Carrier Aggregation (CA)
At the World Radiocommunication Conference 2007 (WRC07), it was strongly argued that additional spectrum would be required for future mobile systems considering the explosive increase in mobile traffic expected over the next 15 years. The WRC07 defined several new bands for IMT-Advanced:
- 450 MHz band;
- UHF band (698–960 MHz);
- 2.3 GHz band;
- C-band (3400–4200 MHz).
In March 2008, the Radiocommunication sector of the International Telecommunications Union (ITU-R) commenced developing ITU-R Recommendations for the terrestrial components of the International Mobile Telecommunications-Advanced (IMT-Advanced) radio interface(s). The key features of IMT-Advanced in the recommendations are:
- a high degree of functional commonality worldwide while retaining the flexibility to support a wide range of services and applications in a cost-efficient manner;
- compatibility of services within IMT-Advanced and with fixed networks;
- capability of interworking with other radio access systems;
- high quality mobile services;
- user equipment suitable for worldwide use;
- user-friendly applications, services, and equipment;
- worldwide roaming capability; and
- enhanced peak data rates to support advanced services and applications (100 Mbps for high mobility and 1 Gbps for low mobility were set as research targets).
Given these features, the ITU-R invited proposals for candidate radio interface technologies for IMT-Advanced. In order to provide the 3GPP proposals for IMT-Advanced ...