ETSI TR 102 651 V1.1.1 (2009-06)

Broadband Radio Access Networks (BRAN); 5 GHz high performance RLAN; Guide to the implementation of Dynamic Frequency Selection (DFS)

DTR/BRAN-00200015

General Information

• Status: Published
• Publication Date: 11-Jun-2009
• Technical Committee: BRAN - Broadband Radio Access Networks
• Current Stage: 12 - Completion
• Due Date: 28-May-2009
• Completion Date: 12-Jun-2009

Standards Content (Sample)

ETSI TR 102 651 V1.1.1 (2009-06)
Technical Report


Broadband Radio Access Networks (BRAN);
5 GHz high performance RLAN;
Guide to the implementation of
Dynamic Frequency Selection (DFS)

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2 ETSI TR 102 651 V1.1.1 (2009-06)



Reference
DTR/BRAN-00200015
Keywords
access, broadband, radio, testing
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© European Telecommunications Standards Institute 2009.
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3 ETSI TR 102 651 V1.1.1 (2009-06)
Contents
Intellectual Property Rights . 5
Foreword . 5
1 Scope . 6
2 References . 6
2.1 Normative references . 6
2.2 Informative references . 6
3 Definitions, symbols and abbreviations . 8
3.1 Definitions . 8
3.2 Symbols . 8
3.3 Abbreviations . 8
4 Purpose of the present document . 9
5 The importance of Spectrum Sharing . 9
6 A short history of "DFS" . 9
6.1 Europe Spawns the Idea . 9
6.2 ITU-R Recommendation M.1652 . 10
6.3 WRC-03 - ITU-R Resolution 229 . 10
6.4 DFS developments outside Europe: the example of the US . 10
7 Regulatory Requirements . 11
7.1 Europe . 11
7.1.1 Regulation . 11
7.1.1.1 ECC Decision . 11
7.1.1.2 EC Decision . 11
7.1.2 R&TTE Directive (Radio & Terminal Telecommunications Equipment Directive) . 11
7.1.3 Harmonized Standard EN 301 893 . 12
7.2 US . 12
7.2.1 Regulation . 12
7.2.2 FCC Part 15.407 . 12
7.3 Other countries . 13
8 Types of Radars . 13
8.1 Maritime radars . 13
8.2 Meteorological radars . 13
8.3 Military radars . 13
9 RLAN Interference into Radar systems . 14
9.1 Introduction . 14
10 Radar Detection and Response - DFS Requirements . 15
10.1 Introduction . 15
10.2 Radar Recognition Requirements . 16
10.3 Radar detection considerations . 17
10.3.1 Radar pulse properties and Detection Thresholds . 17
10.3.2 Scan patterns . 18
10.3.3 Pulse patterns . 18
10.3.4 Radar Pulse Repetition Frequency (PRF) . 18
10.3.4.1 Interleaved/Staggered PRF - Single Pulse based. . 19
10.3.4.2 Interleaved/Staggered PRF - Packet based. . 19
10.3.5 Fixed Frequency versus Frequency Hopping . 19
10.3.6 Radar RF bandwidth . 20
11 DFS Efficiency . 21
11.1 Receiver performance . 21
11.2 Channel bandwidth considerations . 21
11.3 Traffic patterns . 21
ETSI

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4 ETSI TR 102 651 V1.1.1 (2009-06)
11.4 Channel Occupancy . 21
12 DFS implementation in different RLAN configurations . 22
12.1 Access Point (master) with Clients (slaves) . 22
12.2 Point to Point Links . 22
12.3 Point to Multipoint Links and mesh networks . 22
History . 23

ETSI

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5 ETSI TR 102 651 V1.1.1 (2009-06)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Report (TR) has been produced by ETSI Technical Committee Broadband Radio Access Networks
(BRAN).
The basis for this work was a document submitted by the Wi-Fi Alliance Regulatory Task Group as an Associate
Member of ETSI. The initial goal of this coordination was to advance global 5 GHz spectrum access through
harmonization of RLAN regulations.
ETSI

