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Uplink scheduling in LTE ?

+4 votes
769 views

Can anyone explain me the steps involved in scheduling for UE when BSR comes for that UE at eNodeB?

posted Mar 28, 2014 by Sony Mohanty

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1 Answer

+5 votes

Buffer Status Report (BSR) is a kind of Medium Access Control- Control Element (MAC-CE) from UE to Network, carrying the information on how much data is in UE buffer to be send out. Putting it another way, it is a kind of MAC layer message from UE to Network (eNodeB) saying "I have something to transmit, would you give me a Grant to send this data ?

A BSR is triggered if any of the following event occurs:

  • Uplink data for a logical channel becomes available for transmission, and either the data belongs to a logical channel with higher priority than the priorities of the logical channels for which data is already available for transmission,or there is no data available for transmission for any of the logical channels.In this case, the BSR is referred to as“regular BSR.
  • Uplink resources are allocated and the number of padding bits is equal to or larger than the size of the BSR MAC-control element, in which case the BSR is referred to as“padding BSR.
  • A serving cell change occurs,in which case the BSR is referred to as“regular BSR.”
  • There transmission BSR timer expires and the UE has data available for transmission, in which case the BSR is referred to as“regular BSR.”
  • The periodic BSR timer expires, in which case the BSR is referred to as“periodic BSR.”
answer Apr 1, 2014 by Hiteshwar Thakur
I think ,I was not clear with the question.I am interested to know how is the Uplink RBs  determined at MAC for a UE ? which all parameter are taken into consideration in uplink for determining the number of RBs assigned to a particular UE?
Sony: Pardon but i am not getting a clear idea about your query. Is this comment has any relation with upper one. If no, then i suggest you to raise a new question with details.
If yes, then for my convenience please type it in steps, because i am interested to solve it.
Yes above comment was related to the same question.The answer given by Hiteshwar is more related to BSR and its functionality.But my query was how is the TB size determined for a UE in uplink ?
Please refer Section 7.1.7 of
http://www.qtc.jp/3GPP/Specs/36213-920.pdf

Though i could not add all the answer here so giving you this link.
Can you share with me any good document of Scheduling?
piyush.ec.ag@gmail.com
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