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

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user. The awakened MS will send a PS-Poll frame to the base station to get the buffered frames. The base station can choose either immediate response or deferred response to the MS. [17][55] The immediate response means the BS (Base Station) will send the buffered frames to MS after SIFS interval. If the BS chooses a deferred response, it will send an ACK frame back to MS first, and then transmit data frames later. After sending the PS-Poll frame, the MS must stays awake until the whole process is over. The BS notifies the MS for buffered frames by sending a beacon frame. The buffered frames may be fragmented for transmission. [17][55] 3.3.2.7. Security This is a very important part for the whole MAC layer design. So far the most widely used security procedure for wireless communication is WEP (Wired Equivalent Privacy). WEP uses RC4 cipher to encrypt data. The RC4 cipher is a kind of symmetric stream cipher; it generates a keystream and then uses the XOR algorithm to mix with data to produce the ciphertext stream. The receiver will use the same XOR algorithm to recover original data. To encrypt the data, the secret key has to be chosen first and then extended to the same size of data by PRNG (Pseudorandom Number Generator). This extended secret key is called keystream. For recovering data, both transmitters and receivers must have the same secret key and PRNG, and how to distribute the secret key is an important issue; sometimes it may be preloaded by system designers or manufacturers. The other issue is “key to keystream expansion” of RC4 stream cipher, because the safety is dependent upon on how random it is. [17][55] The communication security has three major properties: confidentiality, integrity and authentication. Confidentiality is needed to protect data from being stolen by unauthorized people. Integrity is used to make sure the data has not been changed during transmission. This part is dependent on CRC code. Finally, authentication is the foundation of all security procedures. For transmitting data, the users must be trusted and the source must be reliable. Otherwise, authorization and access control will not be allowed. [17][55] RC4 shared secret key is composed by 40-bit shared secret and 24-bit IV (Initialization Vector) usually called 64-bit WEP and the other one is 128-bit WEP. When framing a frame, WEP will generate an ICV (Integrity Check Value) which is a hash value to combine with payload as an original data. This ICV can use to protect data from unauthorized changes. After entering the original payload, secret key and IV, WEP can generate an encrypted frame for transmission in either secure or not secure network. Figure 3-20[17] shows the frame structure and operation of WEP. Figure 3-21[55] shows the encryption process. [17][55] 32
Figure 3-20 WEP Frame and Operation Figure 3-21 The WEP Encryption Process However there is no perfect encryption in the world. There are some problems that exist in WEP; key management, reusing the keystream, and IV. WEP has been thought of as a very secure way to protect wireless communication. However, a study from University of California, Berkeley called ISAAC (Internet Security Applications, Authentication and Cryptography) showed the defects of WEP design [56]. Also a method for breaking WEP has already been published [57]. 33
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: SIFS (Short InterFrame Spacing) Fig
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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