4G/LTE - PHY Channel

REG (Resource Element Group)

REG is one of resource allocation units which is made up of 4 resource elements. (Refer to Resource Allocation Management Unit page for other type of units and for the relationshipt between REG and other units (e.g, RE or CCE)

Following is the visualization of the description on 36.211 6.2.4 Resource Element Groups.

It may look pretty completed because it has two make a group of 4 REs except the REs allocated for Reference Signal. The location of Reference Signal varies depending on number of antenna configuration and other factors (e.g, Physical Cell ID, Antenna port/DMRS etc)

< Case 1 >

i) In the first OFDM symbol of the first slot in a subframe, the two resource-element groups in physical resource block

ii) In the second OFDM symbol of the first slot in a subframe in case of one reference signals configured, the three resource-element groups in physical resource block

iii) In the third OFDM symbol of the first slot in a subframe, the three resource-element groups in physical resource block

iv) In the forth OFDM symbol of the first slot in a subframe in case of normal cyclic prefix, the three resource-element groups in physical resource block

< Case 2 >

i) In the first OFDM symbol of the first slot in a subframe, the two resource-element groups in physical resource block

ii) In the second OFDM symbol of the first slot in a subframe in case of two reference signals configured, the three resource-element groups in physical resource block

iii) In the third OFDM symbol of the first slot in a subframe, the three resource-element groups in physical resource block

iv) In the forth OFDM symbol of the first slot in a subframe in case of normal cyclic prefix, the three resource-element groups in physical resource block

< Case 3 >

i) In the first OFDM symbol of the first slot in a subframe, the two resource-element groups in physical resource block

ii) In the second OFDM symbol of the first slot in a subframe in case of four reference signals configured, the three resource-element groups in physical resource block

iii) In the third OFDM symbol of the first slot in a subframe, the three resource-element groups in physical resource block

iv) In the forth OFDM symbol of the first slot in a subframe in case of normal cyclic prefix, the three resource-element groups in physical resource block