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6 ETSI TR 102 651 V1.1.1 (2009-06)
1 Scope
Due to the scarcity of radio frequency spectrum, many radio systems have to share spectrum with other radio
systems - in one form or another; 5 GHz Wireless Access Systems including Radio Local Area Networks
(WAS/RLANs), also known as Wireless LANs, radio LANs, or RLANs, are no exception. Wireless LANs are allowed
to operate in the 5 GHz bands which are also used by many radar systems.
The present document is intended to help the designers of Wireless LANs that operate in the 5 GHz frequencies
understand the requirements for radar detection and avoidance. The performance requirements of such a mechanism,
also known as DFS or Dynamic Frequency Selection, is further described in EN 301 893.
NOTE: It is advised to download the latest version of EN 301 893.
The present document deals only with the regulatory requirements and the philosophy under which they were issued. It
does not provide design rules or example implementations. By avoiding such "blueprint" material, innovation among
Wireless LAN designers is maintained and encouraged.
2 References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
• For a specific reference, subsequent revisions do not apply.
• Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
- if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
- for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
NOTE: While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
2.1 Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
Not applicable.
2.2 Informative references
The following referenced documents are not essential to the use of the present document but they assist the user with
regard to a particular subject area. For non-specific references, the latest version of the referenced document (including
any amendments) applies.
[i.1] Directive 1999/5/EC of the European Parliament and of the Council of 9 March 1999 on radio
equipment and telecommunications terminal equipment and the mutual recognition of their
conformity (R&TTE Directive).
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7 ETSI TR 102 651 V1.1.1 (2009-06)
[i.2] ETSI EN 301 893 (V1.2.3): "Broadband Radio Access Networks (BRAN); 5 GHz high
performance RLAN; Harmonized EN covering essential requirements of article 3.2 of the R&TTE
Directive".
[i.3] ETSI EN 301 893 (V1.3.1): "Broadband Radio Access Networks (BRAN); 5 GHz high
performance RLAN; Harmonized EN covering essential requirements of article 3.2 of the R&TTE
Directive".
[i.4] ETSI EN 301 893 (V1.4.1): "Broadband Radio Access Networks (BRAN); 5 GHz high
performance RLAN; Harmonized EN covering essential requirements of article 3.2 of the R&TTE
Directive".
[i.5] ETSI EN 301 893 (V1.5.1): "Broadband Radio Access Networks (BRAN); 5 GHz high
performance RLAN; Harmonized EN covering essential requirements of article 3.2 of the R&TTE
Directive".
[i.6] ETSI TR 102 439 (V1.1.1): "Broadband Radio Access Networks (BRAN); Test Report Template
for testing to EN 301 893 (V1.3.1) (R&TTE)".
[i.7] ETSI TS 101 475 (V1.3.1): "Broadband Radio Access Networks (BRAN); HIPERLAN Type 2;
Physical (PHY) layer".
[i.8] ITU-R Recommendation M.1652: "Dynamic frequency selection (DFS) in wireless access systems
including radio local area networks for the purpose of protecting the radiodetermination service in
the 5 GHz band".
[i.9] ITU-R Recommendation M.1638: "Characteristics of and protection criteria for sharing studies for
radiolocation, aeronautical radionavigation and meteorological radars operating in the frequency
bands between 5 250 and 5 850 MHz".
[i.10] ERC Decision (99)23 of 29 November 1999 on the harmonised frequency bands to be designated
for the introduction of High Performance Radio Local Area Networks (HIPERLANs).
[i.11] ECC Decision(04)08 of 9 July 2004 on the harmonised use of the 5 GHz frequency bands for the
implementation of Wireless Access Systems including Radio Local Area Networks
(WAS/RLANs).
[i.12] ITU-R Resolution 229: "Use of the bands 5 150-5 250 MHz, 5 250-5 350 MHz and
5 470-5 725 MHz by the mobile service for the implementation of wireless access systems
including radio local area networks".
[i.13] Memorandum Opinion and Order FCC 06-96: "Revision of Parts 2 and 15 of the Commission's
Rules to Permit Unlicensed National Information Infrastructure (U-NII) devices in the 5 GHz
band".
[i.14] Report and Order FCC 03-287: "In the matter of Revision of Parts 2 and 15 of the Commission's
Rules to Permit Unlicensed National Information Infrastructure (U-NII) devices in the 5 GHz
band".
[i.15] Commission Decision 2005/513/EC of 11 July 2005 on the harmonised use of radio spectrum in
the 5 GHz frequency band for the implementation of wireless access systems including radio local
area networks (WAS/RLANs).
[i.16] Commission Decision 2007/90/EC of 12 February 2007 amending Decision 2005/513/EC on the
harmonised use of radio spectrum in the 5 GHz frequency band for the implementation of Wireless
Access Systems including Radio Local Area Networks (WAS/RLANs).
[i.17] ITU-R Report M.2115: "Testing procedures for implementation of dynamic frequency selection".
[i.18] NPRM FCC 03-110: "In the Matter of Revision of Parts 2 and 15 of the Commission's Rules to
Permit Unlicensed National Information Infrastructure (U NII) devices in the 5 GHz band".
[i.19] FCC Part 15.407: "Chapter I - Federal Communications Commission; Part 15 - Radio Frequency
