The example embodiments of the invention provide at least a method and apparatus to configure a resource pool for a plurality of user equipment configured with contention based transmission; configure a resource allocation within the resource pool for a contention based transmission by a user equipment of the plurality of user equipment configured for contention based transmissions, wherein the resource allocation is configured with more than one predefined or preconfigured sets of resource allocation granularities; and send information comprising the resource allocation towards the user equipment, wherein the information comprises an indication of a set of the predefined or preconfigured sets of the resource allocation granularities that the user equipment is to use for the contention based transmission. Further, there is receiving resources allocated for a contention based transmission, the resource allocation configured with predefined or preconfigured sets of resource allocation granularities, the information comprises an indication of a set of the predefined or preconfigured sets of the resource allocation granularities to use; and identifying the resource allocation granularities set to use for the contention based transmission.