A subblock is a collection of contiguous component carriers used for transmission and reception by the same user equipment (UE). Intra-band contiguous carrier aggregation uses one subblock. Intra-band noncontiguous and inter-band noncontiguous carrier aggregation use two or more subblocks.

The following table lists some aggregated bandwidth combinations as defined by the 3GPP specification.

Subblock Component Carriers (MHz) Aggregated Channel Bandwidth (MHz) Aggregated Measurement Bandwidth (MHz)
10 MHz + 20 MHz 29.90 27.90
15 MHz + 15 MHz 30.00 28.50
15 MHz + 20 MHz 34.85 32.85
20 MHz + 20 MHz 39.80 37.80
5 MHz + 20 MHz 24.95 22.95

The nominal guard band on either side of aggregated carriers is defined in the following table,

where, a1 = 0.16/1.4 for BWChannel(1) of 1.4 MHz a1 = 0.05 for all other channel bandwidths.

Maximum Number Of CCs Nominal Guard Band (At Both Edges Of The Subblock)
1 a1 * BWChannel(1)
n (where n > 1) 0.05 * max(BWChannel(1), BWChannel(2), ...BWChannel(n))

For more information about noncontiguous carrier aggregation, refer to Table 5.4.2A-1 in the 3GPP TS 36.521-1 specification.

The following image shows two subblocks, subblock A and subblock B, with guard bands above and below the edge component carriers to facilitate transmitter/receiver filtering.