Voice Over 802.11

Frank Ohrtman9781580536776, 1-58053-677-8

Wi-Fi can further enhance your organization’s productivity and savings by increasing portability and eliminating charges for PBX maintenance and for wire-line and cellular phone service. However, concerns about the QoS of Wi-Fi and VoIP prevent many organizations from realizing the full savings and productivity improvements that Wi-Fi can deliver. This guide to deploying Wi-Fi telephony helps you overcome these concerns by showing in detail how to engineer each component of Wi-Fi for reliable, high- quality voice transmission. This informative reference reveals how Voice over Wi-Fi is a scalable, secure networking solution that supports today’s demanding application needs. The book explains the ins and outs of the 802.11 standard, Softswitch architecture and applications, and related transport network technology so you can deploy full-featured Wi-Fi that has optimum range and signaling. You also learn the economics of 802.11 and Softswitch so you can measure the cost savings and return on investment of deploying Wi-Fi.

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Table of contents :
Team DDU……Page 1
Contents……Page 8
Access……Page 17
Transport……Page 18
Vo802.11: Bypassing the Local Loop……Page 19
Reference……Page 20
How Does WiFi Work?……Page 21
How Data Is Transmitted Via Wireless Technology……Page 22
802.11 Variants……Page 24
FHSS (802.11a)……Page 25
Orthogonal Frequency-Division Multiplexing……Page 27
MAC Layer Services……Page 29
MAC Layer Architecture……Page 30
MIB……Page 33
PCF……Page 34
IEEE 802.11 Architecture……Page 35
IEEE 802.11 Components……Page 37
Mobility……Page 38
Conclusion……Page 39
References……Page 40
Origins……Page 41
How Does VoIP Work?……Page 42
Protocols Related to VoIP……Page 43
H.323……Page 44
SIP……Page 45
SIP Architecture……Page 46
Interworking with Other Multimedia Networks……Page 52
H.323 Zone……Page 53
Gateway Control Protocols……Page 54
Media Gateway Control Protocol……Page 55
SS7-Related Protocols……Page 56
OSPF……Page 57
BGP……Page 58
Resource Reservation Protocol……Page 60
RTP……Page 61
Internet Protocol Version 6……Page 62
References……Page 63
Multiplexing……Page 65
Voice Digitization……Page 66
Signaling……Page 71
Transport……Page 74
Softswitch and Distributed Architecture: A “Stupid” Network……Page 75
IP Phones (IP Handsets) Phone-to-Phone VoIP……Page 77
Switching in IP Networks……Page 82
Applications for Softswitch……Page 85
Conclusion……Page 90
References……Page 91
QoS……Page 93
Range……Page 94
Signaling……Page 95
Conclusion……Page 96
References……Page 97
6 Vo802.11: Range Is a Matter of Engineering……Page 99
Antennas……Page 100
Factors Affecting Range……Page 101
Amplifiers……Page 102
Architecture: The Large Network Solution……Page 103
MANs……Page 104
Extending Range Via an Ad Hoc Peer-to-Peer Network……Page 107
Conclusion: Range Is Not an Issue……Page 110
References……Page 112
7 Security and Vo802.11……Page 113
WEP……Page 114
WLAN Security Model……Page 116
Interception……Page 117
Fabrication……Page 120
Modification……Page 122
Replay……Page 124
Denial of Service Attacks……Page 125
Network Architecture……Page 127
Security Policy: A Range of Options……Page 129
Wi-Fi Protected Access……Page 130
802.1x and EAP Advanced Security……Page 131
802.1x Network Port Authentication……Page 132
EAP……Page 133
VPNs……Page 136
SSL……Page 138
Kerberos……Page 139
Conclusion……Page 141
References……Page 142
8 Objections Due to Interference and QoS on Vo802.11 Wireless Networks……Page 145
Interference……Page 146
External Sources of Interference……Page 147
Internal Sources of Interference……Page 151
Line of Sight, Near Line of Sight, and Nonline of Sight……Page 154
Fresnel Zone and Line-of-Sight Considerations……Page 155
Importance of QoS on 802.11 Networks……Page 156
Latency in Wireless Networks……Page 157
Legacy 802.11 MAC……Page 159
DCF……Page 160
PCF……Page 164
References……Page 169
QoS on Vo802.11 Networks……Page 171
Measuring Voice Quality in Vo802.11……Page 172
Detractors to Voice Quality in Vo802.11 Networks……Page 173
Improving QoS in IP Routers and Gateways……Page 176
Measures for Delivering Optimal QoS on Vo802.11 Networks……Page 177
Voice Codecs Designed for Vo802.11 Networks……Page 183
References……Page 186
Bandwidth Considerations for Wireless VoIP……Page 187
Importance of Bandwidth to Scalability……Page 188
802.11g……Page 189
Receiving Antenna Gain……Page 190
Frequency Reuse Planning for Vo802.11 Networks……Page 191
Frequency Reuse at 5 GHz……Page 192
Frequency Allocation……Page 194
Point-to-Point Links……Page 195
Limitations in the AP……Page 196
Scalability in VoIP Switching……Page 197
References……Page 198
Understanding Reliability……Page 199
How Availability Is Calculated……Page 200
Redundancy in Vo802.11 Networks……Page 202
Achieving the “Five 9s” with a Vo802.11 Softswitch……Page 203
Power Availability……Page 206
References……Page 208
12 Vo802.11 Features and Applications……Page 209
Features and Signaling……Page 210
SCE……Page 211
APIs and Services……Page 212
SIP: Architecture for Enhanced Services in Softswitched Vo802.11 Networks……Page 213
Application Servers……Page 214
Interface Between Call Control and Application Server……Page 215
Application Server Interactions……Page 216
E911……Page 217
CALEA……Page 218
The Big “So What!?” of Enhanced Features in Vo802.11 Networks……Page 219
Conclusion……Page 220
References……Page 221
Current Regulatory Environment for 802.11……Page 223
Power Limits……Page 224
Interference……Page 225
Regulatory Issues Concerning VoIP……Page 230
Conclusion……Page 231
References……Page 232
Medical……Page 233
Education……Page 235
Financial Services……Page 237
WISPs……Page 238
Vo802.11 Telephone System Cost Justification in the Workplace……Page 239
MAC……Page 240
Saving Time and Money in Health Care……Page 241
Supervisor Time Savings……Page 242
Efficiencies in Maintenance of the Production Line……Page 243
Enterprise Conclusion……Page 244
Considerations in Bypassing the PSTN with Vo802.11……Page 245
Conclusion……Page 246
References……Page 247
FCC New Spectrum Policy……Page 249
Problem Areas in Spectrum Management and Their Solutions……Page 250
Disruptive Technology……Page 256
Simpler……Page 257
More Convenient to Use……Page 258
Deconstruction of Service Providers……Page 259
Goetterdaemmerung or Creative Destruction in the Telecommunications Industry……Page 260
References……Page 261
About the Author……Page 263
Index……Page 265