what is window stalling in LTE RLC?

Question

While going through specification, a term "window stalling" is mentioned. Can anyone please explain it ?

Answer 1

Hi sripathi,

Say ecxamble RLC window is configured as 10, then RLC will strat transmit the SN(RLC SDU) starting from 1 and so on. when the SN transfer reaches 10 , If still ack pending for SN 1 means (difference of current SN and last ack SN is 10) then RLC wont proceed further. It will do polling to get the ack for those packets. Untill he recieve status it wont go further this is called window stalling.

Comments

Hi janardhan, lets consider 2 to 10 SDUs got ACK (but not SDU-1). In this case all 2 to 10 SDUs present in the window along with SDU-1???

AND as u said (difference of current SN and last ack SN is 10)... here current SN=11 and last ack SN is 10.... in this case how window stalling occured?

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When you recieve status for 2 to 10 (it is with in the window) so which ever SN is missed is NACK. then sender will do re trasmission. window will move from 10 onwards

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So you saying that, once all SNs 1-10 get ACKs thn only window will move right?

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No sripathi, If you didn't recieve ack for SDU 1 then it is NACK SN, sender will move window and will do re transmission of SDU 1. Only one condition is you should recieve atleast one status PDU within those window. once you recieved status for those SDu then window will move.