FlexWave Host Unit II Installation Guide

Cascading Host Units

C

A SC A D I N G

H

O S T

U

N I T S

NOTE: Host-to-Host and Multi-Host systems do not support cascading.

FlexWave systems can be cascaded, which allows a single sector to be simulcasted from Remote Unit to Remote

Unit. By utilizing a fiber daisy chain between Remote Units, you eliminate the need for fiber home-runs between the common Host Unit and simulcasted Remote Units.

Electrical cascading allows you to maximize fiber efficiency, by eliminating the need for individual home-run/star topology configurations, thereby saving on fiber costs, as well as fiber installation costs.

Figure 14

shows a cascade system, in which there is one Host Unit with a single Remote Unit connected to it, and then a second Remote Unit connected to the first Remote Unit. In this configuration, the RF signal passes from the

Host Unit through Remote Unit 1 where it is retransmitted to Remote Unit 2; RF will be present on both Remote

1 and Remote 2.

Host Unit Remote Unit 1 Remote Unit 2

Figure 14.

Cascaded System

Cascade restrictions and requirements are listed below.

•

Up to 8 Remote Units can be cascaded in a system, and each Remote Unit can only subtend one Remote Unit that must be connected directly to it.

•

The maximum number of Remote Units that can be cascaded is 16.

•

A Remote Unit can only cascade to another Remote Unit of the same type. That is, a PRU can only cascade another PRU, and a DRU can only cascade another DRU.

•

Each Remote Unit in a cascade must contain the same DART type or a subset of the DARTs contained in the first Remote Unit of the chain. The DARTs in each Remote Unit of a cascade must be in the same slots as the

DARTs in the first Remote Unit of the chain. DART linking to the Host Unit is the same on every Remote Unit in a cascade.

•

The fibers in and out of a Remote Unit must follow a N+4 rule. That is, if a Remote Unit has an input fiber on

SFP 1, then the output is on SFP5. This applies to all Remote Unit, with the exception of the last cascaded

Remote Unit as it would not require outgoing fibers. See Figure 15 on page 65

for an illustration of this rule.

•

All cascaded Remote Units must have the same number of upstream (RX) and downstream (TX) fibers. If 4 fibers from the Host Unit are directed to the Remote Unit, 4 fibers must cascade to the next Remote Unit. The last Remote Unit in a cascade does not have downstream fibers. This ensures that all RF on a Remote Unit can be cascaded. See

Figure 15 on page 65

for an illustration of this rule.

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Host Unit II Installation Guide

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Cascading Host Units

1

1

Host

Unit

Remote

Unit

1

5 1

1 Fiber Cascade

Remote

Unit

15

5 1

Remote

Unit

155

Host

Unit

1

2

1

2

Remote

Unit

1

5

6

2 Fiber Cascade

1

2

Remote

Unit

15

5

6

1

2

Remote

Unit

155

Host

Unit

1

2

3

1

2

3

Remote

Unit

1

5

6

7

3 Fiber Cascade

1

2

3

Remote

Unit

15

5

6

7

1

2

3

Remote

Unit

155

Host

Unit

1

2

3

4

1

2

3

4

Remote

Unit

1

7

8

5

6

4 Fiber Cascade

1

2

3

4

Remote

Unit

15

5

6

7

8

1

2

3

4

Remote

Unit

155

NOTE:

The Host Unit SFPs can be any of the available SFPs (1 - 8).

Figure 15.

Matching Host Unit and Cascaded Fibers

For information on how to configure cascaded Host Units, refer to the “Cascaded Systems” chapter of the EMS guide that corresponds to the FlexWave Software Release installed on the Host Unit.

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Host Unit II Installation Guide

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Cascading Host Units

FlexWave systems can be configured to operate in Point-to-Multipoint Star and Cascade configurations.

In a point-to-multipoint star configuration, the Host Unit provides the interface between a single group of BTSs

and up to eight Remote Units, each of which is linked directly to the Host Unit by an optical fiber path. Figure 16

shows a Prism system in a star configuration.

Remote

Unit

Remote

Unit

Remote

Unit

Up to 8 Remote Units

Remote

Unit

Remote

Unit

Remote

Unit

Remote

Unit

Remote

Unit

Host Unit

Figure 16.

Star Configuration

In a point-to-multipoint star configuration, in the forward path (Host Unit to Remote Unit), the digitized RF signals are replicated for transport to each of the Remote Units. In the reverse path (Remote Unit to Host Unit),

RF signals from each Remote Unit are transported independently to the Host Unit over dedicated fibers. Within the Host Unit, the signals from all the Remote Units in each band are digitally combined, and a composite RF signal for each band is presented to the corresponding BTS.

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Cascading Host Units

Figure 17

shows a dual-cascade system, in which there are two Spectrum DRUs connected to a single Host Unit on four fibers each. Both DRUs connected to the Host Unit also have seven cascaded DRUs. In this configuration, the RF signal passes from the Host Unit through the two connected DRUs, which then pass the IF signal to the 14 cascaded DRUs.

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

Four fiber pairs

Host Unit

Four fiber pairs

KEY:

DRU

&

IFEU

DRU

&

IFEU

= Four fiber pairs

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

DRU

&

IFEU

Figure 17.

Dual-Cascade System (Spectrum)

DRU

&

IFEU

DRU

&

IFEU

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Host Unit II Installation Guide

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