Wireless grid
Encyclopedia
Wireless grids are wireless computer networks consisting of different types of electronic devices with the ability to share their resources with any other device in the network in an ad-hoc manner.
A definition of the wireless grid can be given as: "Ad-hoc, distributed resource-sharing networks between heterogeneous wireless devices"
The following key characteristics further clarify this concept:
The technologies that make up the wireless grid can be divided into two main categories; ad-hoc networking and grid computing
.
s) such as routers and/or servers for facilitating the throughput of information from one node to the other. These 'routing nodes' have the ability to determine where information is coming from and where it is supposed to go. They give out names and addresses (IP address
es) to each connected node and regulate the traffic between them. In wireless grids, such dedicated routing devices are not (always) available and the bandwidth that is permanently available to traditional networks has to be either 'borrowed' from an already existing network or publicly accessible bandwidth (open spectrum
) has to be used.
A group addressing this problem is MANET
(Mobile Ad-Hoc Network).
, and web services, but also computational power and data storage capacity. Information resources can include virtually any kind of data from databases and membership lists to pictures and directories.
Ad-hoc resource sharing between mobile devices in the wireless grid require for the devices to agree on sharing/communication protocol
s without the existence of dedicated servers.
or NFS for sharing disk space and the distributed.net
client for sharing processor cycles.
that makes use of certificates; now often used in web based email systems, and Kerberos
.
, it has to be able to communicate to the other users that it is a PDA and it has a camera, GPS capabilities, a telephone function and various office applications such as a text editor
. Protocols like UPnP and ZeroConf
can detect a new node in the network when it enters. When detected, other users can send a query to the new device to find out what it has to offer. Commercial service providers can 'advertise' the resources they have to offer through IP multicast
s. Within large grids containing thousands of nodes, a kind of 'friend of a friend' mechanism can be used.
There is a myriad of standards that include resource description protocols. Standards as IETF's ZeroConf
, Microsoft's UPnP, the Grid Resource Description Language (GRDL), the Web Services Description Language
(WSDL) for describing various specific web services and parts of QoS
that describe bandwidths all offer devices a way to describe and publish their specific resources and needs. There are also various systems currently available that can gather these resource descriptions and structure them for other devices to use.
The OpenGrid Services Architecture (OGSA) uses a Web service-style IndexService. The Web services community has defined UDDI which can makes a database of services that are available on the network, and JXTA
uses ZeroConf
to identify resources in a network. However, the problem with using these in wireless grids is that no stable publisher of these descriptions may exist.
came into existence as a manner of sharing heavy computational loads among multiple computers to be able to compute highly complex mathematical problems (a good real-world example being the SETI@Home
project). However, it developed rapidly into a way of sharing virtually any resource that is available on any machine on the grid. Wired grids are now used to share not only computing power, but also hard disk
space, data, and applications. The grid topology is highly flexible and easily scalable, allowing users to join and leave the grid without the hassle of time and resource hungry identification procedures, having to adjust their devices or install additional software on them. The goal of grid computing is described as "to provide flexible, secure and coordinated resource sharing among dynamic collections of individuals, institutions and resources" (McKnight, Howison, 2004).
It is intended to be a dynamic network without geographical, political, or cultural boundaries that offers real-time access to heterogeneous resources and still offer the same characteristics of the traditional distributed networks that are in use everywhere in our houses and offices. These characteristics being stability, scalability, and flexibility as the most important ones. Ian Foster
offers a checklist for recognizing a grid.
to plug into).
One description of the wireless grid is "an augmentation of a wired grid that facilitates the exchange of information and the interaction between heterogeneous wireless devices" (Argawal, Norman & Gupta, 2004)
Argawal, Norman & Gupta (2004) identify three forces that drive the development of the wireless grid:
New user interaction modalities and form factors
Applications that exist on current wired grids need to be adapted to fit the devices used in wireless grids. These devices are usually hand held and therefore the user interface devices (screens, keyboards (if any)) are significantly smaller and availability of additional input devices like a mouse
are limited. This means the traditional graphical interfaces found on PCs are not suitable.
Limited computing resources
Wireless devices do not possess the computing power nor the storage capacity of full size devices like a PC or laptop. Therefore wireless applications need to have access to additional computing resources to be able to offer the same functionality that wired networks do.
Additional new supporting infrastructure elements
In the case of an unforeseen event, there will be the need for major amounts of computational and communications bandwidths. An urban catastrophe, for example, would require a dynamic and adaptive wireless network to alert people within the population as well as those in the various coordination and aid services like the police, army, medical services, and government. Applications to provide for these bandwidths and 'instant' networks need to be addressed.
