Smart Phone and Next Generation Mobile Computing

Supporting Wireless Technologies 171

channel in use:

•

Connectionless — Unidirectional channel used primarily for

broadcasting by the master. A slave can only have one connection-

less channel to the master. Its CID is 2. Connectionless channels

are used to implement connectionless service.

•

Connection-oriented — Full-duplex channel for connection-

mode service. Between a slave and the master there can be multiple

connection-oriented channels, each of which is identified by a

unique CID larger than 63.

•

Signaling — This is not for data exchange but for signaling

between L2CAP entities.

Protocol Data Units (PDUs) handled by the L2CAP layer are of

a similar format across the three types of channels. In addition to

the payload data (in the case of a signaling ...