Marlon, I'll answer this with a re-post of a September post that
explains, in part, why VL is not just regular CSMA:

************
I believe most if not all of the below are features not found among
Trango or Canopy. I list a few of the advanced features. A few of these
(probably some you have never heard of before or even thought of) I show
in detail. Maybe this post will also explain why the VL is not simply an
Atheros chipset in a case and why it is not simply some basic CSMA/CA.
This is just a small sampling. The manual, with lots of tables,
drawings, etc., is 277 pages of which most relate to things that can be
configured/optimized. (I can send the pdf to any who want it.)


*         Chassis-based or stand alone AUs with multiple LEDs on the
chassi blade versions, including current consumption

*         Redundant power supplies with status LEDs, including over
temperature warning

*         GPS-sync module (for hoppers) also can be used for VL for
their alarm capabilities

*         110vAC or -48vDC power options

*         Built-in Ethernet repeater in the chassis blades to support
over 600 feet from network switch/router to ODUs

*         AUs with antenna options, including built-in 60, 90, or 120
degree sectors plus options with external connector

*         OFDM (with FEQ) for NLOS ability to enable connection of more
of the potential subscriber population

*         Adaptive modulation with configurable minimum modulation

*         Up to 40Mbps net (ftp) per sector

*         Over 40,000pps with small packets

*         No loss in capacity with varying frame size (all other UL gear
capacity is dramatically reduced when passing small packets

*         FIPS 197 option. AES standard, no extra charge

*         Virtual LANs based on IEEE 802.1Q with standard QinQ built-in
support

*         Layer-2 traffic prioritization based on IEEE 802.1p and
layer-3 traffic prioritization based on either IP ToS Precedence
(RFC791) or DSCP (RFC2474). It also supports traffic prioritization
based on UDP and/or TCP port ranges. In addition, it may use the
optional Wireless Link Prioritization (WLP) feature to fully support
delay sensitive applications, enabling Multimedia Application
Prioritization (MAP) for high performance voice and video. (MAP can
increase VoIP capacity by as much as 500%)

*         Built-in surge suppression in both ODU and IDU

*         Full management of all components, from any point in the
system. 

*         Components can be managed using standard management tools
through SNMP agents that implement standard and proprietary MIBs for
remote setting of operational modes and parameters. Security features
incorporated in BreezeACCESS VL units restrict access for management
purposes to specific IP addresses and/or directions, that is, from the
Ethernet and/or wireless link.

*         True toll quality VoIP (MOS of 4.1 or better)

*         Upload new or updated configuration file to multiple
(selectable) units simultaneously, thus radically reducing the time
spent on unit configuration maintenance.

*         Back up/shadow flash, can support two different versions of
firmware

*         5MHz (4.9GHz version), 10MHz, or 20MHz channel options. 

*         SUs autorecognize and configure channel size

*         SUs available with external connector or integrated 21dBi with
10.5h/10.5v beamwidth

*         Multilevel password, multi-layer ESSIDs

*         Configuration of remote access direction (from Ethernet only,
from wireless link only or from both)

*         Configuration of IP addresses of authorized stations

*         Numerous LEDs detailing advanced status information, plus
tri-color 10-bar alignment LEDs that directly corresponds to SNR,
including amber for warning signal is too strong (SNR >50dB)

*         Pole mount or band strap mounting options, hardware included

*         Power supply included, with reset feature and integrated surge
suppression

*         Specialty Cat 5 connector 

*         Industrial grade waterproof seal with O rings

*         Auto or configurable maximum cell distance 

*         Automatic distance learning. Per SU Distance Learning
mechanism controlled by the AU enables each SU to adapt its Acknowledge
timeout to its actual distance from the AU, minimizing delays in the
wireless link

*         Low Priority Traffic Minimum Percent feature ensures a
selectable certain amount of the traffic is reserved to low priority
packets to prevent starvation of low priority traffic when there is a
high demand for high priority traffic.

