4G mobile communication  systems achieve high data rates, which could be compared with those provided by landline communications. Several key technologies played a significant role towards this end. A new element to this success is the carrier aggregation (CA) technology, which has been first described in 3GPP LTE-Advanced system. In particular, CA can achieve the highest data rates through dynamic utilization of multiple continuous or non-continuous spectrum bands. This technique will satisfy larger bandwidth demands of emerging services while maintaining higher spectrum utilization factors. The need for an efficient CA deployment is also related to another key aspect of the beyond 4G mobile wireless communications, known as heterogeneous networks (HetNets) and heterogeneous radio access technologies (h-RATs). Considering this kind of heterogeneity, the CA of heterogeneous spectrum bands (HetBands) should be accomplished of micro, pico and femto cells. The main objective of the SOLDER is to provide the aggregation of such HetBands enhancing thereby the overall composite capacity and quality of service at the user equipment (UE). More specifically, the main objectives of the SOLDER project are the following:

  1. To design and develop physical layer techniques for efficient CA over HetNets and h-RATs; new transceiver architecture, aggregation algorithms and diversity techniques in non-continuous multi-carrier communications.
  2. To provide efficient medium access control over the HetNets and h-RATs with aggregation capabilities through link adaptation and scheduling approaches. To develop radio resource management exploiting the full potential of heterogeneous carriers.
  3. To efficiently aggregate HetBands used by 3GPP LTE, WiFi and other systems providing seamless and enhanced service delivery. These HetBands might encompass a range of spectrum types and opportunities, including licensed spectrum, license-exempt spectrum, and “white space” among others.