A definition of the wireless grid can be given as: "Ad-hoc, distributed resource-sharing networks between heterogeneous wireless devices"
The following key characteristics further clarify this concept:
- No centralized control
- Small, low powered devices
- Heterogeneous applications and interfaces
- New types of resources like cameras, GPS trackers and sensors
- Dynamic and unstable users / resources
The technologies that make up the wireless grid can be divided into two main categories; ad-hoc networking and grid computing
Grid computing
Grid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common goal. The grid can be thought of as a distributed system with non-interactive workloads that involve a large number of files...
.
(Wireless) Ad-hoc networking
In traditional networks, both wired and wireless, the connected devices, or nodes, depend on dedicated devices (edge deviceEdge device
Edge devices are routers, routing switches, integrated access devices , multiplexers, and a variety of metropolitan area network and wide area network access devices that provide entry points into enterprise or service provider core networks...
s) such as routers and/or servers for facilitating the throughput of information from one node to the other. These 'routing nodes' have the ability to determine where information is coming from and where it is supposed to go. They give out names and addresses (IP address
IP address
An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. An IP address serves two principal functions: host or network interface identification and location addressing...
es) to each connected node and regulate the traffic between them. In wireless grids, such dedicated routing devices are not (always) available and the bandwidth that is permanently available to traditional networks has to be either 'borrowed' from an already existing network or publicly accessible bandwidth (open spectrum
Open spectrum
Open spectrum is a movement to get the Federal Communications Commission to provide more unlicensed, radio frequency spectrum that is available for use by all...
) has to be used.
A group addressing this problem is MANET
Manet
-MANET as an abbreviation:*MANET is a mobile ad hoc network, a self-configuring mobile wireless network.*MANET database or Molecular Ancestry Network, bioinformatics database-People with the surname Manet:*Édouard Manet, a 19th-century French painter....
(Mobile Ad-Hoc Network).
Resource sharing
One of the intended aspects of wireless grids is that it will facilitate the sharing of a wide variety of resources. These will include both technical as information resources. The former being bandwidth, QoSQuality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
, and web services, but also computational power and data storage capacity. Information resources can include virtually any kind of data from databases and membership lists to pictures and directories.
Ad-hoc resource sharing between mobile devices in the wireless grid require for the devices to agree on sharing/communication protocol
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
s without the existence of dedicated servers.
Coordination Systems
Coordination Systems are the actual mechanisms that enable the sharing of resources between different devices. For different resources, devices use different coordination systems. Examples of such mechanisms are: SMBServer Message Block
In computer networking, Server Message Block , also known as Common Internet File System operates as an application-layer network protocol mainly used to provide shared access to files, printers, serial ports, and miscellaneous communications between nodes on a network. It also provides an...
or NFS for sharing disk space and the distributed.net
Distributed.net
distributed.net is a worldwide distributed computing effort that is attempting to solve large scale problems using otherwise idle CPU or GPU time. It is officially recognized as a non-profit organization under U.S...
client for sharing processor cycles.
Trust Establishment
Before users are willing to share any resource, they demand a certain amount of trust between them and the users and/or systems they share resources with. The amount of trust required depends on the kind of information/resource that is to be shared. Sharing processor cycles requires less substantial trust then the sharing of personal information and commercial information can require another level of trust establishment altogether. There are systems currently in operation that can provide a certain amount of trust like the public key infrastructurePublic key infrastructure
Public Key Infrastructure is a set of hardware, software, people, policies, and procedures needed to create, manage, distribute, use, store, and revoke digital certificates. In cryptography, a PKI is an arrangement that binds public keys with respective user identities by means of a certificate...
that makes use of certificates; now often used in web based email systems, and Kerberos
Kerberos protocol
Kerberos is a computer network authentication protocol which works on the basis of "tickets" to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner. Its designers aimed primarily at a client–server model, and it provides mutual...
.
Resource discovery
Before any resource on a device in the grid can be utilized, those resources that are available must be discovered; all the devices that make up the grid and the resources they possess have to be identified. When a client enters the grid, such as a PDAPersonal digital assistant
A personal digital assistant , also known as a palmtop computer, or personal data assistant, is a mobile device that functions as a personal information manager. Current PDAs often have the ability to connect to the Internet...
