Quiz- 3 Chapter-5, 7, 8 iL Complete the following: 1. Receivers that receive and process the signals. In some cases, transmitters and receivers are on same device, called transceivers. 3. The most common and widely used WLANS are the ones that belong to the IEEE 802.11 family. 4. Bluetooth is a wireless cable replacement standard that provides | Mbps data rate at 10 meters and less. It typically consists of a group of linked devices, such as a computer wirelessly connecting to a set of peripherals, known as a “piconet.”. +. UW (Utes Wideband) the other short-range wireless systems (such a5 Blueicoth) because ofits simpler device designs, lower power consumption and higher data rates 6. HomeRF, was primarily aimed atthe needs of the small office and home office. 7.wireless =. loop (WLL) that is quite popular with the long distance telephone companies. 8. WLLs are fixed wireless networks that deliver between 10 to 50 Mbps over several kilometers. 9. The WLL providers use transmitters instead of wired local loops to deliver content (wireless TV, for example) to the subscribers. 10.A satellite is essentially es: the sky which receives signals from transmitting stations on earth and relays these signals back to the receiving stations on the earth.11. Satellites are used in areas such as telecommunications, weather reports, and scientific exploration. 12. Deep Space Satellites” communicates over hundreds of thousands of miles. 13, Hertz (Hz) = number of cycles per second. Frequency is measured in Hertz. 14, Baucl = number of signal changes per second 15. Data rate = number of bits sent per second (bps). Data rate is equal to the baud rate if one bit is carried per signal. In general, data rate = baud rate x data bits per signal. 16. Channel = a logical communication path. One physical wire can support multiple channels; each channel supports one user. 17. Bandwidth = frequency range used by a signal, measured in Hz. 18.Channel capacity = number of bits that can be transmitted per second. This is the same as data rate. 19. The transmission medium is called guided media if the waves are guided along a solid medium, e.g., copper twisted pair, copper coaxial cable, or optical fiber. 20.Unguided media does not guide electromagnetic signals and is used commonly in wireless transmissions such as atmosphere and outer space. 21. An antenna is an electrical conductor or system of conductors to send/receive RF signals. 22.In a mobile ad hoc network, also known as s the network devices “discover” each other when they are in each other’ without pre-planning. 23. Time Division Duplex (TDD), also known as time compression multiplexing, isused in cordless systems to support multiple users. Question and Answers Transmitters that generate and send signals: Antennas that radiate the electromagnetic energy generated Antennas that by the signals into the air. Receivers that receive and process the signals. In some cases, transmitters and CeiverS are on same device, called transceivers (¢.g., cellular phones). 2. list out several technologies exist for WLL. LMDS (Local Multipoint Distribution Service) — a newer standard. eo 7 MMDS (Multichannel Multipoint Distribution Service) — an older standard. A relatively new entrant in the WLL market is Free Space Optics (FSO) that uses laser beams to deliver extremely high data rates (around 1 Gbps) over a few kilometers. FSO is gaining popularity because of its high security — it is difficult to intercept laser beams: 3. write few differences between wired and wireless networks. The wireless networks in the aforementioned categories are offering higher data rates than before. The wired networks are also offering higher data services. oo The wireless technology is much slower than the wired but is still used heavily because it offers greater flexibility to the users Security is a major concern for corporate use of wireless networks.In addition, the lack of an industry-wide standard in wireless is a major problem. Broadband wireless is suitable for graphics, video, and audio over wireless. Although broadband wireless networks provide higher data rates, they do not support mobility. 4. what are the factors in designing wireless network. Factor ‘Why Important ‘Applications Supported Most data appeations require higher QoS than voice Frequency Allocations [Need to know what frequency range to operate. May need licenses to ‘operate saver ranges Location Services| Essettal because the users ofmable serves change ther location eg, colar phone) Aso important for 911 cals an ‘Muitiple Access Mechanisms | How usors can shar the sare mexium wibod interfenng wih ach oer ‘Antennas and Propagation | Hen understaniag the type of enors and how 0 deal with them 5. write the properties that characterize cyclic waves. The following properties characterize cyclic waves (see the following figure): Frequency which shows the cycles per unit time of the wave Amplitude which shows the height of the wave Phase which shows how far, in degrees, the wave is from its beginning (phase 0). 6. Wireless transmissions can be configured for: Directional transmission, i.e., the wireless communication is point-topoint. For example, a mi i icect all of its signals to a receiver acfoss a Street ~Qrnidiectonal transmission ic. the waves ar transmitted equally in all ‘ae directions. A radio station transmitter is an example reer 7 list the various Microwave frequency NEE w\ 1 GHz to 40 GHz Directional beams possibleSuitable for point-to-point transmis Used for satellite communications _ Communication systems consist of? ransmitters Antennas: radiates electromagnetic energy into air 9. what are the categories Radiation patterns ? _Isotropic antenna (omnidirectional) Radiates power equally in all directions Directional transmissions that radiate power in one direction. Directional transmi: ions are common in higher frequency ranges where preferential transmission and reception directions can be predefined between senders and receivers. 10. Define Antenna gain. It is a measure of directionality of antennas. It simply represents the power output, in a particular direction, compared to that produced in any direction by a perfect omnidirectional antenna with isotropic radiation patterns. > 11. what is the main advantage of adhoc network. The main advantage of ad hoc networks is that they are self organizing wireless networks composed of mobile stations that communicate with each other in a peer- to-peer manner without a fixed and pre-planned infrastructure with access poi 12. show the homeRF environment.13. Write the main characteristics of HomeRF. The main characteristics of HomeRF are: Voice Communications Support. HomeRF uses DECT for voice communications. By using DECT, HomeRF supports up to 4 conversations and up to 8 phone handsets. Interference Resistance. HomeRF uses 2.4 GHz, the same frequency used by 802.1 1b, and is subject to interference from other 2.4 GHz devices like some cordless phones 14, what are broad application areas provided by Bluetooth. Cable replacement Data and voice access points. Ad hoc networking.15. list the different types of channels. Control channels that are used to set up and maintain calls Traffic channels that are used to carry voice and data traffic. 16.write the Advantages of Digital Communications for Wireless. Voice, data and fax can be integrated into a single system Better compression can lead to better channel utilization Error correction codes can be used for better quality Sophisticated encryption can be used \