Call Drops in CDMA

Reasons for decision Drops in CDMA System

The following will be reason for the born decision in CDMA:

In the Forward Link:

1) Improper setting for the overhead channel power level and also the traffic channel power thresholds.

2) Improper hand off parameter setting.

3) Removing the pilot from the active set by the candidate set before the replacement.

4) Pilot is just too weak to lock the code pursuit loop.

5) Distortion of the forward signal by the facility electronic equipment.

6) Improper management of the forward channel power.

7) High Frame Error Rate (FER), poor pilot, or poor RSSI.

within the Reverse Link:

1) Improper setting of the access parameters, improper setting of the open loop power management, or improper setting of the reverse link Eb/No threshold price.

2) variety of communication conditions cause the system to revert to the system determination state of the initiated system setting.

3) Maximized French telephone power and poor link quality.

4) Unsuitable pilot throughout the hand off operation.

5) Poor performance of the forward link power management channel.

6) Link imbalance.

7) High FER, frequent amendment within the transmit gain, and high transmit power.

Possible software package issues inflicting the decision Drop/Failure:

1) associate degree updated neighbor list wasn't received. once a triple-crown inter-MSC laborious hand off, a message carrying associate degree updated neighbor list of the target cell should be received—if the list isn't received, a decision drop happens. In accordance with this embodiment, this drawback is resolved by applying a supplementary package to the BTS software package (i.e., change the software) to forestall decision drops owing to this condition.

2) The guard timer isn't properly operating. once a triple-crown forward channel inter-MSC laborious hand off, the time till the associated reverse channel inter-MSC laborious hand off happens is restricted so as to forestall the ping reek phenomena. In accordance with this embodiment, once analyzing the message, if the above-noted time is shorter than a planned price (e.g., 5 seconds), a supplementary package is applied.

3) associate degree improper message is received whereas acting the laboriousHandOver. In accordance with this embodiment, associate degree improper message of this kind is indicative of a mobile station drawback or a software package drawback, whereat acceptable corrective measures square measure taken.

4) once acting the laborious hand off, the decision isn't sounding and so the decision is born. In accordance with this embodiment, this condition is set to be a mobile station drawback, whereat corrective action is effectuated.

Environmental drawback inflicting decision Drop/Failure

The reason behind the decision drop/failure is also associate degree RF environmental drawback, e.g., excessive path loss or delay unfold, which ends in low signal strength within the inter-MSC hand off space. once acting laborious hand off underneath the condition of a previous signal from the serving cell, the serving cell signal bit by bit worsens as a result of the mobile station is moving towards the target cell. during this state of affairs, if the mobile station fails to receive the signal provided by the serving cell BTS, the laborious hand off towards the target cell can't be performed, and since the FER will increase, the decision is born. In accordance with the embodiment, this condition is remedied by adjusting the transmitpower from BTS in the direction of antena or vice versa. The optimized signal strength (Ec/Io) within the service cell of the inter-MSC laborious hand off is -10˜-7 d