Manchester, Ho Chi Minh City, and Tshwane-Pretoria: these cities are geographically divided and culturally diverse, but they are a small selection of cities which share the common aim of using Information and Communication Technology (ICT) to operate in new ways—smarter ways. "Smart cities" use recent advances in ICT to make buildings, transport systems, healthcare providers and businesses operate in safer, more efficient and more sustainable ways. Making our cities smarter will ultimately allow individuals, regardless of technical ability, to go about their daily activities while minimizing their carbon footprints.

As the global population continues to rise, an increasing number of people are choosing to live in cities. Population growth typically coincides with increased carbon emissions, which many governments are committed to reducing. Many complex systems, such as transportation, utilities, and waste management, must operate more effectively and more efficiently to support expanding populations while attempting to reduce carbon emissions. Smart city initiatives use ICT to connect these seemingly disparate systems so they can be tuned to optimize resource allocation, drive efficiencies, and support sustainable living.

Using ICT to improve the multiple facets of cities has, rather obviously, captured the attention of some of the giants within the computing industry. IBM and Cisco are both involved in the creation and deployment of smart city technologies. IBM's Smarter Cities initiative is a component of its larger Smarter Planet initiative. Smarter Cities looks at how increasingly populated cities can be better equipped technologically to drive a more prosperous and sustainable future. The main focus of the initiative is to build intelligence into a city's interconnected smart systems. In doing so, IBM hopes people and objects can interact in new ways in order to deliver greater prosperity to citizens.

Chiang Mai, Thailand and Tshwane-Pretoria, South Africa are two cities involved in the Smarter Cities initiative. One idea proposed for Chiang Mai is to turn it into a "smart food" city. Research institutions and government departments located in the city will use technology to collect and disseminate weather data and crop-price forecasts; farmers can use the data to become better informed, hopefully enabling them to improve crop yields; and the government will have access to a range of agricultural data, allowing it to oversee agricultural policy more effectively. In Tshwane-Pretoria the initial focus is on the collection, analysis, and dissemination of data from a range of sources, which include data on traffic levels, library usage, and school test scores. Through the gathering of these data, strengths and weaknesses within the city can be identified. The relevant technical solutions can then be put in place to optimize the city's processes and systems, driving progress in the city and increasing citizens' quality of life.

While IBM's initiatives adopt a more software-centric approach, Cisco's Smart+Connected Communities (S+CC) initiative adopts a network-centric approach to smart city development. The network infrastructure is regarded as part of critical national infrastructure, like a water or gas main. Cisco is attempting to make the inclusion of ICT a core-part of building and city development, rather than including it much later in a project's life-cycle; collaboration between building developers and technologists is strongly advocated. Two S+CCs are Chongqinq, China and Ho Chi Minh City, where there is a focus on the development of energy-efficient "smart-buildings." There are also foci on the innovation of green technologies and the use of networked technologies to foster collaboration and knowledge transfer between individuals, businesses, and public services.

The smart city concept is not only championed by large companies but is also gaining momentum in the highest echelons of government. At the 2011 Google Zeitgeist Conference, the United Kingdom's Chancellor of the Exchequer, Rt Hon George Osborne MP, delivered the keynote address, which focused on using ICT to build more open, more innovative, and more prosperous societies. On the issue of openness it was stated ICT should be used to make governments, and those who work on their behalf, such as the police, more accountable. This is achieved by putting more government and public sector data sets online for the public to scrutinize. To increase societal prosperity the Chancellor cited "open source policy making," where members of society are enabled by ICT to influence policy making and engage with the government. In a bid to drive U.K. innovation the Chancellor announced a new Smart Cities Research Centre. This is a collaborative effort between universities in the U.K. and industrial partners, which aims to develop new technologies and to find new ways to use the massive amounts of energy, transport, and social data being generated in cities around the world.

Let's explore in detail that final point on the generation of large volumes of data: How are these data being captured and where are these data likely to come from in the future? One answer is sensors. Sensors are being embedded all around our cities, our transport systems, our homes, and in the devices in our pockets—sometimes they may be on, or even inside, us. They are used to sense the environment around them and transmit data to other devices for collation and processing. Sensors are typically small, low-specification, low-power, wireless-enabled devices. The TELOSB mote by Moog Crossbow, for example, has a small form factor of 65 x 31 x 6 mm, is powered by two AA batteries, and has an 8MHz microcontroller with 10KB of RAM. Wireless connectivity allows sensors to be placed in areas without the need for laying cables, which could otherwise be expensive or impractical, across a bridge or in a tunnel. Additionally the length of a bridge or a tunnel, coupled with a lack of cabling, may preclude the use of wireless access points. So how do sensors use wireless connectivity to communicate?

