NDC comm HWB3163 User Manual

TM

HWB3163-EVAL PRISM II 11Mbps PCMCIA

Wireless LAN Evaluation Kit User’s Guide

Application Note August 2000

Introduction

This kit allows evaluationoftheIntersil
PRISM® II Direct Sequence chip set
design in a Wireless Local Area
Network (WLAN) PCMCIA Card
implementation.

Software driversareincludedallowing data to be transmitted
between cards at 1, 2, 5.5 and 11Mbpstransfer rates, with a
diagnostic program to display the real data throughput from
system to system.

Included in the kit are PRISM II chip set data sheets with
application notes describing the implementation of a
wireless networking card using the chip set.

Contents of Your Evaluation Kit

Your PC Card Wireless LAN Evaluation Kit contains the
following items:

QUANTITY DESCRIPTION

2 PRISM II Wireless LAN PC Cards
1 HWB3163 Wireless LAN Evaluation Kit User’s

Guide, AN9864
1 PRISM II Chip Set Data Sheets
1 PRISM II Application Notes
1 Microsoft®Windows® 95/98/NT/CE/2000, LINUX®

Driver
1 PRISM® Test Utilities (PTU) Software
1 Features/Benefits Card
1 Product Registration Form
1 Notification Card

Should you discover that your PC Card Wireless LAN
Evaluation Kit is incomplete, please contact Intersil
Corporation.

Overview of IEEE 802.11

The IEEE 802.11 specification is a standard for wireless
connectivity for fixed, portable, and moving stations within a
local area.

The IEEE 802.11 standard describes the services required
by a compliant device to operate within an “ad hoc” or
“infrastructure” network, as well as dealing with the issues
related to mobility within those networks. Spread spectrum
techniques are used to tolerate mobility and multipath
effects. They are also a requirement for compliance with
FCC, ETSI and those of other regulatory authorities when
operating within the Industrial, Scientific, and Medical (ISM)
frequency band.

AN9864.1

Author: Richard L. Abrahams

An ad hoc communications network is created quickly and
informally for a temporary time period. An infrastructure
network usually requires more planning so that wireless
stations can communicate over longer distances through
access points, and may also communicate with existing
wired LANs using portals.

The IEEE802.11standard descr ibes Media Access Control
(MAC) procedures. The principal method of communication
is the Carrier Sense Multiple Access with Collision
Avoidance (CSMA-CA) protocol. Using this protocol, each
station senses the communications medium (RF channel),
and does not transmit until the channel is clear. This avoids
collisions and minimizes the retransmission of subsequent
packets.

The standard also supports the operation of a station within
a wireless LAN that may coexist with several overlapping
wireless LANs. To accomplish this, a scheme of
channelization and spread spectrum techniques is used.
Direct Sequence (DSSS) and Frequency Hopping (FHSS)
spread spectrum techniques are supported by the standard
and both operate in the 2.4 to 2.4835GHz frequency band
(the unlicensed ISM band). An infrared technique is also
supported for indoor applications. The standard supports a
1Mbps and 2Mbps data rate for both DSSS and FHSS and
has recently introduced a high data rate standard supporting

5.5Mbps and 11Mbps DSSS using Complementary Code
Keying (CCK) modulation.

The standard has also specified the requirements and services
that enable private and secure communications to occur .

Wireless LAN Configurations

For ease of use in evaluating these cards, an ad hoc
network for peer to peer communications can be created.
An ad hoc network is usually created for a specific purpose
(such as file transfer or accessing a database). Ad hoc
networks simplify the process of creating and dissolving
networks for nontechnical users of the network facilities.
Two cards form an IEEE 802.11 Independent Basic Service
Set (IBSS), the simplest ad hoc networ k. The cards
communicate with each other directly and must remain
within radio range. When both cards are on, they
immediately “see” each other and the ad hoc network is
formed without user intervention.

To use the cards in an infrastructure BSS (also called an
Extended ServiceSet) where the two cards maynot be in direct
radio contact, access points are needed. The association
between a card (station) and an infrastructure BSS - where
communication occurs only between a station and an access
point and not between stations directly is dynamic.

1-888-INTERSIL or 321-724-7143 | Intersil and Design is a trademark of Intersil Corporation. | Copyright © Intersil Corporation 2000

1

Microsoft® Windows® and Windows NT® are registered trademarks of Microsoft Corporation. LINUX® is a registered trademark of Linus Torvalds.

