1. Wireless Communications & Adhoc Networks Jokhio Sultan Salahuddin Kohistani 07CS24 Computer Communication & Network Management Department of Computer Systems Engineering MUET Jamshoro
2. Agenda Wireless Communications Introduction Generations of Wireless Communications EM spectrum Modes/Types Wireless Computer Networks Techniques Security Ad hoc Networks Contents
4. Wireless Without wires or without physical conducting material or carrier. Unguided Medium Communication Information propagation from source to destination. Hence, Wireless Communication; Transfer of information over a distance without utilizing electrical conductors or "wires". Wireless Communications (Introduction)
9. Far Distant (Larger Range) Communication Cellular/Mobile Communications Wireless Computer Networks Radar Communication Satellite Communication Broadcasting (Analog/Digital) TVs Radios Wireless Communications (Modes/Types)
10. Near (Shorter Distance) Communication Bluetooth Infrared Wireless Communications (Modes/Types)
11. Wireless Local Area Networks (WLANs) Wireless Wide Area Networks (WWANs) Wireless Communications (Computer Networks)
12. A LAN with every end device/node having wireless access to share hardware, software and other devices and Resources. Wireless Communications (Computer Networks: WLANs) other devices
14. Limited to single room b/c waves does not penetrate opaque walls GHz to 400 THz Excellent potential for data transmission Keyboard, mouse, Printers, and end devices can communicate Original standard data rate of 75 kbps for a distance up to 8 m. The recent standard defines a data rate of 4 Mbps. Wireless Communications (Computer Networks: WLANs: Transmission Techniques: Infrared LANs)
15. IEEE 802.11 committee Standards Makes use of Spread Spectrum transmission techniques. Most Popular type of WLAN Usable without having to go to licensing procedure Operates in ISM [Industrial, Scientific, and Medical {902-928MHz (915MHz), 2.4-2.4835GHz (2.4GHz), 5.725-5.825GHz(5.8GHz)}] microwave band. Higher the frequency, Higher the potential Bandwidth. Wireless Communications (Computer NWs: WLANs: Transmission Techniques: Spread Spectrum LANs)
17. Access Point (AP) Basic Services Set (BSS) Coordination Function Distribution System Extended Services Set (ESS) MAC protocol data Unit (MPDU) MAC service Data Unit (MSDU) Station/Node/End Device Wireless Communications (Computer NWs : : : IEEE 802.11 Components)
18. Access Point (AP) Also called Wireless Access point (WAP) or central Base Station. a device that allows wireless communication devices to connect to a wireless network using Wi-Fi, Bluetooth or related standards. WAP or AP connects to router or any other Layer 3 device Can perform switching function b/w wireless devices Wired devices can also be connected to it Wireless Communications (Computer NWs : : : : Access Point)
20. Basic Services Set (BSS) Building block of a wireless LAN. is made of stationary or mobile wireless stations and an optional central base station, also known as the access point (AP). *A BSS without an AP is called an ad hoc network ABSS with an AP is called an infrastructure network. Wireless Communications (Computer NWs : : : : Basic Services Set)
21. Access Point is Optional Without Access point stations still can communication Wireless Communications (Computer NWs : : : : Basic Services Set)
22. Coordination Function logical function Uses CSMA techniques with CA Determines when a station is permitted to transmit and may able to receive the PDU. Distribution Function A system used to interconnect A set of BSSs & integrated LAN to create ESS Wireless Communications (Computer NWs : : : : Coordination and Distribution Function)
23. An Extended service set (ESS) is made up of two or more BSSs with APs. In this case, the BSSs are connected through a distribution system, which is usually a wired LAN. The distribution system connects the APs in the BSSs. IEEE 802.11 does not restrict the distribution system; it can be any IEEE LAN such as an Ethernet. Wireless Communications (Computer NWs : : : : Extended Services set)
24. MAC Protocol Data Unit (MPDU) The unit of data exchanged b/w two peer MAC entities using the services of the physical layer. MAC Protocol Data Unit (MSDU) Information that is delivered to the user. Stations Any device that contains an IEEE 802.11 conformant MAC and Physical layer. Wireless Communications (Computer NWs : : : : MPDU, MSDU & Stations)
27. Increase in Portable Devices Simplicity and Flexibility Reliable and Secure Higher Data Rates, Speed and Reach Technology Cost Savings Trend Wireless Communications (Computer NWs : : : : Why Wireless..?)
28. Data less secure The waves could be damaging to our health Modulation technique required for efficient transmission. Wireless Communications (Computer NWs : : : : Why not Wireless)
29. Authentication A function that determines whether a Station is allowed to participate in network communication. Implementing network encryption Security Protocols WEP (Wireless Equivalency protocol) WPA (Wireless Protected Access) Wireless Communications (Security)
30. Data is In Air Even with Encryption creative minded hackers can sniff your data and corporate confidential information. Even with encryption, the data between client and AP’s are available for anyone to capture. Danger for Humanity… Wireless Communications (Issues)
31. An Adhoc network is a peer-to-peer network (no central device) set up temporarily to meet some immediate needs. When all station are mobile stations, with no connection to other BSSs, the BS is called IBSS(Independent BSS), some times referred as Ad hoc network… In simple words, it is decentralized network… Wireless Communications (Adhoc Networks)
35. The World Wide web (Internet) Wikipedia-The Free Encyclopedia http://www.wikipedia.org/en IEEE http://www.ieee.org ACM http://www.acm.org Books Computer Networks Tanebaum S. Andrew 4th ed. Data Communications and Networking Forozon A. Behrouz 4th ed. Data and Computer Communications Stallings William 6th ed. References
