Methods, systems, and devices are described to support multiple timing advance groups for multi-carrier user equipment. Some embodiments provide for utilizing timing advance group synchronization information across multiple timing advance groups. Some embodiments provide support for performing random access procedures in relation to timing advance groups that may not include a primary component carrier. Some embodiments utilize timing advance group indexes to enable cross-carrier random access procedure management. Other embodiments support parallel random access procedures across multiple timing advance groups. Some embodiments provide for a reference downlink component carrier for timing within a timing advance group.