PRISM® is a registered trademark of Intersil Corporation. PRISM logo is a trademark of Intersil Corporation.

Application Note 9864

The IEEE 802.11 protocols are implemented in thefirmware
so that file transfers or database access can begin
immediately.

Direct Sequence Spread Spectrum Approach

The use of spread spectrum techniques for wireless
computer communications is widely accepted because of
its robustness against multipath effects and interference
from intentional or unintentional radiators. The use of
spread spectrum techniques in the ISM frequency band
also allows products to be deployed without the need for an
FCC license.

The two main methods by which spread spectrum
communications can be achieved are Direct Sequence
Spread Spectrum (DSSS) and Frequency Hopping Spread
Spectrum (FHSS). This wireless LAN PC card uses the
DSSS technique. DSSS transmission has the best
performance in terms of multipath immunity and jamming
rejection. In an office environment, jamming sources are
likely to be unintentional such as emissions from
microwave ovens. Even though unintentional, they pose a
threat to the communications network. Direct sequence
techniques are superior to frequency hopping systems in
this case because FHSS gains its immunity to jamming by
avoiding the location of a single tone jammer (such as
other FHSS users). When collisions occur, data is lost.
With a DSSS system, the despreading function in the
receiver gives immunity to jamming by spreading the
interfering energy by the Pseudo Random Number (PN)
code overthe whole bandwidth. This selective despreading
attenuates the jamming power while despreading the
desired signal.

In the office environment, multipath effects may degrade
network communications. Direct sequence techniques offer
better protection than slower frequency hopping systems in
the presence of multipath interference. With frequency
hopped systems, if the hopper jumps to a frequency where a
null resides, then data is lost until the next hop. Multipath
signals can be thought of as a special case of unintentional
jamming. In the DSSS approach, nulls resulting from
multipath fading only eliminate a fraction ofthe signal power
since the bandwidth in the DSSS case is very large. A
significant amount of energy still remains in the signal and
effective despreading still occurs. The probability of burst
errors is reduced significantly.

An often overlooked factor when comparing IEEE 802.11
compliant DSSS and FSSS implementations, is the
achievable data rate. A frequency hopping occupied
bandwidth of 1MHz as specified by the FCC acts as a
limitation when using data rates beyond 2Mbps. A similar
bandwidth limitation has not been imposed when using the
direct sequence implementation. In the new 802.11 high
data rate (11Mbps) standard utilizing Complementary Code
Keying (CCK) modulation, the 5-1/2 times increase in data
rate has been achieved in the same 17MHz bandwidth! This

is accomplished by encoding 6 bits of data in one out of a
possible 64 orthogonal PN spreading sequences. More
information on the new high data rate standard may be found
in Applications Note AN9850 “Complementary Code Keying
Made Simple” which may be found on the Intersil Web Site.

Installation of HWB3163 Windows 95/98
Drivers

Step 1. With the PRISM PCMCIA card removed, boot your

PC under Microsoft Windows 95 or 98.

Step 2. Once your system has booted and is idle, insert

PRISM II Driver for Windows, Disk #1 into the “A”
Floppy Drive. On the Desktop, left click on
<Start> -> <RUN> then type A:SETUP <Enter>
Follow the on-screen instructions. Accept all def aults.

Step 3. When the preliminary installation is complete,

insert the wireless LAN PC card in the lower
PCMCIA slot (see Hardware Installation below).

Step 4. Windows should automatically recognize that the

card has been inserted. It then displays a dialog box
titled “New Hardware Found”.

Step 5. Insert PRISM II Driver for Windows, Disk #1 into

the floppy drive. Tell Windows that the driver is
located on drive “A”. Accept all defaults.

Step 6. Follow the on-screen instructions to complete

installation of the driver. When complete , the NDC
driver icon should appear in the system area on the
desktop (computer monitor with antenna). Clicking on
this icon enables setting of channel, mode, etc.

Step 7. If operating in the Pseudo IBSS mode, you must

assign a unique IP address to the computer in
order for the card to be operable. Left click on
<Start> -> <Settings> -> <Control Panel> .
Double click on Network.Select TCP/IP ... PRISM

IEEE 802.11 PC Card .... and click on Properties.

Select the IP Address tab. Click on Obtain an IP
Address. Enter a valid IP address. Enter a valid
Subnet Mask (suggest 255 255 255 0). Click
on OK.

