1.
Computer network
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A computer network or data network is a telecommunications network which allows nodes to share resources. In computer networks, networked computing devices exchange data with other using a data link. The connections between nodes are established using either cable media or wireless media, the best-known computer network is the Internet. Network computer devices that originate, route and terminate the data are called network nodes, nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices can be said to be networked together when one device is able to exchange information with the other device, Computer networks differ in the transmission medium used to carry their signals, communications protocols to organize network traffic, the networks size, topology and organizational intent. In most cases, application-specific communications protocols are layered over other more general communications protocols and this formidable collection of information technology requires skilled network management to keep it all running reliably. The chronology of significant computer-network developments includes, In the late 1950s, in 1960, the commercial airline reservation system semi-automatic business research environment went online with two connected mainframes. Licklider developed a group he called the Intergalactic Computer Network. In 1964, researchers at Dartmouth College developed the Dartmouth Time Sharing System for distributed users of computer systems. The same year, at Massachusetts Institute of Technology, a group supported by General Electric and Bell Labs used a computer to route. Throughout the 1960s, Leonard Kleinrock, Paul Baran, and Donald Davies independently developed network systems that used packets to transfer information between computers over a network, in 1965, Thomas Marill and Lawrence G. Roberts created the first wide area network. This was an precursor to the ARPANET, of which Roberts became program manager. Also in 1965, Western Electric introduced the first widely used telephone switch that implemented true computer control, in 1972, commercial services using X.25 were deployed, and later used as an underlying infrastructure for expanding TCP/IP networks. In July 1976, Robert Metcalfe and David Boggs published their paper Ethernet, Distributed Packet Switching for Local Computer Networks, in 1979, Robert Metcalfe pursued making Ethernet an open standard. In 1976, John Murphy of Datapoint Corporation created ARCNET, a network first used to share storage devices. In 1995, the transmission speed capacity for Ethernet increased from 10 Mbit/s to 100 Mbit/s, by 1998, Ethernet supported transmission speeds of a Gigabit. Subsequently, higher speeds of up to 100 Gbit/s were added, the ability of Ethernet to scale easily is a contributing factor to its continued use. Providing access to information on shared storage devices is an important feature of many networks, a network allows sharing of files, data, and other types of information giving authorized users the ability to access information stored on other computers on the network
2.
Nanonetwork
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A nanonetwork or nanoscale network is a set of interconnected nanomachines, which are able to perform only very simple tasks such as computing, data storing, sensing and actuation. Nanonetworks are expected to expand the capabilities of single nanomachines both in terms of complexity and range of operation by allowing them to coordinate, share, nanonetworks enable new applications of nanotechnology in the biomedical field, environmental research, military technology and industrial and consumer goods applications. Nanoscale communication is defined in IEEE P1906.1, classical communication paradigms need to be revised for the nanoscale. The two main alternatives for communication in the nanoscale are based either on electromagnetic communication or on molecular communication and this is defined as the transmission and reception of electromagnetic radiation from components based on novel nanomaterials. For the time being, two alternatives for electromagnetic communication in the nanoscale have been envisioned. The different molecular communication techniques can be classified according to the type of propagation in walkaway-based, flow-based or diffusion-based communication. In walkway-based molecular communication, the molecules propagate through pre-defined pathways by using carrier substances and this type of molecular communication can also be achieved by using E. coli bacteria as chemotaxis. In flow-based molecular communication, the molecules propagate through diffusion in a medium whose flow and turbulence are guided. The hormonal communication through blood streams inside the body is an example of this type of propagation. The flow-based propagation can also be realized by using carrier entities whose motion can be constrained on the average along specific paths, a good example of this case is given by pheromonal long range molecular communications. In diffusion-based molecular communication, the molecules propagate through diffusion in a fluidic medium. In this case, the molecules can be solely to the laws of diffusion or can also be affected by non-predictable turbulence present in the fluidic medium. Pheromonal communication, when pheromones are released into a fluidic medium, other examples of this kind of transport include calcium signaling among cells, as well as quorum sensing among bacteria. Such temporal spreading has an impact in the performance of the system e. g. in creating the intersymbol interference at the receiving nanomachine. In order to detect the concentration-encoded molecular signal two detection methods named sampling-based detection and energy-based detection have been proposed, in order to reduce the impact of ISI a controlled pulse-width based molecular communication scheme has been analysed. The work presented in showed that it is possible to realize multilevel amplitude modulation based on ideal diffusion, a comprehensive study of pulse-based binary and sinus-based, concentration-encoded molecular communication system have also been investigated
3.
