User Manual

2
Access Points will be available from a number of suppliers,
enabling a totally wireless network solution. Typical operating
ranges are shown in Table 1..
Functional Overview
The WLAN USB-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 4 for a list of countries and
agencies that have approved the ISL37300XU-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-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 USB-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 PRISM II chip set, the PRISM 2.5 generation
offers:
• Low loss front end designed for maximum range
• 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 ISL37300XU is available to
ensure minimum time-to-market. This information contains details
for manufacturing a USB-card WLAN assembly, including Gerber
PC board files, a Bill of Material with component sourcing,
mechanical drawings, a detailed Radio Description with debug
directions and a test plan.
The ISL3873 Media Access Controller (MAC)
Protocol Handler
The ISL3873 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)
• Beacon Generation in an Ad-Hoc Network
• Probe Response Generation in an Ad-Hoc Network
Card Information Structure
The standard Intersil WLAN USB-card will be supplied with
information embedded in the PDA for use in enumeration. Table 2
shows the Plug Record and the default information. Customization
of the enumeration values can be performed by modifying the
PDA plug records and reflashing the PDA, Primary, and
Secondary. Please refer to the Prism Driver Programmers Manual
for more information.
TABLE 1. TYPICAL OPERATING RANGE (NOTE 2 )
DATA RATE
(Mbps) INDOOR RANGE OUTDOOR RANGE
11 120 feet (37 meters) 500 feet (152 meters)
5.5 200 feet (61 meters) 800 feet (243 meters)
2 240 feet (73 meters) 1300 feet (396 meters)
1 300 feet (91 meters) 1750 feet (533 meters)
TABLE 2.
Plug Record
Contents Usage Default
401 Vendor/Product
ID
XXXX XXXX
407 Bus/Self Powered Bus Powered
(value XXXX)
FNXXXX