Wireless ad hoc networking allows network nodes, e.g., devices such as sensors, to communicate with one another without the need for any centralized network infrastructure (such as access points). Ad hoc networking relies on the autonomy and altruism of individual nodes: nodes need to cooperate with one another in a distributed manner to provide the required network functionality. This functionality includes routing, which would otherwise be provided by the network infrastructure. Nodes are therefore required, when called upon, to perform the role of a router, as well as the usual roles of sources and destinations of data. If the source node of a traffic flow is not in wireless transmission range of the destination node, it relies on a number of intermediate nodes, acting as routers, to forward packets on its behalf toward the destination. This autonomic behavior is key to the self-sufficiency and stand-alone nature of wireless ad hoc networks.

While such networks are designed to operate independently of existing network infrastructure, they can also be used in conjunction with it. For example, one or more ad hoc network nodes, say, sensor nodes in an underground railway tunnel, may be in transmission range of a wireless-enabled PC, say, located in a train station connected to the tunnel. The data obtained by the sensor nodes, e.g., from the detection of cracks in the tunnel walls, can be relayed across the ad hoc network to the PC. These data can be processed on the PC and/or they can be transmitted to another node, located either in the local network or somewhere in the Internet. The data obtained by sensors can therefore be accessed remotely and, in some cases, in real-time.

Wireless ad hoc networking, and its integration with infrastructure-based networking, is an important component of smart cities: Sensed data can be used in real-time to enable us to live in more efficient and environmentally-friendly ways. Examples of where sensors and ad hoc networking technologies are used in smart cities include intelligent buildings, healthcare, environment monitoring, and intelligent transport systems.

Intelligent buildings are those where the monitoring and control of services such as lighting, elevators, air conditioning, and access control systems are integrated onto a common platform with other wired and wireless networked systems, including networks of sensors. The main aim of this service integration is to reduce a building's energy consumption and carbon footprint. This can be achieved using sensors to automatically control building services. For example, employees in Le Hive—a collection of energy efficient buildings in Paris—are issued RFID (radio frequency identifier) cards that interact with sensors to automatically adjust lighting, heating, and air conditioning based on the cardholder's presence or absence. RFID tags can also be used as a means of identity management within buildings. The Baja Beach Club in Barcelona, has used RFID tags inserted under people's skin to eliminate the need to carry credit cards or cash as all transactions are conducted via the RFID tag. This is an interesting but ethically dubious idea—it may be a little too Orwellian for most punters' liking. (For a fictional look at what happens when an intelligent building becomes too intelligent for its own good read Phillip Kerr's 1995 novel Gridiron.)

A more obvious application scenario for using technology inside the body is in healthcare. The last few years have seen noteworthy advances in wireless-enabled implantable medical devices. Example devices include pacemakers and defibrillators, such as those produced by St. Jude Medical. Doctors can use these devices to remotely monitor a patient's condition over the Internet, rather than having the patient attend clinical check-ups. These technologies make life easier for the patient as the burden of regular check-ups is reduced. Moreover, altering the behavior of an implanted device becomes a simpler task. Another benefit of these smart devices is that they can automatically alert a healthcare provider if a patient is losing consciousness, enabling emergency response staff to be mobilized as quickly as possible. In a similar manner, external sensors can be used to monitor patient activity in the home: networks of sensors can be used to detect falls or a lack of movement of elderly or infirm patients; and a caregiver and/or a family member can automatically be notified of an extended period without movement being detected.

Sensors can also be used outside of buildings. The use of sensors for environment monitoring is a wide-ranging application area. For example, civil infrastructure can be monitored for damage (like in the earlier tunnel example); elements of the physical environment which affect people's health, such as pollution levels and air quality, can be monitored; the energy consumption of a building can be monitored in real-time; and if the building has its own methods of energy production, e.g., wind turbines and/or solar panels, the energy produced can also be monitored. In addition to sensing and reporting on the environment, sensors can also be used to improve the efficiency of certain activities within society. Waste collection is one such activity benefiting from sensor network and smart city technologies. For example, solar-powered, 3G bins, such as that from BigBelly Solar, Inc., improve efficiency in two ways: firstly, solar energy is used as the power source to compress the bin's contents, resulting in increased capacity; secondly, on sensing it is almost full the bin sends an SMS or email to the relevant authorities indicating that it is ready for collection. Both of these characteristics shrink CO2 emissions by reducing the number of collections required.

Intelligent Transport Systems (ITS) are another area where sensors are being deployed to help reduce CO2 levels and drive efficiencies. When we say "intelligent" we don't quite mean the driverless cars in the movie "The Minority Report." We're not quite there yet—although people are working on it. In fact, the state of Nevada, has recently passed a law authorizing driverless cars (Assembly Bill No. 511), and Google has been road-testing its own prototype driverless car. The current vision for ITSs, however, is closer to science fact than science fiction. ITSs involve the large-scale deployment of sensors in both individual vehicles and transport infrastructure (roads, bridges, traffic signals, etc.). An obvious application of sensor technologies is to monitor traffic flow and congestion. An example of a vehicle in an ITS is the Connected Bus, which is a part of Cisco's Smart+Connected Communities initiative in San Francisco. The bus's position is tracked in real time, allowing for accurate scheduling. This provides passengers with a better estimate of the bus's arrival time. The bus also has sensors that interact with the traffic signals to provide it with priority over other traffic—where possible and safe to do so—to avoid congestion. The data generated from intelligent transport systems can, amongst other things, be used to predict traffic jams and provide alternative routes to ease congestion.

