized antennas V (Default)

H

V

H

Vertical pol.V

H

Horizontal pol.

Polarization is set by turning the antenna feeder

Polarization

Carrier

Carrier

InterfererInterferer

The interference situation (and thereby the performance) in the above example can be very much improved by letting one of the hops be horizontaly polarized

Hint: A way to improve the performance would be to use different channels for the two hops. Using an additional channel shall however be the ”last resort” when trying to reduce interference. Frequency channels are costly and always a lack of, so use them with care and try other means first!

Dual polarized antenna• Two wave guide interfaces

One per polarization• Integrated mounting of radios to

0.3 and 0.6m antennas• Separate mounting of radios to

1.2 – 3.7m antennas• Cross polarization discrimination

in main beam, XPD, typically 32dB

Pol.1

Pol.2

Dual polarized antenna

With or without XPIC

Ch.1

Ch.1

Ch. 1, Pol.2 Traffic stream 2

Pol.1

Pol.2

Ch. 1, Pol.1 Traffic stream 2

Dual polarized hop gives the possibility to double the traffic capacity per bandwidth compared to single polarized.

Dual polarized antennaDual polarized antennas are availablefor integrated mounting in the sizes0.3 and 0.6m.

• No flexible waveguide losses, 0.2-1.4 dB gained per terminal depending on frequency

• Reduced necessary output power• Reduced footprint by up to 70%

0.3 m• Frequencies from 15 to 38 GHz

0.6 m• Frequencies from 13 to 38 GHz

Dual polarized antenna

Maximum XPD in main beam

Mid-band main beam gain

Wind loadOperational Requirement• All antennas: 50 m/s

Survival Requirement• 0.2 - 1.2 m: 70 m/s• 1.8 m: 67 m/s• 2.4 - 3.7 m: 55 m/s

FM

Wind load torque M [Nm] at 50m/s:

Antennasize [m]

0.3 1.2 2.41.8 3.0 3.7

1000

3000

5000

7000

9000

11000

0.3 1.2 2.41.8 3.0 3.7

Antennasize [m]2000

6000

10000

14000

18000

22000

Wind load force F [N] at 50m/s:

Do

not u

se fo

r cal

cula

tions

!

Power splitters (coupler)

for RAU1 radios for RAU2 radios

~3dB loss

~3dB loss

Symmetrical Power Splitter1+1 Working stand-by

2+0

Radio 1

Radio 2

~1dB loss

~6dB loss

Asymmetrical Power Splitter1+1 Hot stand-by

Radio 1

Radio 2• 1+1 Hot stand-by (without Space diversity)• 1+1 Working stand-by with Frequency diversity• 2+0 using different channels, same polarization

Power splitters (coupler)Introduced loss

S13

S23

Symmetrical Power Splitter

Radio 1

Radio 2

S13

S23

Asymmetrical Power Splitter

Radio 1

Radio 2

Loss

in d

B p

er b

ranc

h

Flexible wave guide

Flexible wave guides are used to interconnect the radio and the antenna at separate mount

• 2.4m, 3.0m and 3.7m single polarized.• All dual polarized. • RAU1 power splitter to antenna.• Special installations

Configurations1+1 Hot stand-by

1 radio channel

Power Splitter

• 2 radios per terminal connected to 1 antenna • Improved availability by hardware redundancy• 1 radio channel• 1 transmitter active per terminal

• Tx switch on hardware alarm• 2 radios receiving per terminal

• 1 Rx per terminal selected as active• Rx switch on hardware alarm

TX RX

ConfigurationsDiversity

Space diversity is a technique to get ”long” radiohops at ”low” frequencies.

Frequency diversity is a technique to get ”long” radiohops at ”low” frequencies but is rather seldom used due to the need for two radio channels.

In most cases Hot stand-by with space diversity is the prefered solution as it gives equal performance improvment with just one channel.

Working standby with frequency diversity can be the better choice if diversity is needed but to mount two antennas would mean great difficulties and/or costs.

Configurations1+1 Hot stand-by with space diversity

TX RX

• Radios connected to separate antennas • Hardware availability improvement, channel arrangement

and Tx switching as 1+1 Hot Stand• Improved transmission quality by Space Diversity• Rx switching on hardware and radio propagation alarms

• Multipath fading • Reflection

1 radio channel

Configurations1+1 Working stand-by with frequency diversity

2 radio channels

• 2 radios per terminal connected to 1 antenna• Improved availability by hardware redundancy• Improved transmission quality by frequency diversity

• Multipath fading• 2 radio channels• 2 radios transmitting, 2 radios receiving per terminal• 1 receiver per terminal selected as active• Receiver switch on alarm

• Hardware and propagation alarms

Power Splitter

RXTX

Configurations1+1 Working stand by with frequency and space diversity

TX RX

• Radios connected to separate antennas • Hardware availability improvement and channel arrangement

as 1+1 Working Standby• Improved transmission quality by combination of frequency

and Space diversity• Rx switching on hardware and radio propagation alarms

• Multipath fading • Reflection

2 radio channels

For ”severe” propagation conditions.