NB- IoT
NB-IoT is a low power,low data rate service at 250kbpsSigFox
It's a proprietary standard operated by a company with the same name.
It uses ultra narrow band modulation which requires only 100hz of bandwidth per message with low rate of 100600bps
Currently deployed more in western Europe than in the United States.
LoRaWAN and LoRa
Open standards for low power WWAN.
LoRaWAN specifies the MAC
LoRa specifies the physical layer
LoRa has a built-in resistance to interference and multipath fading as it uses spread spectrum modulation
LoRa has a very low data rate
MQTT
Message queue telemetry transport is targetted for device to server communication
It is used for collecting data from a large number of devices and transferring that onto the server
The telemetry name indicates its use in remote monitoring and control
Since latency of several seconds is tolerable over the reliability of data transfers,TCP is used instead of UDP in its transport layer.
MQTT is not suitable for device to device communication.
XMPP
Extensible messaging and presence protocol is designed for connecting devices to humans
It uses XML text and name@domain.com acdressing.
It is used in consumer IoT applications such as connecting home appliances to the web server which a user can access using a smart phone.
AMQP
Advanced message queuing protocol is a queuing system designed to connect servers
Transactional messages are exchanged between servers which are buffered by using queues.
Since reliability is of great importance here TCP is used.
CoAP
Constrainted application protocol uses HTTP commands like PUT and GET for device to device communication.
It is a web transfer protocol designed for constrainted nodes and constrainted networks that are low power but lossy.
The end nodes are typically constrained of computing power and memory.
DDS
Data distribution service is used for device device communication which can deliver millions of messages per second to many devices
Offers ways to filter data and select multiple destinations thus implementing multicast operation.
It requires very low latency that can vary depending on the device and hence instead of TCP ,DDS uses quality of service (QoS) control scheme.
This protocol finds use in hospital environments and millitary.
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