How to Spot Sprint 8T8R TDD-LTE RRHs (Samsung)

[awsum gam3r]

Lookin good, I had to be next to the tower to get a decent 2500 signal. It doesn't seem to reach very far. I managed to pulled a 18mb DL on 105 DB

[mobileopticsguy]

Caught a decent shot of a 2.5 RRH just before the tower crew flew it. I got pulled into a ticket for an outage at the site and noticed the door was open, so I went for a ride to see who was there. I added another photo of the entire assembly as well.

 

Because of the way they had to mount the pole to the t-frame, they couldn't connect the jumpers until it was secured.

 

 

The RRH-B8 shown in the photo connects to the BBU via a hybrid power/CPRI cable (that plugs into the black port on the left of the box in the photo.).  THe installation manual says the cable has '4 optical fiber cores plus a spare'..  Does anyone know what that translates to in terms of the number of individual fibers in the cable? If its duplex there would be 2x4+2x1=10 fibers.. but that is an oddball number.. they are usually 6 or 12 as I understand it. Another way to ask the question is how many LC connectors are on the other end of the cable? The install manual shows three LC connectors plugging into the BBU, which would be 6 fibers.  Anyone know for sure what the answer is?  Thanks

[jeremyandrew]

The fiber "cans" have 4 LC connections in them. And a single fiber runs full duplex, TX and RX are different wavelengths and the GBICs are specific to the Radio head or the element they are seated in.

[mobileopticsguy]

The fiber "cans" have 4 LC connections in them. And a single fiber runs full duplex, TX and RX are different wavelengths and the GBICs are specific to the Radio head or the element they are seated in.

So since LC connectors are two-fiber, there are 8 individual fibers serving the RRU?   And since each fiber is bi-directional, one fiber can carry a CPRI channel, so a total of 8 CPRI channels (max) are carried from the RRU to the BBU? I guess that makes sense if this is a 8T8R unit.

 

More generally, is it as simple as just counting the number of coax jumper ports on the RRU to get the number of fiber links to the BBU? 

[lilotimz]

The RRH-B8 shown in the photo connects to the BBU via a hybrid power/CPRI cable (that plugs into the black port on the left of the box in the photo.).  THe installation manual says the cable has '4 optical fiber cores plus a spare'..  Does anyone know what that translates to in terms of the number of individual fibers in the cable? If its duplex there would be 2x4+2x1=10 fibers.. but that is an oddball number.. they are usually 6 or 12 as I understand it. Another way to ask the question is how many LC connectors are on the other end of the cable? The install manual shows three LC connectors plugging into the BBU, which would be 6 fibers.  Anyone know for sure what the answer is?  Thanks

 

[jeremyandrew]

So since LC connectors are two-fiber, there are 8 individual fibers serving the RRU? And since each fiber is bi-directional, one fiber can carry a CPRI channel, so a total of 8 CPRI channels (max) are carried from the RRU to the BBU? I guess that makes sense if this is a 8T8R unit.

 

More generally, is it as simple as just counting the number of coax jumper ports on the RRU to get the number of fiber links to the BBU?

LC connectors are not "two fiber", each LC connector supports a single piece of glass. This design is odd in the fact that it uses a single fiber for TX/RX. I have stress tested the Single-mode fibers in a hybrid cable and they do just fine at 1Gbps throughput.

 

1 fiber from each RRH goes to each of the 3 channel cards, that is of course assuming an 8T8R configuration.

[mobileopticsguy]

JeremyA -  Thanks for clarifying how that system works for me.

 

FWIW LC connectors do come in simplex and duplex flavors; I know duplex is more common for fronthaul so I assumed that's what this system used.

Bi-directional (simplex) links will have higher loss due to the wavelength filter required, which limits the maximum distance vs. 2-fiber systems.

[techfranz]

Certainly is not an ideal condition, but yes they can be put into what some call a ground mount radio unit type setup. Essentially the way most setups were done before network vision decided to pop em up top and get all that distance out of the way.

 

 

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Ok, a radio burns out and needs replaced...am I correct in how this goer?

Old Way -Technician drives to the Cell Site and never leaves the ground to replace the Cellular Radio.

New Way -Technician must climb the tower to replace the radio.

 

Will Maintenance be more expensive with the radios so close to the antennas high off the ground?

Also makes a nice "cabley" mess up top of the tower.

[payturr]

Ok, a radio burns out and needs replaced...am I correct in how this goer?

Old Way -Technician drives to the Cell Site and never leaves the ground to replace the Cellular Radio.

New Way -Technician must climb the tower to replace the radio.

 

Will Maintenance be more expensive with the radios so close to the antennas high off the ground?

Also makes a nice "cabley" mess up top of the tower.

There was never an old way; Sprint started using RRUs in Network Vision, before that it was amplifiers on the coax lines.

 

RRUs are only ground mounted in cases where they don't replace the legacy panels. They hang RRUs when they get the permits to replace the panels with NV ones. Putting the RRUs behind the panel is the smart thing to do because the signal loss from the coax is lowered significantly.

[techfranz]

There was never an old way; Sprint started using RRUs in Network Vision, before that it was amplifiers on the coax lines.

 

RRUs are only ground mounted in cases where they don't replace the legacy panels. They hang RRUs when they get the permits to replace the panels with NV ones. Putting the RRUs behind the panel is the smart thing to do because the signal loss from the coax is lowered significantly.

I understand from your comment, before network vision the actual radio was in a cabinet on the ground and the amplifier was where the RRU is now on top of the tower behind the antenna panel?

 

Sent from my LGLS991 using Tapatalk

[payturr]

I understand from your comment, before network vision the actual radio was in a cabinet on the ground and the amplifier was where the RRU is now on top of the tower behind the antenna panel?

 

Sent from my LGLS991 using Tapatalk

Well the amplifier wasn't necessary behind the panel, it depends on the length of coax really.

This photo sums up past, present, and future of network gear:

[techfranz]

Well the amplifier wasn't necessary behind the panel, it depends on the length of coax really.

This photo sums up past, present, and future of network gear:

Wow that photo is worth a 1000 s4gru blog words[emoji4]

-I suppose the active heads need a power connection.

-It seems the advantage of the future method seems to be that the active head antenna panels could be mounted anywhere you can get a simple fiber connection and the base station server can be placed wherever it is convenient. In other words less components, less weight, more configurations, more flexibility....

 

Sent from my LGLS991 using Tapatalk

[payturr]

1) Of course

2) The major advantage is there is essentially no signal loss because the radio is built into the antenna. Also, less space. Not sure about the weight.

 

Fun fact: T-Mobile uses activate antennas. Ericsson AIR21 panels. They're pretty cool and pretty easy to find.

[jeremyandrew]

Stumbled across a new 2.5 sector in the wild. It's not live yet, but when it is, it will be covering Heinz field in Pittsburgh.

 

 

 

 

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[RAvirani]

Question out of curiosity - is there a noticeable difference in the signal strength/performance with these Samsung antennas over the old clearwire huwei antennas?