What is difference in UL and DL RB Allocation?

Question

Is there any limitation on giving no of static allocation in DL or UL? an we give complete Radio resource for allocating SPS/CG

Answer 1

Hi sripathi,

DL RB allocation has 3 types.

RAT 0 : This is interms of RBG, ENB will send RBG bitmap to UE , like ********** , which ever bit is set corresponding RBG is scedhuled.

RAT 1 : This is also a bitmap allocation but it hasw one more field called RB shift(0 to 2), based on this valure divide the whole BW, and bitmap will tell which RB's scheduled in those RBG.

RAT 2 : This is continuous allocation , like start RB and total no of RN will be given.

In UL allocation only one type that is RAT 2, There is no other RAT available for UL.

Comments

Hi jaganathan,

here i have few questions... please clarify

1) In RAT-1 type ,  RB shift value ( for suppose 0 ) ... How bW can be divided ?

2) RAT-0 or RAT-1 when to be use , how to decided by eNodeB ?

3) How eNodeB convey this information to UE?

Please help ...

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Hi sripathi,

RAT 0 and 1 will be used in case of DCI 2 or 2A or 1 , 0 or 1 will be decided based on scheduler implmentation, If you dont want linear allocation then you can go with type 1. Type 2 only for transmit diversity.

This RAT type will be as part of DCI info in PDCCH.

There is no subset 0 concept, No of subset will de based on the no of Rb's in RBG.
Say examble in 10 MHz no of Rb's in Rbg is 3 , so subset will be subset 0 ,subset1,subset2.
subset 0 == Rbg0,rbg3,rbg6,rbg9...
subset 1 == Rbg1,rbg4,rbg,7,rbg 10...
subset 2 == Rbg2.rbg5.....
In 20 Mhz No of rb's in rbg is 4 so subset will be 4.
Subset 0 == Rbg0,rbg4,rbg8 ...
subset 1 == rbg 1, Rbg 5,Rbg 9....
subset 2 == Rbg2,rbg6,rbg10
subset 3 == Rbg3,rbg7,rbg11..
subset 4 == rbg 4,rbg 8....

Minimum no of subset in 1.4mhz is one subset..i.e all Rb's will comes under same subset.

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Jaganath , How eNodeB intimates selected RAT type to UE ... Is there any L3 IE present or through DCI format?

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through DCI formats, In DCI there is one field called RAT types