Guide to Wireless LANs

Guide to Wireless LANs 	Getting Started

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295 North Bernardo	Internet (general info.)

Mountain View, CA  94043	Sales@proxim.com

Phone	(415)960-1630	Tech@proxim.com

Fax	(415)960-1984	Marketing@proxim.com

Technical Tips	FAXBack

Copyright © 1994.  All Rights reserved.


Proxim Partner Plus Program

PROXIM Partner Plus Program®

What it takes to become authorized on the PROXIM Partner Plus (P3) Program?

1.	Fill out the PROXIM Partner Plus (P3) Application.

2.	Have one (1) or more qualified technicians pass the RangeLAN2 Certification Test.

3.	Provide information on primary markets in terms of geography and vertical focus.

4.	Attend a PROXIM Partner Plus (P3) training seminar during the first six months of authorization.

Program Benefits	Contact Information

Co-Selling and Marketing Activities	Sales and Techical Training

Bid Partnering and Special Pricing	Technical Support

Risk-Free Demonstration Units	Executive Staff

Technical Sales Training

Timely Product Information	Sales Support

Technical Support


Co-Selling and Marketing Activities

PROXIM Partner Plus Authorized Reseller Guide®

Co-Selling and Marketing Activities

Sales Leads - PROXIM understands that in a developing the wireless LAN market, exposure to new customers and lead generation are key to success.  With a consistent schedule of professional, high-impact advertising and trade show participation, we will be able to provide you with leads that are pre-qualified.  All corporate end-user leads will be routed to PROXIM Partner Plus resellers.


Bid Partnering and Special Pricing

PROXIM Partner Plus Authorized Reseller Guide®

Bid Partnering and Special Pricing

If you are making a major presentation to a large corporate account, a member of our first class sales team is available to help you win the opportunity by lending sales and wireless expertise as well as pre- and post-sales support.

Facing stiff competition from another wireless vendor?  PROXIM Partner Plus resellers may also qualify for special pricing to ensure that large opportunities are not lost.  Your regional manager will work with you on each special opportunity, and all bid pricing will be guaranteed for the term of the contract.  Fulfillment of your orders will be handled through a PROXIM authorized distributor.

By making us part of your sales efforts, you will profit

from our experience - and we will learn from yours.


Demo Program

PROXIM Partner Plus Authorized Reseller Guide®

Risk-Free Demonstration Units

At PROXIM, we understand that, very often, seeing a product in action is the most direct path to selling that product.  Being a member of the PROXIM Partner Plus (P3) program entitles you to participate in our Risk Free Demo Program.  Units can be purchased at a very attractive price, and a 30-day money back guarantee is included to ensure that you are completely satisfied with your purchase.


Demo Offer

PROXIM Partner Plus Authorized Reseller Guide®

Demo Program (Limit 2 of each per customer)

To order, call our toll-free number at (800)229-1630, fax to (415)960-1984, or mail this offer.

     Quantity of each

1(  )  2(   ) RangeLAN2/ISA   16-bit ISA RangeLAN2 adapter	$399.00/unit

1(  )  2(   ) RangeLAN2/PCMCIA   PCMCIA adapter RangeLAN2 adapter	$449.00/unit

1(  )  2(   ) RangeLAN2/Access Point   Access Point for RangeLAN2	$1399.00/unit

         2(   ) ProxLink (PL/PL2)   Wireless Modem for RS-232 connectivity	$1095.00/pair

         Circle  One	Sold in Pairs Only

(Offer good while supplies last)

Please include the following information with your order.

Company Information

________________________________________________

Company Name

________________________________________________

Contact Name 	Job Title

________________________________________________

Street Address

________________________________________________

City	State	  Zip Code

________________________________________________

Phone	Fax

________________________________________________

Signature (Required)

Payment Method

___ COD

___ Visa/MasterCard  Card #  _______________________   Exp.  _____

___ Purchase Order 	#     _______________________

Shipping Method

___ UPS 3-day

___ UPS 2-day

___ UPS Overnight

___ Other.  Please specify  _______________________

Note:  Shipping charges and any applicable sales tax are in addition to the prices listed above.


Technical Sales Training

PROXIM Partner Plus Authorized Reseller Guide®

Technical Sales Training	Technical Tips

Technical sales training is provided on an as-needed basis.  In addition, PROXIM can provide training at our corporate headquarters in Mountain View, CA with advance notification.

A full technical sales training presentation is available for use in presenting PROXIM wireless solutions to your customers as well.  Please call your inside account manager to receive a copy of available presentations.


Timely Product Information

PROXIM Partner Plus Authorized Reseller Guide®

Timely Product Information

One of the keys to success in the fast-moving computer industry is timely information on new products and promotions.  As a member of our team, you receive updates by phone or fax before the programs begin.  It is our way of helping you to keep the competitive edge.


Sales Support

PROXIM Partner Plus Authorized Reseller Guide®

Sales Support

Inside Sales Support - As a PROXIM Partner, you will be assigned a Partners Plus reference number, inside sales representative, and technical contact.

Outside Sales Support - An outside regional manager for each territory will make an account call to introduce PROXIM from an individual basis, and build rapport with you, our new partner.

System Engineering and Support - Field support personnel will be made available on an as-needed basis to provide on-site factory expertise for major installations.  This support includes technical presentations, training, product demonstrations, and reseller trade show support.


Technical Support

PROXIM Partner Plus Authorized Reseller Guide®

Technical Support	Technical Tips

Priority Technical Support - PROXIM wireless products are supported by an experienced technical support staff to assist with questions or issues you might have regarding the technical aspects of the product, as well as warranty returns.  As a participant in the PROXIM Partner Plus program, you will be entitled to priority technical support for all your technical needs.

Advanced RMA - As a participant in the PROXIM Partner Plus (P3) program, you will be entitled to the privileges of our advanced RMA program.  Designed to minimize the time and effort associated with product return and replacement, this policy states that we will ship a replacement unit to any location in advance of receiving a returned unit.  Specific details will be provided after your company is part of the PROXIM Partner Plus program.

24-Hour BBS Support - When you dial into a BBS, you expect up-to-the-minute information thats easy to retrieve.  Well, thats what you get as part of the PROXIM Partner Plus program.  Youll find information like software/driver updates, installation and application notes, technical tips, and marketing information on our latest products and promotions.

24-Hour Faxback Service - Need a set of datasheets at the last minute? How about the latest marketing programs and promotions? What about applications notes or a technical tip?  No problem with the PROXIM 24-hour Faxback service.  Just dial into our Faxback system, follow the voice prompts, select the documents you would like to review, and within minutes the information will be on your fax.


Authorized Reseller Application
PROXIM Partner Plus - Profile

Type of Business

_____  VAR

_____  System Integrator

_____  Corporate Reseller

_____  Consultant

_____  Wiring Installer

_____  Other (Please Specify):________________________

Application Focus

_____  Healthcare

_____  Warehouse/Distribution

_____  Legal

_____  Banking/Finance

_____  Education

_____  Manufacturing/Factory Floor

_____  Auto ID

_____  Wiring Plants

_____  General LAN

_____  Other (Please Specify): ____________________

Other Certification

_____  Novell Platinum

_____  Novell Gold

_____  Banyan Premier

_____  Microsoft

_____  Artisoft

_____  SCO

_____  Other  (Please Specify) ____________________

Distributors Used (Please Specify) ____________________________________

Value Added (Please describe your principal Value Added Product or Service)

__________________________________________________

__________________________________________________

__________________________________________________

Acceptance:

By signing this application I am requesting participation in

PROXIMs Partners Plus Program.

I agree to:

Promote the sale of PROXIM wireless products

Staff an individual who is technically knowledgeable on PROXIM wireless products

Handle all leads PROXIM delivers within one week

Provide top-quality service and support on PROXIM wireless products

Signed:	Date:

___________________________	_______________

___________________________

(Print Name)


Executive Staff

Corporate Contacts

President:  David King	702

Chief Financial Officer:  Keith Glover	706

Vice President of Sales:  Warren Hackbarth	693


Sales Staff

Western Regional Manager:  Tom Mitchell	685

West Inside Manager:  Diane Robinson	682

Eastern Regional Manager:  Tim Adlington	680

East Inside Manager:  Matt Aver	681

Channel Sales Manager:  Mike Nydam	761

Channel Inside Representative:  Tara Villasenor	683

Director of International Sales:  Jacques Foussourier	690


Technical Staff

Director of System Engineering:  Bill Pabst	704

System Engineer:  Dan Stuart	688

Technical Support Engineer:  Judith Eisenberg	751


Technical Tips

Technical Resources

Site Survey Tool	Things to Consider

Certification Test	History of Spread Spectrum

Network Operating Systems	Glossary of Terms

Recommended Reading

ProxLink Wireless Modems	RangeLAN2 Wireless Networks

ProxLink Broadcast Mode	Security

ProxLink Delay Estimation Sheet	Roaming

ProxLink Markers	RangeLAN & RangeLAN2 Compatibility

Corrections to Packetized Mode Spec	Health Issues of Spread Spectrum

ProxLink Cable	CSMA/CA and Near/Far Defined

ProxLink Terminal Synchronization	Determining Master Stations

ProxLink Battery	Frequency Hopping-vs-Direct Sequence

ProxLink / MSU Flow Control	Power Management

ProxLink Packetized Mode

Site Survey (Fluke Wireless Logger)


Recommended Readings
Recommended Reading

Title:	Spread Spectrum Communications

Author(s):	Marvin K. Simon

Jim K. Omura

Robert A Scholtz

Barry K. Levitt

Publisher:	Computer Science Press

Title:	Spread Spectrum Systems

Author(s):	Robert C. Dixon

Publisher:	Wiley Interscience


History of Spread Spectrum

Spread Spectrum Technology

In 1985, the FCC (Federal Communications Commission) allocated three frequency bands for a radio transmission technique know as spread spectrum communications, originally developed by the military.  This transmission technique has much greater immunity to interference and noise compared to conventional radio transmission techniques.  In addition, an increasing number of users can use the same frequency (similar to cellular). These rules are designed to drive usage towards local data communications.  Under the regulations, users of FCC certified spread spectrum products do not require a license from the FCC.  The only requirement is that the manufacturers of Spread Spectrum products must meet FCC spread spectrum regulations.

