ARIB, MMAC and the Tokyo IEEE section had taken the opportunity of our presence to organize a Wireless LAN Seminar, including an exhibition. The event drew some 500 people! On Friday the exhibition included 13 exhibiters, ranging from the current 802.11 devices to various high data rate devices in the 2.4 GHz band and prototypes for high data rate equipment in the 5, 6 and 19 GHz bands.
On the Friday afternoon, a half-day Wireless LAN seminar was held after
the closing plenary meeting of 802.11. 5 Papers were presented by respectively
MMAC, 802.11 chair, 802.11a chair, 802.11b chair and the interim 802.15
Representatives from BRAN and from MMAC contributed comments and participated
in discussions. The structure of the packet preamble and its parameters
were a hot discussion item. The changes to the 802.11a Draft were relatively
minor. At the end of the meeting a liaison statement was issued to BRAN
and MMAC-PC, acknowledging their contributions and updating them on the
March and May changes in the draft standard.
The draft 802.11a standard is based on Orthogonal Frequency Division Multiplexing (OFDM) to modulate the data. The main benefit OFDM modulation is its robustness to multipath echoes, which are typical to the indoor and mobile environments. Each OFDM symbol is composed of 52 subcarriers, of which 48 carry data and 4 subcarriers serve as phase reference pilots. 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.
As of May 7, 1999 92% of the ballots had been submitted . Out of these ballots the approval percentage is 89% with 8% of the sponsor ballot members abstaining. The editor already produced Draft 5.3. In June, after the decision of the May 28, 1999 meeting, the final outcome will be posted and submitted to Sponsor Recirculation Ballot.
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 away could switch back to the 2 and 1 Mbit/s
capablities of the DSSS modultaion.
The task group discussed its proposed work and believes that “super domains” can be defined that will cover several political/geographic domains. The desire of the people attending this meeting is to ultimately have only a single regulatory domain that will allow operation of 802.11 equipment on every square metre of planet Earth. To achieve this goal, the task group solicits submissions for the July meeting from interested individuals, proposing new regulatory domains and methods for achieving the aggregation into super domains.