, it has to be able to communicate to the other users that it is a PDA and it has a camera, GPS capabilities, a telephone function and various office applications such as a text editor
Text editor
A text editor is a type of program used for editing plain text files.Text editors are often provided with operating systems or software development packages, and can be used to change configuration files and programming language source code....
. Protocols like UPnP and ZeroConf
Zeroconf
Zero configuration networking , is a set of techniques that automatically creates a usable Internet Protocol network without manual operator intervention or special configuration servers....
can detect a new node in the network when it enters. When detected, other users can send a query to the new device to find out what it has to offer. Commercial service providers can 'advertise' the resources they have to offer through IP multicast
IP Multicast
IP multicast is a method of sending Internet Protocol datagrams to a group of interested receivers in a single transmission. It is often employed for streaming media applications on the Internet and private networks. The method is the IP-specific version of the general concept of multicast...
s. Within large grids containing thousands of nodes, a kind of 'friend of a friend' mechanism can be used.
There is a myriad of standards that include resource description protocols. Standards as IETF's ZeroConf
Zeroconf
Zero configuration networking , is a set of techniques that automatically creates a usable Internet Protocol network without manual operator intervention or special configuration servers....
, Microsoft's UPnP, the Grid Resource Description Language (GRDL), the Web Services Description Language
Web Services Description Language
The Web Services Description Language is an XML-based language that is used for describing the functionality offered by a Web service. A WSDL description of a web service provides a machine-readable description of how the service can be called, what parameters it expects and what data structures...
(WSDL) for describing various specific web services and parts of QoS
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
that describe bandwidths all offer devices a way to describe and publish their specific resources and needs. There are also various systems currently available that can gather these resource descriptions and structure them for other devices to use.
The OpenGrid Services Architecture (OGSA) uses a Web service-style IndexService. The Web services community has defined UDDI which can makes a database of services that are available on the network, and JXTA
JXTA
JXTA is an open source peer-to-peer protocol specification begun by Sun Microsystems in 2001. The JXTA protocols are defined as a set of XML messages which allow any device connected to a network to exchange messages and collaborate independently of the underlying network topology.As JXTA is based...
uses ZeroConf
Zeroconf
Zero configuration networking , is a set of techniques that automatically creates a usable Internet Protocol network without manual operator intervention or special configuration servers....
to identify resources in a network. However, the problem with using these in wireless grids is that no stable publisher of these descriptions may exist.
Resource description
For any device to be able to use any resource, a way to identify and describe the resource has to be agreed on by all available devices. If, for instance, storage capacity is to be shared, it first has to be clear what the capacity of each device is and what the storage need is. As said, there are many techniques to describe certain resources but there is not one technique that is able to provide this service for all resources. The available techniques combined, however, cover most of what is needed.Grid Computing
Grid computingGrid computing
Grid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common goal. The grid can be thought of as a distributed system with non-interactive workloads that involve a large number of files...
came into existence as a manner of sharing heavy computational loads among multiple computers to be able to compute highly complex mathematical problems (a good real-world example being the SETI@Home
SETI@home
SETI@home is an Internet-based public volunteer computing project employing the BOINC software platform, hosted by the Space Sciences Laboratory, at the University of California, Berkeley, in the United States. SETI is an acronym for the Search for Extra-Terrestrial Intelligence...
project). However, it developed rapidly into a way of sharing virtually any resource that is available on any machine on the grid. Wired grids are now used to share not only computing power, but also hard disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...
space, data, and applications. The grid topology is highly flexible and easily scalable, allowing users to join and leave the grid without the hassle of time and resource hungry identification procedures, having to adjust their devices or install additional software on them. The goal of grid computing is described as "to provide flexible, secure and coordinated resource sharing among dynamic collections of individuals, institutions and resources" (McKnight, Howison, 2004).
It is intended to be a dynamic network without geographical, political, or cultural boundaries that offers real-time access to heterogeneous resources and still offer the same characteristics of the traditional distributed networks that are in use everywhere in our houses and offices. These characteristics being stability, scalability, and flexibility as the most important ones. Ian Foster
Ian Foster
Ian Foster is a Distinguished Fellow and the Associate Division Director in the Mathematics and Computer Science Division at Argonne National Laboratory, where he leads the Distributed Systems Laboratory, and he is a Professor in the Department of Computer Science at the University of Chicago...
offers a checklist for recognizing a grid.