*         MAC address deny and allow list 

*         Able to configure size of concatenated frames (enables
customization/optimization based on expected applications)

*         Best AU and preferred AU options in the SUs. (Best AU
explanation: each of the AUs can be given a quality mark based on the
level at which it is received by the SU. The SU scans for a configured
number of cycles, gathering information from all the AUs with which it
can communicate. At the end of the scanning period, the SU reaches a
Best AU decision according to the information gathered. The AU with the
highest quality mark is selected as the Best AU, and the SU will
immediately try to associate with it. The quality mark given to each AU
depends on the level at which it is received by the SU. The Best AU
selection mechanism can be overridden by defining a specific AU as the
preferred AU.)

*         Broadcast rate limiting, selectable

*         Configurable threshold for lost beacon watchdog

*         Support of packet sizes to 1600 bytes, including VLAN(s) for
single or double-tagged packets

*         Advanced event log feature. The event log is an important
debugging tool and a flash memory sector is dedicated for storing it.
Events are classified according to their severity level: Message (lowest
severity), Warning, Error or Fatal (highest severity). The severity
level of events that should be saved in the Event Log is configurable.
Events from the configured severity and higher are saved and may be
displayed upon request. Log history can be displayed up to the full
number of current active events. In the log, an event is defined as
active as long as it has not been erased (a maximum of 1000 events may
be stored). The Event Log may be read using TFTP, with remote file name
<SNMP Read Community>.log (the default SNMP Read Community is "public").
The Event Log may also be uploaded to a remote FTP server. The Event Log
Menu includes the following options: Event Log Policy, Display Event
Log, Erase Event Log, Event Load Upload

*         Multiple DHCP options: From Wireless Link Only, From Ethernet
Only, From Both Ethernet and Wireless Link

*         Intelligent ATPC (The algorithm is controlled by the AU that
calculates for each received frame the average SNR at which it receives
transmissions from the specific SU. The average calculation takes into
account the previous calculated average, thus reducing the effect of
short temporary changes in link conditions. The weight of history (the
previous value) in the formula used for calculating the average SNR is
determined Menus and Parameters Operation and Administration by a
configurable parameter. In addition, the higher the time that has passed
since the last calculation, the lower the impact of history on the
calculated average. If the average SNR is not in the configured target
range, the AU transmits to the SU a power-up or a power-down message.
The target is that each SU will be received at an optimal level, or as
high (or low) as possible if the optimal range cannot be reached because
of specific link conditions. Each time that the SU tries to associate
with the AU (following either a reset or loss of synchronization), it
will initiate transmissions using its Transmit Power parameters. If
after a certain time the SU does not succeed to synchronize with the AU,
it will start increasing the transmit power level. In an AU the maximum
supported transmit power is typically used to provide maximum coverage.
However, there may be a need to decrease the transmitted power level in
order to support relatively small cells and to minimize the interference
with the operation of neighboring cells, or for compliance with local
regulatory requirements. In some cases the maximum transmit power of the
SU should be limited to ensure compliance with applicable regulations or
for other reasons.

*         And ATPC is highly configurable (only highly advanced
operators should do so), with parameters like: ATPC min. SNR level, ATPC
Delta from min. SNR level, Min. interval between ATPC messages, ATPC
power level change step (1-20dB with default of 5dB)

*         Advanced Transmit Control. The Tx Control option enables
turning Off/On the AU's transmitter, or having the AU Tx status
controlled by the status of the Ethernet port/link.