Near-field communication
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NFC devices are used in contactless payment systems, similar to those used in credit cards and electronic ticket smartcards and allow mobile payment to replace/supplement these systems. NFC is used for networking, for sharing contacts, photos, videos or files. NFC-enabled devices can act as electronic identity documents and keycards, NFC offers a low-speed connection with simple setup that can be used to bootstrap more capable wireless connections. Similar ideas in advertising and industrial applications were not generally successful commercially, outpaced by technologies such as barcodes, NFC protocols established a generally supported standard. When one of the devices has Internet connectivity, the other can exchange data with online services. NFC-enabled portable devices can be provided with software, for example to read electronic tags or make payments when connected to an NFC-compliant apparatus. NFC reader/writer—enables NFC-enabled devices to read information stored on inexpensive NFC tags embedded in labels or smart posters, NFC peer-to-peer—enables two NFC-enabled devices to communicate with each other to exchange information in an adhoc fashion. NFC tags are passive data stores which can be read, and under some circumstances written to and they typically contain data and are read-only in normal use, but may be rewritable. Applications include secure personal data storage, NFC tags can be custom-encoded by their manufacturers or use the industry specifications. The standards were provided by the NFC Forum, the forum was responsible for promoting the technology and setting standards and certifies device compliance. Secure communications are available by applying encryption algorithms as is done for credit cards, NFC standards cover communications protocols and data exchange formats and are based on existing radio-frequency identification standards including ISO/IEC14443 and FeliCa. The standards include ISO/IEC18092 and those defined by the NFC Forum, in addition to the NFC Forum, the GSMA group defined a platform for the deployment of GSMA NFC Standards within mobile handsets. GSMAs efforts include Trusted Services Manager, Single Wire Protocol, testing/certification, a patent licensing program for NFC is under deployment by France Brevets, a patent fund created in 2011. This program was under development by Via Licensing Corporation, an independent subsidiary of Dolby Laboratories, a platform-independent free and open source NFC library, libnfc, is available under the GNU Lesser General Public License. Present and anticipated applications include contactless transactions, data exchange and simplified setup of more complex such as Wi-Fi. This is used for identification, authentication and tracking,1983 The first patent to be associated with the abbreviation RFID was granted to Charles Walton. 1997 Early form patented and first used in Star Wars character toys for Hasbro, the patent was originally held by Andrew White and Marc Borrett at Innovision Research and Technology. The device allowed data communication between two units in close proximity,2002 Sony and Philips agreed to establish a technology specification and created a technical outline on March 25,2002
4.
Home network
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A home network or home area network is a type of computer network that facilitates communication among devices within the close vicinity of a home. Establishing this kind of network is necessary when there is need to distribute residential Internet access to all internet capable devices in the home. Due to the effect of IPv4 address exhaustion, most Internet service providers provide only a single WAN-facing IP address for each residential subscription, in homes these usually come in the form of a DSL modem or cable modem. A router manages network layer connectivity between a WAN and the HAN, most home networks feature a particular class of small, passively cooled, table-top device with an integrated wireless access point and 4 port Ethernet switch. These devices aim to make the installation, configuration, and management of a network as automated, user friendly. A network switch is used to allow devices on the network to talk to one another via Ethernet. While the needs of most home networks are satisfied with the built-in wireless and/or switching capabilities of their router, for example, When the routers switching capacity is exceeded. Most home routers expose only 4 to 6 Ethernet ports, most home networks rely on one wireless router combination device to fill this role. A home automation controller enables low-power wireless communications with simple, non-data-intensive devices such as light bulbs, a network bridge connecting two network interfaces to each other, often in order to grant a wired-only device, e. g. Xbox, access to a wireless network medium. Home networks can use either wired or wireless technologies to connect endpoints, wireless is the predominant option in homes due to the ease of installation, lack of unsightly cables, and network performance characteristics sufficient for residential activities. One of the most common ways of creating a network is by using wireless radio signal technology. Most wireless-capable residential devices operate at a frequency of 2.4 GHz under 802. 11b and 802. 11g or 5 GHz under 802. 11a, some home networking devices operate in both radio-band signals and fall within the 802. 11n or 802. 11ac standards. Wi-Fi is a marketing and compliance certification for IEEE802.11 technologies, the Wi-Fi Alliance has tested compliant products, and certifies them for interoperability. Low power, close range communication based on IEEE802.15 standards has a presence in homes. Bluetooth continues to be the technology of choice for most wireless accessories such as keyboards, mice, headsets and these connections are often established in a transient, ad-hoc manner and are not thought of as permanent residents of a home network. A low-rate version of the original WPAN protocol was used as the basis of ZigBee, ZigBee utilizes mesh networking to overcome the distance limitations associated with traditional WPAN in order to establish a single network of addressable devices spread across the entire building. Z-Wave is a standard also built on 802.15.4. Most wired network infrastructures found in homes utilize Category 5 or Category 6 twisted pair cabling with RJ45 compatible terminations and this medium provides physical connectivity between the Ethernet interfaces present on a large number of residential IP-aware devices
5.
