transmission of the highest priority data within an allowed limit step 310 tbs size is chosen based on the node b 104 signaled maximum mcs and tbs size transmit power available for the e dch 108 mcs and the data available in the buffer 112 for transmission for each transport channel trch dedicated channel medium access control mac d flow or logical channel a list of allowed tbs sizes a retransmission limit and allowed transmission latency i e mac data u201c lifespan u201d are determined the allowable mcs and tbs sizes are the maximum that the wtru 102 is allowed to transmit for the current physical resources allocation period the configuration is either signaled from the rnc 106 in accordance with radio resource control rrc procedures or uniquely specified by a standard the chosen mcs and tbs size may be either explicitly signaled preferably from the node b or derived from an associated parameter such as a channel quality indicator cqi and or transport format combination tfc index the cqi may represent the maximum allowed wtru interference or transmit power the node b 104 may signal this information in the initial channel assignment alternatively the node b 104 may send this information when the wtru 102 requests additional eu channel allocations in step 312 the wtru 102 then generates at least one eu mac mac e protocol data unit pdu based on the.