- This topic has 26 replies, 1 voice, and was last updated 12 years, 10 months ago by pix.
11th June 2008 at 08:50 #48614pixGuest
you didn’t write “synchro”, but johan did 🙂 not pointing fingers though :))11th June 2008 at 10:25 #48615AbdelGuest
I am really confused now days sorry guys:)lol12th June 2008 at 12:20 #48616ZHTGuest
Does anyone know the hopping sequence or collision ratio efficiency between cyclic hopping sequence and pseudo hopping sequence?
Comparing a network using only HSN=0 and another network using HSN=1~63.
Thank you12th June 2008 at 13:08 #48617pixGuest
nobody uses cyclic hopping. there is no point in cyclic hopping, because if two cells have a collision, all their timeslots are going to collide all the time.
it’s possible to design a plane with only one wing, but 2 wings are definitely better. And i’m not sure anyone is ever going to build a 1-wing plane to check that…12th June 2008 at 15:50 #48618VICKYGuest
HI MR. PIX,
THE QUESTION WAS REALLY VERY WEIRED BUT AS I KNW THAT THE HSN WHICH CAN NOT USE IS 13 N THE MULYIPLE OF 13 COZ ALGO ID WHICH IT RUNS N CREATES THE NO OF FREQUENCY, NOT SO PERFECTLY,SO THE PROBABLITY OF COLLISION IS MORE,AS PER MY CONCERN
IF WRNG CRRECT ME….12th June 2008 at 20:04 #48619pixGuest
i don’t know about the algorithm for the pseudo random hopping law… i think this is just an “engineering” legend that the number 13 is not so random.
🙂 can you find the random law in the 3GPP ?14th June 2008 at 05:45 #48620ZHTGuest
Well in some parts of the world there are operators who uses cyclic hopping sequence.
🙂14th June 2008 at 08:21 #48621pixGuest
that is very strange, did you ask them the reason of their choice ?
i have been to many parts of the world, and i never met an operator who consciously decides to use cyclic hopping. unless the BTS are all synchronized and they spend a great deal of time making a MAIO planning.
I’m always open to good ideas, but in this specific usage of SFH I really don’t see any benefit of cyclic law.
The ultimate point of SFH is to make freq planning easier. But if you must do a MAIO planning to make it works, you loose the benefit.17th June 2008 at 07:52 #48622ZHTGuest
Not sure why they did it. But as soon as I’ve proposed to change them, they quickly implemented without asking much. My guess is that they are too busy to do the planning themselves… hahaha!17th June 2008 at 16:02 #48623pixGuest
ok, so it wasn’t a “conscious” choice 🙂19th June 2008 at 20:44 #48624AterGuest
Returning to the original question i think that in Ericsson there are not forbidden HSNs.
But due to the procedure used by the mobile stations for measurement reporting, the use of cyclic hopping with a multiple of 13 frequencies should be avoided when DTX is used. (For measurement reporting when using DTX, a subset of TDMA frames, SACCH, are used for the measurements which is sent every 13:th TDMA frame)20th June 2008 at 12:06 #48625pixGuest
thanks for this information ! that is tricky 🙂 cyclic hopping with 13 frequencies means that the SACCH is transmitted always on the same frequency.
however, the measurements by the MS are most of the time “FULL”, on all timeslots. The SUB measures are done only when the DTX is “on”.
I think the main issue is to send and receive the SACCH always on the same freq. If by any chance this frequency is interfered, then the SACCH will be lost ==> Call drop.