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Carrier aggregation is a technique that is used in wireless communication to increase the data rate per user, whereby multiple frequency blocks (called ''component carriers'') are assigned to the same user. The maximum possible data rate per user is increased the more frequency blocks are assigned to a user. The sum data rate of a cell is increased as well because of a better resource utilization. In addition ''load balancing'' is possible with carrier aggregation. Channel selection schemes for CA systems taking into account the optimal values for the training length and power, the number of the probed sub-channels and the feedback threshold such that the sum rate is also important for optimal achievable capacity.
Depending on the positions of the component carriers three cases of carrier aggregation are distinguished:
*The case where the component carriers are contiguous in the same frequency band is called ''intra-band contiguous'' carrier aggregation.
*If the component carriers are in the same frequency band but are separated by a gap the carrier aggregation is called ''intra-band non-contiguous''.
*The most complex case is when the component carriers lie in different frequency band. This is called ''inter-band'' carrier aggregation applied to heterogeneous networks.
There is no difference between these three cases from a baseband perspective. However, the complexity from an RF point of view is increased in the case inter-band carrier aggregation.
Management architecture for aggregation of heterogeneous systems and spectrum bands
" IEEE Communications Magazine, vol. 54, no. 9, Sep. 2016 ) 112- 118.
Types of carrier aggregation
Depending on the positions of the component carriers three cases of carrier aggregation are distinguished:
*The case where the component carriers are contiguous in the same frequency band is called ''intra-band contiguous'' carrier aggregation.
*If the component carriers are in the same frequency band but are separated by a gap the carrier aggregation is called ''intra-band non-contiguous''.
*The most complex case is when the component carriers lie in different frequency band. This is called ''inter-band'' carrier aggregation applied to heterogeneous networks.
There is no difference between these three cases from a baseband perspective. However, the complexity from an RF point of view is increased in the case inter-band carrier aggregation.
Applications
UMTS
The Universal Mobile Telecommunications System (UMTS) is a third generation mobile cellular system for networks based on the GSM standard. Developed and maintained by the 3GPP (3rd Generation Partnership Project), UMTS is a component of the Inte ...
/ HSPA+
The channel bandwidth for UMTS/HSPA+ is about 3.8 MHz with a carrier spacing of 5 MHz. Carrier aggregation is also called Dual Cell in the context of UMTS/HSPA+.
Through carrier aggregation (part of the UMTS extension HSPA+) two downlink
In a telecommunications network, a link is a communication channel that connects two or more devices for the purpose of data transmission. The link may be a dedicated physical link or a virtual circuit that uses one or more physical links or shar ...
carriers may be assigned to one user since Release 8. Release 10 supports four-carrier aggregation and eight-carrier-aggregation is supported since Release 11. 3GPP standardized carrier aggregation for HSPA+ for the uplink
In a telecommunications network, a link is a communication channel that connects two or more devices for the purpose of data transmission. The link may be a dedicated physical link or a virtual circuit that uses one or more physical links or sha ...
for up to two component carriers since Release 9.
LTE/
LTE-Advanced
LTE Advanced (LTE+) is a mobile communication standard and a major enhancement of the Long Term Evolution (LTE) standard. It was formally submitted as a candidate 4G to ITU-T in late 2009 as meeting the requirements of the IMT-Advanced standar ...
LTE supports since its first release channel bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz. Since LTE-Advanced Rel. 10 any two channels (of possibly different bandwidths) may be aggregated and be assigned to a single user. A difference between two aggregated 10 MHz component carriers and a single ordinary 20 MHz channel is that in the case of carrier aggregation the control information is transmitted on both component carriers.
LTE Advanced with carrier aggregation allows Gigabit LTE. This is made possible through higher-order modulation (256QAM), carrier aggregation and 4x4 MIMO
In radio, multiple-input and multiple-output, or MIMO (), is a method for multiplying the capacity of a radio link using multiple transmission and receiving antennas to exploit multipath propagation. MIMO has become an essential element of wir ...
. Since LTE Release 10 up to 5 component carriers may be aggregated, allowing for transmission bandwidths of up to 100 MHz. Using five aggregated component carriers, MIMO and 256QAM allows theoretical data rates of up to 2 gigabits per second. A management architecture that can aggregate particular systems, networks, and terminals in view of better managing the collection of available resources on a heterogeneous system level, taking into account all systems', networks', and terminals' traffic requirements and technical capabilities is considered for LTE-A system with potential deployment to 5G networks.S. O. Holland, A. Aijaz, F. Kaltenberger, F. Foukalas, G. Vivier, M. Buczkowski and S. PietrzykManagement architecture for aggregation of heterogeneous systems and spectrum bands
" IEEE Communications Magazine, vol. 54, no. 9, Sep. 2016 ) 112- 118.
References
{{reflist Wireless networking