The movement of wireless-enabled devices during a communications session, such as vehicles in an ITS, presents a challenge to ad hoc networking; that of maintaining an ad hoc communications session while devices roam in and out of one another's wireless transmission ranges. Mobile ad hoc networks (MANETs) are ad hoc networks which use routing protocols designed to handle the issues arising from device mobility. Any device—the source, the destination, or any router—in a MANET may be moving, and different nodes may move at different velocities and in different directions. The wireless links between the devices break as the devices move beyond one other's wireless transmission ranges, causing the route between the source and the destination to fail. MANET routing protocols aim to determine a new route with minimal disruption to the communications session. Finding routes quickly and efficiently is of vital importance because the time when the route is broken means communication is not in progress. Coping with device mobility will likely be an important aspect of smart cities as wireless devices are increasingly being used while on the move.

Wireless ad hoc networking technologies continue to gain in popularity, but a number of interesting research challenges still remain. One significant challenge is the wide-variety of security threats these networks are exposed to. The threats can largely be divided into three categories: physical, general, and cyber. Physical threats include the damage, loss, or theft of wireless-enabled devices. General threats refer to those annoying situations where batteries run-out, software crashes, and devices are carried beyond the wireless transmission ranges of networked devices. The occurrence of one or more of these physical or general threats will lead to the temporary or prolonged interruption of a communications session.

Cyber threats refer to intentional, computer-based attacks launched against networked devices to disrupt or altogether prevent communications. Some of the well-known attacks in ad hoc networks have been given rather emphatic names, examples of which include "sinkhole" and the "blackhole" attacks. These names are used because the attacks' mechanisms of operation reflect the phenomena after which they are named. In a sinkhole attack, a malicious node attempts to attract IP-packets being transmitted in its surrounding area toward itself. It does this by modifying routing metrics to make any route through itself appear favorable. This attack can be used as a platform to perform other, more serious attacks such as the blackhole attack. A node performing a blackhole attack discards any data packets that it is given to forward. This can have a severely detrimental effect on the quality of a communications session. These attacks, and many others, are made possible by the distribution of routing operations to peer devices—one of the key characteristics enabling ad hoc communications.

While these security threats have been described in the context of ad hoc networking there are of course some which also apply to fixed networks. Software crashes, a loss of power, and cyber attacks are the obvious examples. There are, however, some less obvious examples too, which may become more prevalent as the communications technologies in smart cities become increasingly pervasive. For example, the theft or damage of fixed-routers (access points) may not currently be commonplace, as they are normally located within buildings. But, in the future, there is likely to be a proliferation of fixed-routers in public places. In London there are plans to install wireless routers in bus stops and train and underground stations in advance of the 2012 Olympic Games. Thus the placement of network infrastructure may expose it to threats that have previously not applied.

As older technologies are used in new ways and as new technologies continue to enter our lives and our cities, the threat landscape associated with these technologies continues to change. Mitigating the effects of new and evolving threats is a necessity in smart cities, since technology is at the core of what makes these cities "smart." Moreover, with the potential for an increasing use of monitoring technologies in our homes and in our bodies, the preservation of people's privacy is paramount. Generating and maintaining people's confidence in smart city technologies requires security issues to be addressed; security is likely to be a key driver of people's acceptance of the ever-expanding role that computing technologies play in their day-to-day lives.

So where do all of these smart city technologies get us? We—society—probably won't get far unless the users and beneficiaries of these technologies know how to exploit them to their full potential. To quote a key tenet of the Manchester SMARTiP project, "Smart cities require 'smart citizens' if they are to be truly inclusive, innovative and sustainable." Advances in technology should be mirrored with advances in citizens' acceptance of and interaction with such technologies. The landscape of smart cities may therefore contain challenges and hurdles that are not solely of a technical nature. Computer scientists continue to develop the technologies of tomorrow to help meet the social, economic, and environmental targets of today; but the effective use of these smart city technologies rests in the hands of governments, businesses, and citizens, who must be empowered to cultivate a sustainable existence for today, tomorrow, and beyond.

  Authors

Peter McNerney is a Ph.D. candidate in the School of Computer Science at the University of Manchester, UK. His research focuses on the integration of security and quality of service in mobile ad hoc networks..

Ning Zhang is a senior lecturer in the School of Computer Science at the University of Manchester, UK. She received her Ph.D. in electronic engineering from the University of Kent at Canterbury, UK. Her research interests are in computer networks, mobile computing and security and privacy in networked environments..

©2011 ACM  1528-4972/11/1200  $10.00

Permission to make digital or hard copies of part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page or initial screen of the document. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, republish, post on servers, or redistribute requires prior specific permission and a fee. Permissions requests: [email protected].

The Digital Library is published by the Association for Computing Machinery. Copyright © 2011 ACM, Inc.

To comment you must create or log in with your ACM account.