User's Manual

2
Functional Overview
The WLAN USB 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 ISL37101U-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 USB 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 USB 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 PRISM II chip set, the PRISM 3 generation
offers:
• Low loss front end designed for maximum range
• Higher level of chip integration and less peripheral components
to reduce material costs (3-chip solution)
• Support of optional IEEE 802.11 Short Preamble for
significantly increased data throughput with room for additional
user defined functions
• Has a mini-USB interface
A complete Reference Design for the ISL37101U is available to
ensure minimum time-to-market. This information contains details
for manufacturing a USB WLAN assembly, including Gerber PC
board files, an accurate Bill of Material with component sourcing
and complete mechanical drawings and a complete Radio
Description and test plan.
The ISL3871 Media Access Controller
(MAC) Protocol Handler
The ISL3871 MAC/Baseband Processor and its firmware are
responsiblefor 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
•WEPSecurity
• 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 USB will be supplied with
informationembeddedinthePlugandPlay(PnP)showninTable
2. It should be noted that in most systems this information is
displayed when the card is inserted. Customization of the PnP for
specific customer requirements is available upon request, to enable
customer information to be displayed when the card is inserted.
TABLE 2.
Plug Record
Contents Usage Default
401 Vendor/Product
ID
09AA XXXX
407 Bus/Self Powered Bus Powered
(value 8000)
ISL37101U-EVAL