38. Multiple path waves can add at the receiver either constructively, strengthening the signal, or destructively, weakening the signal a. True b. False 39. Cellular network features (check all that apply) a. Many low power transmitters over a large area b. Each transmitter covers a hexagonal cell that does not overlap neighboring cells c. Same frequencies are re-used at neighboring cells 40. Transmitter and antenna that provides radio coverage within a single cell is called a. Base station b. Base station controller c. Mobile subscriber 41. Station that controls multiple cell transmitters is known as a. Base station b. Mobile Subscriber c. Base station controller 42. A 'Mobile Switching Center' switches calls from cell sites to existing wired Public Switched Telephone network a. True b. False 43. Automatic change of radio frequencies from one cell to another as a mobile subscriber moves among coverage areas is called a Handoff a. True b. False 44. The stores complete local information for a mobile phone user. a. VLR b. HLR 45. What kind of security attack masquerades as a trusted user to access secure environment in a source routed network a. Spoofing b. Man-in-the-middle c. Replay attack d. Denial-of-service e. Trojan horse f. Session hijacking g. Phishing 31. Radio waves can be characterized by either frequency in Hz or by wavelength in meters a. True b. False 32. Radio communications system consists of: transmitter and antenna, free space medium, and receiving antenna with receiver a. True b. False 33. Free space radio wave propagation includes (check all that apply) a. Ground wave b. Sky wave c. Direct wave 34. When a radio wave contacts an object with different electrical property than free space and changes direction as a result is: a. Reflection b. Diffraction c. Scattering 35. When a radio wave bends as a result of hitting a sharpedged object is called a. Reflection b. Diffraction c. Scattering 36. A radio wave contacting objects much smaller that its wave-length and scatters in all directions weakening a signal a. True b. False 37. A radio signal can take only one path from transmitter to receiver a. True b. False 38. Multiple path waves can add at the receiver either constructively, strengthening the signal, or destructively, weakening the signal a. True b. False