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

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for the channel, timing and fine frequency offset estimation. The Head contains two parts, the signal and data’s service section. The head is 40 bits long (signal is 24 bits plus service 16 bits). The signal field is always transmitted with BPSK at 6 Mbps. Figure 3-11 OFDM PLCP Structure In the OFDM-PMD sub-layer, to maintain the speed 6, 12 and 24 Mbps is required. An operation channel (20 MHz bandwidth) is divided into 52 sub-channels (sub-carriers). Four of them are pilot carriers; the rest of the 48 sub-channels are used to transmit data. The data will be divided and modulated into sub-channels, then transmitted parallel. [17][21][29] 3.3.1.6. IEEE 802.11g and the Physical Layer 3.3.1.6.1. Background and Backward Compatibility As 802.11b became more and more popular, people started to notice the convenience of wireless LAN. At that time, 802.11b could only provide a maximum 11Mbps. Compared to Ethernet, this was not a good performance – it was just barely acceptable. When 802.11a started to join the market, end users also wanted 802.11b to become faster. In fact, 54 Mbps really was not very fast and most of the time, in a wonderful environment, the performance could only achieve 50% of the possible speed. However WLAN has its own advantages and “wireless” has become a trend gradually. Under these conditions, 802.11g is the answer. It has the same speed with 802.11a, but it has a longer area of coverage. Moreover, it operates in the 2.4 GHz band. According to 802.11g clause, this standard is not a “new” standard. It is an integrated standard using many existing technologies. Its physical layer is called ERP (Extended Rate PHY) 24
and contains DSSS, CCK, PBCC (Packet Binary Convolution Coding) and OFDM. It supports the speed: ERP-DSSS: 1, 2, 5.5 and 11 Mbps ERP-PBCC: 22 and 33Mbps ERP-OFDM: 6, 9, 12, 18, 24, 36, 48 and 54 Mbps (6, 12 and 24 Mbps are mandatory) For backward compatibility, these methods have some slight changes, but are pretty much the same original standard. An 802.11g stationary must have the ability to communicate with both old 802.11b stations and other 802.11 stations. For that reason, the ERP-DSSS and ERP-CCK were added. A problem of backward compatibility is that the 802.11g can receive and decode 802.11b signals, but the converse is not true. Therefore a protection has to be added to the 802.11g standard. The first part of the protection is that when doing transmission with 802.11b stations, the Beacon frames cannot be transmitted higher than 11 Mbps. The second part is to avoid network interference between 802.11b and 802.11g. When 802.11g is transmitting data, in order to avoid disturbing 802.11b, it will send CTS (Clear To Send) frames to notify the 802.11b stations and update the NAV (Network Allocation Vector).This process is called CTS-self Protection. To make sure every station in the network can receive and process the CTS frames, they have to be sent under 802.11b protocol. The protection is controlled by the ERP information element in Beacon frames and will limit the data rate of 802.11g. [13][14][17][20][21][29] 3.3.1.6.2. ERP-OFDM and DSSS-OFDM The ERP-OFDM is very similar to the OFDM used in 802.11a with only a slight difference. The PLCP is shown in Figure 3-12[21]. When comparing these two OFDM-PLCP, the difference is the “signal extension” field. This 6µs extra time is used to prepare and decode the 802.11a frames. 802.11a uses 16 µs SIFS (Short Inter-Frame Space) which is different form 802.11b 10 µs SIFS. 802.11g chooses 10 µs because of backward compatibility, therefore, it adds 6 µs after a frame to match timing and frame with 802.11a. Beside the PPDU structure, the transmission method is exactly the same with 802.11a. 25
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: Tab ble 3-5 OFDDM Modulaation and D
Page 39 and 40: 3.3.2. MAC Layer 3.3.2.1. Introduct
Page 41 and 42: Virtual channel sensing he other me
Page 43 and 44: SIFS (Short InterFrame Spacing) Fig
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
Page 117 and 118:
[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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