Smart cities

A smart grid is a form of electricity network using digital technology. The idea of two-way communications from suppliers to consumers to control appliances is not new, and systems have been implemented using analog technology for many years. The growth of an extensive digital communication network for the internet has made it practical to consider a more sophisticated type of smart grid: smart cities.

What are smart cities?

A smart city is a city that uses data and information technologies to provide better services to citizens, track progress toward policy goals, optimise existing infrastructure. A smart city enables new business models for public and private sector service provision.

In a smart city, all man-made systems come together and interact with one another: healthcare, public safety, transportation and mobility, energy, education and government services (public safety, street lighting, efficient waste collection or public infrastructures).

Smart Infrastructure and technology

There are a few key technology enablers for a city to become smart: pervasive sensor networks throughout city, node connections through standardized low-cost communications, real-time analysis and control of city systems, and integration of isolated systems across cities (IPv6 like Internet of Things). Nowadays several companies are working in order to provide and enhance this infrastructure.

Smart cities use four different technologies in order to collect, transmit, storage and process the data. Moreover, a service delivery platform is needed.

Example: Smart Santander

Smart Santander is an European research facility for Internet of Things architectures, services and applications in the context of the smart city. It combines three projects WISEBED (tools and mechanisms for wireless sensor networks), SENSEI (interconnection of sensors) and Telefonica’s Ubiquitous Sensor Network service platform (storage and interfaces).

The first pilot experience was on June 2011 with 300 Internet of Things (IoT) devices. Phase 1 started on December in order to expand infrastructure with 2000 IoT devices. Next phase will be on December 2012 with 5000 IoT devices and last phase is expected to be on August 2013 where all the advanced features will be prepared for exploitation.

The Internet of Things and 6LoWPAN networks

The Internet of Things allow communications and data sharing from mobile phones, industrial/building automation, logistics, personal sensors, etc. It uses the IP network which provides a simple and ubiquitous interaction between devices and an increasing interaction with the services provided.

6LoWPAN working group of IETF is researching on Low-power RT with IPv6: The Wireless Embedded Internet. 6LoWPAN has a broad range of applications:

6LoWPAN

6LoWPAN is the acronym of a working group in IETF who provides IPv6 over Low-Power Wirelles Area Networks. They stateless header compression, enable a standard socket API, minimize the usage of code and memory and alow direct end-to-end Internet integration whith multiple topology options.

By communicating natively with IP, LoWPAN networks are connected to other IP networks simply by using IP routers. LoWPANs will typically operate on the edge, acting as stub networks. The LoWPAN may be connected to other IP networks through one or more border routers that forward IP datagrams between different media.

6LoWPAN introduce an adaptation layer that enables efficient IPv6 communication over IEEE 802.15.4 LoWPAN links. Because of that, 6LoWPAN format defines how IPv6 communication is carried in 802.15.4 frames and specifies the adaptation layer’s key elements:

• Header compression: IPv6 header fields are compressed by assuming usage of common values. Header fields are elided from a packet when the adaptation layer can derive them from link-level information carried in the 802.15.4 frame or based on simple assumptions of shared context. 40Bytes of IPv6 header are compressed into 2 Bytes of 6LowPAN header.

• Fragmentation: IPv6 packets are fragmented into multiple link-level frames to accommodate the IPv6 minimum MTU requirement. 1280 Bytes of IPv6 frame (minimum IPv6 MTU) have been fragmented to 127Bytes, which is the  802.15.4 MTU.

• Layer-two forwarding: To support layer-two forwarding of IPv6 datagrams, the adaptation layer can carry link-level addresses for the ends of an IP hop. Mesh Addressing header is used to forward 6LoWPAN playloads over multiple radio hops and support layer-two forwarding and includes the Hop Limit, Source Adrress and Destination Adress.

