Introduction connection point between a wired andIntroduction connection point between a wired and

Introduction to wireless and mobile networksIntroductionThe Areas which wireless and mobile systems take under consideration are Mobility and computing.Mobility is responsible for providing uninterrupted accessibility to its users and wireless communication is concerned with supplying communication without wires.Wireless Network technology IEEEE 802.11 can provide flexibility in terms of cost saving and mobility1 The major applications of Wireless Networks comprise ofCellular networks: A Wireless network composed of sizable number of cells in which each cell has its own transmitting antenna. A base station in a cellular network consists of a transmitter, receiver, and control unit.The cells are designed in a way so have all the neighboring antennas equidistant from one another, also the cells are alloted different frequency in order to avoid crosstalk or interference.Eg: PDAs ,Cellular phones, Palm PilotWireless LAN: Wireless LAN or Wireless Local Area Network is the reference  to the local area network ,it does not require wires to  with different devices,  it utilizes Radio waves and IEEE 802.11 for communication. Wireless LAN consists of an Access Point (AP) which is a wireless LAN transceiver and also serves as the focal point of a standalone network acting as the linking or connection point between a wired and wireless network 2. This has resulted in a simplified network as multiple computing devices can communicate simultaneously through wireless medium without  facing an additional cost of wires.Main features of Wireless LAN includeFlexibility of LocationRoaming capabilityCost EffectiveAdhoc Networks: A Wireless Ad hoc network (WANET) is a decentralized in nature. It doesn’t comprise of any pre-existing infrastructure. The network is constructed dynamically depending on  when the devices connect simultaneously. The time span of the network is very small,it is created when a group of individuals need to share data at a short range Eg:Bluetooth.Wireless Sensor Networks: communication in wireless sensor network takes place through sensor nodes. This devices are simple processing devices which are cost effective,they are equipped with ability to sense temperature,humidity etc3. A WSN is made up of large number of sensor nodes which are densely deployed inside the are under consideration or very close it. A sensor networks is composed of a large number of sensor nodes that are densely deployed either inside the phenomenon or very close to it. These sensor nodes consists of data processing, messaging and communication components 4.The WSN gives sensors the independence to relocate at will, resulting in a dynamic network . As this network is wireless, the sensors dynamically change their topology and do not have any central point of contact which allows the nodes to join and leave the network at will.The major applications of wireless sensor network areSeismic Monitoring Habitat and Ecosystem Monitoring Civil Structural Health Monitoring Monitoring Groundwater ContaminationRapid Emergency ResponseIndustrial Process MonitoringPerimeter Security and SurveillanceAutomated Building Climate ControlIntroduction to wlan Computer technology has seen a rapid  growth  in the area of network and communication 5 in the past decade. One of the most essential area is the Internet. A transformation can be observed from wired wireless network steady-going increase in the demand of wireless networks can be credited to the network architecture where in it allows multiple users to share resources simultaneously without having to install additional wiring. It implements orthogonal frequency-division multiplexing (OFDM) radio or spread spectrum technology, while connecting to the wider network by utilizing  access points 6. The users are given flexibility to move to and fro  the local coverage area and while continuing to be  connected to the network. It offers features like high flexibility and network installation is very simple when compared to the wired infrastructure 7.It offers the similar features to the wired LAN which includes high capacity, full connectivity among the stations attached and broadcasting capability.Wireless networks have become the widely used technology and are gaining popularity due to features like Flexibility of Location Cost EffectiveMobilityProductivityConvenienceDeploymentCostExpandabilityThe network has  lead to an increase in the productivity as the accessibility increases to the information resources 4.The configuration is also very simple, less expensive and quick. The major element which has influenced the development and growth of the wireless network are convenience ,cost efficiency and ease of integration. Most of the computers come equipped with the technology required for wireless networks.The most commonly used  standard  in the modern WLAN is IEEE 802.11The table below shows the evolution of the IEEE protocols in terms of transfer Rate and range of the network.IEEE Protocol FamilyProtocolDate of ReleaseFrequencyRateRate(Maximum)RangeLegacy19972.4 GHz1 Mbps2 Mbps-802.11a19995   GHz25 Mbps54 Mbps~30 m802.11b19992.4 GHz6.5 Mbps11 Mbps~30 m802.11g20032.4 GHz25 Mbps54 Mbps~30 m802.11n20082.4-5 GHz200 Mbps540 Mbps~50 mbrief history of wlanIEEE 802.11 wireless LAN operative group was established in the year 1987 8 with the objective  to standardize the spread spectrum in WLAN. It is used chiefly inside a building as the power utilization is low  and is by and large does not need license for the spectrum usage.In the recent  years WLAN has gained a lot of value and  importance.In the beginning of early 1990’s 9 WLAN did not find a lot a success. The devices were not very fast ,hardware was expensive ,equipment was bulky whose power consumption was huge.  The first significant growth for WLAN was observed in late 1990’s in the form of broadband Internet connection for Personal home computers for various networked devices. The end of 1990’s observed the early development in which  proprietary protocols and industry-specific solutions were replaced with different versions of IEEE 802.11. The  two main standards available for WLAN IEEE 802.11HIPER LANIEEE 802.11 is a developed and mature standard from an industrial standpoint. IEEE 802.11 access points and cards are produced by various manufactures 10.It functionally operates at 2.4 GHz Ism band and  provides wireless connectivity for  portable station and mobile station  within a local area.HIPERLAN (High Performance Radio Local Area Network) is a family of standards formed and provided by European Telecommunication standard institute (ETSI).This technology is suitable for interconnecting portable devices  and also for broadband core network like ATM.IP and UMTS.But to the best of our knowledge this technology is still under formulation and  at prototype level.