If LTE packet size is smaller than Transport block size, what will lte do?

[Y Jian]

If LTE packet size is smaller than Transport block size, the time needed for transmitting the packet will be smaller than subframe transmission time 1ms. Modulation and coding rate are predefined based on CQI measurement. In this case, is the subframe transmission time smaller than 1ms?

Please give me any advice about this question

Thanks a lot.

[akin soysal]

I am not sure if you ask it based on NS3 or the specifications but in NS3 code the mac forwards the scheduler grant to the RLC. If the packet is smaller than the grant, then the whole packet will be sent and the extra grant will be nothing but excess grant and be discarded.

If you ask based on the real base station, I would guess the RLC would do zero padding because if the scheduler gives a grant, it reserves the physical resources for that grant. An option would be that the scheduler takes the buffer occupancy into account and determines a lower MCS if the TBS is going to exceed the buffer occupancy. Since the TBS may not be exactly the same size of the buffer occupancy there is always a chance of zero padding.