Node B-Located OLPC for Enhanced Uplink

In this article, systemic aspects related to the Outer-Loop Power Control (OLPC) for WCDMA enhanced uplink are investigated. A Node B-located OLPC algorithm based on the number of Hybrid Automatic Repeat Request (HARQ) transmission attempts is introduced. Traditionally, the OLPC functionality is located in the Radio Network Controller (RNC) and operates on the Radio Link Control (RLC) Block Error Rate (BLER) striving to maintain the pre-established QoS requirement. In the Enhanced Uplink (E-UL), the utilization of a correctly working Node B HARQ operation diminishes the RLC BLER remarkably. The proposed Node B-located OLPC can take full advantage of the number of HARQ retransmissions since its operation is not affected by the signaling exchanged between Node B and RNC entities over the Iub interface. However, when the Node B-located OLPC is considered in a Soft Handover (SHO) situation, the CIR-drift problem that emerges compromises the OLPC performance, and some mechanism to compensate for the CIR-drift problem is required. Both an aggressively tuned anti-windup function and an Retransmission Sequence Number (RSN)-based functionality handle this problem. It is observed that the Node B-located OLPC provides gains in terms of lower CIR since there is no delay due to the signaling exchange between RNC and Node B network entities.