Research On Power Control For Utran LTE Uplink

Single Carrier Frequency Division Multiple Access (SC-FDMA) is the access scheme chosen by 3GPP for uplink UTRAN Long Term Evolution Project. As SC-FDMA provides intra-cell orthogonality, one of the main reasons for performance degradation is the inter-cell interference.This degradation is accentuated by the frequency reuse factor of 1 deployed in the system, which makes the Power Control (PC) functionality a critical issue. Recently, a PC formula containing an open loop power control (OLPC) compensates for slow varying pathloss and shadowing, while the closed loop power control to compensate for fast variations and manage the interference.Firstly, this thesis introduces the theory of related technology in LTE network, including the LTE design targets, requirements and system structure, meanwhile the principle of SC-FDMA, resource allocation, frame structure and slot structure. Secondly, a system-level platform is built up and 3GPP OLPC formula is analyzed. The simulator is used for evaluating the uplink performance of SC-FDMA based on OLPC including the cell edge UE throughput, the cell center UE throughput, SINR, the transmit power of the UE. Thirdly, an inter-cell power control method based on IoT (Interference over Thermal) is proposed. This method gives an amendment step size on traditional power control through the exchange of the interference of neighbor cells. This power control in uplink is an effective method to control the inter-cell interference. And it can make IoT more steady compared to conventional fractional power control scheme.Lastly, this paper proposes a new power control method based on interference and improved power control method based on interference. The first method is better than 3GPP OLPC in the cell total throughput. But the cell edge UE throughput is lower than 3GPP OLPC. This scheme restricts the UE the transmit power in the cell edge. It generates the more interference than the cell center UE. Meanwhile it increases the UE transmit power in the cell center. The pathgain is used in the second method.It is better than the first in the cell edge throughput. In addition it can switch between various power control algorithms.