Calculating E1s and Bandwidth

i want to know
what is e1 ?
how it works?
how the data trasmit through e1?
what is the A law of companding?

E1 is one of the standard Transmission Techniques.
It is the Infrastructure needed to transmit Traffic (Voice native, Voice over IP, Data…) or to transmit signalling (MAP, ISUP, C7, …)

it consists of 32 time slots, each can be used for one application or one call channel.

if the maximum frequency in human voice is 4K Hz this voce should be sampled minimum at 8K sample per Second so that it could be re-constructed without voice quality degradation.
This 8000 sample is coded with 8 Bits PCM coding the resulting is 64000 bit per second.
This is one voice sample for one Voice channel at a time.

for the complete 32 Channel it becomes 32*64000 which is the 2048 K bps or the 2 Mbps.

For some applications that requires bandwidth more than 64 K, group of channels (5 time Slots for example) can be considered as a one set capable of providing (5*64K =320K).
some other applications requires the complete 32 Time Slots to be considered as a one channel with complete 2 Mbps Bandwidth)

E1 is working in Layer 1 and Layer 2 of the OSI Reference Model provided by ISO.

For Layer 2, it allocates one time slot from the 32 Time Slots for E1 availability and reliability Management; this reduces the number of Time Slots that could be used for transmission to 31 Time Slots.

i want to know how we allocate the e1 in gsm as well as in cdma?

to jood: Why you wrote “thus 1 TRX = 2.5 E1 ts” ? if you have 1 TRX per cell then you have to set BCCH at TS=0 on Air int, so first 2 bits in firtst TS on E1 is free of traffic channels, so you may put LAPD link in those 2 bits,
so 1 TRX = 2 TS
Alex
http://www.dx200.biz

jood, yes, you right, the minimum amount of TS on A-bis is 24. every TRX need own LAPD link, you may put LAPD link inside traffic channel allocation of that TRX, so 2 bits on A-bis will not be used for traffic, so 1 TS on Air interface also can’t be allocated for traffic, you may put BCCH on that TS on Air int.(if it’s BCCH TRX), or you may put SDCCH . Also Base Station needs O&M link which also allocate at least 2 bits on A-bis, you may alos put it inside traffic channel allocation of some TRX, so 1 TS on Air int will not be allocated for traffic…. but of cource you may put all LAPD links and O&M link on separate TS on Abis, so BS with 12 TRX will need at least 27 TS + 1/4 TS

How to derive in-terms of Erlnags in for Each TRX considering all time slots have engaged for 1Hrs duration(Ex:for calculations purpose)….In short Each TRX card generates how much traffic/Erlangs in Hr period.

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