*         Cell Distance Mode feature: The higher the distance of an SU
from the AU that is serving it, the higher the time it takes for
messages sent by one of them to reach the other. To ensure appropriate
services to all SUs regardless of their distance from the AU while
maintaining a high overall performance level, two parameters should be
adapted to the distances of SUs from the serving AU: The time that a
unit waits for a response message before retransmission (ACK timeout)
should take into account the round trip propagation delay between the AU
and the SU (The one-way propagation delay at 5 GHz is 3.3 microseconds
per km/5 microseconds per mile.). The higher the distance from the AU of
the SU served by it, the higher the ACK timeout should be. The ACK
timeout in microseconds is: 20+Distance (km)*2*3.3 or 20+Distance
(miles)*2*5. To ensure fairness in the contention back-off algorithm
between SUs located at different distances from the AU, the size of the
time slot should also take into account the one-way propagation delay.
The size of the time slot of all units in the cell should be
proportional to the distance from the AU of the farthest SU served by
it. The Cell Distance Mode parameter in the AU defines the method of
computing distances. When set to Manual, the Maximum Cell Distance
parameter should be configured with the estimated distance of the
farthest SU served by the AU. When set to Automatic, the AU uses a
special algorithm to estimate its distance from each of the SUs it
serves, determine which SU is located the farthest and use the estimated
distance of the farthest SU as the maximum cell distance. The value of
the maximum cell distance parameter (either computed or configured
manually) is transmitted in the beacon messages to all SUs served by the
AU, and is used by all units to calculate the size of the time slot,
that must be the same for all units in the same sector. When the Per SU
Distance Learning option is enabled, the AU uses the re-association
message to send to each SU its estimated distance from the AU. The
per-SU distance is used to calculate the ACK timeout to be used by the
SU. When the Per SU Distance Learning option is disabled (or if it
cannot be used because the SU uses a previous SW version that does not
support this feature), the SU will use the maximum cell distance to
calculate the ACK timeout. The AU always uses the maximum cell distance
to calculate the ACK timeout. It should be noted that if the size of the
time slot used by all units is adapted to the distance of the farthest
unit, then no unit will have an advantage when competing for services.
However, this reduces the overall achievable throughput of the cell. In
certain situations, the operator may decide to improve the overall
throughput by reducing the slot size below the value required for full
fairness. This means that when there is competition for bandwidth, the
back-off algorithm will give an advantage to SUs that are located closer
to the AU. The Cell Distance Parameters menu includes the following
parameters: fairness factor, per SU distance learning, show cell
distance parameters.

*         Arbitration Inter-Frame Spacing feature

*         Max association feature

*         Wireless Link Trap Threshold feature: defines the threshold
for the wireless quality trap, indicating that the quality of the
wireless link has dropped below (on trap) or has increased above (off
trap) the specified threshold. The Wireless Link Trap Threshold is in
percentage of retransmissions, and the allowed range is from 1 to 100
(%). The default is 30 (%).

*         Lost Beacons Transmission Watchdog Threshold feature: When it
is unable to send beacon frames for a predetermined period of time, such
as in the case of interferences, the AU resets itself. The Lost Beacons
Transmission Threshold parameter represents the number of consecutive
lost beacons after which the unit will reset itself. The range for this
parameter is 100 - 1000 or 0. When the parameter is set to 0, this
feature is disabled, i.e. internal refresh will never be performed. The
default value is 218.

*         Disassociate (AU only) feature: enables disassociating all SUs
associated with the AU or a selected SU. This feature is useful during
configuration changes, enabling to force the SU(s) to re-initiate the
association process, including the search for the best AU (or a
preferred AU) using the Best AU process, without performing a full
reset. The Disassociate submenu includes two options: Disassociate All
SUs, Disassociate SU By MAC Address: to disassociate a selected SU.

*         Configurable Minimum and Maximum Contention Windows (The
BreezeACCESS VL system uses a special mechanism based on detecting the
presence of a carrier signal and analyzing the information contained in
the transmissions of the AU to estimate the activity of other SUs served
by the AU.) The available values are 0, 7, 15, 31, 63, 127, 255, 511 and
1023. A value of 0 means that the contention window algorithm is not
used and that the unit will attempt to access the medium immediately
after a time equal to DIFS. The default min. value is 15. The default
max. is 1023.

*         Advanced MIR/CIR (controlled by both the SU and AU) with
special configurable graceful degradation algorithm ensuring that the
degradation of performance for each individual SU is proportional to its
CIR.


Patrick Leary
AVP WISP Markets
Alvarion, Inc.
o: 650.314.2628
c: 760.580.0080
Vonage: 650.641.1243
[EMAIL PROTECTED]

-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marlon K. Schafer (509) 982-2181
Sent: Friday, December 22, 2006 12:30 PM
To: WISPA General List
Subject: Re: [WISPA] Alvarion Comnet Radios have arrived

OK then, Patrick, Ed, whoever, is the VL a CSMAK based product like WiFi
or 
a polling based product like Trango?