RPL

RPL is a routing protocol over low-power and lossy networks like 6LoWPAN. It’s very useful in urban networks (including Smart Grid applications) and in building, industrial and home automation. DODAG (Destination Oriented Directed Acyclic Graph) is specified  to use in LLNs (Low Power and Lossy Networks) and support traffic with very different requirements in terms of path quality (poor, fair and good).

Nowadays, several groups are working on 6LoWPAN networking. ISA100 group, for example, is working to standardize wireless systems for automation.

The Internet of Things

Can you imagine being able to turn on the heating of your house from your mobile phone? Can you imagine a city where taxis broadcast their position in real-time? Can you imagine receiving a notification when someone knocks the door of your house when you aren’t home? Seeing him on real-time? Are you ready for the Internet of Things? 

Smart Objects

A smart object is an item equipped to interact with the physical world and communicate with the outside world and other smart objects. For example, a light sensor collects information from the environment and when it’s going dark, it orders the light-controller to switch on the lights and it also orders the window-controller to lower the binds. All of this devices are Smart Objects and they communicate between them in a Smart Grid.

Smarts Objects are equipped with a sensor or actuator, a microprocessor, a communication device and a power source. Moreover, technical aspects take into account such as power consumption and physical size, as well as  network mechanisms and structures had to be design.

Communication between Smart Objects

Smart Objects transmit information that they collect to other smart objects and they also receive information from other ones. Because of that, it is necessary to design network protocols, mechanisms and structures to allow an efficient communication between them taking power consumption and low-speed into account.

The current situation of smart objects is like some kind of islands where they communicate with an own protocol. Differents islands are interconnected by complex multi-protocol gateways. Although, Internet Protocol for Smart Protocols Alliance and IEEE working groups are currently standardizing protocols, architecture and mechanisms:

• end-to-end IP-based architectures.
• IPv6 Adress.
• Low-power and Lossy Networks (LLNs) made of smart objects interconnected by unstable low-speed links.
• Routing at the network layer (IP).
• UDP (small packet headers, not packet control mechanisms) to send data in networks with smart objects like automation, temperature, sensors which may periodically report data.
• TCP (high packet headers, packet control mechanisms) to send data to smart objects networks where is more important reliable delivery of data than high throughput.
• Three models of connectivity:
  • Autonomous Smart Object Networks Model: internal smart object network without connection to the public Internet.
  • The Internet of Things: any Internet user will have access to the information provided by smart objects either directly accessing the device or by means of intermediate servers.
  • The Extended Internet: smart object networks partially or completely connected to the Internet with security protection.
• Energy Management with Time-Synchronized Power-Saving Protocol (TSMP) . This protocol consists on constantly switching the physical radio frequency on which packets are sent and switch the radio off as often as possible.
• Communications patterns divided into one-to-one communication, one-to-many communication and many-to-one communication.
• Three different mechanisms to Physical Communication Standards divided by the range of physical signals:
  • IEEE 802.15.2: radio transmission mechanism for only a few meters.
  • IEEE 802.11: radio low-power transmission mechanism for serveral hundred meters.
  • PLC: wired transmission mechanism to send data over power lines. It has many uses ranging from long-range and it provision high-speed broadband.

Applications

Smart Object Networks applications cover a wide range of areas:

• Smart Grids: the electric power grid will in the future be replaced by smarter components that talk to each other.

• Industrial automation: automation of industrial processes by means of modern computer-assisted technology.

• Smart Cities and Urban Networks: a large IP network interconnecting devices via various links for support these services like traffic management, speed control, vehicle tracking, emergency warning, education networks, biometric card systems, climate control, data collection and monitoring, social networking… 

• Home Automation: multiple and diverse applications that include lighting control, security and access control, comfort, energy management, remote home management….

• Building Automation: applications to save energy in buildings and provide critical functions such as fire emergency evacuation.

• Structural health Monitoring: monitoring the conditions for a physical structure such as a bridge, tower, building or heavy machinery. 

• Container Tracking: track the movement of containers.