Storage area network
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A storage area network is a network which provides access to consolidated, block level data storage. A SAN typically has its own network of devices that are generally not accessible through the local area network by other devices. The cost and complexity of SANs dropped in the early 2000s to levels allowing wider adoption across both enterprise and small to medium-sized business environments, a SAN does not provide file abstraction, only block-level operations. However, file systems built on top of SANs do provide file-level access, essentially, a SAN consolidates such storage islands together using a high-speed network. Operating systems maintain their own systems on their own dedicated, non-shared LUNs. If multiple systems were simply to attempt to share a LUN, any planned sharing of data on different computers within a LUN requires software, such as SAN file systems or clustered computing. Despite such issues, SANs help to increase capacity utilization. Common uses of a SAN include provision of transactionally accessed data that require high-speed block-level access to the hard drives such as servers, databases. Network-attached storage was designed independently of SAN systems, both NAS and SAN have the potential to reduce the amount of excess storage that must be purchased and provisioned as spare space. In a DAS-only architecture, each computer must be provisioned with enough storage to ensure that the computer does not run out of space at an untimely moment. In a DAS architecture the spare storage on one computer cannot be utilized by another, in a NAS the storage devices are directly connected to a file server that makes the storage available at a file-level to the other computers. In a SAN, the storage is available at a lower block-level. SAN protocols include Fibre Channel, iSCSI, ATA over Ethernet, instead the CPUs use the LAN to communicate, potentially creating bandwidth as well as performance bottlenecks. To understand their differences, a comparison of SAN, DAS and NAS architectures may be helpful, sharing storage usually simplifies storage administration and adds flexibility since cables and storage devices do not have to be physically moved to shift storage from one server to another. Other benefits include the ability to allow servers to boot from the SAN itself and this allows for a quick and easy replacement of faulty servers since the SAN can be reconfigured so that a replacement server can use the LUN of the faulty server. SANs also tend to more effective disaster recovery processes. A SAN could span a distant location containing a secondary storage array and this enables storage replication either implemented by disk array controllers, by server software, or by specialized SAN devices. Since IP WANs are often the least costly method of long-distance transport, the traditional physical SCSI layer could support only a few meters of distance - not nearly enough to ensure business continuance in a disaster
6.
Wireless LAN
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This gives users the ability to move around within a local coverage area and yet still be connected to the network. A WLAN can also provide a connection to the wider Internet, most modern WLANs are based on IEEE802.11 standards and are marketed under the Wi-Fi brand name. Wireless LANs have become popular for use in the home, due to their ease of installation and they are also popular in commercial complexes that offer wireless access to their customers. Norman Abramson, a professor at the University of Hawaii, developed the worlds first wireless communication network, ALOHAnet. The system included seven computers deployed over four islands to communicate with the computer on the Oahu Island without using phone lines. Wireless LAN hardware initially cost so much that it was used as an alternative to cabled LAN in places where cabling was difficult or impossible. Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by standards, beginning in 1991, a European alternative known as HiperLAN/1 was pursued by the European Telecommunications Standards Institute with a first version approved in 1996. This was followed by a HiperLAN/2 functional specification with ATM influences accomplished February 2000, in 2009802. 11n was added to 802.11. It operates in both the 2.4 GHz and 5 GHz bands at a data transfer rate of 600 Mbit/s. Most newer routers are able to utilise both wireless bands, known as dualband and this allows data communications to avoid the crowded 2.4 GHz band, which is also shared with Bluetooth devices and microwave ovens. The 5 GHz band is wider than the 2.4 GHz band, with more channels. Not all channels are available in all regions, a HomeRF group formed in 1997 to promote a technology aimed for residential use, but it disbanded at the end of 2002. All components that can connect into a medium in a network are referred to as stations. All stations are equipped with wireless network interface controllers, Wireless stations fall into two categories, wireless access points, and clients. Access points, normally wireless routers, are base stations for the wireless network and they transmit and receive radio frequencies for wireless enabled devices to communicate with. The basic service set is a set of all stations that can communicate with other at PHY layer. Every BSS has an identification called the BSSID, which is the MAC address of the access point servicing the BSS, there are two types of BSS, Independent BSS, and infrastructure BSS. An independent BSS is an ad hoc network that contains no access points, an extended service set is a set of connected BSSs