Introduction

FCC rule changes in 1985, combined with the continuing evolution of digital technology has catalyzed the development of spread spectrum data communication radios.  These radios offer significant performance and operation benefits to end-users.

In this section, the operation of spread spectrum radio technology is presented, performance differences between spread spectrum and conventional radios, regulatory implications, and applications are discussed.

Conventional Radio Operation

Narrow Band Radio Signal

The conventional radio signal is referred to as narrow-band, which means that it contains all of its power in a very narrow portion of the radio frequency bandwidth.  Due to the relatively small portion of the radio band that an individual radio transmission occupies, the FCC has traditionally favored these conventional radios.  However, as a result of the very narrow frequency, these radios are prone to interference (a single interfering signal at or near their frequency can easily render the radio inoperable).

Spread Spectrum Radio Operation

Spread spectrum is a technique that takes a narrow band signal and spreads it over a broader portion of the radio frequency band.  This has the operational advantage of being resistant it interference, however, due to unfounded concerns over the increased frequency space it occupies, the FCC until recently, did not permit commercial use of the technology.

Spread Spectrum Radio Signal

In performing Spread Spectrum, the transmitter takes the input data and spreads it in a predefined method.  Each receiver must understand this predefined method and despread the signal before the data can be interpreted.

There are two basic methods to performing the spreading: (1) Frequency Hopping, and (2) Direct Sequencing.  Frequency hopping spreads its signals by "hopping" the narrow band signal as a function of time.  Direct sequencing spreads its signal by expanding the signal over a broad portion of the radio band.

The FCC allows the use of Spread Spectrum technology in three radio bands, 902-928 MHz, 2400-2483.5 MHz and 5752.5-5850 MHz for transmission under 1 Watt of power.  This power limit prevents interference within the band over long distances.

Advantages to Spread Spectrum

No FCC Site License - The FCC will grant a one time license on the radio product.  After that license is granted, the product can be sold anywhere in the U.S.

Interference Immunity - Spread Spectrum radios are inherently more noise immune than conventional radios.  Thus they will operate with higher efficiency than conventional technology.

Multi-Channel - Conventional radios operate on a specific frequency controlled by a matched crystal oscillator.  The specific frequency is allocated as a part of the FCC site license, and the equipment must remain on that frequency (except for very low power devices such as cordless phones).

Spread Spectrum data radios offer the opportunity to have multiple channels which can be dynamically changed through software.  This allows for many applications such as repeaters, redundant base station and overlapping antenna cells.


ProxLink Battery Applications

Proxim's ProxLink radio modems were designed to be run off Proxim-supplied AC adapters.  Some customers would like to make them more portable by running them off batteries.  There are a few tips you should keep in mind if you are attempting to make a battery-powered ProxLink.

First, the ProxLink requires between 6V and 9V DC.  If you are running the unit off a battery, when the battery output dips below 6V, you must either hold the unit in reset mode or shut off all power to the ProxLink.  Supplying less than 6V to the ProxLink or ProxLink XR may cause the EEPROM to get improperly written to, thereby corrupting your parameter settings.  OEM customers using the MSU should never supply less than 5V to the MSU, or you will experience the same behavior.  If you are designing with a battery, there are undervoltage sensing circuits available that will reset a unit when an undervoltage condition exists.

Secondly, if you supply less than 9V but more than 6V to the ProxLink XR, you will not achieve 500 mW output and may decrease expected range.  Therefore, when using the ProxLink XR you may want to cut off voltage before reaching 6V.  The same applies to the MSU-500.  When you supply less than the 9V required on pin 2, you will not see 500 mW output.

Applying more than 9.5V to either the ProxLink or pin 2 of the MSU-500 or MSU-500/2 may result in permanent damage to your unit.  Never apply too much voltage!

Typical current draw on the ProxLink XR is 350 mA when transmitting and 150 mA when the unit is in receive mode.  The ProxLink only draws 250 mA when transmitting.  The MSU-100 draws 225 mA when transmitting and 130 mA when in receive mode.  The MSU-100/2 draws 230 mA when transmitting and 140 mA when in receive mode.  The MSU-500 draws 125 mA from the 5V line and 200 mA from the 9V line when transmitting and 130 mA when in receive mode.  The MSU-500/2 draws 130 mA from the 5V line and 225 mA from the 9V line when transmitting and 140 mA when in receive mode.


ProxLink Broadcast Mode

ProxLink - Applications for Broadcast Mode

Many customers, particularly those using packetized mode, read about ProxLink's broadcast mode capabilities and decide to use this mode of operation for all applications. This is often not the correct assumption to make.

Broadcast mode was intended to be used when sending data from one ProxLink unit to many remote units where data loss is not a problem.  For example, a typical broadcast mode command might be requesting the serial numbers of the units that are currently within range and in receive mode.  The receiving units send back a directed message indicating their serial numbers.  Then the transmitter can send directed messages individually to those units that are available.

Broadcast mode is not an acknowledged mode, so that the host machine attached to the ProxLink that is broadcasting only knows that the ProxLink transmitted, not that the data packet was received by anyone.  Once the broadcast command is made, there are no retries.

Point-to-point mode has a very high chance of assuring that the data will be received.  There are both acknowledgments that the data was received and retries if the data was not received successfully.  If in pass-through, point-to-point applications, you add the use of hardware flow control, the data will be guaranteed to be received if the receiving ProxLink is within range and on the same channel and subchannel.

If the correct transmission of data is essential to your application, broadcast mode is not the mode you should be using. However, if data loss is permissible and many units need to be spoken to at the same time, broadcast mode is the proper mode to use.


Protocal Delay Estimation

PROXIM'S PROTOCOL DELAY ESTIMATION

Using Proxim's CSMA protocol, several layers of software and ACKs are needed to get the job done. Below is a pictorial description of the flow of data/control.  Using it, we shall estimate the time taken for typical/worst case/best case times for sending a data packet.

LLC (Processing)        	MAC               	Data         	ACK

|---------------------|----------------------|------------------------------|---------------------------|

First time = 3ms    	0-32 ms (MAC     	Compute using # of      	1ms

       	does the CSMA thing     bits and radio data

       	so we have variable        data rate

       	delay

Retries = 1ms	0-12 ms         "                  	1 ms

Number of retries at LLC	 = 64 for pass through / point-to-point / no CTS

 = 3 for packetized / point-to-point

 	 = unlimited for pass through / point-to-point / CTS

Number of retries at MAC layer = 7

EXAMPLE

Worst Case (no CTS flow control) :

(MAC retries 7 times, and LLC retries 64 times)

LLC1 = LLC time first time; MAC1 = MAC time first time

WC approx. = 64*(LLC1 + DATA + MAC1 + ACK + 6*(MAC + ACK))

   = 64*(1+32+1+6*(12+1))

   = 64*(112) = 7168ms = 7 seconds + 64*DATA

WC with avg. MAC retry time (typical case, because retry time is chosen randomly in CSMA to be between 0 and 32, or 0 and 12 ms)

   =  Compute as above, but use 32/2 for MAC1, and 12/2 for MAC.

BC (No retry at LLC or MAC) = LLC1 + MAC1 + T-DATA + ACK

(must use typical MAC here) = 3 + 16 + T-DATA + 1 = 20ms + T-DATA


Network Operating Systems

Am I Limited in Network Software Choices by Using a RangeLAN2 Network Interface Card?

Although wireless LAN technology may be new and foreign to you, Proxim has been developing wireless network interface cards for a long time.  With RangeLAN2, we have designed in compatibility with almost all software you might want to use on your network.

RangeLAN2 meets the IEEE 802.3 frame type specification.   What this means to you is that most bridges, gateway software, and other products you use on your network will interoperate with RangeLAN2 just like any other network card.  For example, you may have both Novell and TCP/IP attached through a gateway.  Your RangeLAN2 workstations and servers will be able to access the UNIX side of the network in the same way other wired workstations do.

