How is CA configuration notation read?

CA notation follows the pattern CA_nX-mY where n and m are the band numbers and X, Y are the bandwidth classes: CA_3A-7A = Band 3 (one CC, class A ≤ 20 MHz) + Band 7 (one CC, class A). CA_1A-3A-7A = three-band CA. CA_41C = Band 41 intra-band contiguous (class C = two contiguous CCs, ≤ 40 MHz). Bandwidth classes: A (≤ 20 MHz, 1 CC), B (≤ 20 MHz, 2 CC), C (≤ 40 MHz, 2 CC), D (≤ 60 MHz, 3 CC). The letters A-D define both the maximum aggregated bandwidth and the number of component carriers within that band. For 5G NR: notation is similar but uses NR band numbers (n1, n3, n41, n78, etc.). Example: CA_n78A-n257A = NR sub-6 + mmWave combination.

What RF challenges does each CA type present?

(1) Intra-band contiguous: simplest. Single PA, single antenna path. Challenge: PA must support the wider aggregated bandwidth. Example: 2×20 MHz = 40 MHz requires PA with 40 MHz instantaneous bandwidth. Filter must pass the full aggregated bandwidth. (2) Intra-band non-contiguous: same band, gap between CCs. Challenge: the gap creates in-band intermodulation products that may fall on other carriers. PA linearity requirements increase. May require dual-uplink capability if the gap exceeds PA linearization bandwidth. (3) Inter-band: different bands. Challenge: requires multiple PA and filter paths (one per band). Intermodulation between the two transmit frequencies (2f1-f2, 2f2-f1) can fall in receive bands, causing receiver desensitization. The 3GPP specification defines maximum sensitivity degradation (MSD) for each configuration. This is the dominant constraint in inter-band CA design. (4) RF front-end complexity: a 5-band CA phone may need 5 PAs, 5 duplexers, and RF switches with very low loss and high isolation to prevent desensitization.

How do you determine which CA configurations to support?

Selection factors: (1) Operator spectrum holdings: the CA configuration must match the bands the operator has licenses for. Example: T-Mobile US holds B2, B4, B12, B66, B71, n41, n71, n258. Practical CA combinations: CA_2A-66A, CA_2A-66A-71A. (2) UE capability: the handset must support the specific CA configuration. UE capability is reported to the network during attach. Chipset determines supported configurations (Qualcomm Snapdragon, MediaTek Dimensity). (3) IMD analysis: every candidate configuration must be analyzed for intermodulation products. If 2f1-f2 or 2f2-f1 falls in a receive band, the configuration either requires MSD allowance or harmonic filtering. Some combinations are impractical due to severe self-interference. (4) Antenna sharing: some inter-band CAs can share antenna paths; others require dedicated antennas. Antenna space in the handset is limited. (5) 3GPP standardization: the configuration must be defined in TS 36.101/38.101. Operators and chipset vendors submit CA combination requests to 3GPP working groups for standardization.

5G / LTE

CA Configuration

Carrier Aggregation Configuration

Band combination for CA: CA_nX-mY notation. BW class: A (≤20 MHz, 1 CC), B (≤20 MHz, 2 CC), C (≤40 MHz, 2 CC), D (≤60 MHz, 3 CC). Types: intra-band contiguous (widest PA), non-contiguous (IMD in gap), inter-band (multiple PAs, desense risk, MSD). 3GPP: TS 36.101 (LTE), TS 38.101 (NR). UE capability determines support.

3GPP: TS 36.101/38.101

Max: 5 CC (LTE)

NR: 16 CC

Understanding CA Configurations

Carrier aggregation is the key technology enabling peak throughput in LTE-Advanced and 5G NR. Each CA configuration represents a specific combination of spectrum resources that the network and UE have agreed to use simultaneously. The RF front-end design of a smartphone is largely determined by which CA configurations it must support, as each combination brings unique challenges in intermodulation management, PA design, and filtering.

CA Notation and Bandwidth

Carrier Aggregation:
BW_total = ΣBW_CC,i
Max: 5 CCs (LTE), 16 CCs (5G NR)

Throughput:
R = ΣBW_i×SE_i×MIMO_i

Types:
Intra-band contiguous/non-contiguous
Inter-band

CA Type Comparison

Type	Bands	RF Challenge	PA Count	Example
Intra contiguous	Same, adjacent	Wider PA BW	1	CA_41C
Intra non-contig	Same, gap	In-band IMD	1-2	CA_41B
Inter-band 2CC	Different	Desensitization	2	CA_3A-7A
Inter-band 3CC	3 different	Complex IMD	3	CA_1A-3A-7A
NR-LTE DC	NR + LTE	Dual connectivity	2+	EN-DC

Key Equations

Decibel conversion:
Power: dB = 10log(P₂/P₁)
Voltage: dB = 20log(V₂/V₁)

dBm to watts:
P(W) = 10^{(dBm−30)/10}
0 dBm = 1 mW, +30 dBm = 1 W

Wavelength:
λ = c/f = 300/f(MHz) meters

Comparison

Config	Bands	BW total	Peak DL	Standard
CA_1A-3A	B1+B3	20+20=40 MHz	300 Mbps	LTE Cat 6
CA_1A-3A-7A	B1+B3+B7	60 MHz	450 Mbps	LTE Cat 9
5CC LTE	5 bands	100 MHz	1 Gbps	LTE Cat 20
NR CA sub-6	n77+n78	200 MHz	4 Gbps	5G NR
NR CA mmW	n257+n258	800 MHz	20 Gbps	5G NR FR2

Common Questions

Frequently Asked Questions

Notation?

CA_nX-mY: n,m = band numbers, X,Y = BW class (A≤20MHz/1CC, B≤20MHz/2CC, C≤40MHz/2CC, D≤60MHz/3CC). Intra: same band. Inter: different bands. 3GPP TS 36.101/38.101 standardize combinations.

RF challenges?

Intra-contig: PA bandwidth. Intra-noncontig: in-band IMD. Inter-band: desensitization (2f1-f2 falls in Rx), MSD allowance, multiple PAs/duplexers. 5-band CA phone: 5 PAs, 5 filters, complex switching.

Selection?

Operator spectrum, UE chipset capability, IMD analysis (every combo), antenna sharing feasibility, 3GPP standardization status. Qualcomm/MediaTek chipsets determine which combos a phone supports.

Related Terms

← CA-CFAR Cadence AWR →

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