Master and slave operation Essay

Bluetooth devices exist in small ad-hoc network configuration with the ability to execute as every earn or the slave the spec similarly allows a mechanism for master key and slave to switch their roles. The configurations raft be single point, which is the simplest configuration with one master and one slave. Multipoint, called a Piconet, ground on up to 7 slaves clustered around a single Master. And a third type called a Scatternet, this is a group of Piconets effectively hubbed via a single Bluetooth device acting as a master in one Piconet and a slave in the other Piconet.The Scatternet permits either larger coverage areas or number of devices than a single Piconet can offer. Figure 5 outlines the different master and slave topologies permitted for networks in the bill (see Bluetooth Goodbye infrared frequency). The role of the master is to control the available bandwidth among the slaves, it calculates and allocates how often to communicate with each slave and locks t hem into the appropriate frequency hopping judgment of conviction.The specification describes an algorithm that calculates the hop sequence, the seed being based on the masters device address and clock. In addition to hop sequence control, the master is responsible for move control by dividing the network into a series of time expansion slots amongst the net members, as divorce of a beat Division Multiplexing (TDM) scheme. These time slots can consist of selective information and potentially surplus region dealing i. e. you will always need a information channel before you can add a instance channel.The time slot is defined as 625 s and all software package traffic is allocated 1, 3 or 5 slots, grouped together in transmit and receive p stresss. Prior to connection some operations such as inquiry, paging and scanning operations may sometimes occur on half slots (see Bluetooth Goodbye Infrared). Figure 5 Point to point, Piconet and Scatternet. A. 2. 3 express and Data Li nks. Bluetooth carries communication traffic over two types of air interface cogitate defined as Asynchronous ConnectionLess (ACL) or coincidental Connection Oriented (SCO).During a connection the links carry voice and data traffic in the time slots and are categorised as either time little, as used for voice and audio, or high-pitched speed non-time critical data with a mechanism for acknowledgement and re-transmission. The first-year link established between master and slave is the ACL link and carries high speed data that is insensitive to time. It is piece of land switched, as the data is periodic in nature, asynchronous, contains asymmetric and symmetric services and uses a polling access scheme.A master may be permitted to have a number of ACL links up to the maximum number of slaves permitted by the specification but wholly one link is allowed between any two devices (see Bluetooth Goodbye Infrared). Once an ACL has been established a SCO link can be created on top o f the ACL link. The SCO link is circuit switched it has symmetric synchronous services and has slot reservation at obstinate intervals, making it suitable for time critical data such as voice. The specification restricts the number of SCO links that a master can support to three.Summarising the two types of links ACL ? bundle constructed of a 72 bit access code, a 54 bit packet header, a 16 bit CRC and Payload data ? Largest data packet is DH5 giving 723. 2 Kb/s as highest data tell in one direction. ? Non time critical data ? Asynchronous ? Packet switched ? Polling access SCO ? Same access code and header as ACL packets ? ARQ (Automatic reprize reQuest) and SEQ (SEQuence) flags redundant since flow control and re-transmissions do not apply ? cyclical Redundancy Code (CRC) field is absent?Payload fixed at 30 bytes, with source data of 10, 20 or 30 bytes ? locomote switched ? Symmetric synchronous services ? Slot reservation at fixed intervals A special case exists that mixes S CO and ACL packets. Known as the Data Voice (DV) packet it carries data and voice on regular intervals like the SCO. The voice data has no flow control or CRC as per SCO packets, whereas the data part of the DV packet has flow control, re-transmission of the data part is permitted and the data part is CRC protected (see Bluetooth Goodbye Infrared).