islamhasabo
2012-08-11, 11:30 PM
-Power control (PC) is an essential feature of any CDMA based cellular system.
-Without accurate PC these systems can't operate ____> Single overpowered mobile could block a whole cell.
-How can PC help them?
1-Removes Near-Far effects.
2-Mitigates Fading.
3-Compensates changes in propagation conditions.
4-Decrease Intra-cell (Ul) and Inter-cell interference (UL & DL).
-The result ___> Increased system capacity
-The Mechanism
29068
-As shown Open loop Power control (OLPC) mechanism (coarse tuning) is used in the initial random access through Physical Random Access Channel (PRACH).
-The UE increase it's initial power with defined level and timing (received from the broadcasted information) steps until it gains access to the cell .
-But OLPC will be not effective especially in fast fading conditions so___> we add a fine tuning mechanism Closed loop power control
-The outer closed loop at rate 100 times per second set the target SIR that can be compared with measured SIR in order to BS and UE know what to do with
mesured SIR at rate 1500 times per second in the inner fast closed loop power control.
-Without accurate PC these systems can't operate ____> Single overpowered mobile could block a whole cell.
-How can PC help them?
1-Removes Near-Far effects.
2-Mitigates Fading.
3-Compensates changes in propagation conditions.
4-Decrease Intra-cell (Ul) and Inter-cell interference (UL & DL).
-The result ___> Increased system capacity
-The Mechanism
29068
-As shown Open loop Power control (OLPC) mechanism (coarse tuning) is used in the initial random access through Physical Random Access Channel (PRACH).
-The UE increase it's initial power with defined level and timing (received from the broadcasted information) steps until it gains access to the cell .
-But OLPC will be not effective especially in fast fading conditions so___> we add a fine tuning mechanism Closed loop power control
-The outer closed loop at rate 100 times per second set the target SIR that can be compared with measured SIR in order to BS and UE know what to do with
mesured SIR at rate 1500 times per second in the inner fast closed loop power control.