PRISM Test Utility (PTU) Software
Installation

NOTE: Perform after Windows Driver Installation.

Step 1. Insert the PTU disk #1 into the floppy drive.
Step 2. On the Desktop, left click on <Start> -> <RUN>

then type A:setup <Enter>. Follow the on-screen
instructions. Accept all defaults. When the
installation is complete, an icon should
automatically appear on the Desktop.

2

Application Note 9864

Hardware Installation

Step 1. Ensure that power to the PCMCIA slot is OFF by

noting that the PCMCIA icon

does not appear in the
System Tray on the Desktop. If unsure, re-boot the
computer.

Step 2. Insert the wireless LAN PC card extender card into

the PCMCIA slot.

Step 3. Insert the wireless LAN PC card into the end of the

extender card. Ensure that the LED and pin
headers of the extender card are on the same side.
Both the card and the extender are keyed so they
will fit correctly. The HWB3163 is a 3V only device.
Do not therefore force it in a 5V-keyed system as
permanent damage may occur.

PC Card Evaluation

This chapter describes several software programs supplied
with the kit. It also details some diagnostic test points that
may be accessed on the card.

Using the PRISM Test Utility (PTU) Software

The PTU permits continuous operation of the transmitter. It
is therefore convenient for performing RF measurements
such as Transmitter Power. It also provides a handy method
of changing channels within the ISM band, Use of the
PRISM Transmitter Test Utility is basically self explanatory.
An icon was automatically created on the desktop when the
PTU installation was performed. It may be run by double­clicking on this icon.

INSTRUMENT MANUFACTURER MODEL

Frequency Counter Hewlett-Packard 53181A (012 Option)
Digital Scope
General-Purpose Multimeter
Computer with a PCMCIA Connection Slot (2 required)
3V PCMCIA

Extender Card

Differential Probe Tektronix P6247
RF Probe, 500Ω Hewlett-Packard 54006A + 11742A

Swart Interconnect EXT PCM-68-CC

NOTE: This is a 5V
Extenderand must be
mechanically
modified for 3V
operation)

Using the LANEVAL Software

LANEVAL provides a convenient method of analyzing
Packet Error Rate (PER) and Receiver Sensitivity. An icon
for starting LANEVAL was automatically placed on the
desktop when the PTU installation was performed. In order
for LANEVAL to form a successful link, the same packet
parameters (e.g., Packet Length, Packet Pad Words, etc.)
most be programmed at each end of the link.

LANEVAL runs in conjunction with the NDC Driver. The
Driver permits selection of Data Rate and Channel. It is
normally run in the Pseudo IBSS mode as this provides a
simple wireless Ad Hoc link between two computers. The
NDC Drivermay be easily accessed by double-clickingon its
icon (looks like a computer with an antenna on top) located
in the System Tray area on the desktop.

List of Test Instruments

The following instruments may be used for conducting tests
on the wireless LAN PC card.

INSTRUMENT MANUFACTURER MODEL

Spectrum Analyzer Hewlett-Packard 8595E
Power Meter Giga-tronics 8541B
Signal Generator Hewlett-Packard 8648C

3

HFA3861B BBP

(FILE #4816)

1

RF

HFA3683A

4

HFA3983
(FILE #4635)

PA

PLL

(FILE #4634)
RF/IF CONVERTER

RF LO

BUFFER

REF_OUT

PLL

HFA3783 (FILE #4633)

IF I/Q MOD/DEMOD

I/Q LO

IF LO

DAC

RF

ADC

IF

DAC

I ADC

Q ADC

I DAC

Q DAC

TX

DAC

TX

ADC

1

AGC

6

CTL

6

RAKE

AND

6

DEMOD

I/O

6

MOD

AND

6

FILTER

TX

7

ALC

6

CONTROL

TEST I/O

RADIO

DAT A

INTERFACE

RADIO

CONTROL

PORTS

GP

SERIAL

PORTS

HFA3841 MAC

(FILE #4661)

WEP

ENGINE

CPU

16-BIT

PIPELINED

CONTROL

PROCESSOR

MEMORY

ACCESS

ARBITER

HOST

INTERFACE

LOGIC

HOST PC

INTERFACE

Application Note 9864

44MHz

OSC

V

CTRL

VCO

V

VCO

CTRL

FIGURE 1. WIRELESS LAN PC CARD BLOCK DIAGRAM

EXTERNAL

MEMORY