Combination of centralised and distributed radio resource management – Proof of Concept 1
Proof of Concept 1 (POC1) is about the combination of centralised and distributed radio resource management (hierarchical RRM) with a novel MAC protocol for higher capacity in small cells.
POC1 shows how the SPEED-5G outcomes can be implemented to optimize the usage of spectrum resources and deliver the best QoS in dense heterogeneous networks in order. The POC relies on the hierarchical RRM framework which mixes both distributed and centralized RRM agents (dRRM and cRRM, respectively) and two multi-RAT small cells. Depending on the traffic load, the dRRM agent of a small cell may decide to offload some traffic on a channel of the 5 GHz unlicensed band, and it notifies the cRRM agent about this decision. In order to avoid interference on the 5 GHz band, cRRM provides the other cell with a spectrum mask which prevents it from transmitting on the same channel. In this POC, the second cell implements a novel MAC protocol based on post-LTE waveform (FBMC), which is capable of autonomously selecting the least interfered channel on the 5GHz band. Relying on a mandatory listen-before-talk procedure and a channel selection based on reinforcement learning, this MAC protocol is able to apply the guideline of the cRRM and determine the best possible channel to transmit data to UEs, avoiding interference from other coexisting systems like WiFi access points and stations.
The overall scenario of this PoC is presented as a sequence diagram in Figure 1. This diagram shows the different entities involved, while the interactions between them are illustrated. According to this scenario, initially, the network can anticipate a new situation based on the collection and analysis of measurements (e.g. a sudden increase of the load in a specific area). This information can be alternatively reported to the network by some components outside of the network (e.g. vertical mechanisms). In response to the new situation, the dRRM is initially responsible to make the appropriate decision to handle this new situation (e.g. decides on the set of channels that can be selected by the MAC). The decision of dRRM is delivered to the cRRM for further acceptance and handling. In detail, based on the assumed scenario, either dRRM just informs cRRM about its decision (cRRM just updates its database of allocated resources) or ask cRRM to contribute in the final decision (e.g. cRRM may decide to exempt a channel which knows to have low quality). In addition, dRRM informs the fronthaul/backhaul about the new situation, so that resource optimization can also be performed by the backhaul segment. Finally, dRRM communicates with the MAC in order to provide the set of appropriate solutions to be used (e.g. a set of channels that can be selected by the MAC). MAC is responsible to make the final decision on channel selection e.g. select the channel with the best quality from the channels reported by the dRRM.