Wireless Access Point
Installing the Wireless AP
47
Higher Precision in the Physical Layer
Wi-Fi utilizes several digital modulation techniques and automatically switches
between them to optimize for throughput or range. The basic unit of data
transmitted is called a symbol. The number of points in the modulation
constellation determines the number of bits of data conveyed with each symbol.
Figure 21. Physical Layer Data Encoding
802.11n uses 16 Quadrature Amplitude Modulation (QAM), which conveys
log2(16) = 4 bits per symbol and 64 QAM, which conveys 6 bits per symbol.
802.11ac adds 256 QAM which conveys 8 bits per symbol for a 33% increase in
throughput vs. the highest 802.11n data rate.
You may select the highest Modulation and Coding Scheme (MCS) level allowed
with
1
,
2
, or
3 Spatial Streams (
see the
Max MCS
setting in
Configuring Global 802.11ac IAP Settings” on page 350
). You may limit the
highest level of modulation to 64-QAM, or allow 256-QAM. It also determines the
coding scheme used for error correction. Higher MCS levels allocate fewer bits to
error correction, and thus more bits are used for data. The default value is
MCS9
,
the highest level.
256-QAM
I
Q
64-QAM
Q
+1
-1
+1
+3
+5
+7
-3
-5
-7
+3
+5
+7
I
-7
-5
-3
-1
I
Q
Phase˚
Amplitude
Summary of Contents for XR Series
Page 1: ...August 11 2015 Release 7 5 Wireless Access Point User s Guide ...
Page 2: ......
Page 17: ...Wireless Access Point xiii Glossary of Terms 607 Index 619 ...
Page 18: ...Wireless Access Point xiv ...
Page 26: ...Wireless Access Point xxii List of Figures ...
Page 54: ...Wireless Access Point 28 Introduction ...
Page 120: ...Wireless Access Point 94 The Web Management Interface ...
Page 186: ...Wireless Access Point 160 Viewing Status on the Wireless AP ...
Page 434: ...Wireless Access Point 408 Configuring the Wireless AP ...
Page 535: ...Wireless Access Point Appendices 509 Appendices ...
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Page 544: ...Wireless Access Point 518 ...
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Page 601: ...Wireless Access Point 575 Declaration of Conformity Brazil XR 1000 XR 2000 XR 4000 ...
Page 612: ...Wireless Access Point 586 ...
Page 624: ...Wireless Access Point 598 ...
Page 660: ...Wireless Access Point 634 Index ...
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