A comparison of wi-fi and wimax with case studies - Florida State ...

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3.3.2.4. Fragmentation In most occasions, the frames from the upper layer maybe longer than the fragmentation threshold. In this situation, the frames have to be fragmented before transmitting. The advantages for using fragmentation are that it can improve throughput and reliability. By fragmenting frames, the interference only destroys small pieces of frames, but not the entire frames. Thus the overall effective transmission is improved. Also, only the destroyed pieces need to be retransmitted, therefore, the reliability is also improved. The transmission process of fragmented frames is called fragmentation burst. In the clause, there are no rules for fragmentation threshold. It depends on network designers. During the transmission, each fragment has the same frame sequence number and an increasing fragment number for recombination. To keep occupying the channel for completing fragmentation burst, each fragment will reset the NAV for next fragment including ACK. Figure 3-18[55]. [17][55] 3.3.2.5. Interframe spacing Figure 3-18 A Fragment Burst Interframe spacing is a very important protocol for coordinating medium access. There are four different intervals which are shown in figure 3-19[55]. To avoid collision, stations wait a certain period of time until channels are idle before transmission. These different intervals decide the priority for different types of transmission. High priority transmissions wait a shorter amount of time, so it can occupy the channel first. [17][55] 30
SIFS (Short InterFrame Spacing) Figure 3-19 Frame Interval for IEEE 802.11 This is the shortest interval and mainly used for high priority transmission; including a receiver sends CTS back to a transmitter, a receiver sends an ACK for a fragment or a full frame and a transmitter of a fragmentation burst send the next fragment without sending RTS again. PIFS (PCF InterFrame Spacing) This interval is used for competition-free transmission by PCF. If the SIFS interval passed and no stations occupy the channel, after PIFS, the base station will send a poll frame or a beacon frame. Any stations which have data or fragment sequence waiting for transmitting can start to send after PIFS without disturbance or competition. DIFS (DCF InterFrame Spacing) After DIFS, every station can start to compete for earning the channel usage and then the winner takes all. The all transmission rules and Ethernet binary exponential back off algorithm are applied. EIFS (Extended InterFrame Spacing) This is only used when a mistake has happened during a transmission. 3.3.2.6. Power saving To extend the battery’s life of the MS (Mobile Station), the 802.11 MAC layer provides a power management protocol. A base station can direct a MS to go into the sleep mode and buffer frames for it. Later the MS could be awakened by a base station which sends a beacon frame or a 31
Page 1 and 2: THE FLORIDA STATE UNIVERSITY COLLEG
Page 3 and 4: TABLE OF CONTENTS List of Tables…
Page 5 and 6: 5. Case study…………………
Page 7 and 8: LIST OF FIGURES Figure 2-1 The Evol
Page 9 and 10: LIST OF ABBREVIATIONS Abbreviation
Page 11 and 12: PSS Portable Subscriber Station 89
Page 13 and 14: CHAPTER ONE 1. Introduction The cel
Page 15 and 16: Table 1-1 Cont. 802.3an 2006 10GBAS
Page 17 and 18: 2.1. Introduction CHAPTER TWO 2. 3G
Page 19 and 20: 2.3. Development 3G has been in dev
Page 21 and 22: 2.5. Conclusion WAP (Wireless Appli
Page 23 and 24: IEEE 802.11n is the newest standard
Page 25 and 26: Table 3-3 Cont. 10 2.457 X Y Y Y Y
Page 27 and 28: 3.3.1.2. PLCP and PMD The physical
Page 29 and 30: Noise Codes). The most powerful con
Page 31 and 32: Figure 3-5 CCK Modulation HR-DSSS P
Page 33 and 34: other problem is inter-carrier inte
Page 35 and 36: Tab ble 3-5 OFDDM Modulaation and D
Page 37 and 38: and contains DSSS, CCK, PBCC (Packe
Page 39 and 40: 3.3.2. MAC Layer 3.3.2.1. Introduct
Page 41: Virtual channel sensing he other me
Page 45 and 46: Figure 3-20 WEP Frame and Operation
Page 47 and 48: 3.4.2. MIMO (Multiple-Input/Multipl
Page 49 and 50: 4.1. The background of IEEE 802.16
Page 51 and 52: The working groups of WiMax Forum a
Page 53 and 54: Table 4-1 Thee Basic Datta of IEEE
Page 55 and 56: Figure 4-1 The Layer Structure of I
Page 57 and 58: codes ( (CTC) and low densityy pari
Page 59 and 60: 4.3.1.2.2. AAS (Advanced Antenna Sy
Page 61 and 62: Best-effort service (BE) This schem
Page 63 and 64: Encryption Figure 4-4 PKM Protocol
Page 65 and 66: 4.3.2. IEEE 802.16e-2005, the newes
Page 67 and 68: transmiission, the aadjacent cellls
Page 69 and 70: the uplink bandwidth periodically f
Page 71 and 72: Figure 4-7 Coverage and Capacity fo
Page 73 and 74: CHAPTER FIVE 5. Case study This cha
Page 75 and 76: increased bandwidth, fixed connecti
Page 77 and 78: Figure 5-3 Landis Green Figure 5-4
Page 79 and 80: Table 5-2 Xirrus XS-3700 AP Technol
Page 81 and 82: • Automatic Tx power selection
Page 83 and 84: Table 5-4 Cont. 71
Page 85 and 86: 5.1.3. Analysis The FSU wireless ne
Page 87 and 88: since the January 2006. The populat
Page 89 and 90: Table 5-5 Parameters of WLAN and Me
Page 91 and 92: Table 5-6 Features of Nortel Wirele
Page 93 and 94:
• -101 dBm typical @ 1 Mbps Recei
Page 95 and 96:
Operating environment specification
Page 97 and 98:
uilding density, high population de
Page 99 and 100:
epeater r is developping and it wil
Page 101 and 102:
Figure 5-17 WiBro Features The data
Page 103 and 104:
Figure 5-19 U-RAS Premium Figure 5-
Page 105 and 106:
In KT’s recent report, 60% of sub
Page 107 and 108:
Figure 5-21 An Example Application
Page 109 and 110:
Name Parameters Standard Table 5-10
Page 111 and 112:
WiFly used Wi-Fi to cover 60% of th
Page 113 and 114:
BIBLIOGRAPHY [01]. IEEE 802.11 offi
Page 115 and 116:
[37]. Sun, Y.; "Bandwidth-efficient
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[88]. Mineno T.; Babji T.,"Issues a
Page 119 and 120:
[117]. Yun Z.; Yuguang F., "Securit
Page 121 and 122:
Network Operations and Management S
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