Multicarrier Systems
The basic idea behind the multicarrier systems is dividing the broadband into several parallel sub-bands called subcarriers. As the number of the subcarriers increases, the bandwidth of each subchannel becomes narrower which increases the ability of the communication system to overcome the problem imposed by frequency-selective channels.
The dominant transmission technology nowadays is based on the orthogonal frequency division multiplexing (OFDM) scheme and is the modulation of choice in most of the current wireless communication standards such as: Long-Term Evolution (LTE), Worldwide Interoperability for Microwave Access (WiMAX), wireless local area networks (WLAN), digital video broadcasting-terrestrial (DVB-T) and digital audio broadcasting (DAB).
Frequency representation of three subcarriers in OFDM signal.
Next generation communication systems have to comply with very strict requirements for increased flexibility in heterogeneous environments, high spectral efficiency and agility of carrier aggregation. This fact motivates research in advanced multicarrier modulation schemes, such as enhanced versions of OFDM or filter bank-based multicarrier (FBMC) modulations which has the possibly to shaping subcarrier signals with waveforms that are well-localized in both frequency and time axes.
Frequency response of OFDM and FBMC filters
We have the right choice
The A&MSP has extensive experience and a wide expertise in the area of the multicarrier systems. The focus is generally on the following three areas:
- Solve the challenges related to the particularities of the different advanced multicarrier modulation schemes like the challenges related to multiple-input multiple-output (MIMO) signal processing and the challenges related to the non-availability of the channel state information at the receiver.
- Design of efficient management strategies of the available system resources in order to improve the system performance and achieve the required service quality. The team has a solid knowledge in applying the different optimization techniques like convex and game theoretic based ones.
- Crosslayer design of the communication systems, which not include only the physical (PHY) and medium access layers (MAC) but also take into account the link layer. The team has expertise in applying these design techniques in different scenarios like cognitive radio ones, hybrid terrestrial-satellite networks and cooperative communications.
Example of hybrid terrestrial-satellite wireless backhauling network
Example of cognitive radio network