of both aspects. Obviously, aspect B has a major impact on the user perceived packet delay. Therefore, different combinations of A and B can be appro- priate for different services. For instance, a voice service requires a low-delay, regular access to the wireless medium with a relatively low average bit rate requirement. In contrast, the perceived QoS of a file download service is largely determined by the overall bit rate rather than by the experienced delay of individual packets. Regarding the operation of the admission control algorithm, it can be use- ful to distinguish two load regimes. In the "abundance of resources" regime, the resources for newly arriving bearer requests are available with a broad margin, SO a thorough inspection of the current resource situation (including radio and trans- port resources) is not necessary. In the "tight resource" regime, the resource require- ment of newly arriving radio bearers and the availability of the necessary resources must be checked before the admission decision. © 2009 by Taylor & Francis Group, LLC Long Term Evolution: GPP LTE Radio and Cellular Technology 4.2.2 Dynamic Packet Assignment-Scheduling As it has been described in Section 4.1.2, the radio interface in LTE is used as one common channel, shared by all users in the cell, which are scheduled in the time- frequency domain, optionally extended with the antenna configuration as a third dimension of the resource space. The eNode B controls the assignment of resources on the uplink and on the downlink shared channels, called the PUSCH (physi- cal uplink shared channel) and the PDSCH (physical downlink shared channel), respectively. Correspondingly, it is necessary to differentiate a downlink scheduler and an uplink scheduler function in the eNode B. The location of the DL scheduler in the eNode B is a straightforward choice; actually, it is the only feasible choice. However, in principle, the UL scheduler function could have been distributed into the UEs as well, resulting in a UE-controlled multiple acces