Spectrum for wireless communication is scarce and fragmented, and the rules for its use are very heterogeneous. Most of the spectrum is licensed to a specific operator or service, for example for cellular communication systems like GSM, UMTS and LTE. There is also unlicensed spectrum, most notably the industrial, scientifically and medical (ISM) bands, which are open to all users and all services as long as some “fair use” is guaranteed and technical constraints such a maximum transmission power are adhered to. Recently, there has also been a strong interest in the use of TV white spaces (TVWS) for mobile communication. These refer to channels within TV bands that are locally unused, typically due to the switching of TV broadcast from analogue to digital. Some countries, most notably the United States and the United Kingdom have made use of TVWS “license-exempt”, as long as the devices are certified as communicating directly with a geolocation database, implementing the channel/power usage instructions sent from the geolocation database, take into account security considerations, and comply with requirements such as achieving their stated or given spectrum mask, among others.
Future, data-hungry mobile communication systems will need to make use of all possible parts of the spectrum – relying on only one frequency band will not be an optimal solution. For example, a terminal connected to a licensed LTE network may experience network congestion, while other parts of the spectrum are temporarily underutilized. Switching completely to another band and/or radio technology might only provide a short-lived remedy, until the primary user claims back its spectrum. Therefore, aggregation of multiple bands and radio access technologies is of high importance.
The main objective of SOLDER is to develop tools and methods for the aggregation of such heterogeneous bands. This report follows up on D2.1, where we have described the state of the art and the different scenarios considered in the SOLDER project. In this report, we specify for each scenario the high-level architecture of the proposed solution, identifying functional components and their interfaces. We further specify the requirements of the different components and their interfaces.
In summary, there are 9 scenarios. All of the scenarios have in common that they use LTE as a state-of-the-art baseline technology as the main vehicle of carrier aggregation technology. The first three scenarios focus on traditional carrier aggregation as defined by 3GPP LTE Release 10 in homogeneous and heterogeneous networks as well as in the case where spectrum of multiple operators can be aggregated. In these scenarios, we are planning to develop PHY/MAC and RRM functions and algorithms (within WP3) as well as to demonstrate the proof-of-concept (within WP4). The next three scenarios focuses on the aggregation of LTE in licensed spectrum with a carrier in either unlicensed spectrum or TVWS. The main idea is to use one carrier as an anchor point to the system for control information and basic services while another (opportunistic) carrier could be used for broadband, delay tolerant services. The aggregation of licensed LTE spectrum with LTE in unlicensed spectrum has recently also gained attention within 3GPP, where a study item called LTE-U is being prepared for release 13. In SOLDER we are planning to produce simulation studies as well as a proof-of-concept for these scenarios.
Last but not least, we consider a scenario of a 5G communication system employing a new waveform, called filter bank multicarrier (FBMC). This new waveform has the advantage of lower peak-to-average power ratio (PAPR) as well as adjacent carrier leakage (ACLR). Further, it does not have as stringent requirements on synchronization as OFDMA used in LTE. We also study the possible aggregation of this new 5G carrier with existing LTE and HSPA carriers, as a multi-RAT CA scenario, through simulation as well as through proof-of-concept.