RangeLAN2 ships with ODI and NDIS compliant drivers. If you have an unusual operating system in your office that can use a NIC with ODI or NDIS drivers, you'll be just as successful using RangeLAN2 as any other wired card.


ProxLink Flow Control

ProxLinks and MSUs have 20 buffers that each hold one packet of data to be transmitted, determined by the maximum line length, input time-out, and delimiter parameters.  These same 20 buffers also hold the received data.  So, it is possible that, if there are many small packets being transmitted and received, the buffers could fill up.  Fortunately, the ProxLinks and MSUs have a feature designed to handle this occurrence.

There are three kinds of outbound flow control that the ProxLink and MSU products can use.  Two of the hardware flow control methods are CTS and DSR generation.  Using this flow control method means that when the ProxLink / MSU buffers are full, the unit will enable either the CTS or DSR pins on the RS-232 line.  The device that is attached to the serial port must be able to understand what these pins are trying to indicate.  A similar method involves software flow control.  When the buffers of the ProxLink / MSU are full, the unit will send an XOFF (Ctrl-S) character as part of the data stream through the RS-232 port.  Again, the device that is attached to the serial port must be able to understand what this flow control method means.

There is only one method in which the device attached to the ProxLink / MSU can signal that its buffers are full.  This is to use the XON/XOFF Recognition feature of the ProxLink / MSU.  When the buffers on the device are full, it will send an XOFF character in the data stream through the serial port to the ProxLink / MSU.  The ProxLink / MSU will begin storing data in its buffers until it receives an XON character from the device.

It is important to understand that none of these flow control methods are transmitted through the radio link to the other ProxLink / MSU.  And ProxLinks and MSUs do not transmit anything but data across the radio link.  Therefore, if you must enable flow control between devices that are being hooked up wirelessly, you will need to disable XON/XOFF Generation and XON/XOFF Recognition on the ProxLink / MSU.  Then you can use these characters as flow control data that will be sent from one device to the other.  The ProxLink / MSU will not be filtering any data coming in from the serial port and will transmit the XON/XOFF characters to the other unit so that it can interpret them as flow control.  There are delays imposed by using a wireless link rather than cabling, though, so the flow control characters may not apply any longer by the time they are received at the other end.


Glossary Terms

Glossary of Terms

Bandwidth - The size (In hertz) of the frequency range that a signal transmission occupies.  Typical narrow band signals occupy a 25Khz bandwidth.  Spread Spectrum signals can occupy up to 26Mhz in the 902-928Mhz band.

Bridge - An internetworking device that incorporates the first two layers of the OSI model and allows connection of networks or subnetworks with similar architectures.

CSMA/CA - (Carrier Sense Multiple Access/Collision Avoidance) - CSMA is a protocol in which each node senses whether or not a channel is in use before attempting to transmit information.

Direct Sequencing - A spread spectrum technique by which the transmitted signal is spread over a particular frequency range.

FCC - Federal Communications Commission - A federal agency that regulates the use of Radio Frequency equipment.

Frequency Hopping - A spread spectrum technique by which the band is divided into a number of channels and the transmissions hop from channel to channel in a pre-specified sequence.

Interference - A situation that occurs when the RF signals are blocked due to physical barriers such as steel-reinforced concrete floors or collisions of RF signals transmitting in the same band.

Narrow Band - A channel of about 25Khz bandwidth in the RF spectrum.  The FCC allocates Narrow Band channels and issues a license to the user.  Each user of a specific narrow band frequency range must obtain a license from the FCC to use

OSI - ISO's (International Standards Organization) seven -layer communications network architecture reference model.  The seven layers include Application, Presentation, Session, Transport, Network, Data Link and Physical.

Router - An internetworking device which incorporates the first three layers of the OSI model and connects multiple networks together.

Spread Spectrum - A radio data transmission modulation technique by which the transmitted signal is spread over a bandwidth wider than the information bandwidth.  Spread Spectrum bands are designated by the FCC and require no user license.


Health and Safety

How Safe are PROXIMs Spread Spectrum Radios?

Below is a summary of the safety characteristics of PROXIMs RangeLAN products:

All of PROXIMs radio products are approved by the Federal Communications Committee (the FCC).  This government agency sets guidelines for spread spectrum products with the well-being of the public in mind.  These guidelines include power output limits which are below the limits specified by the public health authorities.

While the FCC limits spread spectrum radio output to 1 watt of power, PROXIMs RangeLAN radios emit only 100 milliwatts of power.  As a point of comparison, cellular telephones usually emit between 1 and 3 watts.

Radio power is reduced in proportion to one, divided by the square of the distance from the radio.  That means that the further your body is from the transmitting device, the lower the effect of the radio is on you.  Proxim radios are typically located inside a computer at least 12" - 24" away from the user's body, a distance much further than most cellular phones. As described above, PROXIMs products emit 1/10th - 1/30th the power of most cellular phones.

Proxim radios have a very low duty cycle.  Most of the time, the radio is not transmitting but is sitting idle waiting to receive data.  Cellular telephones are constantly transmitting when you are speaking on them.

A more detailed report on the health and safety factors associated with spread spectrum radios is available from Proxim on request.


ProxLink Markers

MARKERS

When a user is communicating using a pair of Proxim wireless radio products and he goes outside of the range of the other radio, he will likely see a communication error.  There are some schemes the software developer can use to warn the user they are moving out of range in a more friendly manner.

One of these schemes involves the use of "markers."  Markers are unique streams of data that are sent from the stationary or base unit at specific intervals in time.  The idea is that the remote radio will expect one of these data streams every interval.  If more than a couple of these streams is missed, it's likely the user has stepped out of range.

The software developer can decide how large an interval to use and the unique data stream to be contained in the marker.  Keep in mind that each time there is a marker sent, the data channel will be unusable by actual data, so performance may decrease with too small a marker time interval.  On the other hand, if the interval is too long, the response time to the user with the "out of range" message may be too long to be feasible as a warning type of message.

The marker data itself can be anything that would not otherwise be part of actual data.


ProxLink Manual Corrections

Packetized Mode Specification - Manual Corrections

There are several misprints in the Proxim RF Modem Packetized Mode Specification Manual.

1.	The Initialize command response packet has an additional byte after the version number string.  This byte is either a 01 if the radio speed is 121 Kbaud or 02 if the radio speed is 242 Kbaud.

2.	On page 4, the example destination serial number of 0015 (decimal) is incorrectly translated into a point to point mode address of 0000000E.  It should correctly be addressed as 0000000F.

3.	On page 10 in the Radio Channel Confirmation command, the radio channel will be reported as a channel between 31H to 37H, not 21H to 27H as written in the manual.

4.	On page 10 the Baud Rate Confirmation command incorrectly states that the response baud rate will be between 03 and 08H.  The correct response is a number between 03 and 07H as in the original Set Baud Rate command.

5.	On page 11, there is a description of an Error Report command.  This message is no longer part of the ROM and therefore the modem will never spontaneously generate this command.

6.	There is are 2 additional valid values in the Status Indication of Transmitted Packet command described on pages 7 and 8.  The value 80H indicates that the receiving modem's internal buffers are full so that it cannot receive the packet. The value A0H indicates that the receiving modem views this packet as a duplicate packet, probably indicating that the original 00H acknowledgment was never received by the transmitter.  An A0H indicator should be treated the same as a 00H successful transmission indicator.

7.	The Request Radio Signal Strengths command and Signal Strength Report are not useful commands in determining signal strength.  Therefore Proxim recommends that you do not use them for this purpose.  The Request command only polls the channels at the moment at which you issue the command, so that if the other transmitting unit is not sending at that moment (which is likely), you will get a signal strength of 0.

8.	The Go to Standby command described on page 5 incorrectly states that there is no response expected from the modem.  Actually, the response should be a Standby Confirmation which is described on page 9.

There is a sample program available written in C that gives the initialize and transmit data commands to a ProxLink.  Contact Proxim if you would like a copy of this code, or call our BBS.


ProxLink Packetized Mode

ProxLink / MSU - Packetized Mode Features

Proxim's RF Modem Series has a very powerful feature called the packetized mode.  In this mode, you can program a ProxLink / MSU to respond to a series of software commands.

Using packetized mode, you can dynamically configure a unit to change the baud rate, radio channel, and radio subchannel.

With each packet that is to be transmitted, you assign a destination serial number.  Each packet can be broadcast or sent to a different remote unit.  Many customers will find this feature useful in polling, master-slave applications.

Received packets contain the serial number of the transmitter, so that you can respond with a directed message.

Additionally, packetized mode allows you to take advantage of power-saving standby mode.  Using a software command, you put the modem to sleep.  Toggling the RTS pin on the serial port wakes the unit up.  In standby mode, the modem draws less than 5mA.  It is important to understand, though, that a modem in standby mode will neither transmit nor receive packets.

Although packetized mode is very powerful, remember that it does involve extensive programming.  A sample packetized mode program is available on the Proxim BBS.  The filename is PACKET.ZIP.


ProxLink Serial Cable

The ProxLink Serial Cable

All ProxLink units ship with a DB-9 to DB-25 serial cable.  The pinout for this cable can be found in Appendix C of the ProxLink Radio Mode.

