M171L_1_3_W Ch & WLAN_F_10

M171L_1_3_W Ch & WLAN_F_10 - LAB 3 WLAN 1....

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
1 LAB 3 WLAN (10/14) 1. Introduction 2. Review of Modulation Techniques a. Principles of SS Transmission b. CDMA spreading. 3. Radio Waves and Basics of Antenna Theory a. Propagation theory b. Basic of antenna theory 4. Antenna Selection 5. Wireless Link Power Budget Analysis 6. MAC in Wireless 802.11b LANs 7. Motivation for a specialized MAC a, Hidden and exposed terminals; b. Classical Aloha; c. Slotted Aloha; 8. MACA a. MACAW 9. MAC 802.11 Sub-layer Protocol a. CSMA/CA 10. TCP/UDP over 802.11b 11. TCP Congestion Control a. Topology; b. MAC; c. Data transmission;
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 Wireless Transmission The Electromagnetic Spectrum Radio Transmission Microwave Transmission Infrared and Millimeter Waves Lightwave Transmission In vacuum, all electromagnetic waves travel at the same speed, no matter what their frequency. This speed is the speed of light- c , is about 1 foot (30cm)/ns. In copper or fiber the speed slows to about 2/3 of this value and is slightly frequency dependent. The relation between frequency , wavelength , and speed – c is . As a rule of thumb, when is in meters and is in MHz- . f λ c f = f [ ] 300 = f
Background image of page 2
3 Radio frequencies in the 100 kHz to 10 GHz range . 535 kHz AM Radio : 1705 kHz 2-way radio (cordless phones): 42-49.6 MHz TV Channels 2-4 : 54-72 MHz TV Channels 5-6 : 76-88 MHz FM Radio: 88-108 MHz TV Channels 7-13 : 174-216 MHz TV Channels 14-36: 470-608 MHz TV Channels 38-69 : 614-806 MHz Cellular Service: 806-902 MHz PCS Service: 1.850-1.990 GHz Unlicensed Usage: 5.725-5.850 GHz Unlicensed Usage: 2.390-2.4835 GHz Unlicensed Usage: 902-928 MHz 10 MHz 1 MHz 100 MHz 1 GHz 10 GHz 100 kHz microwave
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Microwave radio systems: 1. Microwave voice/data transmissions: No AM . 1.Data -modulate the carrier wave using : PM, FM, and SS modulation techniques . 2a. Links (channels) are separated with: FDMA. 1. Voice data-to encode signal digitally use: PCM 3a. Several voice signals in one channel are separated by: TDMA
Background image of page 4
5 Modulation Techniques A , φ , and f BPSK : 0° or 180°, QPSK 0°, 90°, 180°, 270° A higher K f value can be used in modulating the audio signal, Higher K f value decreases the signal error rate. However, decoding an FM signal becomes very difficult at high K f , So we cannot increase K f to use FM transmission in a wide frequency band. In the radio spectrum, the available bandwidth exceeds the necessary data rate. For instance , FM radio stations have about 100 kHz , bandwidth of an audio signal 20 kHz . Spread spectrum techniques are necessary to for efficient use of a wide frequency band at low error rates . ( 29 π + = f A t S c 2 sin ) (
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Shannon’s law shows the relationship between channel (analog) bandwidth and digital channel capacity. When the SNR < below 1 (wireless channel is noisy channel), less than 1 bit can be transferred by each sample. If the SNR ratio = 3 , and the C=<2B. + = N S W C 1 log 2 Transmission Rate R is provided C R Equality is achieved only when SNR is infinity In practice: impossible to create an encoding scheme that allows accurate transmissions near to the Shannon limit.
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 77

M171L_1_3_W Ch &amp;amp; WLAN_F_10 - LAB 3 WLAN 1....

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online