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

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The reason that WEP was safe was because the secret key was not easily broken. However in some cases, the network designers use the same shared key for all users. That means that people can read each other’s packets. That is not good for security. If it is a small network, trying to use the different keys for each user should not be a big problem, but if it is a big network, for security reasons, if a secret key changes once in a period of time, it is a huge job. How to distribute a secret key and how to assure it is not repeated are very important issues at this point. Moreover, IV is another potential risk. The WEP protocol recommends that the IV value should be different for every packet to avoid the keystream attack. If IV is not a random value, the encryption will be broken easily. Unfortunately some wireless network cards set the initial IV as 0 and increase the number by one for each packet sent. With this kind of IVs, to break the encryption is way too easy. Unless the secret key is changed often or assuring the use of random and different IV for each packet, the risk will remain high. If a hacker collects enough packets with repeated IV from the same user, the cipher will be broken. [17][55] 3.4. The next generation standard 3.4.1. IEEE 802.11n IEEE 802.11n is the standard of WLAN for next generation which also called Wi-Fi (Wireless fidelity). This standard was initiated in 2004 by TGn. The goal of this standard was to improve the net transmission speed up to 100 Mbps. In the beginning, there were six proposals that had been posted. After many discussions, there were only two proposals left and they were from TGnSync and WWiSE. These two groups have their own support from chip makers. TGnSync has Athero, Agere, Marvell and Intel, while WWiSE has Airgo, Broadcom, Conexant and Texas Instruments. The first draft was approved in March 2006 and draft 2.0 was approved in March 2007. Since the demands from the market are becoming higher, Wi-Fi Alliance decided to start to certifying IEEE 802.11n products based on the draft 2.0 in summer 2007. Now, these pre-n products are already in stores, such as routers and network cards for desktops or notebooks. The official approval of IEEE 802.11n standard had been delayed many times because TGnSync and WWiSE kept fighting for their own proposal to become the official standard. However, they finally agreed to propose a merged proposal to speed up the birth of official IEEE 802.11n standard. Therefore, the IEEE 802.11n standard may be finally approved in early 2008. [17] [65] [66] Actually, the ideal of these two groups have may be different, but the technologies are the same. TGnSync emphasizes on improving the peak data rate and WWiSE wants to ameliorate the MAC-layer. Both of them can reach the goal, or even much better than that. The common points are they both use MIMO-OFDM as the transmission function and support the bandwidth for both 20 MHz and 40 MHz. IEEE 802.11n PHY-layer is extended from IEEE 802.11a PHYlayer. So it is also an OFDM-based PHY-layer and just introduced MIMO technology to increase the speed. [17] [61]-[66] 34
3.4.2. MIMO (Multiple-Input/Multiple-Output) Usually, the IEEE 802.11 air-interface only transmits data with single antenna. Although some systems use two antennas, systems that only use the one have the best performance. Therefore, no matter how many antennas that systems has, there is only one used to transmit and receive data, and there is only one input chain and one output chain. The basic operation of MIMO is to distribute the RF chain to every system antenna and each RF chain can do simultaneous transmission and reception. This can enormously increase throughput. Moreover simultaneous receiver processing can solve multipath interference and improve the quality of the received signals. A frame can be split, multiplexed and then transmitted by more than one spatial stream. The antenna configuration of MIMO usually express as “YxZ “format. For example, in both TGnSync and WWiSE proposals require “2x2” operation, which means there are two transmit chains, two receiving chains and two spatial streams. That is mandatory mode in both proposals and there is optional mode included. [17] When setting up hardware, the BS and end users may have different numbers of antenna. For example, a BS has three and the end user has two. Usually BS has more antennas, because of saving power and cost for the end users. In this situation, 2x3 is for uplink and 3x2 is for downlink. Two spatial streams are distributed to three antennas. One spatial stream is transmitted by multiple antennas; this is called STBC (Space-Time Block Coding). This method is also used in IEEE 802.16 PHY-layer. [17] [61]-[66] 3.5. Limitation As the Internet goes into the wireless stage, internet access seems become more and more convenient. Wired Internet access, such as ADSL, can provide at least 100 Mbps data rate, and Wi-Fi, with the g standard, can achieve 54 Mbps, and it depends on the air-interface conditions however, if Wi-Fi wants to share the ADSL market, it still has a long way to go. Wi-Fi is strict to the operation environment and sensitive to channel fading, so reliability is a big issue. Since Wi- Fi is designed for small area not BWA, such as home or office, VoIP (Voice over IP), video service and a large file download are heavy duty for it. If a business building wants to install a wireless network for the whole building, every floor may need an individual AP (access point) or even more than one, depending on the location structure. This is because the signals suffer the short transmission range, channel fading and interference, therefore the installation cost and complexity will be high. The other problem of Wi-Fi is the market share. This is caused by fundamental infrastructure, completion rate users’ behavior patterns and technologies maturity. What is Wi- Fi’s market positioning? And who is the major customer group? The answers of these two questions are the key to the future of Wi-Fi. If Wi-Fi wants to take VoIP, for example, as the kill 35
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 and 42: Virtual channel sensing he other me
Page 43 and 44: SIFS (Short InterFrame Spacing) Fig
Page 45: Figure 3-20 WEP Frame and Operation
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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