the downlink scheduler because data buffering is done in the eNode B. However, because the UL buffers are located in the UE, the UL scheduler in the eNode B can have some (approximate) knowledge of the UL buffer status only if the UE reports this information to the eNode B. Regarding the UL buffer status reporting, it is useful to differentiate two cases depending on whether the UE has a valid UL grant (i.e., the UE is in the middle of a continuous UL transmission) or does not have a UL grant (i.e., its UL buffers were emptied in a previous scheduling instance and it needs to request new UL resources upon arrival of the first packet into the empty buffer). To request resources in this latter case, there are two possibilities in LTE: using the random access channel (RACH) or a dedicated scheduling request (SR) resource on the PUCCH, if there has been such a resource assigned to the UE by the eNode B. The SR sent on the PUCCH consists of only one bit of information, indicating only the arrival of new data. The main advantage of the dedicated SR as compared to RACH-based request is that it provides a faster access to UL resources, due to being contention free, and at the same time off-loads the RACH channel from frequent UL resource requests resulting from bursty packet data sources. A prerequisite for having a dedicated SR resource is that the UE must have UL time synchronization; that is, it must have up-to-date time alignment value from the network, requiring that the UE had UL transmission within the past x100 ms (the maximum time before the clocks in the UE and in the eNode B drift in the order of the cyclic prefix, 4.7 us). However, not all UEs with UL time synchroniza- tion may have such a dedicated resource because the number of such resources is limited. The eNode B can assign and revoke SR resources via higher layer signaling, depending on the number of active UEs in the cell, the activity of the UE, etc. If the UE does not have such a dedicated SR resource, it has to rely on the normal RACH procedure to r