rts both synchronous Application Applications/Profiles Presentation OTHER Session RFCOMM Transport Logical Link Control Network Adaptation Protocol Audio (L2CAP) Control Logical Link Link Manager Control (LLC) Medium Access Baseband Control (MAC) Physical Physical (PNY) Physical Radio ISO OSI IEEE 802 IEEE 802.15.1 Layers Standards Bluetooth WPAN Figure 13.2 Mapping OSI into the IEEE 802.15.1 Bluetooth WPAN five layers. (From IEEE 802.15.1-2002, Fig. 2, page 23, Ref. 6.) METROPOLITAN AREA NETWORKS communication channels for telephony-grade voice communication and asynchronous communication channels for data communications. These facilities enable a rich set of devices and applications to participate in the Bluetooth WPAN. For example, a cellular phone may use the circuit-switched channels to carry audio to and from headset while concurrently using a packet-switched channel to exchange data with a notebook computer. The Bluetooth WPAN operates in the unlicensed 2.4-GHz ISM band. A fast frequency- hop (1600 hops/sec) transceiver is used to combat interference and fading in this band (i.e., reduce the probability that all transmission is destroyed by interference). A Gaussian- shaped binary frequency shift keying (FSK) with a symbol rate of 1 Msymbols/sec minimizes transceiver complexity. A slotted channel is used, which has a slot duration of 625 usec. A fast time division duplex (TDD) scheme is used that enables full duplex communications at higher layers. On the channel, information is exchanged through pack- ets. Each packet is transmitted on a different frequency in the hopping sequence. A packet nominally covers a single slot, but can be extended up to either three or five slots. For data traffic, a unidirectional (i.e., symmetric) maximum of 723.2 kbps is possible between two devices. A bidirectional 64-kbps channel supports voice traffic between two devices. Figure 13.3 shows the general format for a single-slot, payload-bearing packet trans- mitted over the air in a Bluetooth WPAN. The packet comprises a fi