What is Outer loop power control?
Outer loop power control is used to maintain a certain quality in terms of Frame Error Rate (FER). This is done by comparing a measured FER value with a FER target and using the difference to regulate the SIR target used by the fast power control.
Why power control is used in UMTS?
Fast power control is important in keeping interference to a minimum and improving capacity. Without it, transmit power would have higher to meet quality targets. The gain from this control is as much as 5.8 dB at the receiver for pedestrian speeds for 8kbps speech with 10ms interleaving and antenna diversity.
What is the main reason for open loop power control?
Open-loop power control is easier to implement but cannot usually compensate for multipath fading, which is not reciprocal if the transmitted and received signals occupy different frequency bands. Therefore, in order to be able to compensate for multipath, closed-loop power control is usually envisioned.
What is close loop power control?
Closed Loop Power Control (CLPC) measurement, as defined in TS 34.122 Section 5.4. 1.4, is used to test the ability of the UE transmitter to adjust its output power in accordance with one or more TPC commands received in the downlink.
Why is power control important in CDMA?
In CDMA, since all the mobiles transmit at the same frequency, the internal interference of the network plays a critical role in determining network capacity. Further, each mobile transmitter power must be controlled to limit the interference. Power control is essentially needed to solve the near-far problem.
What is the difference between open loop and closed loop control?
The main difference between open-loop and closed-loop control system is, the required output within the open loop doesn’t depend on the controlled act whereas, in closed-loop, the required output mainly depends on the controlled act.
What is Sir in UMTS?
The SIR indicates the ratio between the received signal level and the level of interference. This parameter is used in WCDMA systems to control transmission power of user equipment (UE).
What is open loop power control?
Open Loop Power Control Measurement Description 1.3, the open loop power control is the ability of the UE transmitter to sets its output power to a specific value. The open loop power control measurement can only be initiated when the Operating Mode is Active Cell and the call status is Idle.
What type of power control is applied in WCDMA UMTS?
closed-loop PC
Power control in WCDMA is a closed-loop PC which is a combination of outer and inner closed loop control (see Figure 1). The inner (also called fast) closed loop PC adjusts the transmitted power in order to keep the received Signal-to-Interference Ratio (SIR) equal to a given target.
Why power control is used in cdma2000 and UMTS?
The power control in cdma 2000 and WCDMA is to minimize interference due to presence of other mobile users, fading, log normal shadowing as well as from fast Rayleigh fading. viii. In cdma2000, power control is at the rate of 800Hz in both the links and it is at a rate of 1500Hz in both the links in WCDMA.
Which is more stable open loop or closed loop?
As compared to closed loop system an open loop control system is more stable as all its roots are in left half of s plane only, but it less accurate since there is no feedback to measure the output value and compare it with the input value.
Is open loop better than closed loop?
The open loop system is not reliable whereas the closed-loop system is reliable. The accuracy of the system is less as compared to the closed-loop system. The open loop system is more stable as compared to a closed loop system.
How is outer loop power control used in UMTS?
Outer loop power controlis used to maintain the quality of communication at the level of bearer service quality requirement, while using as low power as possible. The uplinkouter loop power control is responsible for setting a target SIR in the Node B for each individual uplink inner loop power control.
How does the uplinkouter loop power control work?
The uplinkouter loop power control is responsible for setting a target SIR in the Node B for each individual uplink inner loop power control. This target SIR is updated for each UE according to the estimated uplink quality (BLock Error Ration, Bit Error Ratio) for each Radio Resource Control connection.
Why does UTRAN use outer loop power control?
Upon receiving the TPC commands UTRAN adjusts its downlink DPCCH/DPDCH power accordingly. Outer loop power controlis used to maintain the quality of communication at the level of bearer service quality requirement, while using as low power as possible.
What is the target Sir of the downlinkouter loop?
This target SIR is updated for each UE according to the estimated uplink quality (BLock Error Ration, Bit Error Ratio) for each Radio Resource Control connection. The downlinkouter loop power control is the ability of the UE receiver to converge to required link quality (BLER) set by the network (RNC) in downlink.