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Abstract-In this paper, we explore the idea that 5G will permit the use of multiple waveforms, with each service employing a waveform that is best suited for it. We look at a 5G machinetype communication (MTC) scenario consisting of clustered user equipment employing device-to-device (D2D) communication, such as a smart factory with inter-communicating machinery. The overhead associated with synchronising a large number of machine-type D2D user equipment (DUE) comes at a cost that may render synchronous communication infeasible or undesirable. Based on this motivation, we consider multiple possible combinations of prominent 5G waveform candidates for cellular users and DUEs, examining the asynchronous performance of all waveforms under consideration and using the performance of synchronous OFDM as a baseline for comparison. Specifically, we focus on the coexistence of waveforms in which the ordinary cellular users employ OFDM for synchronous communication, as in LTE, and the machine-type DUEs, operating asynchronously, employ a different waveform. When DUEs employ FBMC/OQAM, the average achieved rate is marginally greater than the synchronous OFDM baseline case, and approximately 43% greater than the asynchronous OFDM case. This result is encouraging, as the benefits of asynchronous D2D communication could be enjoyed in MTC scenarios without suffering any performance reduction compared to the synchronous OFDM scenario. We then investigate how the relative performance of different waveform choices depends on the scenario by varying key parameters. Notably, for asynchronous communication, increasing the transmit power of DUEs results in diminishing benefits unless the DUEs employ a waveform that mitigates inter-device leakage interference.

The heterogeneity of the requirements for 5G necessitate a versatile 5G radio access network (RAN); slicing offers a way of realising a flexible RAN through customised virtual subnetworks. In this paper, we focus on how enabling lower layer flexibility in the RAN affects the development of RAN slicing, particularly in relation to ensuring isolation between RAN slices. We first examine how RAN slices may be individually tailored for different services. We follow this up with an examination of the potential time-frequency resource structure of the RAN, focusing on the trade-off between flexibility and the overhead related to ensuring coexistence between contrasting RAN slices. Based on this analysis, we suggest an approach that permits the allocation of resources to a service-type to be performed separately to resource allocation for individual services belonging to that type.

Device-to-device (D2D) communication is being heralded as an important part of the solution to the capacity problem in future networks, and is expected to be natively supported in 5G. Given the high network complexity and required signalling overhead associated with achieving synchronization in D2D networks, it is necessary to study asynchronous D2D communications. In this paper, we consider a scenario whereby asynchronous D2D communication underlays an OFDMA macrocell in the uplink. Motivated by the superior performance of new waveforms with increased spectral localization in the presence of frequency and time misalignments, we compare the systemlevel performance of a set-up for when D2D pairs use either OFDM or FBMC/OQAM. We first demonstrate that inter-D2D interference, resulting from misaligned communications, plays a significant role in clustered D2D topologies. We then demonstrate that the resource allocation procedure can be simplified when D2D pairs use FBMC/OQAM, since the high spectral localization of FBMC/OQAM results in negligible inter-D2D interference. Specifically, we identify that FBMC/OQAM is best suited to scenarios consisting of small, densely populated D2D clusters located near the encompassing cell's edge.

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