Rach Receiver - Cellular communication basic - Scenario of two phones connecting each other (multiple UE's)

Thread Starter

JimmyCho

Joined Aug 1, 2020
97
Im trying to understand the Scenario of two UE's connecting each other (they have 4g lte network)and what's the purpose of the RACH in this situation, what parameters does the RACH give the UE's in order to get access between two cellphones that connecting each other?
Im not that much understands how the RACH works and what parameters does the RACH gives the UE's and how the RACH related to the lte 4g Network ? ...in other words if there wasn't RACH in the cellular 4g lte network what happen to the process of cellular communication process?

I will try to give a scenario that Im confused with and still not understand what's the purpose of RACH in cellular 4g network communication and what parameters does it handle in order to do a cellular communication process (like two cellphones connectnig each other ..etc)

lets assume I'm calling my friend on his phone number (another UE) ..how all the procedure of connecting between my phone(UE) till the end of calling my friend done? her I mean in aspect of flow blocks what's the flowchart blocks of cellular communication procedure that could represent all the the situation once connecting my friend by my cellphone till I end the call? what parameters should be considered in this case(two phones connecting each other) ?


Appreciated guys for any help / explanation , thanks alot.
 

andrewmm

Joined Feb 25, 2011
1,468
I've not worked on 5G
but in LTE , the Random Access Channel is used as part of the set up procedure of a call between the phone and the tower.
If I remember its relatively easy to decode, and is broadcast without checking that any one else might be using it.
Its promiscuous, and phone can transmit it at any time, the higher layers of the transport channel take care of re scheduling

I think its also very useful as part of the soft handover between towers, as it is used to keep a track of what towers are around.
 

Thread Starter

JimmyCho

Joined Aug 1, 2020
97
I've not worked on 5G
but in LTE , the Random Access Channel is used as part of the set up procedure of a call between the phone and the tower.
If I remember its relatively easy to decode, and is broadcast without checking that any one else might be using it.
Its promiscuous, and phone can transmit it at any time, the higher layers of the transport channel take care of re scheduling

I think its also very useful as part of the soft handover between towers, as it is used to keep a track of what towers are around.
I understand, so is there soft handover and hard handover? I didnt hear with this, all what I hear that there's what's called handover. could you please explain what do you mean by soft handover and the other type in simple words? in 4 lte or 5g I guess it's the same handover procedure.

thanks!
 
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