Personal Health Device WG Transport Issues

Transport Adaptation Layer 11073 Protocol Stack Application Profiles Application Layer Services Transport Adaptation Layer Proprietary Wireless Link layer 802.15.4 Zigbee TCP/IP Bluetooth RS232

Logical Link Control Adaptation Protocol (L2CAP) 802.15.1 Protocol Stack Application layer Application Profiles Other Service discovery RFComm Telephony Middleware layer LLC Control Audio Logical Link Control Adaptation Protocol (L2CAP) Data Link layer Link manager Baseband The 802.15.1 protocol stack does not follow the normal OSI model, and in addition to the lower layers, defines a set of specialised application services and profiles built on top of the functions of the lower layers. It also has services designed to be real time (audio). Physical radio – Uses rapid pseudo-random frequency hopping in the 2.4GHz band on 79 channels using frequency shift keying (FSK) to give 1Mbps gross bit rate. The hops are specific to a piconet and determined by the master. Master and all slaves follow the hopping sequence. The hops are every 625 μs (1600/s) and 250 μs are used to allow the receiver to settle, so only 366 bits are left for transmission, although the frequency will remain fixed for the duration of a complete packet. There is also significant overhead in each packet further reducing throughput. It can interfere with 802.11 Baseband – this defines frame format, state model for the radio connection, command protocol. It establishes a link between master and each slave and supports two Link manager – performs authentication, encryption L2CAP – has three functions; performs fragmentation of 64k blocks passed from higher layers; handles multiplexing of streams from different sources; QoS and establishes maximum packet size for link. It is connection-oriented. Physical layer Physical radio

Simple point to point link Communication Application Profiles Application Profiles Application Layer Application Layer Transport Adaptation Layer Transport Adaptation Layer Link Link Simple point to point link

Bridging identical point to point links Communication 1 Application Profiles Application Profiles Application Layer Application Layer Transport Adaptation Layer Transport Adaptation Layer Bridge Link Link Link Link Bridging identical point to point links

Relaying dissimilar point to point links Communication 2 Application Profiles Application Profiles Application Layer Application Layer Relay Transport Adaptation Layer Transport Adaptation Layer Transport Adaptation Layer Transport Adaptation Layer Link Link Link Link Relaying dissimilar point to point links

Spanning dissimilar technologies perhaps with filter Communication 3 Application Profiles Application Profiles Filter Application Layer Application Layer Appl Appl Transport Adaptation Layer Transport Adaptation Layer Transport Adaptation Layer Transport Adaptation Layer Link Link Link Link Spanning dissimilar technologies perhaps with filter

Error control Flow control ACK vs ACKless Transport Layer Characteristics Error control Flow control ACK vs ACKless

Link Layer Characteristics Error control Flow control Serial vs packet 1 message per packet Packet size Connection oriented vs connectionless Device discovery Topology (Peer, Piconet, point to point)