Variable Inquiry Delay

From Mobitouch cube

Due to its nature, the Inquiry process generates a lot of "interference" with the transmitting radios (i.e. many packets are lost and need to be retransmitted). This results in a lower transmission speed and a lower throughput.

To minimize the effect of the Inquiry process on the dispatching antennas, it is convenient to increase the OFF-STATE in the Inquiry Duty Cycle. This will reduce packet collision but also will impact the Latency in device detection. So it is always necessary to find a trade off between these two conflicting objective.

Mobitouch implements an intelligent algorithm which dynamically changes the Inquiry duty Cycle according to the number of established connections.

When no connections are established, the OFF-STATE in the Inquiry Duty Cycle has a duration of MIN_INQUIRY_DELAY, thus minimizing latency.

When the maximum number of parallel connections has been established (the maximum number of parallel connection equals to: MAX_CONNECTIONS_PER_ANTENNA x NUMBER_OF_ANTENNAS) and thus latency is not a big problem any more, Mobitouch sets the OFF-STATE duration to MAX_INQUIRY_DELAY.

Changing these two parameters has a huge impact on the following performance metrics:

• LATENCY (decreasing the delay)
• SPEED (increasing the delay)
• THROUGHPUT (finding the best compromise with parameters)