with the most recent channel information, i.e. the scheduler can adapt the modulation to match the current channel conditions and 2.3 Evolution of UMTS fading environment in a better way, and thus the channel adaptation can be performed in a more rapid and efficient manner. 4) Fast Hybrid Automatic Repeat Request (HARQ) with soft combining: HARQ is an effective technique to correct the erroneous transmission where the mobile terminal (UE) attempts to decode each transport block received and reports to the Node B upon the reception of the transport block, which allows for rapid retransmissions of unsuccessfully received data and significantly reduces the delays associated with retransmissions compared to Rel99. Additionally, soft combining is used, which means that the soft information from the previous transmission attempts is combined with the retransmissions to increase probability of successful decoding. In order to reduce the delay associated with HARQ, the entity of HARQ is located in the base station Node B without RNC involvement. Thus, in case of packet decoding failure, retransmission automatically takes place from the Node B. The RNC-based radio link control (RLC) layer retransmission may still be applied on top in case of the Node B exceeding the maximum HARQ retransmissions. In Release 5, HSDPA is operated together with the Rel99 Dedicated Channel (DCH) where the uplink data are transmitted, whereas in Release 6 an alterative for transferring the uplink data is provided by the Enhanced DCH (E-DCH) with the introduction of HSUPA, as covered in the next section. 2.3.3 High Speed Uplink Packet Access (HSUPA) After the successful introduction of HSDPA in 3GPP Release 5, the downlink capabilities are enhanced significantly, but the uplink capabilities did not match the HSDPA downlink. Therefore, High Speed Uplink Packet Access (HSUPA), also referred to as Enhanced Uplink, is promoted in 3GPP Release 6 as an enhancement on the uplink of UMTS [3GP06a]. It provides high-speed transmission with uplink speeds u