Colocation ePTP and TDD different frame rate utilization

Products ePMP
1

Hi everyone.

I'm have deployed 2 sites with 2 ptp in epmp mode and in every of them I do distribution using 120° sector (in one 1 and in the other site 2 sectors). The ptp antenass are all F110 GPS synced with 25db dish and all the systems uses latest firmware (v2.6). So we have in the first site:

- 3 antennas 2 PTP and 1 PMP 

second site:

- 3 antennas 1 PTP and 2 PMP 

in all sites the rules are equal:

Ptp mode used is eptp

MTMP mode used is Gps TDD 

My question is:

I think we could have a prblem here because the frame rate in TDD used is 2.5ms and in eptp is not possible to be choosed?

Could anyone have an opinion or a NOT to do deploy like for me to be suggested here?

Many thanks

OC

2

Hi, 

First of all, ePTP mode cannot synchronize using GPS sync as it does not use a TDD frame structure. Hence there is no option to choose the frame size. 

Regarding whether your deployment will work, can you share a little bit more info:

1. For each tower where you have colocated PTP and PMP links, what frequencies are they operating on?

2. What is the orientation of the antennas with respect to each other on each colocated site

It is ok to deploy ePTP and TDD PMP along side each other as long as you have enough frequency seperation. Ideally the guard band would be 2X the channel bandwidth. 

Thanks,

Sriram

2 Likes
3

Hi Sriram.

I have not at all the 2x bandwidth channel for al the radios as obvious it is.

Into 1st site in wihc I have 2 pTP in eptp mode and 1 PMP in TDD mode the details of those radios are:

A tower (POLE 3 meters)  1st and 2 sc PTP are one on the top and the other on the base of the pole. The PMP synced is positioned in the middle of this envioroinment. Every antenna has about 30/40 cm space the one from the other.

For test purpose i'm doing this:

1st ptp:

- radio f110 with dish 25dmm

- frequency 5440ghz

- channel 40mhz

- eptp mode

2st ptp:

- radio f110 with dish 25dmm

- frequency 5840ghz

- channel 40mhz

- eptp mode

PMP:

- radio epmp1000 synced with 120° antenna sector

- frequency 5100ghz

- channel 20mhz

- TDD mode

- dw ratio 75/25

- frame 2.5ms

- colocation mode

- Gps both source and for colocation source

every frequency radio has at least 15mhz left and right free.

Let me know if there are other infos to know.

1 Like
4

OC, that all looks good to me! You can use the SA to check to see if you're interfering with yourself or others as you install each radio and tune and adjust as necessary. The only thing you might want to consider would be using GPS capable radios on the tower for the PtP radios just in case you wanted to do some sync in the future.

2 Likes
5

Many thank for your fast reply.

All of those in the site are gps synced radios even F110 (in eptp gps is not wonrkink by design as cambium says).

Do you suggest t use TDD PTP instead of eptp to better frame utilization?

6

In a clean RF environment, ePTP will give you the lowest latency of all the frame options at the cost of a bit of throughput and the lack of GPS sync.

If you're goal is to have the lowest latency PtP links, and you have enough clean spectrum, then try ePTP first.

We typically use TDD-PTP when there's limited spectrum and we're trying to use frequency reuse between radios to conserve spectrum.

2 Likes
7

Hi Eric.

Very clear to me now.

It seems that the lack of spectrum is not a problem for me now at the tower/s in the epmp mode.. it seems..

but seems that I have in a couple of SMs a higher SNR of other ISPs AP.

In software version 2.4.2 it is not a problem, the AP2SM link in PMP scenario is stable. But other software versions obove v2.4.2 the problem pops out and this couple of SMs are not so stable anymore. the link at first goes down avery 5 mins with the latest configuration at the AP that is mentioned @ previous message here the links stand still 1/3 hours and then drops.

Now my doubts are:

- self interference? thin not beacuse my 3 radios at the site are in a larger than 100mhz spectrum space (actually)

- firmware lack of latest v2.6 towards v2.4.2

- other?

Attached the SM on that AP from GUI

Many thanks,

OC