User's Manual

4-2
Functional Overview
The WLAN PC Card is designed to operate in the 2.4GHz ISM
frequency band, channels 1 to 11, as specified by the FCC in
the USA. The Card will also operate on channels 12 through
14, where permitted by local regulatory authorities. Radio
equipment must be certified in a country prior to use. Refer to
Table 3 for a list of countries and agencies that have approved
the ISL37400M-EVAL for operation.
The Intersil PRISM Chip Set allows for high level integration
for reduced size, increased throughput, improved radio
performance and faster time to market. The WLAN PC card
implements Direct Sequence Spread Spectrum DSSS
technology providing superior noise and signal jamming
immunity including less severe impact from unintentional
radiators such as microwave ovens. The user can connect
the PC Card in an ad-hoc peer to peer networking scheme,
allowing for instant network setup in any office environment.
By using an access point, the wireless LAN can be set up to
allow for a greater number of users to interconnect, and to
increase the coverage area. With a portal (i.e., Access Point),
the wireless LAN can be easily connected into an existing
wired LAN, allowing for easy expansion of the service.
Compared to the first generation PRISM II chip set, the
PRISM 2.5 generation offers:
• 3.3V operation for reduced power dissipation
• Reduction in current drain for extended battery life
• Dual antenna’s for use with Diversity circuits to
improved multipath performance
• Higher level of chip integration and less peripheral
components to reduce material costs
• Support of optional IEEE 802.11 Short Preamble for
significantly increased data throughput
A complete Reference Design for the ISL37400M is
available to ensure minimum time-to-market. This
information contains detailesfor manufacturing a miniPCI
WLAN assembly, including Gerber PC board files, an
accurate Bill of Material with component sourcing and
complete mechanical drawings.
Related Literature
To learn more about what the IEEE 802.11 is, refer to:
• Tech Brief TB337, Intersil Corporation, “A Brief Tutorial
on Spread Spectrum and Packet Radio”[1].
For a more detailed description of radio operation, please
refer to:
• Application Note AN9951, Intersil Corporation,
“ISL37400M-EVAL PRISM 2.5 11 Mb miniPCI Wireless
LAN Radio Description” [2]
The HFA3841 Media Access Controller
(MAC) Protocol Handler
The ISL3874 MAC/Baseband Processor and its firmware are
responsible for running the IEEE 802.11 protocol in the
WLAN card. This section describes the features of IEEE
802.11 that are implemented.
The functions supported by the STA (station) Firmware are:
• CSMA/CA (Carrier Sense Multiple Access with
Collision Avoidance) with Random Backoff
• WEP Security
• Short/Long Preamble with multirate
• RTS/CTS Handshake (Ready To Send/Clear To Send)
and NAV Management (Network Allocation Vector)
• MAC Level Acknowledgments (Media Access Control)
• Re-Transmission of Unacknowledged Frames
• Duplicate Detection and Rejection
• Broadcast and Multicast Frames
• Fragmentation and Re-Assembly
• Power Management (Planned)
• Timestamp Synchronization
• DCF (Distributed Coordination Function)
• PCF (Point Coordination Function)
• Beacon Generation in an Ad-Hoc Network
• Probe Response Generation in an Ad-Hoc Network
Card Information Structure
The standard Intersil WLAN PC Card will be supplied with
information embedded in the CIS shown in Table 2. It should
be noted that in most systems this information is displayed
when the card is inserted. Customization of the CIS for
specific customer requirements is available upon request, to
enable customer information to be displayed when the card
is inserted.
TABLE 2. CIS EMBEDDED INFORMATION
FUNCTION NAME CONTENT
Manufacturer’s ID 00
Function ID Network Adapter
Product Revision 1
Manufacturer Intersil Corporation
Product HFA3841
PROG
LOT