If you intend to use a cable other than the one that came in the package, there are 2 pins you should be aware of and not connect.

Pin 1 on the DB-9 side of the cable is the NMI pin.  Grounding and then bringing high this pin on the ProxLink will cause the menu to come up in the same way that pressing the white button will.  If the pin is left grounded, the ProxLink will be in a constant state of trying to bring up the menu.  You should not have this pin connected on the DB-9 side of the

ProxLink cable.

Pin 9 on the DB-9 side of the cable is the reset pin.  Grounding and then bringing high this pin will reset the ProxLink in the same way it would if power were cycled.  If this pin is left grounded, the ProxLink will be in a constant reset state.  You should not have this pin connected on the DB-9 side of the ProxLink cable.


RangeLAN and RangeLAN2 Compatibility

Is RangeLAN2 Compatible with RangeLAN?

Although RangeLAN2 and RangeLAN do not operate on the same frequency, it is possible to have both products on one network.

RangeLAN2 operates in the 2.4 - 2.483 GHz frequency range while RangeLAN works in the 902 - 928 MHz range.  The two cards do not hear one another's transmissions.  However, if you have an existing RangeLAN network, you may add a RangeLAN2 card along side the RangeLAN card in your server, and the attach as many RangeLAN2 workstations as you would like. The two systems will be compatible in the same way that Ethernet wiring and RangeLAN are.  They will operate as independent, non-interfering systems.  Note that you may only use RangeLAN and RangeLAN2 on the same network if your network supports bridging.  Novell netware is an example of a network that has bridging support.


Fluke Site Survey Tool for ProxLink

John Fluke Site Survey Tool and the ProxLink

One of the most common questions asked of Proxim about our radios is how to test their range.  Unfortunately, there is no way to determine the actual range you will achieve in a given environment without testing in that environment.  Therefore, we recommend that you actually take a pair of our units and test them in your environment.  In most cases, we believe you will be pleasantly surprised!

John Fluke Manufacturing Company has taken this suggestion from Proxim and incorporated it into their Hydra Wireless Logger Data Acquisition Tool.  The Hydra is used for data collection and ships with Proxim's ProxLink

Radio Modems and Windows base-station software.  One ProxLink attaches to the Hydra unit itself and another ProxLink is attached to a base computer running the Windows software.

In addition to its uses as a wireless data collection device, the Hydra has a Site Survey feature. To implement this, the Windows software instructs the base ProxLink to send packets to the remote Hydra / ProxLink.  A Totalizer button on the Hydra counts the packets, and the number should be always increasing at a constant rate matching the number of the packets sent by the Windows software.  Once you move the portable Hydra out of range, you will no longer see the Totalizer increasing.

For more information on the Hydra, its data collection, and its site survey capabilities, call Fluke at 206/347-6100.


Site Survey Tool

Performing An Effective Site Survey

Why perform a Site Survey ?

The range of any wireless LAN is affected by the composition of material in the floors, walls and ceilings of any building.  It is best to select various areas of the building and test the wireless LAN system.  When planning an installation, it is best to complete a site survey of your entire buildings environment before selecting the installation locations for your Access Points.

Take Inventory

Before you begin the site survey you will need some tools:

1.  Two blueprints, layouts or maps

2.  Markers (highlighters, colored pencils, crayons)

3.  RangeLAN2/Access Point (completely configured)

4.  Laptop with a RangeLAN2/PCMCIA (configured to run Site Survey)

5.  Notepad

These are optional:

1.  A device used to measure long distances.

2.  100 - 250 Power / Electrical cord [to power Access Point]

3.  Markers for denoting distances in environment - i.e. chalk, spray paint or colored sticky backed tape.

4.  Duct tape for mounting antenna.

5.  A wired network drop for the Access Point

The Lay of the Land

A good site survey will usually begin with a layout, preferably a blueprint of the site with details of exterior walls, interior walls and doors.  If youre asking, get a 1/4 or 1/8 print for best detail.  Two maps are better than one.  Get a set of colored pencils or highlighters ready.

A physical site survey may not be needed if you are very familiar with the coverage area, but it is recommended.  Actual placement of the Access Point and a walk-around while using the site survey tool is optimal.  Variations on this theme may produce an adequate survey if the survey environment is relatively open (radio penetration requirements are minimal) and fixed (environment is not subject to change).

Marking Coverage Areas

If users are mobile, determine the roaming areas.  In most cases the user's application helps to define the coverage area needed (i.e., Warehouse Inventory System is probably not needed in the business office).  Requirements differ from customer to customer so it is best not to take anything for granted.  These days hallways and lunch rooms can be a legitimate place to work on E-Mail, etc..

Are there particular areas that a large concentration of users may roam into ? A conference room, classroom or a stock exchange floor are good examples.  Depending upon the application, more than one Access Point may be required.

Use color codes to represent radio penetration hazards. There are two basic types of Radio Penetration structures.  Low Radio Penetration Structures and Moderate Radio Penetration Structures.  Each has varying degrees of radio penetration but can be characterized with the same general attributes.

As the signal radiates out from the Access Point and it encounters objects within the environment it will penetrate, bounce off (reflect) or be absorbed. (In most cases, all three.)  This is the propagation of the signal.  The strength of the signal decreases as it propagates.  Penetration, reflection and absorption all factor in to the signal as it travels, each taking with it some amount of signal strength.  Eventually the signal strength will fall below acceptable levels.  The Receive Signal Strength Indicator (bundled as diagnostic software with both the RangeLAN2/PCMCIA and RangeLAN2/ISA) or RSSI is a measure of that strength.

Low Radio Penetration Structures are generally floor-to-ceiling structures that have a significant effect on the Receive Signal Strength, either completely blocking the signal or reducing the signal strength by greater than 60 percent.  Penetration of more than one of these structures is unlikely.  Usually these structures are made of dense material and have varying degrees of metal associated with them.  These structures include firewalls, cement walls, elevator shafts, bathrooms and exterior walls.  Computer rooms are sometimes tempest shielded and can create a low penetration area as well.

Moderate Radio Penetration Structures consist generally of floor to ceiling structures that can reduce Radio Receive Signal Strength by 5 to 40 percent.  While the existence of one of these structures within the path of the radio is not seen as a significant issue, the additive effect of multiple structures can reduce the Receive Signal Strength to a potentially unacceptable level. The greatest effect is usually on fringe areas where the Receive Signal Strength is quite low to begin with. These structures include interior walls, doors and floor to ceiling partitions.  Standard US construction walls made with drywall and metal studs (16) on center would be a prime example.

Fortunately Spread Spectrum Devices are fairly immune to interference and the 2.4 GHz band is relatively quiet (compared with the more popular 902-928 MHz band), but interference can still occur.  In determining placement of the Access Point you should be sure the Access Point is located at least 15 away from any other Non RangeLAN2 product.  Microwave ovens can also create interference so the same rule should apply.

Now that you have all this mapped out, you need to place the Access Point and antenna and run the site survey tool (bundled as diagnostic software with both the RangeLAN2/PCMCIA and RangeLAN2/ISA).

Locating the Access Point

The Access Point or Master Station provides the synchronization (timing) for all clients on its channel.  It is the conductor of the orchestra.   A well positioned Access Point can mean the difference between a Philharmonic  network and a Forest Gump Kazoo Band network.

The Access Point antenna is omni-directional. The best place to start is the center of the coverage area.  Start by drawing a circle with a 50 radius around the Access Point.  Increment every 50 to 100 out to 500 with circles and mark each ring.  Note:  An easy way to do this is to draw a Bulls-eye to scale with 50 increment rings on a transparency and use it as an overlay.

Using your notes on the Low and Medium Radio Penetration structures in the coverage area, adjust the rings so that the outside ring (500) corresponds with the outside edge of the coverage area.  Keep in mind the Low Radio Penetration structures will reduce the signal strength 60 to 100 percent and Medium Radio Penetration structures will reduce the signal strength between 5 and 40 percent. If your coverage area requires multiple Access Points and the users need to roam, plan on overlapping these zones.

The Access Point should be placed somewhere within the bulls-eye. Note:  We are going to run the site survey tool next, so plan on moving the unit to different locations, based on your findings.   Find a suitable place within the bulls eye and assemble and power on the Access Point.  During the site survey it may not be possible to place the antenna exactly where you will need it because of the environment (obstacles), AC power availability and possible disruption of workers activities.

The Access Point antenna should be placed in a vertical position.  It can be mounted upside down on a ceiling or beam.

The antenna height will vary depending upon the environment,  somewhere between 4 above the ground and 1 below the ceiling.  A rule of thumb is to take the average height of the environmental surroundings that define boundaries (6 cubicle partitions {office} or 15 milling machines {factory} or 20 warehouse shelves).  Mount the antenna at or 2 - 3 above this height.  In an office this can be a file cabinet or on the cubicle partition.

Note the Access Points location on the Map.

The RangeLAN2 Site Survey Tool

Proxim includes a site survey tool with each wireless LAN adapter.  This tool is used to determine the placement of antennas and Access Points to provide the best coverage for your wireless network.  Proxims site survey tool measures both the Link Quality and Received Signal Strength of all radios within the same domain.

