Group-wise channel sensing and resource pre-allocation for LTE D2D on ISM band

Device-to-Device communication has been regarded as a promising technology to improve the cellular system efficiency, which allows mobile devices communicate directly with each other on the licensed frequency resources under the control of a base station (or eNB). However, the benefits of D2D using license exempt bands, such as ISM bands, have not been sufficiently taken into account yet. The main challenges arise from the coexistence of D2D and WLAN in the same frequency band and geographical area. In this paper, we propose a group-wise channel sensing and resource pre-allocation scheme for D2D user fairly contending and utilizing the ISM band resource with its WLAN rivals, where D2D pairs with different QoS or bandwidth requirements are grouped and pre-scheduled to approximately fill in an overall flexible resource block and then a representative D2D pair is appointed in each group for contending resource to avoid intra-group collisions. By using the proposed scheme, the resource on ISM band can be used more efficiently so that D2D applications can be applied to a much wider scope.