Summary report of the January 1999
meeting of IEEE P802.11
Our January 1999 meeting was hosted by Harris Semiconductor
in Orlando, Florida, so that weather conditions had the least impact on
the conference and traveling members. Because our host was ready to organize
meetings for 3 other groups at the same time and at the same place, this
meeting became the summit of wireless standards-making bodies from all
over the world, with 240 people attending! The other groups besides the
Wireless Local Area Network group, IEEE P802.11, were:
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the Project for Broadband Radio Access Networks European
Telecommunications Standards Institute (ETSI/BRAN),
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the Study Group of IEEE Project 802 for Broadband Wireless
Access (N-WEST) and
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members from the Multimedia Mobile Access Communication Systems
Promotion Council (MMAC/PC) from Japan.
It was recommended by a number of attendees that this summit
become an annual event.
Work in the 5 GHz band
The Task Group working on the high data-rate extension in
the 5 GHz band, project 802.11a, was able to produce a new draft standard
that has the support of at least 80 % of the members. (75 % is required,
but the IEEE is looking for the highest level of consensus).
The group received a liaison letter from the MMAC/PC
Wireless Ethernet working group stating that they adopted the 802.11a draft
as well as the Medium Access Control (MAC) of 802.11 for their standards
making work.
In a series of joint meetings with the Physical Layer
working group of ETSI/BRAN, we made further agreements on the technical
details of the PHYs of both groups.. TGa’s chair presented a tutorial to
802.NWEST (broadband access in millimeter wave bands) Study Group to familiarize
them with our work and to suggest our physical layer as a candidate for
their work. We are looking at a candidate for worldwide standardization!
The draft 802.11a standard is based on Orthogonal Frequency
Division Multiplexing (OFDM) to modulate the data. OFDM enables the utilization
of wide band signals in an environment where reflected signals would otherwise
disable the receiver to recover the data from the received signal.
The specifications of the Physical Layer encompass data
rates from 6 Mbit/s up to 54 Mbit/s, with 20 MHz spacing between adjacent
channels. All implementations are required to support 6, 12 and 24 Mbit/s.
Optional extensions are for 9, 18, 36, 48 and 54Mbit/s. The range of data
rates is provided to match the wide range of radio channel characteristics
in both indoor and outdoor environments. The multirate mechanism of the
MAC protocol ensures that all devices communicate with each other at the
best data rate in the present channel.
The editor will implement the agreements which were reached
this week into Draft D2.1, which will be sent out for Working Group, Reconfirmation,
Letter Ballot.
Regulatory issues in the 5 GHz band
IEEE 802.11 decided to support a letter from ETSI/BRAN to
the European Spectrum Engineering group (CEPT WGSE) to ensure that the
Radio LAN devices would not harm co-existence with existing users in 650
MHz of the 5 GHz band. IEEE 802.11 also decided to join in sponsorship
of a letter prepared by ETSI/BRAN and MMAC-PC to the related Working Party
of the ITU-R to support lower restrictions in the 5.15-5.25 GHz band.
Work in the 2.45 GHz band
The Task Group working on the extension of the 1 and 2 Mbit/s
data rates in the 2.45 GHz band with 5.5 and 11 Mbit/s has reached a technical
compromise solution to improve the co-existence and interoperability characteristics
between options.
The modulation used is Complementary Code Keying (CCK).
CCK is the mandatory mode of operation for the (draft) standard, it is
derived from the Direct Sequence Spread Spectrum (DSSS) technology. The
multirate mechanism of the Medium Access Control (MAC) warrants that the
11 Mbit/s operation can switch back to 5.5 Mbit/s if the radio channel
is below the required value because of the distance between the stations
or because of interference. Stations that are even further could switch
back to the 2 and 1 Mbit/s capablities of the DSSS modultaion.
The compromise yielded the Frequency Agility option. In
this option the High Rate DSSS signal may hop in its entirely over the
2.45 GHz band in a predetermined manner. This option will ease the migration
of Frequency Hopping systems to the High Rate DSSS standard. Another option
is to use Packet Binary Convolutional
Coding (PBCC).
The editor for
this project will make a new draft (D2.last) which will contain the agreements
reached this week and send the draft out for a Working Group, Reconfirmation,
Ballot. So far the new draft is supported by 81 % of the members.
Regulatory issues in the 2.45 GHz band
The FCC has sent
out a Proposed Rule Making (Docket No. 98-42) proposing to allow lighting
devices in the 2.45 GHz band which employ magnetrons as sources of RF energy
to excite the light emitting material. The part 15 industry has objected
towards the unrestricted levels of in-band emissions from those devices.
Under the auspices of the FCC, the part 15 industry and lighting industry
has come up with a proposed limit. IEEE 802.11 has prepared a draft letter
to the FCC with comments on that proposed limit and the definition of the
measurement method. The draft letter is up for approval by the IEEE 802
Executive Committee and the IEEE-USA Activity Board for Technology Policies.
Wireless Personal Area Networks
The WG letter ballot on the Project Authorization Request
(PAR) and 5 Criteria, as proposed by the Study Group on Wireless Personal
Area Networks (WPAN) resulted in an 81 percent approval. The balloted version
will be sent to the IEEE 802 community for review and approval at the March
99 meeting. Resolution of comments into new drafts of the PAR and 5 Criteria
will be sent out for reconfirmation ballot to be reviewed at the March
meeting.
The Study Group has recommended that the work be done
in an 802.11 Task Group, provided the rules of 802 provide for the possibility
of a difference in MAC. If that would not be true, it recommends to become
a Working Group under 802. The 802.11 Working Group did not have any objection
to host a tutorial from the Bluetooth industry consortium they would request
the chair to do so.
Revision of IEEE Std.
802.11-1997
Although not discussed at the January meeting, the revision
of the standard will be submitted to the Standards Board for approval at
their March meeting.
Invitation for
joining Sponsor Ballot Groups
With both projects 802.11a and 802.11b at over 80 % approval,
the chair will ask the IEEE Sponsor Ballot Service to send out invitations
to join the related Sponsor Ballot Groups.