Always run the site survey tool from the type of RangeLAN2 client your actual application will run on. You are probably running the site survey tool on a laptop with a RangeLAN2/PCMCIA card.  But just in case your into that body building thing, you can run the same test with a RangeLAN2/ISA.  There are a few applications where portable carts with desktop PC and battery are used.

When you run RL2SETUP and before entering the site survey tool, your RangeLAN2 node will listen for a master within its domain.  If it cant find one, it will report this and the site survey tool will be grayed out.

If an Access Point (on the same domain) is within range of your RangeLAN2 node then your node will synch to this master.

When you enter the site survey tool, your RangeLAN2 device immediately begins broadcasting messages to all other units within that domain. They respond to each broadcast.    After 10 of these broadcast packets are sent, the acknowledgments from each device are recorded and a list of those responding devices are displayed with a Link Quality number and an RSSI value.  The process is continuously repeated.

The Link Quality number represents the percentage of  packets that were responded to.  If all 10 packets are acknowledged then the Link Quality number displayed will be 5, representing 100% packet acknowledgment.  4 represents  80%, 3 - 60% and so on.

The RSSI value is there to complement the Link Quality value, a sort of  Checks and Balances.  The RSSI (Receive Signal Strength Indicator) by itself is not a very effective tool.  You can have a very low RSSI and still have an excellent Link Quality.  A high RSSI and a low Link Quality means something is wrong ( i.e., interference,  network is overloaded, hardware is busy).  The RSSI value can be used as a quasi distance indicator by telling you how close you are to losing the signal completely (i.e.  a 5 % RSSI would mean you are rather close to falling off the edge).  The real value comes when you combine the RSSI and Link Quality numbers.

An analogy would be your cars speedometer and tachometer. By itself, the tachometer (RSSI) is probably not telling you a whole lot unless youre in the red (5% RSSI). The speedometer (Link Quality) information tells the user the most useful information in an everyday environment where MPH can be important  (and  the police do the roaming).  The tachometer complements the speedometer by explaining the current performance the speedometer indicates.

Site Survey On An Existing RangeLAN2 Network

In order to run the site survey tool in an existing RangeLAN2 network, make sure all access points are turned on and that all client machines have either the ODI or NDIS drivers loaded.  Select one separate machine to run the site survey tool. The site survey tool can operate on both a network with active wireless connections or one where the RangeLAN2 NDIS and/or ODI drivers are running on each PC.

A Quick Step By Step Site Survey

1.  Load the site survey tool on a PC and note the link quality and received signal strength measurements at your location on the building map.

2.  Move the site survey tool PC to various locations in your building and record the coresponding Link Quality and Received Signal Strength measurements.

3.  To optimize placement of your Access Point, move the unit to different locations or try different antenna placement options to see if it affects your measurements.

4.  Place the Access Point in the best location that produces the highest overall numbers for the area you want to cover.

The Site Survey Process

There are several ways to run an effective site survey with the site survey tool.  Documenting your findings is key to setting up an effective roaming network.  Knowing the Basic Service Area for each Access Point will not only help during the initial installation, but will assist you when doing basic troubleshooting after the network is installed.

Use the Grid or Boundry methods described below.  Surveying a location using the grid approach provides more information then the boundary approach but takes longer to document and is more difficult to analyze.

The Grid System

One way to document your findings is to lay out a grid pattern and record the Link Quality and RSSI at each intersection.  Many floor plans have a grid layout already using a grid system (i.e., post location).  If your survey layout / blueprint does not have a grid system in place you need to create one.

Define the grid pattern with increments depending on how detailed you want your survey.  Generally 50x50 is sufficient.  Create a spreadsheet using the grid coordinates you have chosen.  Record the Link Quality and the RSSI value at each coordinate.

You are going to move the Access Point around to get the best coverage but your grid will not move.  Its helpful to mark the grid points the first time.  If you are outside, use chalk or spray paint .  If you are inside you will want a less destructive form of marking. (colored tape maybe)

Mapping Link Quality Boundaries

Another way to document your finding is to draw out the Link Quality boundaries.  This takes less time and will give you roughly the same data.  To do this you will basically ignore the RSSI value and map out the area where you have a Link Quality of 5. This is your Basic Service Area.  If the LQ drops below 5 momentarily this is OK.

As you continue away from the Access Point the Link Quality will begin to drop below 5 more consistently.  When it reaches a Link Quality of 2 or less,  STOP.  The area between the Link Quality of 4 and 2 is  your Fringe Area.

There is a spatial variable that can be eliminated by rotating in a circle at a slow pace.  This slow rotation is especially recommend when making measurements at the fringe of range.

(Access) Points To Ponder

Plan on relocating the Access Point (Master Station) several times during the Site Survey.

Always optimize for Link Quality.

If one Access Point does not cover the complete area and multiple Access Points are required, optimize the configuration with overlapping coverage areas.

If a single point of failure is a concern, locate an additional Access Point (different channel) in the same coverage area (antennas should be at least 10 apart).  Remember you can have up to 15 independent channels in the same coverage area without interference or sacrificing bandwidth.

Do not make changes to the environment for the sake of coverage unless the change can be made permanently.  Putting metal deflectors up near the antenna or moving furniture to get hidden areas is a poor solution at best and will most likely cause problems down the road.

The maximum antenna cable length from the Access Point to the antenna is 4.

If you are mounting the Access Point (on a pole, ceiling, or wall) try to place it so that you can see the front LAN activity LEDs or the rear Link LEDs (without climbing on your co-workers desk).  Both will give you basic information as to the status of the Access Point (see manual).

Locating the Access Point antenna near an exterior wall does not take advantage of the OMNIdirectional capability inherent in its design.

If your coverage area is very large and network drops are not possible, consider using the repeating function of the master.  Repeating allows you to locate a Master Access Point away from the wired network  (AC Power Only) and still provide connections to the wired network (including roaming !).

The Repeating Funtion

In order for wireless users to communicate back to the wired network or roam between Access Point cells, you must have a wired network connection.  The wired side of the Access Points conforms to Ethernet standards for 10-Base2 and 10-BaseT.  Plan accordingly.

Roaming can ONLY  be accomplished between two or more MASTER ACCESS POINTS on the same domain.

DO NOT set up a roaming network across different segments (across routers) unless you are using a mobile protocol.  As of the time of this writing there are no non-beta protocols that allow for roaming across routers.

Do not use the site survey tool during throughput testing.  The tool communicates with all units within range decreasing the overall performance of the wireless LAN.


Certification Test

RangeLAN2 Wireless Certification Test

1.  What do you need to set on a RangeLAN2/Access Point if you have TCP/IP traffic on the network?

A.  Network type

B.  IP address

C.  Station type

D.  Frame type

2.  What do you need to attach to a RangeLAN2/Access Point for normal use?

A.  Antenna

B.  Ethernet drop

C.  AC  power

D.  All of the above

3.  Which of the following will help increase performance?

A.  LSL

B.  NET5

C.  VLM

D.  IPXODI

4.  Which of the following is not a valid Ethernet frame type?

A.  802.2

B.  802.1d

C.  II

D.  SNAP

5.  Which type of Ethernet cabling requires a hub?

A.  Coax

B.  10BaseT

C.  Thick Ethernet

D.  LocalTalk

6.  What year was the earliest U.S. patent filed for a Spread Spectrum device?

A.  1891

B.  1924

C.  1940

D.  1957

7. What is a major benefit of Spread Spectrum systems?

A.  Very high data rates

B.  Can listen to signal with simple AM radio

C.  Immune to interference

D.  FCC license is required

8.  RangeLAN2 products utilize what type of Spread Spectrum technology?

A.  Frequency  Hopping

B.  Direct  Sequence

C.  Direct Hopping

D.  Frequency Sequence

9.  What frequency range does RangeLAN2 operate in?

A.  902-928 MHz

B.  2.4-2.483 GHz

C.  3.8-4.234 GHz

D.  5.7-5.83 GHz

10. The radio power output of RangeLAN2 is ?

A.  1 W

B.  500 mW

C.  250 mW

D.  100 mW

11. How many channels are available on RangeLAN2?

A.  3

B.  7

C.  15

D.  16

12. Match the station type with its appropriate definition.

Master  	_____  	A. Takes over when Master is not present.

Station	  _____  B.  Determines the hopping frequency.

Alt. Master  _____  	C.  Follows the instructions of the acting Master.

13. The RangeLAN2 Domain is primarily used as?

A.  A subnet separator

B.  A Frequency Hopping pattern

C.  An additional security parameter

D.  A Roaming parameter

14. RangeLAN2 radios will NOT roam unless?

A.  They are on the same domain AND security I.D.

B.  They are on the same channel and sub-channel

C.  They are on the same network segment and access point

D.  They are in the same coverage area

15 - 18  Answer True Or False:

15. _____  	There is no way to know the exact the range the radios will achieve without testing.

16. _____  	RangeLAN2 has antenna connectors that allow you to change antenna types per new U.S. Government rules.

17. _____  	Penetration of the radio signal through leaded glass, cement floors and concrete walls is impossible.

