Device Discovery Illustrated

Scanning units

Device A wants to search for stations

Device A wants to search for stations.

A does an inquiry (page with ID 000).

• Devices B,C,D are doing an inquire scan.

B answers with FHS packet.

Contains DeviceID and Clock.

A does an inquiry again.

C e D answer at the same time with FHS packet.

Packets are corrupted.

A does not answer.

C and D will wait an random number of slots.

A wants to search for stations.

A does an inquiry again.

C answers with FHS packet.

A wants to search for stations.

A does an inquiry again.

D answers with FHS packet.

A has all the information it needs about the units in the cell.

Summary

Inquiry scanning has a common address.

• and a common frequency pattern (from 32 frequencies).

All devices can page this address (and become masters).

All machines hearing an inquiry will answer the inquiry request.

There is a detector (correlator hit) in the slaves, that detects inquiries, before answering with a FHS providing:

• Device ID and Clock

A machine in low power waits a random time before answering again to a scan.

If there is a collision on answering to a scan, they also wait a random period before answering again.

Timing: Inquiry

Inquiry requires two packets before the slave answers.