Mumbai University > Electronics Engineering > Sem 6 > Embedded System and RTOS
The wireless embedded communication can take place through Bluetooth, Zigbee or Wifi which work as explained below:
i) Bluetooth is a low cost, low power, short range wireless technology for data and voice communication. Bluetooth was first proposed by ‘Ericsson’ in 1994.
It is synchronous, full-duplex, serial-data communication having low cost, low power, short range wireless technology for data and voice communications.
iii) Bluetooth operates at 2.4 GHz of Radio Frequency spectrum and used frequency Hopping spread spectrum. The data rate is 1 Mbps. There are 2 ports: Physical link part and Protocol part.
- Physical link is responsible for physical transmission of data between devices.
- Protocol part is responsible for defining rules of communication.
iv) Bluetooth devices contain BT wireless radio for transmission and reception of data. It has a 48 bit unique certification number.
v) BT supports point-to-point and point-to-multipoint communication.
- Point-to-point communication follows a master-slave relation between the devices.
- The devices act as master or slave. When a network has 1 master device and more than 1 slave devices then the network is called as Piconet.
- This is point-to-multipoint communication network. Piconet supports 7 slaves and is short range communication method.
vi) The Generic Access Profile (GAP) defines requirement for detecting Bluetooth device and forming connection with it.
vii) Bluetooth’s physical layer has 3 sub layers- Radio layer Baseband layer Link manager (Host controller) – This layer manages master and slave link. It specifies data encryption and authentication handling. It gives specifications for state transition mode.
i) Zigbee is an IEEE standard 802.15.4 protocol. Its communication latency is 30 ms and protocol stack overhead is 28 kb.
ii) The physical layer radio has a 2.4 GHz band carrier frequency with DSSS. It supports the range up to 70m. The data transfer rate is 250 kbps and supports 16 channels.
iii) Zigbee network –A zigbee network is a self-organizing network which detects nearby zigbee devices and establishes communication. It supports peer-to-peer (2 devices) and mesh (1 device to multiple devices) networks. Peer-to peer communication means each node at network functions as requesting as well as responding device and mesh communication means each network functions as mesh. A node is connected to another node directly or through mutually interconnected nodes.
iv) Zigbee protocol supports large number of sensors, lighting devices, air conditioning and other devices for home and office automation.
v) The components of Zigbee network are- Zigbee router: It transfers packets from neighbor source to nearby node. Coordinator: It connects zigbee network with another. Also it connects WLAN cellular network with each other. End devices: these are the transceivers of data.
i) Wireless- Fidelity is the popular wireless communication technique for networked communication devices.
ii) It follows 802.11 standards. It supports Internet Protocol (IP) communication.
iii) Here, each device is identified by its IP address.
iv) Wi-Fi based communication requires Wi-Fi agent called router/ wireless access point to manage communication. Router is responsible to access network, assign IP address to devices on the network.
v) Wi-Fi enabled devices contain wireless adaptor for transmitting and receiving data in the form of radio signals through an antenna.
vi) The hardware part is known as Wi-Fi radio.
vii) Wi-Fi operates at 2.4 GHz or 5 GHz of radio spectrum. Wi-Fi supports data rates 1 mbps to 150 mbps. The operating range is 100 to 300 feet.