Adaptive resource allocation in LTE vehicular services using LDM

In recent years, vehicular communications have attracted much attention both in the research and technology development communities. What is more, they have been considered a very important use case not only for the most important current broadband wireless standards such as Long Term Evolution-Advanced (LTE-A), but also for the emerging generation communication systems included in the 5G framework. Even if broadband wireless systems usually work in unicast mode, in order to maintain the spectrum efficiency, they should switch to a multicast mode when on average more than one user per cell is accessing the same content. Therefore, it is reasonable to think that the broadcast/multicast services will play an important role in vehicular communications, where several vehicles or road units will be sharing the same content) in a very small radius. Up to now, LTE-A resource allocation for both broadcast/multicast and a unicast service is performed distributing the resources into time and frequency domains. Nonetheless, recent studies have shown that Layered Division Multiplexing (LDM) technology can outperform the classical T/FDM approaches in terms of spectrum efficiency. Therefore, in this work LDM is proposed as a new multiplexing access technology for resource allocation. In particular, the LDM performance is evaluated for the case when a subgrouping mechanism is implemented within a scheduler for providing multicast services in LTE-A over vehicular networks.