November 2006
IEEE P802.19-06/0036r2
IEEE P802.19
Wireless Coexistence
Project
IEEE P802.19 Coexistence TAG
Title
Coexistence Scenario for Dynamic Frequency Selection (DFS)
Date
Submitted
[November 12, 2006]
Source
[Stephen J. Shellhammer]
[Qualcomm, Inc.]
[5775 Morehouse Drive]
[San Diego, CA 92121]
Re:
[]
Abstract
[Text describing the DFS coexistence scenario]
Purpose
[]
Notice
This document has been prepared to assist the IEEE P802.19. It is offered as a
basis for discussion and is not binding on the contributing individual(s) or
organization(s). The material in this document is subject to change in form and
content after further study. The contributor(s) reserve(s) the right to add, amend or
withdraw material contained herein.
Release
The contributor acknowledges and accepts that this contribution becomes the
property of IEEE and may be made publicly available by P802.19.
Submission
Voice:
Fax:
E-mail:
Page 1
[(858) 658-1874]
[(858) 651-3004]
[shellhammer@ieee.org]
Steve Shellhammer, Qualcomm, Inc.
November 2006
IEEE P802.19-06/0036r2
1 Dynamic Frequency Selection (DFS) Coexistence Scenario
The DFS coexistence scenario consists of a primary wireless system operating in one or
more of the channels within a frequency band and a secondary wireless system that dynamically
selects it channel of operation so as to avoid causing harmful interference to the primary wireless
system.
2 Definitions
Dynamic frequency selection: A method, used by a secondary system, of selecting the
channel(s) of operation so as to avoid causing harmful interference to the primary wireless
system.
NOTE: The TAG should review the definition of DFS and compare to the definition in 11h.
Primary wireless system: A wireless system operating in one of more of the channels within the
frequency band of operation. The primary system may have higher precedence in the frequency
band than the secondary system, based on regulatory rules.
Secondary wireless system: A wireless system operating in one or more of the channels with the
frequency band of operation. The secondary system uses dynamic frequency selection (DFS) to
select it channel(s) of operation so as to avoid causing harmful interference to the primary
system.
3 Abbreviations and Acronyms
DFS
Submission
Dynamic frequency selection
Page 2
Steve Shellhammer, Qualcomm, Inc.
November 2006
IEEE P802.19-06/0036r2
4 Frequency Band for the DFS Coexistence Scenario
The frequency band in use by both the primary and secondary wireless system is show in
Figure 1. We see that the frequency band has been subdivided into N channels. Each of these N
channels could possibly be occupied by a primary wireless system. The DFS-enabled secondary
wireless system avoids use of any channel whose use would cause harmful interference to the
primary wireless system.
Channel 1
Channel 2
Channel 3
...
Channel N
Figure 1: Frequency band of operation
5 Various DFS Coexistence Scenarios
There are several types of DFS coexistence scenarios based on the type of primary
wireless system. The geometry of these various DFS coexistence scenarios are given in this
section.
5.1 DFS Coexistence Scenario 1
Figure 2 illustrates the geometry of the DFS coexistence scenario 1 in which the primary
transmitter and receiver are collocated at the same physical location. We see that the secondary
wireless network is operated a distance from the primary transmitter/receiver. If the distance is
too small then the secondary wireless system can cause harmful interference to the primary
receiver which in this case is collocated with the licensed transmitter. This DFS coexistence
scenario is indicative of the DFS radar coexistence scenario.
Submission
Page 3
Steve Shellhammer, Qualcomm, Inc.
November 2006
IEEE P802.19-06/0036r2
Secondary Wireless
System
Primary TX/RX
Figure 2: Geometry of DFS Coexistence Scenario 1
5.2 DFS Coexistence Scenario 2
Figure 3 illustrates the geometry of DFS coexistence scenario 2 in which the primary
receivers are not collocated with the primary transmitter. In this case the primary receivers are
typically distributed around the licensed transmitter within a region of operation. The secondary
wireless system must be a distance from the primary receivers if it is to operate on the same
channel as the primary transmitter. DFS coexistence scenario 2 is indicative of the case of
unlicensed operation in the unused TV channels.
Submission
Page 4
Steve Shellhammer, Qualcomm, Inc.
November 2006
IEEE P802.19-06/0036r2
Primary RX
Primary RX
Primary TX
Secondary
Wireless System
Primary RX
Primary RX
Figure 3: Geometry of DFS Coexistence Scenario 2
5.3 DFS Coexistence Scenario 3
Figure X illustrates the geometry of DFS coexistence scenario 3 in which each of the
primary stations includes both a transmitter and a receiver. DFS coexistence scenario 3 applies
when the primary wireless is frequency static wireless network (possibly unlicensed) and the
secondary is a DFS-enabled wireless network which uses DFS to select the best frequency of
operation. In this case the primary and secondary wireless systems may both be unlicensed and
have equivalent regulatory status.
Submission
Page 5
Steve Shellhammer, Qualcomm, Inc.
November 2006
IEEE P802.19-06/0036r2
Primary TX/RX
Primary TX/RX
Primary TX/RX
Secondary
Wireless System
Primary TX/RX
Primary TX/RX
Figure 4: Geometry of DFS Coexistence Scenario 3
6 DFS Spectrum Sensing
In dynamic frequency selection the secondary wireless system scans the N channels to
identify which channels are occupied by a primary wireless system and which are unoccupied by
a primary wireless system. This scanning of the frequency band is often referred to as spectrum
sensing.
Submission
Page 6
Steve Shellhammer, Qualcomm, Inc.