18. _____  	The distance covered by RangeLAN2 varies with the environment.

19. The RangeLAN2/ISA supports the following protocols.

A.  Windows NT 3.0

B.  ODI supported protocols

C.  NDIS supported protocols

D.  ASCII

20. RangeLAN2/PCMCIA requires ?

A.  An Intel 365 controller chip

B.  Card & Socket Services V2.X

C.  A & B

D.  A or B

21. The RangeLAN2/ISA Card is configured?

A.  through software only

B.  through hardware only

C.  through software and hardware

D.  none of the above

22. In a roaming network all Access Points?

A.  Are on different domains but with the same security I.D.

B.  Have a unique channel/sub-channel pair.

C.  Are configured as Alternate Masters

D.  Use the same frequency Hopping pattern

23. Work stations will initiate Roaming when?

A.  They lose sync with an Access Point

B.  Another Access Point comes on line

C.  A server determines it is O.K.

D.  A router is detected

24. The following can cause an entire RangeLan2 Network cell to fail?

A.  Incorrect hardware I/O, IRQ setting

B.  Out of range station

C.  Incorrect Domain on station

D.  No active Master

25. On a RangeLAN2/ISA card the upper yellow LED indicates?

A.  Carrier is detected

B.  Sync to the Master

C.  It is configured as a Master

D.  It is transmitting

26 - 29 . True or False?

26. _____  	The RangeLAN2/PCMCIA Driver will not load without antenna.

27. _____  	Dip switch settings on the RangeLAN2/ISA can be overridden by the software driver.

28. _____  	Multiple master on the same channel will cause communication problems.

29. _____  	If using Card & Socket Services, I/O, IRQ, memory address, and slot are read from the configuration  file.

30. The Access Point may be configured through?

A.  The RS232 port

B.  A wired Ethernet NIC

C.  A RangeLAN2 client

D.  All of the above

31. The most important indicator in the Site Survey tool is?

A.  Receive Signal Strength Indicator

B.  Link Quality

C.  Radio Data Rate

D.  Distance Indicator

32.  To extend the range of the wireless network you can ?

A.  Modify the environment

B.  Use the Access Point as a repeater

C.  Change the power setting

D.  Change the antenna

33.  Interference in the RangeLAN2 operating frequency can be caused by ?

A.  Cellular phones

B.  Cordless phones

C.  Infrared terminals

D.  Microwave ovens

34.  When performing a site survey, a Link Quality of 5 means ?

A.  Excellent - No data lost

B.  Moderate - 50 % data lost

C.  Poor - 5 packets out of 100 were received.

D.  None of the above

35. The maximum number of users on a single channel is ?

A.  5

B.  10

C.  25

D.  40

E.  Unlimited

36.  The average throughput (Bits Per Second) on a RangeLAN2 network is ?

A.  1.6 Mbps

B.  1 Mbps

C.  500 Kbps

D.  50 Kbps

37.  The signaling rate of the RangeLAN2 is ?

A.  1.6 Mbps

B.  1 Mbps

C.  500 Kbps

D.  50 Kbps

38.  To increase the throughput on a Novel Network ?

A.  Use an ODI driver

B.  Use Ethernet_II in Net.CFG

C.  Set Buffers to 256

D.  Run VLM instead of NETX

39.  Which is NOT a default setting for the RangeLAN2/ISA card ?

A.  Interrupt 15

B.  I/O base address 320

C.  Channel 1

D.  Subchannel 1

E.  Domain 0

40 - 45 True or False

40.  _____	  Two RangeLAN2 clients can communicate with each other without an Access Point.

41.  _____  	Two Access Points can communicate with each other without RangeLAN2 clients configured.

42.  _____	  A steady red LED on the back of the Access Point indicates a broken Access Point.

43.  _____  	The Access Point will boot without the antenna attached.

44.  _____  	Metal in a building will stop a radio signal.

45.  _____  RangeLAN2/PCMCIA can communicate with an NCR wireless radio.

46.   The RangeLAN2 products are compliant with what current standards ? (pick all that apply)

A.  802.11 Standard

B.  Token Ring

C.  IEEE Ethernet compliant addressing

D.  82.11 ETISI standard

E.  802.3 Standard

47.  The SLIP.BAT file is used for ?

A.  Bridging between two dissimilar networks

B.  Passing TCP/IP messages between Access Points

C.  Out of band Configuration Management

D.  SNMP management of RangeLAN2 clients

48.  Multiple active Access Points configured with the same domain can be used for ?

A.  Building to Building configurations

B.  Single Point of failure protection

C.  Roaming

D.  Spanning Tree Configurations

E.  All of the above

F.  None of the above

49.  The number of domains that can be active within the same coverage area is ?

A.	0

B	1

C.	15

D.	16

50.  RangeLAN2 wireless contention access method is ?

A.	CSMA/CA

B.	CSMA/CD

C.	CSMA/CD with RTS/CTS

D.	CSMA/CA with RTS/CTS


ProxLink Terminal Synchronization

WHAT TO DO IF YOUR PROXLINK UNIT DISPLAYS THE MENU AT 19.2 KBAUD

When a ProxLink unit is put into configuration mode by hitting the white reset button, it displays a menu on your terminal. This menu is sent out to the terminal at 9600 baud, no matter what your baud rate is set in your ProxLink unit for regular communication. Sometime, however, a unit will be set so that it sends out the menu at a baud rate other than 9600. Below is

how you fix this so that the menu is always displayed at 9600 baud.

Your menu is sent at say, 19.2 Kbaud (for example). With your terminal set to this baud rate, type the character "~" at the main menu. This will take you to a test menu. Look for a parameter called termsync. If it is ON, leave it that way. If it is OFF, turn it ON by typing "t".

Now go into your terminal's set up mode and change its operating baud rate to 9600. Next, unplug power from your ProxLink unit. After a few seconds, insert the power jack into the unit. Hit Enter continuously on your keyboard.  Start this within 5 seconds of powering up. The ProxLink unit will sync to 9600 and should display the menu on your terminal.

Go into the test mode again by typing "~". Turn termsync OFF.

Your unit is now set to display the menu at 9600 baud always, upon hitting the white button.


Frequency Hopping vs Direct Sequence

Direct Sequence vs. Frequency Hopping

Proxim manufactures spread spectrum radio products that utilize both direct sequence and frequency hopping techniques.

Frequency Hopping

RangeLAN2 uses a frequency hopping radio technique.  This means that the radio signal hops across frequencies in the 2.4 - 2.483 GHz band in pre-defined patterns.  The signal is not at any one place in the band long enough to be hampered by the presence of an interfering signal somewhere in the band.

Direct Sequence

The ProxLink and RangeLAN families use direct sequence technology in the 902-928 MHz frequency band.  This means that the radio signal in the 902-928 MHz spread spectrum band is "spread" over a specific portion of the frequency band.  ProxLink has seven different channels for this type of transmission. RangeLAN has three channels.


Determining the Master Station

Determining Master Stations and Alternate Master Stations

RangeLAN2 uses a spread spectrum frequency hopping technique.  This means that the radio signal is constantly moving from one frequency to another in a pre-defined sequence.  In order for several RangeLAN2 radios to communicate, they must be at the same frequency at the same time.

Proxim has devised a method whereby one unit, called the Master Station, sets the pace for the other radios.  All stations look to the Master to determine where and when to hop.  If there is no master present, a station configured as an Alternate Master will decide to become the master for that session.

This configuration leaves the system administrator for the network with the task of configuring each wireless station on the network as Master, Alternate Master or a non-master station.  In most cases, using the default configurations for each of the drivers will work fine.  But there may be times, when the administrator wants to change the configuration for performance,  or other issues.  Here are several factors to consider:

1.	In every wireless RangeLAN2 network, at most one station must act as the Master.  If you need to set up additional master stations, they should be configured as Alternate Masters so that there is only one true master on the network.

2.  	The Master Station must be within range of the other wireless stations on the network.  The typical range for a RangeLAN2 radio is up to 500' in office environments and up to 1000' in open areas.

3. 	The Master Station should not be a station which will be moved or turned off like a notebook computer or a user's personal machine.

4. 	On a server-client based network, it usually makes sense for the server to be the Master Station.

5.  	On a peer-to-peer based network, it is probably a good idea to designate at least one computer as an Alternate Master  in the event that the Master is unavailable.

6. 	On a network with all notebook or pen-based computers, it may be advisable for all machines to be Alternate Masters.

7.  	You will achieve better performance by configuring the fewest number of machines possible as Masters or Alternate Masters.

8.	For roaming, configure each RangeLAN2/Access Point as a master but place them on different channels.


Near/Far Phenomenon

The Near/Far Phenomenon & CSMA/CA Defined

When you are using radio frequency products, there is a phenomenon which can occur called Near/Far.  When both remote units A and B are communicating with the file server (assume that both remote units are identical except for the fact that they are located at unequal distances from the file server).  When both remote units attempt to communicate with the file serfer at the same time, the RF signal received from Unit A will be much stronger than the signal from Unit B.  Due to the difference in signal strength, the server can have a difficult time communicating in a "fair and equal" way with unit B.  This is called the Near/Far phenomenon.