Devices - General technical requirements".
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8 ETSI TR 102 651 V1.1.1 (2009-06)
[i.20] IEEE 802.11: "IEEE Standard for Information Technology - Telecommunications and information
exchange between systems - Local and Metropolitan networks - Specific requirements - Part 11:
Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications".
[i.21] IEEE 802.11a-1999 [ISO/IEC 8802-11:1999/Amd 1:2000(E)] (Supplement to IEEE Std 802.11,
1999 Edition): "Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer
(PHY) specifications: High-speed Physical Layer in the 5 GHz Band".
3 Definitions, symbols and abbreviations
3.1 Definitions
For the purpose of the present document, the terms and definitions given in EN 301 893 and the following apply:
HIPERLAN 2: High Performance Radio Local Area Network type 2 as described in e.g. TS 101 475 [i.7]
3.2 Symbols
For the purposes of the present document, the following symbols apply:
dBi antenna gain in decibels relative to an isotropic antenna
dBm dB relative to 1 milliwatt
GHz GigaHertz
Hz Hertz
kHz kiloHertz
MHz MegaHertz
3.3 Abbreviations
For the purposes of the present document, the abbreviations given in EN 301 893 and the following apply:
DFS Dynamic Frequency Selection
EIRP Equivalent Isotropically Radiated Power
FCC Federal Communications Commission
FH Frequency Hopping
HIPERLAN High Performance Radio Local Area Network
ITU International Telecommunications Union
LAN Local Area Network
MIMO Multiple-Input and Multiple-Output
NTIA National Telecommunications and Information Administration
pps pulses per second
PRF Pulse Repetition Frequency
R&TTE Radio and Telecommunications Terminal Equipment
RADAR RAdio Detection And Ranging
RF Radio Frequency
RLAN Radio Local Area Network
TCAM Telecommunication Conformity Assessment and Market surveillance committee
TPC Transmitter Power Control
WAS Wireless Access System
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9 ETSI TR 102 651 V1.1.1 (2009-06)
4 Purpose of the present document
DFS is a sharing mechanism that will allow wireless LANs to share the 5 GHz frequency spectrum with various radar
systems. DFS assures that the wireless LANs do not cause interference to the radar systems. EN 301 893, which is
based on ITU-R Recommendation M.1652 [i.8] on DFS characteristics and parameters, provides detection threshold
criteria and test patterns for DFS implementation. A DFS design that is able to meet all the test criteria may not
necessarily detect all of the various radars in the real world.
The interaction between radar systems and wireless LANs is complex and the variation in radar characteristics is
considerable. In order for DFS to be effective, it should be designed with a good understanding of these complexities
and variations. The present document aims to facilitate that understanding and to help, indirectly assure that DFS
designs meet their main purpose: effective detection and avoidance of co-channel operation with radar systems.
5 The importance of Spectrum Sharing
Spectrum sharing is rapidly becoming the solution to the increasing demands for bandwidth of many different
applications. In the case of wireless LANs, the initial air interfaces used licence exempt spectrum (often called
unlicensed spectrum) in the 915 MHz (US only) and 2,4 GHz bands, in which various kinds of low power radio and
non-radio devices are allowed to operate, including industrial, scientific and medical systems.
As wireless LANs developed into a major communications technology, the market demand for more spectrum became
apparent. Regulators world-wide stepped up to that challenge and after a long period of preparation, agreed to allow
wireless LANs to operate in the 5 GHz band.
This is only one example of how demand for spectrum was met by allowing two different systems, RLANs and radar
systems, to share a given frequency range.
Essential to the success of sharing spectrum now and in the future is that the deployed systems meet the necessary
technical requirements for sharing. These requirements include the detection of other primary spectrum users and
avoiding interference to them. Establishing the sharing criteria may be a technically complex and involved process, but
it is of the utmost importance that technical experts developing such techniques are aware of the wider issues of sharing
and communicate well with spectrum managers and incumbents.
Failure of the sharing regime in a given band has potentially severe ramifications. Depending on the regulatory regime,
national administrations may take appropriate measures to withdraw non-compliant equipment from the market or from
service, prohibit its placing on the market or putting into service or restrict its free movement.
With the above in mind, it will be clear that, to secure access to shared spectrum for future technologies and
applications, the DFS based sharing regime developed for the 5 GHz band has to succeed. Its success depends primarily
on the effectiveness of the DFS implementations in products that are brought to market. The present document is
intended to help designers of DFS based equipment, to achieve that objective.
6 A short history of "DFS"
6.1 Europe Spawns the Idea
In 1999, the CEPT published ERC Decision (99)23 [i.10] on the harmonized frequency bands to be designated for the
introduction of High Performance Radio Local Area Networks (HIPERLANs). In total 455 MHz of spectrum was
