Lte Carrier Aggregation Band Combinations – 3GPP Releases 10 and 11

CA enables the sharing of spectrum across multiple spectrum channels (component carriers) and multiple bands. CA can be implemented with both FDD and TDD spectrum. It can be intra-band using spectrum in the same band that is either contiguous or non-contiguous. Or, CA can involve the combined use of inter-band of spectrum in different bands. While CA makes possible the combination of 5x20MHz carriers across 5 spectrum bands, current activity – both in standards bodies and from service providers – centers on CA with single band or dual band scenarios.

According to Third Generation Partnership Project (3GPP) Releases 10 and 11, there is an array of band combinations now specified for LTE-A CA as shown in Table I, below.

Table 1: Carrier Aggregation Band Combinations – 3GPP Releases 10 and 11

Source: 3GPP, 2013

There is a significant omission in the spectrum band combinations detailed in Table 1, namely, options for CA with the Asia Pacific (APT700) MHz band plan, which is now widely adopted across the Asia Pacific region and by a growing pool of service providers in Latin America. However, this issue, along with the addition of multiple CA band configurations are being addressed as part of the current 3GPP Release 12 agenda, as detailed in Table 2, below.

Table 2: Carrier Aggregation Band Combinations – 3GPP Release 12

Source: 3GPP, 2013

Candidate spectrum bands for CA vary by region, with service providers in the US primarily focusing on combining 700MHz spectrum in either Band 12, 13 or 17 with AWS spectrum. Canadian operators are expected to follow the same path once 700MHz (based on the US band plan) is awarded next year. Although not reflected in Table 2, 3GPP Release 12 also includes work items for CA 3-band implementations across the North American bands – 2, 4, 5, 13, 17 and 30. In the United States, Sprint will initially focus on CA within the 2600MHz TDD. In Canada, Rogers is also looking to CA with its AWS and 2600MHz spectrum holdings.

European CA activities are focused on different combinations of spectrum across the 800MHz, 1800MHz and 2600MHz FDD bands. 1800MHz combined with 2600MHz FDD spectrum is also of interest to operators in the Asia Pacific. Service providers in the region will also examine sharing with 700MHz as it is progressively released across the region. This is also the case for service providers in Latin America. 3GPP Release 12 includes a work item for CA in the 1800MHz band with the APT700MMhz band. As shown in Tables 1 and 2, 3GPP releases also account for country specific band allocations such as in Japan, China and South Korea.

The 3GPP CA work item lists are also devoid of options for TDD-CA, other than in single band mode. While CA combining both FDD and TDD spectrum will eventuate in the longer term, CA TDD deployments will initially focus on intra-band deployments. This is made possible as, unlike FDD spectrum licenses, service provider TDD holdings are generally based on larger bandwidth (MHz) allocations (i.e. 2x20MHz) capable of supporting LTE-A delivery.