INTERNET OF THINGS

Smart Object is an item equipped with a form of sensor or actuator, a tiny microprocessor, a communication device and a power source. They can to interact with the physical world by performing limited forms of computation as well as communicate with the outside world and with other smart objects.

The apparition of modern smartphones changed the general view on connectivity because Internet access it’s truly ubiquitous.

Technical challenges for smart objects include the node-level internals of each smart object, such as power consumption and physical size, as well as the network-level mechanisms and structures formed by the smart objects. The design of the network protocols for smart objects must take power consumption into account, when, for example, deciding when and where to send data.

IP->To communicate these smart objects we can use IP. Internet Protocol for Smart Objects (IPSO) Alliance was set up for the purpose of spreading the awareness of the technology around smart objects.

IPv6-> IETF is working in IPv6. It enhances many of the IPv4 functionalities, offers a much larger address pool, and provides better support for security and mobility while preserving the fundamental protocol architecture of IPv4, but the “cost” of migration has slowed down the adoption rate of IPv6.

ROUTING->Networks of smart objects significantly differ from “traditional” IP networks. Routing implies protocols and mechanisms to compute paths in a multi-hop network at layer 3 (IP). With the emergence of multiple types of low-power link layers it became obvious that routing at the network layer is the best option.

TRANSPORT->For smart objects the advantages of TCP are reliability, control of the maximum size of its packets, and interoperability with existing systems. TCP headers are large compared to UDP headers, but header can be compressed. Many smart object networks operate over links where packets can be lost and reliable delivery of data is more important.The TCP MSS option is very useful.

TECHNOLOGY->The hardware of smart objects consists of four main components: Communication device, Microcontroller, Sensors or actuators and Power source

ENERGY MANAGEMENT-> Power optimization must occur both at the hardware and the software level. For radio-equipped smart objects the radio transceiver is the most powerconsuming component.

In a star network, the central node has its radio turned on all the time. All of the other battery-powered nodes keep their radios switched off to conserve energy and only when the nodes have data to send do they switch on their radio to transmit a message. This network is simple and useful, but it constrains the range of the smart object network to that of the physical transmission range of the radio transceivers.

In a mesh network, all nodes can talk to each other and form a robust multi-hop network. The network can be dynamically extended as needed by adding more nodes. The new nodes automatically join the network and act as relay nodes that forward traffic.

Asynchronous low-power listening LPL, X-MAC protocol achieves low-power operation by switching the radio off most of the time and periodically switching it on for a short time. The time during which the radio is on and off is configurable and depends on the predicted traffic load of the network.

Time-synchronized, power-saving protocol TSMP Provide a long lifetime by switching the radio off as often as possible and achieves high reliability by constantly switching the physical radio frequency on which packets are sent. The network is centrally managed so that the entire network is scheduled by a network manager.

COMMUNICATION->Smart object communication patterns can be divided into three categories and they are used in different applications: one-to-one, one-to-many and many-to-one.

Physical Communication Standards: we discuss three different mechanisms for smart objects, two radio transmission mechanisms, IEEE 802.15.4 and IEEE 802.11 low power, and PLC.

The most important difference between the three mechanisms is the range of physical signals.

The technology of the PLC which permits the send of information in the power lines allows to use a big network to communication and it's a great option for the implementation of the smart objects. The wi-fi has the reestriction of the low consum.

APPLICATIONS->The applications are home automation, building automation, container tracking and a lot of more possibilities.