RAT Protocols and Radio Resource Management

Task 3.4 RAT Protocols and Radio Resource Management (M10 - M24) Task leader: NOM Participants: BBC, FS, NOK, NOM, SEUK, UNIS, TIM, TUAS, UPV LTE eMBMS is constrained by rather rigid resource allocation splits between unicast and broadcast transmissions. Flexible resource allocation methods (e.g. accounting among others for the flexible frame structure of Task 3.2) are needed for 5G-Xcast to ensure QoS requirements for all services in mixed traffic scenarios and to provide seamless transition between unicast and multicast/broadcast modes. The work will be conducted by analysing RRM aspects, by taking into account the traffic volumes (which will impact the cell throughput), the performance requirements, grouping of users, unicast/multicast switching criteria under the MSMB RAN architecture outlined in Task 3.3. In this task, PHY-MAC cross-layer optimization will be investigated by considering 4-tier 5G-Xcast MSMB frequency resource structure (namely system bandwidth, service bandwidth, physical resource block and subcarrier), flexible and intelligent RRM algorithms will be designed to exploit service band diversity for optimized content delivery in the 5G-Xcast RAN. The cross-layer optimization will be investigated in the context of both SFN and SC-PTM. One aspect of this is that it will be made possible to trigger the mobile device to start MBMS reception from a trigger from the network which eliminates the need for the mobile device to continuously monitor MBMS channels. The intrinsic flexibility of a virtualised radio access network will be considered as well. The outcome of this study will contribute to the implementation of a more flexible and automated 5G-Xcast system, Broadcast/multicast shall be possible in a dynamically defined target area with cell-site granularity (rather than in a static and pre-configured fashion) for services such as PWS. It will also enable optimal adaption between SFN and single-cell PTM modes, etc. Another interesting topic to explore is the feasibility and value of link adaptation in the form of adaptive modulation and coding for multicast/broadcast transmissions. This task involves the investigation of introducing a secondary FEC level in the upper MAC layer to be expediently integrated and it might even replace FEC at the distant application layer, where cross-layer optimization would be required and tight interaction would appear difficult to perform. It is expected that this will improve transmission efficiency by reducing signalling overhead and delays. This will also be compared against the single bit-level rateless FEC considered in Task 3.2. The design of an appropriate feedback mechanism and feedback channel also plays a pivotal role in achieving efficient operation of the mechanisms applied to the downlink channels. The performance of the multi-service system will be assessed though system-level simulations, and the potential gain of using PTM transmissions compared to PTP connections identified under realistic conditions (including type of service, user reception conditions, user density, network topology, etc.). This task will also perform coverage, network and frequency planning exercises in a realistic scenario with different network topologies and frequency bands, and it will propose implementation guidelines for the deployment of 5G broadcast networks, taking into account existing regulation and spectrum allocations.