Proxim has solved this issue by modifying the Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) protocol,  adding a propritetary version of Collision Avoidance.  This protocol ensures that Unit B will be able to communicate with the file server even if Unit A is closer to the file server.  Proxim's CSMA/CA protocol eliminates the Near/Far phenomenon.

Here's how it works: Before Unit A transmits, it first listens on the radio channel to see if Unit B is "talking."  If the channel is clear, Unit A will send.  If the channel is not clear, Unit A waits until the channel is free for transmissions.  In the unlikely event that there is still a collision, Proxim's radios will retry the transmission.  The radio protocol is an acknowledged protocol, so that there must be confirmation of the transmission of a packet or the data is retried.


RangeLAN2 Power Management

RangeLAN2/PCMCIA Advanced Power Management

Since most mobile computers rely exclusively on rechargeable batteries in order to be completely unattached to an AC outlet,  Proxim designed RangeLAN2/PCMCIA with power conservation as a key objective.  Since batteries can only hold a limited charge, many mobile computing manufacturers use sophisticated power management schemes to reduce overall power consumption.  Proxim has designed in advanced power management features to accomodate the power management features built into a wide range of "mobile," or portable computers.

Proxim radio current requirements without power management (All RangeLAN2 radios operate at 5V):

1.	Transmit at 300-325 mA

2.	Receive at 150-170 mA

Without power management, the radios constantly stay in the receive state waiting for any information.  In most LAN environments, you will spend most of your time in the receive state.

Proxim added three different power management modes to help conserve power.  The radios still transmit and receive at the same current levels, however they spend most of their time in one of the following power management modes.

Proxim radio current requirements in power management mode:

1.	Doze Mode at 20mA

2.	Sleep Mode at 5 mA

3.	Suspend/Resume Mode at 0 mA

Doze mode - This mode keeps the radio off most of the time and wakes up periodically to see if there are any messages using a mailbox technique.  In this mode, the client will not lose any messages.  This is the default mode setting for the RangeLAN2/PCMCIA.  In tests run by PC Week, they were able to get an increased battery life of almost 50% using the doze mode over no power management.  This mode is best used when the mobile computer is up and running and you are not in the process of accessing the wireless network.

Sleep mode - This mode keeps the radio asleep until the client sends information to another wireless unit.  The client will not be able to receive messages when it is in this mode.  This mode is best used when the mobile computer is in suspend/resume mode and power is still maintained on the PCMCIA port.

Suspend/Resume - This mode suspends the function of the RangeLAN2/PCMCIA when power is turned off the PCMCIA port.  In this mode, the client will maintain a connection to the network as long as the server has not logged the client off the LAN.


RangeLAN2 Roaming

In order to enhance our wireless solutions, Proxim offers roaming capability to break the wireless distance barrier.  To accomplish this, run the site survey tool to determine the placement and number of access points required to cover your building.  The coverage of each access point should overlap in order to provide uninterrupted wireless access at any location within the building.  The RangeLAN2/Access Points act as cells, similar in concept to those of a cellular phone network.  With the installed wireless network, mobile users attach to any access point within range.

Each RangeLAN2/Access Point within a roaming network should be  configured for a different channel/subchannel pair (which sets the frequency hopping sequence) but must have the same domain number and security ID.  The portable PCs are equipped with RangeLAN2/PCMCIA cards which are also set to the same domain.  As the portable PC seamlessly switches from cell to cell, its wireless connectivity is preserved.

The user can move freely between the RangeLAN2/Access Points in the network. When the roaming PC leaves the transmission range of one RangeLAN2/Access Point, the software automatically polls the other access points in the same domain to continue the network connection.

Please note that the cells must overlap to ensure that there are no gaps in coverage, and that the roaming PC will always have a connection available.


The PROXIM Fax on Demand Information

To receive information from the PROXIM FAXBack system, please dial (415)969-1741

or (415)969-2485 and follow the instructions.

RangeLAN2 Networking Products

RangeLAN Networking Products

ProxLink Wireless Modems

General Information


RangeLAN2 Security

How Secure is My RangeLAN2 Network?

"Can someone else buy a spread spectrum radio and receive my data?"

Spread spectrum radio technology was first used heavily during World War II by the military.  The primary reason it was utilized was because of its inherently secure nature (i.e the signals are spread prior to being sent and are therefore very difficult to interpret if intercepted.)  This technical note addresses the secure design of the RangeLAN2 products.

RangeLAN2 uses a spread spectrum frequency hopping technique.  This means that the radio signal is constantly moving from one frequency to another.  In order for someone to intercept the data, they'd first have to find the signal.

Next, the radio hardware scrambles the data that is sent across RangeLAN2.  These first two reasons mean that the only way someone would even have a chance of intercepting RangeLAN2's radio stream would be to buy a RangeLAN2 device and get within range of your network - usually within 1000'.

So, let's suppose your company is the unfortunate target of a very intelligent corporate spy who buys a RangeLAN2.  There is still more security built into RangeLAN2 to prevent someone from gathering your valuable data.  RangeLAN2 has a choice of 16 different domains.  On each of these sequences, you can choose from over 16 million security IDs.   And 2 RangeLAN2 radios will not communicate unless the domain and security ID match. This means there are 16 x 16,777,216  - over 2 billion possible choices.

Here's a summary of the steps someone would have to successfully negotiate through to get to your data:

1.  Buy a RangeLAN2 card.

2.  Get within range of your transmitter.

3.  Choose the proper domain from a choice of 16.

4.  Choose the proper security ID from a choice of 16,777,216.

5.  Wait for approximately 1/2 second per choice to see if the network server responds.

This procedure alone would take almost 4 years to go through all the choices.

6.  Then bypass the network security.

Rest easy!


RangeLAN2 Fax on Demand Info

RangeLAN2 Fax on Demand Information

Doc #	Document Name

101	RangeLAN2 Full information Kit

102	RangeLAN2 Fact Sheet

103	RangeLAN2/ISA Datasheet

104	RangeLAN2/PCMCIA Datasheet

105	RangeLAN2/Access Point Datasheet

107	RangeLAN2 Roaming Tech Tip

108	RangeLAN2 Setup Tech Tip

109	RangeLAN2 Demo Program

110	RangeLAN2 Near Far Tech Tip

111	RangeLAN2 Power Management Tech Tip

112	RangeLAN2 Security Tech Tip

113	RangeLAN2 Master Stations/Alternate Master Stations

114	RangeLAN2 Frequency Hop-vs-Direct Sequence


RangeLAN Fax on Demand Info

RangeLAN Fax on Demand Information

Doc #	Document Name

300	RangeLAN Full Info Kit

301	RangeLAN Fact Sheet

302	RangeLAN/ISA Datasheet

303	RangeLAN/PCMCIA Datasheet

304	RangeLAN/Parallel Datasheet

305	RangeLAN/LT Datasheet


ProxLink Modem Fax on Demand Information

Doc #	Document Name

400	Proxlink PL/PL2 Data Sheet

401	MSU Data Sheet

402	Full OEM Modem Kit - ProxLink, MSU, RangeLAN

403	ProxLink Full Information Kit

404	Radio Modules - RXA, RDA, RDA2 (OEM)

405	Proxlink/XR Data Sheet (International Only)

600	ProxLink Broadcast Mode Tech Tip

601	ProxLink Delay Estimation Sheet

602	ProxLink Markers Tech Tip

603	ProxLink Corrections to Packetized Mode Spec.

604	ProxLink Cable Tech Tip

605	ProxLink TermSynch Tech Tip

606	ProxLink Battery Tech Tip

607	ProxLink / MSU Flow Control Tech Tip

608	ProxLink Packetized Command Specification


General Fax on Demand Info

General Fax on Demand Information

Doc #	Document Name

800	Proxim Partner Plus Reseller Authorization Form

801	Credit Application


Company Information

Proxim, Inc.

295 North Bernardo Avenue

Mountain View, CA  94043

Phone	(415)960-1630

Fax	(415)960-1984 Sales

(415)964-5181 Corporate

Faxback	(415)969-1741

(415)969-2485

BBS	(415)960-2419   9600 N81


Fax on Demand Info

Fax on Demand

Proxim, Inc.

295 North Bernardo Avenue

Mountain View, CA  94043

Phone	(415)960-1630

Fax	(415)960-1984 Sales

(415)964-5181 Corporate

Faxback	(415)969-1741

(415)969-2485

BBS	(415)960-2419   9600 N81


Authorized Distributor Information

Question:  If I am a reseller, where do I purchase Proxim products?

Answer: From one the following Proxim Authorized Distributors.

Action Data	(800)654-4848

Alternative Technology	(800)544-7674

Connectronics	(800)366-3780

Gemini Associates	(800)255-7708

Tech Data	(800)237-8931


Reseller Information

Question:  If I am a government, education, or corporate end-user, where do I purchase product?

Answer:  Please contact Proxim to get the name of an authorized reseller in your area.  If you are able to purchase from the GSA schedule, please request contact information on a GSA approved reseller.


BBS Information

Proxim, Inc.