allocated in Europe to these Hiperlans under more or less similar conditions (power levels, DFS, TPC), and this was
later adopted as the basis for a global allocation at WRC-03. Devices operating in the band 5 150 MHz to 5 350 MHz
were restricted to indoor use only and were limited to 200 mW EIRP. Outdoor operation was limited to 5 470 MHz to
5 725 MHz but they could use power levels up to 1 W EIRP. DFS and TPC were required when operating in
5 250 MHz to 5 350 MHz or 5 470 MHz to 5 725 MHz.
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10 ETSI TR 102 651 V1.1.1 (2009-06)
In the mean time ETSI had started the development of a Harmonized Standard that included the first DFS conformance
specification ever developed. Initially, a standard was drafted specifically for HIPERLAN 2. That approach was
changed in light of the success of the IEEE 802.11 [i.20] technologies and finally, in June 2003, ETSI sent the first
version of the technology neutral harmonized standard, EN 301 893 [i.2], into national voting just prior to the start of
the WRC-03.
6.2 ITU-R Recommendation M.1652
ITU-R Recommendation M.1652 [i.8] states that DFS is recommended in the 5 250 MHz to 5 350 MHz and 5 470 MHz
to 5 725 MHz bands in order to eliminate potential RLAN interference to the radar systems. This mechanism is
assumed to detect radar and to ensure that wireless LANs do not operate on those channels on which radars are
operating.
This recommendation specifies the DFS detection and performance requirements but does not specify how DFS is to be
implemented. However, it does define test procedures for validating DFS detection and performance.
6.3 WRC-03 - ITU-R Resolution 229
In 2003, after a preparation of many years, the International Telecommunications Union (ITU), at its World Radio
Conference 2003 (WRC-03), agreed on a new frequency allocation on a co-primary basis to the mobile service for the
implementation of wireless access systems including radio local area networks (WAS/RLANs) systems noting however
that in the bands 5 250 MHz to 5 350 MHz and 5 470 MHz to 5 725 MHz, stations in the mobile service shall not claim
protection from radiodetermination services. This was subject to technical and regulatory provisions included in the
radio regulations, given in Resolution 229 [i.12] (WRC-03) that makes the Annex 1 of ITU-R
Recommendation M.1652 [i.8] mandatory. This includes specific provisions to protect the incumbent systems;
including military and weather radars.
6.4 DFS developments outside Europe: the example of the US
In 2000, as the RLAN industry in the US was preparing to enter the 5 GHz spectrum market with products designed to
the IEEE 802.11a [i.21] standard, manufacturers with worldwide distribution were concerned that Europe would restrict
this band to HIPERLAN (High Performance Radio LAN) products as specified in ERC Decision (99)23 [i.10].
HIPERLAN was a specific RLAN technology developed by ETSI. The ERC Decision (99)23 [i.10] mandated two
mechanisms to protect radars and other primary users of this band: DFS (Dynamic Frequency Selection) and TPC
(Transmit Power Control). As a result, a project, P802.11 TGh, was started to add these mechanisms in the
IEEE 802.11 [i.20] standard, with the assumption that if these additional regulatory requirements were met, global
adoption of IEEE 802.11a-1999 [i.21] would be possible.
At that time the 5 GHz band for RLANs in the US was restricted to the 5 150 MHz to 5 250 MHz, 5 250 MHz to
5 350 MHz and 5 725 MHz to 5 825 MHz bands, but planning was already in the works for the 2003 meeting of the
World Radiocommunication Conference, to add the 5 470 MHz to 5 725 MHz band. This made DFS even more
important for the US market. Over the course of the next three years, the FCC, with the help of the wireless LAN
industry and the NTIA, developed the DFS rules for the US.
The spectrum used within US Federal agencies is administered by an Executive Branch organization known as the
NTIA (National Telecommunications and Information Administration). Spectrum allocated for use by US commercial
and private citizens is administered by the FCC (Federal Communications Commission).
When considering opening the 5 GHz band for use by wireless LANs, the NTIA expressed a strong desire that products
entering the new band would adequately protect US military radars. This requirement was the basis of the US position
at the WRC-03 which developed the first DFS requirements document - ITU-R Recommendation M.1652 [i.8].
During the period 2003 to 2006, the FCC with the help of the wireless LAN industry and the NTIA, developed the DFS
rules for the US.
Since ETSI BRAN developed the first 5 GHz Harmonized Standard (EN 301 893 (V1.2.3) [i.2]) in 2003, the DFS test
specification included in this standard became the basis for the development of the FCC DFS test specification and
other test specifications in other countries.
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11 ETSI TR 102 651 V1.1.1 (2009-06)
In the US, the FCC, NTIA and the wireless LAN industry collaborated to develop an extended set of DFS equipment
test specifications that would ensure compliant equipment would provide protection of radar systems not previously
addressed by the ITU-R Recommendation M.1652 [i.8]. The new requirements and the related radio certification
process were released in July of 2006 (FCC-06-96 [i.1
...