Quality of Service

Other benefits of the improved receive sensitivity include improved handover performance and improved integrity of coverage within the main footprint. These will result in a better quality of service as perceived by the customer in fewer dropped calls and call quality improvements.

The potential causes of a dropped call include:

• Handover Failure
• Handover region too small
• Not enough hand-over margin
• Blocking on target cell
• Poor Signal Strength
• Interference
• Network Issues
• Hardware Failure
• Transmission Faults
• Poor configuration of network parameter (e.g. neighbour lists)

Improvement in the receive sensitivity can improve most of these causes, with the exceptions of handover blocking on target cells (capacity or configuration problems) and network issues.

Worked Example 5: Dropped Call Churn Costs

Retrofitting of Mesaplexx product into existing cell sites reduces interference between operator networks and improved receiver sensitivity = improved QoS = reduced customer churn.

If the average monthly churn is 2% the potential revenue lost due to churn is 50%*Customer Lifetime Value = A$902 per churn. Then the additional cost of A$212 per replacement customer, is added giving a total financial burden of A$1,114 per customer lost.
A 4/4/4 base station supports 2,640 customers, so that the average churn cost per month is A$58,820 per base station. As discussed earlier, for a 3 dB receive sensitivity improvement, the reduction in churn is assumed to be 6.3%, which gives a monthly saving of A$3,705. For 6 dB improvement, the reduction in churn is 10.5%, giving a monthly saving of A$6,175.

Poor call quality is generally a result of bit error rates that exceed the correction capabilities of the codec. These can be caused by handset issues (e.g. the crystal oscillator within a handset can go off center frequency if it has been frequently dropped) or network issues: low signal strength and/or high levels of interference.