295 North Bernardo Avenue

Mountain View, CA  94043

Phone	(415)960-1630

Fax	(415)960-1984 Sales

(415)964-5181 Corporate

Faxback	(415)969-1741

(415)969-2485

BBS	(415)960-2419   9600 N81


Authorized Distributors

Proxim Authorized Distributors

Action Data	(800)654-4848

Alternative Technology	(800)544-7674

Connectronics	(800)366-3780

Gemini Associates	(800)255-7708

Tech Data	(800)237-8931


Trademark Information

Trademarks

RangeLAN, the RangeLAN logo, RangeLAN/ISA,  RangeLAN/PCMCIA, RangeLAN/LT, RangeLAN/Parallel, ProxLink, and Proxim are trademarks of Proxim, Inc.  NetWare and Personal NetWare are trademarks of Novell, Inc.  Windows for Workgroups is a trademark of Microsoft Corporation.  All other trademarks are the property of their respective owners.


Customer Returns

Warranty Return Policy

If you have a problem with your RangeLAN product, please call Proxim Technical Support at (415)960-1630. Proxim Technical Support will assist with resolving any technical difficulties you may have with your Proxim product.

After calling Proxim Technical Support, if your product is found to be defective, you may return the product to Proxim after obtaining an RMA (Return Materials Authorization) number from Proxim Customer Service. The product must be returned in its original packaging. The RMA number should be clearly marked on the outside of the box. Proxim cannot be held responsible for any product returned without an RMA number, and no product will be accepted without an RMA number.

When calling Proxim, please provide the following information to expedite service:

1.  Customer (account) number

2.  Invoice number or distributor invoice number

3.  Date of purchase

4.  Model number of product

5.  Serial number of product


RangeLAN2 Things to Consider

Things to Consider When Reviewing Wireless LAN Products

Because wireless LAN technology is so new and dynamic, Proxim thought it might be helpful to outline considerations for both the writer to address in wireless review "write-ups" and the reviewer to address in wireless comparison testing.

Before you get started ...

Remember to catalogue all of the various PCs used for clients and servers.

Site Survey Tool

The link quality is a measurement from 0-5 recording roughly how many packets sent out by the site survey tool are being received by the adapters within range.  A reading of 5 means that most of the packets are being received while a reading of 0 means that only a few packets are received.  The received signal strength parameter measures the radio signal strength between the various LAN adapters and the site survey machine.  Although it might seem odd, the link quality and received signal strength parameters do not always track each other.  For example, the received signal strength might be 50% but the link quality could still be 5.

Recommended Configurations for testing Wireless LAN Products

Here are a number of test configurations for wireless LAN products that can be used for product reviews and comparisons.

There are a number of ways to benchmark performance of a wireless LAN.  Here are a few that are commonly used.  Proxim does not recommend one method or the other except for the fact that the same test should be used in each configuration for comparison.

1.	File Transfer

2.	Printing

3.	Loading Applications over the Network

4.	Running Client/Server Applications

Single client to an Access Point

Measure throughput with the units at close range of 5-10ft. with line of sight between the antennas.

Measure the throughput moving the client to various points within the network using the locations on your building map

Measure the throughput at locations near the fringe of range

Multiple clients to a single Access Point

Measure throughput with one client at close range of 5-10ft. line of sight between the antennas.  Add additional clients and measure the change in overall throughput and the throughput for each client

Repeat the same test with the clients spaced at various locations on your building map.

Multiple clients to multiple Access Points

Install multiple access points all within the same range.  Space them roughly 10 ft. away and configure each to communicate on a different channel with the same domain number.

Have the client machines attach to the network.  They will randomly attach to one of the multiple access points.  Place the units at close range or within 5-10ft line of sight with the access points.  Compare the throughput numbers to the previous test.

Repeat the same test with the clients spaced out at different locations on your building map.

Roaming

Install multiple access points throughout your building.  Use the site survey tool to optimize access point placement and make sure you have overlapping wireless coverage.

Use one client and move throughout the building.  The PC will beep when it roams from one cell to another.  Note the performance at different locations on your building map.  You may need to move your access points to optimize your wireless coverage.

Set up two access points out of range.  See if you can still roam from one cell to another even though you're are disconnected from the network for a short period of time.

Cost of Wireless Coverage

It is critical that whenever wireless solutions are being ranked that price be a factor considered.  This is important because both the price and the hardware requirements for existing solutions vary so widely.  For example, a Proxim wireless LAN solution requires only two adapters costing between $595 and $695, while other solutions require hardware hubs, transceivers, bridges concentrators, and/or access points.  Compare prices based on a complete wireless solution for a particular size building.  For example, what would it cost to provide wireless access for 10 mobile PCs in a building that is 1000ft X 1000ft?

Power Management

Many mobile computing platforms are battery powered and require peripherals that use as little power as possible.  In order to compare various wireless LAN options, it is important to measure the power consumption through various typical uses.  For example, most users do not require constant access to the network so the test should run some kind of typical tasks such as printing every 15 minutes and sitting idle for the rest.  Here are some example tests:

1.	Create a batch file that prints a file on a network printer every 15 minutes.  For the rest of the time, the unit sits idle.  Record the amount of time before the unit runs out of power.

2.	Logon to the network and let the unit go into suspend/resume mode.  Monitor how long the unit still has power.  Compare this test both with and without the wireless LAN adapter.

3.	Run a file transfer between the mobile computer and a network drive continually and record the amount of time before the unit runs out of power.  This test will drain the battery quicker than any other test.

Proxims RangeLAN2/PCMCIA units support three different advanced power management features.  All are important to conserving the battery life of the mobile computer.

1.	The first feature is known as doze mode.  In this mode, the adapter powers down to a low level and will wake periodically to see if there are messages from the network.  In this mode, the performance of the adapter is roughly the same as an adapter fully awake adapter but the power savings is substantial.

2.	The second feature is known as sleep mode.  In this mode, the adapter powers down to a very low level and will only wake up if the mobile computer transmits information on the network.  (In this mode, packets sent to the mobile computer from other wireless stations are not received)

3.	The final feature is know as power down mode.  In this mode, the mobile computer shuts power off to the PCMCIA port.  When the unit wakes, the RangeLAN2/PCMCIA product maintains the network connection as long as the server has not logged the node off the network.

Wireless Protocol Issues

Although you can measure the performance of wireless network in the same manner as a wired network, there a number of issues that are specific to wireless.  These issues include the following:

1.	Near/Far Phenomenon

2.	Hidden Terminal

3.	Fringe Communication

4.	Overlapping Cells

5.	Varying throughput with range

6.	Microwave Interference

Near/Far Phenomenon

A phenomenon we refer to as "near/far" might be encountered during the review process.  Each unit tested should be evaluated in this scenario.  Assume that two units are attempting to communicate with one wireless access point.  Both units are within range of the wireless access point but unit A is closer than unit B.  The radio signal received from unit A will be stronger than the signal from unit B.  If both attempt to transmit at the same time, there is a chance that unit B will never communicate with the access point.  Robust Radio protocols insure that all units can communicate regardless of the distance from the access point.  In this example, both unit A and unit B should be able to communicate at all times with the access point.

Hidden Terminal

Another scenario you might encounter and should evaluate is the "hidden terminal" phenomenon.  When multiple radios establish communications, messages are sent and received by all units to insure that only two units communicate at any one time.  However in some environments, not all of the radios will be in range to receive these messages.  For example, assume that three radio units are placed in a single row - unit A, unit B and unit C.  Both unit A and unit C are in range of unit B, however unit A and unit C are not in range.  If both unit A and unit C attempt to transmit to unit B at the same time, unit B will not be able to receive the transmission.  Good radio protocols consider the possibility of "hidden terminal" issues allow both unit A and unit C to communicate with unit B even through unit A and unit C are not in range.

Fringe Communication

As you move to the fringe of the range of any wireless product, it should be robust enough to maintain communication as you move in and out of range.

Overlapping Cells

Wireless cells that overlap can create confusion for clients connected to a particular access point.  The protocol must be able to resolve these conflicts even when the units are on the same channel.

Varying throughput with range

As the client moves farther and farther from the access point, the throughput will begin to degrade.  Robust protocols allow communication to slowly drop off as the client reaches the fringe of coverage.

Microwave Interference

Many microwave ovens operate in the 2.4 GHz frequency range.  The ovens operate at 600-1000W of power.  Even though the units are shielded, a good amount of energy still can block the transmission of wireless LAN products.  With robust protocols, wireless LAN products can still communicate even in the presence of microwave oven interference.

We hope that these points will prove useful to you in the review process.


About the Proxim Guide to Wireless LANs

This on-line resource guide can be found in a number of locations, including our BBS, CompuServe, America Online, and is also part of our standard Proxim Partner Plus Authorized Reseller program.

This information is meant for general distribution to all parties that find this information helpful in their understanding and implementation of wireless LANs.  This information is not meant for distribution to competing wireless LAN manufacturing companies.

Contributing writers include:

Judith Eisenberg

Dan Stuart

Dean Chang

Mike Nydam

Tom Mitchell

Please forward all comments and suggestions for future releases to Mike@Proxim.com.