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8th November 2007 at 11:15 #49615KeithGuest
I’ve been reading up on A-bis interface structure and have ended up a bit confused. I hope you can help
The standards and books tend to discuss the E1 method with a number of structures for differing numbers of TRX etc. Which of these structures tends to get deployed?
I also see a lot of attempts to make the Abis interface more efficient, using ATM or IP backhaul ( usually over the same E1 bearers ) how widespread are these solutions?
Keith10th November 2007 at 23:26 #49616pixGuest
E1 is divided in 32 TS. Each TS = 64 kbps.
TS 0 is reserved for synchro or adressing (??? to be verified ???).
Then each TRX occupies 2 TS for its traffic, and need few kilobits for its signalling (the RSL)..
There are many possibilities regarding the RSL : mostly it can be carried on one quarter, one half, or on full TS.
Sometimes it can even be carried within the 2 TS reserved for the TRX traffic (that’s a special configuration, with restrictions on TRX configuration)
Most common configurations : 4 RSL within one TS, or 2 RSL within one TS (depending on how much signalling & SMS the cell is carrying)
FYI, the OML (link with OMCR, for supervision) is multiplexed with the RSLs, because it doesn’t require much bandwidth.
About Abis over IP, it is spreading. I believe some vendors already have this solution available in their portfolio. For alcatel, it will be available end of next year (release B11).15th November 2007 at 00:40 #49617TedGuest
If Alcatel makes available A.bis over IP, will it be on totally new BTS and BSC models or existing BTS can be used? Or using external boxes? Thanks15th November 2007 at 14:52 #49618KeithGuest
Pix, Many Thanks, that helps a lot.
I also notice the A-bis protocol includes cyphering commands to protect the air interface. Is the cyphering done on the BSC or the BTS nodes? That is , is the speech within the TRAU frames in clear channels on the A-bis interface and then cyphered/decyphered on the BTS?27th November 2007 at 16:06 #49619RKGuest
Just wonder how the Abis over IP will work – will it be Abis over IP over TDM (E1) ? or somekind of ethernet cable running from BTS using ADSL or something ?
I would also think the IP network will have to be private since QoS (bandwidth) necessary otherwise cannot be maintained.
I believe Ericsson and Nokia already offer this feature but wonder how they’ve implemented this on their BSS- any significant changes to BTS or BSC design ?
PLease extend your comments.
RK27th November 2007 at 22:12 #49620pixGuest
regarding ABIS IP : i don’t know for sure, but it seems impossible for alcatel to design a new feature that would force customer to change their BTS’s.
For the BSC, it might be needed to use the latest BSC/MFS EVOLUTION (MX) (i’m 80% sure about this info). so the BSC G2 will not support Abis IP.
The ciphering is performed inside the BTS and the MS(encryption/decoding)? The TRAU frames are not ciphered.
The Abis over IP uses the same physical link as before (2 Mb/s link or more, over microwave, sattelite, or cable). The benefit of IP-protocol is to have some kind of flexibility in the usage of this link. I don’t think the BTS-BSC link will ever be carried on the Internet 🙂
Sorry about the late answers, i missed out this thread..28th November 2007 at 23:38 #49621RKGuest
But Femto BTSs (the home base stations thats catching-up) are using the public internet for backhauling. But maybe since you’re talking about 1-2 users only the public IP network is OK (?)
I fully agree though, that for a macro BTS with say 12 radios per sector an IP backhaul and using public IP doesn’t sound logical.
Another solution that vendors are using to save on the backhaul is the Abis compression technique in case their IP backhaul solution is not ready.
RK4th December 2007 at 10:09 #49622KeithGuest
Is the structure on an A-bis T1 trunk anything like the E1? I.e how are the TRX/signalling channels organised compared to an E1?9th January 2008 at 09:51 #49623KeithGuest
I’m still trying to figure out the differences in A-bis on T1 from E1. Can anyone help? Much Appreciated9th January 2008 at 13:19 #49624pixGuest
i think this can be found easily on wikipedia, doesn’t it ?11th January 2008 at 22:12 #49625bertGuest
has a full ip solution implementing a extra node between the bts and the bsc from bsc to the siu ip connection from
siu to bts lapd e1 or t1 up to 64 trx’s.
total ip towards a micro or a pico is also possible7th February 2008 at 14:57 #49626JoeeeGuest
What is the meaning of interface ?8th February 2008 at 08:45 #49627pixGuest
interface is the link between two equipments. i.e. between BTS and BSC, it is a abis link, a.k.a. an abis interface.
check wikipedia for more details 😉8th February 2008 at 16:34 #49628inderGuest
Is ciphering done on bts side,whn VLR sends a command to MSC.about Ciphering of a particular MS.
Wht is the parameter that BTS has(if it does the Ciphering)8th February 2008 at 16:38 #49629inderGuest
why do we use transcoder for Packet Control unit to link with SGSN.
As SGSN has its own parametrs,still we have to link it with Transcoder for Gb link.(For data Transmission)