 In addition to this "scheduled" mode of transmission, the standards allows a self-initiated transmission mode from the UEs, denoted "non-scheduled".The non-scheduled mode can, for example, be used for VoIP services for which even the reduced TTI and the Node B based scheduler will be unable to provide the very short delay time and constant bandwidth required.Each MAC-d flow (i.e., QoS flow) is configured to use either scheduled or non-scheduled modes.