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Hello,
It would very helpful if anyone can tell me the correlation between PDCH in air and GCH in Pb interface ? and depending on that how to dimension a Pb interface ?
Not Pb, but Gb interface
One PDCH can carry a certain useful throughput, which can vary from 6kb/s up to 60kb/s.One GCH on the Gb interface can carry only 16kb/s !
Therefore, One PDCH will need more than one GCH if the PDCH throughput is above 16kb/s (or a bit less than 16kbps actually, due to signalling).
For instance, at 60kb/s (59.2kb/s, more exactly), one PDCH will need 4.5 GCH.
Regards,
PixNot GCH, but Frame Relay packets:)
The structure of Gb-interface is another than Abis. There is Frame Relay Protocol stack on it. It is a packet switching technology. The Gb-interface is realized by PCM lines. The Gb-interface phisical layer is called Frame Relay Link (FRL). FRL is a nx64 kbit/s phisical channels, created oher a PCM-line. Each FRL carries the packet switched data traffic of a specific number of cells.but the frame relay occurs at layer 1.. GCH is at layer 3. A PDCH is also at layer 3, and is “attached” to n GCH. What happens in the lower layers is transparent (well, not you, definitely 😀 )
Sorry Pan, i got mixed up… GCH are on the Ater PS interface.
Fahim, the GCH is not on Gb !
On Gb interface, you can find L3-BSSGP frames. But there is no static allocation of Gb interface timeslots to the PDCH, it’s all dynamic, and based on Frame Relay (thx Pan !).
Hello guys,
I need to make somethings more clear… if we are using two E1 lines for Pb of a certain BSC and only one E1 line for Gb — how will that help me or what could be the possible reason behind that ? will the speed decrease or increase for a subscriber ?
fahim,
have you read anything we said below ?
so, you need to tell us what is PB.Pb is the interface between BSC and PCU. They have this in Huawei network since BSC is separated from PCU.
Pb interface?
IS it really standardized?If it is,then no of Pb can be equal as Gb..!
hi pix &pan,
What is the difference between frame relay and gb over ip for gprs?
And as per trailing messege what will be exact structure of gb ?is it gch or frl?
Plz help frnds.
safar,
Gb interface can use FR or IP transport mode, but the protocol is still the same :
TS 48.018 BSS – SGSN interface ; BSS GPRS protocol (aka “BSSGP”)In other words, the “BSSGP” messages sent between PCU and SGSN are the same, they are just “transported” differently.
With IP, what you get is a BSSGP message within an IP packet.
With FR, the BSSGP message is transported within a frame relay PDU.Hi pix,
thanks and can u explain abt gch and if i have to monitor sgsn capacity as per gch then how to check ?
GCH is a nibble located on Ater PS and Abis interface, that carries RLC-MAC blocks.
They don’t belong to Gb interfac, they are not related to SGSN.The GCH is basically a logical link between the PCU (MFS in alcatel) and the BTS.
pix
Hi Pix,
is GCH related to Abis E1/ EDAP.
or is some huawei/ALU specific term.I believe GCH is a vendor specific term, but it is probably used widely among several vendors. It means GPRS CHannel so Iwouldn’t be surprised if *all* vendors are using this acronym to describe the ressources to carry rlcmac blocks from PCU to BTS.
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