Otto Lehtinen

Convergence of UTRA TDD uplink power control

In this article convergence of UTRA TDD uplink dedicated physical channel (DPCH) power control is studied. Current uplink power control is based on several measurements, which involve both random and systematic errors. Outer loop power control is used to compensate the systematic error. Since the amount of systematic error is unknown in the beginning of a call and after each handover, the outer loop power control should adapt to the current conditions as fast as possible. In this paper the effect of the convergence speed of the outer loop power control to the UTRA TDD system performance is analyzed by the means of dynamic system level simulator.

Downlink power control of dedicated channels in UTRA TDD

This paper discusses downlink power control of dedicated channels in UTRA TDD. The current UTRA TDD downlink power control is similar to the one in UTRA FDD mode, that comprises of closed inner loop and quality based outer loop. However, due to the time division feature and associated flexibility with asymmetry of TDD, the inner loop can not operate as fast as in FDD and it is affected by rapid changes in environment. Therefore, the effect of downlink power control of dedicated channel inner loop algorithm to the performance of UTRA TDD network is studied in this paper. A dynamic system level simulator is used for this purpose.

Signaled step size for downlink power control of dedicated channels in UTRA TDD

This paper discusses downlink inner loop power control in UTRA TDD. The current UTRA TDD downlink power control is similar to one in UTRA FDD mode, but due to the time division feature of TDD it can not operate as fast as in FDD and it is affected by rapid changes in environment. In this paper an improvement for the downlink inner loop power control algorithm is presented in which the power control step size is based on the difference between UE measured SIR and target SIR. This difference is then signaled from UE to UTRAN. Since the effectiveness of this algorithm depends on available signaling bandwidth that is used, dynamic system simulations are carried out to find out how many bits are needed for the signaling and how this algorithm is affected by signaling and measurement errors.

Improving UTRA TDD downlink power control with asymmetrical steps

This paper discusses downlink power control of dedicated channels in UTRA TDD. The current UTRA TDD downlink power control is similar to the one in UTRA FDD mode, that comprises of closed inner loop and quality based outer loop. However, due to the time division feature and associated flexibility with asymmetry of TDD, the inner loop can not react as fast as in FDD and it is affected by rapid changes in environment. Therefore, the effect of the inner loop algorithm to the performance of UTRA TDD network is studied in this paper. Especially, the use of asymmetrical step sizes in power adjustment is proposed, and the achieved gains are highlighted by the means of dynamic system simulations.

Signaled Step Size for Downlink Power Control of Dedicated Channels in UTRA TDD

This paper discusses downlink inner loop power control of dedicated channels in UTRA TDD. The current UTRA TDD downlink power control is similar to one in UTRA FDD mode, that comprises of closed inner loop and quality based outer loop. However, due to the time division feature and associated fexibility with asymmetry of TDD, the inner loop can not react as fast as in FDD and it is affected by rapid changes in environment. Therefore, the effect of the inner loop algorithm to the performance of UTRA TDD network is studied in this paper. Especially, the use of asymmetric step sizes for “power up” and “power down” commands is evaluated in contrast to the conventional symmetric power adjustment. Since it would be beneficial for the downlink inner loop power control to reach the target SIR as fast as possible, the power control step size based on the difference between the UE measured SIR and target SIR would be the most desirable power adjustment. Since the effectiveness of this type of an algorithm depends on available signaling bandwidth that is used, a study is carried out to find the tradeoff between the signaling bandwidth and related network performance.