Implementation of a dynamic spectrum access protocol
SPEED-5G has done a real-time implementation of the novel Filter-Bank Multicarrier (FBMC)-based MAC protocol, which is capable of dynamic channel switching.
The FBMC-MAC protocol has been described in public SPEED-5G deliverables, especially D5.2, “MAC approaches with FBMC”. It has now been implemented on a custom HW/SW board designed in CEA, called the FleX board.
This board is able to run the FBMC transceiver in a large Field Programmable Gate Array (FPGA), whereas the software protocol stack is executed on an ARM processor running an embedded Linux operating system. It is worth noting that the PHY design is out of scope of SPEED-5G and was re-used from previous projects.
The implementation complies with the extended Dynamic Spectrum Access (eDSA) framework proposed by SPEED-5G, which is built on a close cooperation between the MAC layer and an RRM entity in charge of managing interference in the context of dense networks. In addition, eDSA specifications split the MAC layer into higher MAC (HMAC) and lower MAC (LMAC) entities, the former being in charge of communicating with the RRM entity and configuring the latter. LMAC is the time-constrained part of the MAC layer, mainly in charge of resource allocation and interfacing with the PHY for data packets management.
The implementation is able to perform the following procedures:
– MAC configuration by RRM
– Device association/de-association
– RRM-triggered measurement configuration and collection
– Channel switching
– Service establishment
– Device paging
– Data management with adaptive modulation
Lab tests have allowed to validate the design with one small cell and 2 UEs, using RF transmission over coaxial cables. It shows that the implementation complies with the specifications. Early outdoor field trials have been realised as well, showing that the design is also able to cope with real-life conditions. The next step is the integration of a channel selection algorithm on top of this MAC, in order to dynamically select the best channel when coexisting with neighbouring systems. This combined system will be tested with off-the-shelf Wifi equipment. Special attention will be paid to the fairness between Wifi and FBMC-MAC design when dealing with QoS demanding services like video.