- A grid allows:
- Coordination of resources that are not subject to centralized control
- Use of standard, open, general-purpose protocols and interfaces
- Delivery of nontrivial qualities of service
The Wireless Grid
One of the biggest limitations of the wired grid is that users are forced to be in a fixed location as the devices they use are to be hard wired to the grid at all times. This also has a negative influence on the flexibility and scalability of the grid; devices can only join the grid in locations where the possibility exists to physically connect the device to the grid (i.e. there is the need for a hub or a switchNetwork switch
A network switch or switching hub is a computer networking device that connects network segments.The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer of the OSI model...
to plug into).
One description of the wireless grid is "an augmentation of a wired grid that facilitates the exchange of information and the interaction between heterogeneous wireless devices" (Argawal, Norman & Gupta, 2004)
Argawal, Norman & Gupta (2004) identify three forces that drive the development of the wireless grid:
New user interaction modalities and form factors
Applications that exist on current wired grids need to be adapted to fit the devices used in wireless grids. These devices are usually hand held and therefore the user interface devices (screens, keyboards (if any)) are significantly smaller and availability of additional input devices like a mouse
Mouse (computing)
In computing, a mouse is a pointing device that functions by detecting two-dimensional motion relative to its supporting surface. Physically, a mouse consists of an object held under one of the user's hands, with one or more buttons...
are limited. This means the traditional graphical interfaces found on PCs are not suitable.
Limited computing resources
Wireless devices do not possess the computing power nor the storage capacity of full size devices like a PC or laptop. Therefore wireless applications need to have access to additional computing resources to be able to offer the same functionality that wired networks do.
Additional new supporting infrastructure elements
In the case of an unforeseen event, there will be the need for major amounts of computational and communications bandwidths. An urban catastrophe, for example, would require a dynamic and adaptive wireless network to alert people within the population as well as those in the various coordination and aid services like the police, army, medical services, and government. Applications to provide for these bandwidths and 'instant' networks need to be addressed.
Wireless Grids infrastructure
The infrastructure of the wireless grid consists of three basic levels:- The physical layerPhysical layerThe physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....
technologies and policies. The physical layer contains the spectrum on which the wireless devices can operate and communicate. - Network infrastructure
- MiddlewareMiddlewareMiddleware is computer software that connects software components or people and their applications. The software consists of a set of services that allows multiple processes running on one or more machines to interact...
to provide communications between heterogeneous devices
See also
- BluetoothBluetoothBluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...
- IEEE 802.11IEEE 802.11IEEE 802.11 is a set of standards for implementing wireless local area network computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee . The base version of the standard IEEE 802.11-2007 has had subsequent...
- Mesh network
- Metcalfe's lawMetcalfe's lawMetcalfe's law states that the value of a telecommunications network is proportional to the square of the number of connected usersof the system...
- Overlay networkOverlay networkAn overlay network is a computer network which is built on the top of another network. Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network...
- P2PPeer-to-peerPeer-to-peer computing or networking is a distributed application architecture that partitions tasks or workloads among peers. Peers are equally privileged, equipotent participants in the application...
- SOAPSOAPSOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks...
- Wi-FiWi-FiWi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
- Wireless local loopWireless local loopWireless local loop , is a term for the use of a wireless communications link as the "last mile / first mile" connection for delivering plain old telephone service and/or broadband Internet to telecommunications customers....
- X.509X.509In cryptography, X.509 is an ITU-T standard for a public key infrastructure and Privilege Management Infrastructure . X.509 specifies, amongst other things, standard formats for public key certificates, certificate revocation lists, attribute certificates, and a certification path validation...
Further reading
- Jürgen Falkner, Fraunhofer Institute for Industrial Engineering; JNF/842, 2004), The Fraunhofer Resource Grid - making Grids usable
- Lee W. McKnight, James Howison (2004). Wireless Grids; Distributed Resource Sharing by Mobile, Nomadic, and Fixed Devices.
- Agarwal, Norman and Gupta (2004). Wireless grids: approaches, architectures, and technical challenges.
- Lee McKnight and Howison (2003). Towards a sharing protocol for wireless grids
- Sridhar Iyer (2000). Routing in Mobile Ad Hoc Networks
- Hwang & Aravamudham. Proxy-based middleware services for peer-to-peer computing in virtually clustered wireless grid networks
- Wijngaert, v.d, Bouwman, Moerbeek and Kwiatkowska. Would you Share? Predicting the Potential Use of a New Technology using Multilevel Linear Regression Analysis
- Uzunner and Davis. Digital fingerprinting for distributed volume tracking: intellectual property protection in wireless grids