inal in multiple cells is fundamentally beneficial as it provides diversity. Another major difference between HSDPA and HSUPA is that the latter will not support adaptive modulation because it does not support any higher order modulation schemes and only uses the BPSK modulation scheme. The reason behind is that the higher modulation schemes requires more energy per bit to be transmitted than the BPSK modulation scheme. The common resource of the enhanced uplink is the amount of tolerable interference. It is represented by the Noise Rise (NR) which is defined as (Io+No)/No where No and I are the noise and interference power spectral densities, respectively. A too large noise rise would cause some terminals not to have sufficient transmission power available to reach the required Eb/No, i.e. the ratio of Energy per Bit (Eb) to the Spectral Noise Density (No), at the base station. Hence, the uplink scheduler must keep the noise rise within acceptable limits. The basis for the HSUPA scheduling is scheduling grants (RG - Relative Grant and AG - Absolute Grant) sent by the Node B to the UE and limiting the E-DCH data rate, and scheduling requests sent by the UE to the Node B to request permission to transmit. The scheduler uses E-DCH Absolute Grant channel (E-AGCH) for transmitting Primary AG (PAG) or Secondary AG (SAG) information, and E-DCH Relative Grant channel (E-RGCH) to send relative grants (UP, Down, and Hold) to the UE. PAG or SAG are used for large changes in the data rate, while the relative grant is typically used for smaller adjustment of the data rate during an ongoing packet transmission. The HSUPA scheduler algorithm is vendor specific. More details can be found in [HT06]. More introductions of HSDPA/HSUPA and their UTRAN networks are given in Appendix A.9. 2.3.4 Introduction of "All-IP" UMTS Networks It is now widely recognized that using Internet Protocol (IP) as the foundation for next generation mobile networks enables strong economic and technical profits, since it (1) takes advantage of the ubiqu