2 way receive diversity + space diversity ( 2 antenna)

[mypp]

Hi Bro,Could you please let me know how to set up 2 way receive diversity + space diversity ( 2 antenna) model in GSM ? Many thanks.

[Optimustron]

Normally you have the output of RBS DUPLEXED, then as you said if you spatial diversity then you are going to use some model with vertical polarization, if that is the case you need to separate, rule of thumb, about from 8 to 10 lambda, but if you need less separation, then you can use an Analizer capable of measure ISOLATION, then you put the antennas in such a way that you have at least 30 dB of isolation, then you connect each jumper in the available poles and don't care about the order only maintain the same order always, i.e. DUPLEX1 at right and DUPLEX2 at left for example at least in the same site.
If you are going to use XPOL polarization this doesn't make sense because you use both poles, in the case of the vertical polarization is like you has divided the XPOL antenna in two because again you have two poles one per antenna.
Please let me know if I was clear enough or if I don't understand your question, best regards,

[primig]

I also don't know how to do this automatically, within the planning too but I use this process:
In the planning phase, use the diversity gain which you need to have (within manufacturer recommendations) minimum to help balance the link budget.
This will let you setup a useful TX ERP in the tool.
During site survey for implementation (or pricing for offer) - specify the min. distance between antennas you need to get the diversity Gain you calculated with in planning phase. check for manufacturer tip if you cant work it out.

For 2 way rx diversity, If using omni directional antennas be aware that in 2 directions you wont have any diversity gain and as you move more towards these directions the diversity gain will drop to zero.
Try to select an azimuth for the diversity so that the most gain is within your required coverage area or that the lowest gain areas are overlapped to another Cell.

[mypp]

Normally you have the output of RBS DUPLEXED, then as you said if you spatial diversity then you are going to use some model with vertical polarization, if that is the case you need to separate, rule of thumb, about from 8 to 10 lambda, but if you need less separation, then you can use an Analizer capable of measure ISOLATION, then you put the antennas in such a way that you have at least 30 dB of isolation, then you connect each jumper in the available poles and don't care about the order only maintain the same order always, i.e. DUPLEX1 at right and DUPLEX2 at left for example at least in the same site.
If you are going to use XPOL polarization this doesn't make sense because you use both poles, in the case of the vertical polarization is like you has divided the XPOL antenna in two because again you have two poles one per antenna.
Please let me know if I was clear enough or if I don't understand your question, best regards,
I read one document said that to enhanced the coverage on the sea with using MCPA ( Booster ), must have use 2 way receive diversity combined with space diversity ( 2 antenna Xpol). I don/t khow why do this and how ?

[Optimustron]

mypp, In general when you need space diversity you use vertical or horizontal polarization, you don't use XPOL polarization because each side of the XPOL is complementary in order to have diversity gain. In the begining we used to set up BTS with vertical polarization, AMPS system, we used two RX antennas and one TX antenna, with 10 lambda for spacing because we used omni antenas of 12 dBi with variable electrical tilt, but one step before we have duplexed systems then we used one RX/TX antena and one RX antenna, that worked fine. In the past of time:



We learned that for cities the XPOL solution is better because you have many reflections and the phone can be at any position.
In the rural areas we learned that the main phenomena is attenuation then the VPOL antennas give us more coverage.
The VPOL antennas worked well too for lakes and ocean/sea because you don't have reflections like in cities, is almost free space and with big ground plane, by the way you have in this places refraction too but of course you don't speak under the water.


If you are going to put MCPA then I recommend you to use TMA/MHA too in order to have compesate for loses in the cable, of course VPOL is better than XPOL in this situation, however I can't tell you quatitatively how much is the difference but I remember that is better with VPOL.

That is because in the sea the main phenoma is attenuation by fading because the boats are going up and down and is better to have two antennas at diferent locations, i.e. space separation better if 10 lambda but using VPOL if you use XPOL then you can use splitters to have to sets of antennas at different places and then you need to compesate the loss of 3 dB of splitter with TMA/MHA.

I hope this can help you, kindly,