The success of multimedia devices like smartphones and tablets has seen demand for wireless soar across the globe. It has also put pressure on both regulatory and standardisation bodies to define new requirements for the communication technologies of tomorrow. Advanced techniques for increasing spectrum usage efficiency are required to meet both needs. Examples include Carrier Aggregation (CA) (also known as Spectrum Aggregation) and Multi User-Multiple Input Multiple Output (MU-MIMO).
SAMURAI tested both techniques in real-world conditions. The ultimate goal was to ensure that, in the future, consumers would seamlessly use sophisticated next-generation multimedia devices.
Both CA and MU-MIMO are considered hot topics from academic and industrial points of view. While CA refers to the simultaneous usage of multiple chunks of a spectrum, MU-MIMO uses a transmitter equipped with multiple antennae that communicate with several users simultaneously. However, despite thorough investigations of both techniques at the theoretical level, practical implementation had received little attention and raised numerous challenges.
The SAMURAI team examined real-life system implementation, such as the signalling needed to support both techniques. The researchers developed various prototypes to examine hardware and software implementation issues in detail. A simulator was also used to model the impact of MU-MIMO and CA on capacity, user performance and cost efficiency.
Much of the work was devoted to demonstration activities. Proof of Concept (PoC) prototypes, known as 'OpenAirInterface' (www.openairinterface.org) and 'ASGARD' (http://blog.asgard.lab.es.aau.dk), were used to check the feasibility and performance of these two key technological enablers.
The project showed that spectrum efficiency can be improved by up to 20% through the optimisation of spatial multiplexing (re-use) at the multi-user level. Moreover, as the CA building block allowed for the simultaneous use of several single bands of spectrum, bandwidth was increased by some 80%.
The SAMURAI project ended in 2012 and the CA results are expected to be incorporated into next-generation base stations, mobile phone chipsets, as well as test and measurement products. MU-MIMO may follow in later deployment. In addition, companies other than those in the consortium are free to use the project's publications and open source code.
Both the OpenAirInterface and ASGARD code are available to the scientific and industrial communities under an open development licence. This ensures that SAMURAI’s contribution will feature prominently in any future studies.
The SAMURAI results already have the potential to position Europe as a major player in next generation wireless systems.