System and methods are disclosed in which an uplink frame is configured to accommodate each, some, or all of the following types of access: (1) demand assigned access in which a UE requests resources and is then granted a partition of resources of the uplink frame; (2) free assigned access in which one or more UEs are granted a partition of resources of the uplink frame without UEs requesting the grant of the resources; and (3) random access in which a partition of resources of the frame are used by UEs for random access communication. The frame may be configurable on a semi-static or dynamic basis. In this way, the base station may be able to better accommodate UEs having different traffic characteristics and/or different latency requirements.