Marlon
(509) 982-2181                                   Equipment sales
(408) 907-6910 (Vonage)                    Consulting services
42846865 (icq)                                    And I run my own wisp!
[EMAIL PROTECTED]
www.odessaoffice.com/wireless
www.odessaoffice.com/marlon/cam



----- Original Message ----- 
From: "Brad Belton" <[EMAIL PROTECTED]>
To: "'WISPA General List'" <wireless@wispa.org>
Sent: Friday, December 22, 2006 12:21 PM
Subject: RE: [WISPA] Alvarion Comnet Radios have arrived


Hello Tom,

Just speaking from first hand experience and the experiences of the
references Alvarion gave me.  Nothing more.  <grin>

The VL gear is a great product for a "best effort" solution, but not a
committed rate business class service.  Two very different animals.

Again, my post was only because Marlon indicated he intended to use the
VL
gear for a business class rollout.  I just wanted to give him a heads
up,
that's all.

I do believe Alvarion's move to lower the price on the VL gear was to
put it
within the reach of the market the product could best perform.  The VL
gear
does fly on "bursty - up to" traffic.  It is amazing when it works, but
it
isn't able to maintain that level of service 24x7.  It's like the VL
flys
when it can and then holds off looking for clean air time then flys
again.
This is perfectly fine for 99% of the residential requirements, but
doesn't
cut it for a business that is pushing and pulling 5Mbps+ FDX 12hrs a
day.

In contrast a Trango M5830 will push and pull 4.5Mbps FDX or 8-9Mbps HDX
all
day long regardless of the RF environment if the link is engineered
correctly.

Best and Merry Christmas!

Brad






-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Tom DeReggi
Sent: Friday, December 22, 2006 2:05 PM
To: WISPA General List
Subject: Re: [WISPA] Alvarion Comnet Radios have arrived

Brad,

I'm not sure that is a fair statement.
I agree, TDD/DSSS/Pol Diversity solutions can tackle that noise better,
one
of the reasons Trango is still the only clear choice for a good number
of my

cell sites.
But there are many reasons WISPs are making the move to OFDM.  Alvarion
handles OFDM as well if not better than other OFDM solutions.
If we are comparing apples to apples (OFDM to OFDM) Alvarion has many
built
in features to help guarantee QOS for high end business compared to
other
OFDM solutions.
If OFDM is an Option for the WISP, Alvarion is as good an option as
anyone
else for the job.

I do not agree that Alvarions move to go after residential market
negates
their quality for business markets. Residential markets will simply sell
higher volume of CPEs, allowing a lower sale cost.

For me the distinguishing factor in available OFDM gear is.... Ease out
of
the box  versus Built-in testing tools and flexibility.

Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband


----- Original Message ----- 
From: "Brad Belton" <[EMAIL PROTECTED]>
To: "'WISPA General List'" <wireless@wispa.org>
Sent: Friday, December 22, 2006 2:11 PM
Subject: RE: [WISPA] Alvarion Comnet Radios have arrived


Hello Marlon,

VL won't be a good choice as a committed rate business grade product as
it
will modulate down in a noisy environment.  Without any RX threshold
mechanism the VL radio begins to slow and drop packets under heavy
business
class loads in unfriendly RF environments.  Even the references given to
me
by Alvarion while overall have been happy with the product are not using
VL
for committed rate business class service.  IMO, Alvarion is now pushing
the
VL product as a residential "best effort" solution...hence the dramatic
drop
in price.

In Patrick's words:
"A $285 all inclusive CPE with nothing extra to buy, piece together,
etc.
should fall within the residential business model of even small WISPs."

We've been there and almost lost a valuable client trying to use VL for
a
committed rate business class customer.

The VL gear is a high quality product with a number of valuable
features,
but it is missing a few key items that keep it form performing well (or
at
all) as a committed rate business class solution.  Only reason for my
post
was because of your intended use of the VL product.

Best and Merry Christmas!


Brad






-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marlon K. Schafer (509) 982-2181
Sent: Friday, December 22, 2006 11:05 AM
To: WISPA General List
Subject: Re: [WISPA] Alvarion Comnet Radios have arrived

Right on!  Can't wait till I build another business grade system out
here.
That's what I plan on using.

Marlon
(509) 982-2181                                   Equipment sales
(408) 907-6910 (Vonage)                    Consulting services
42846865 (icq)                                    And I run my own wisp!
[EMAIL PROTECTED]
www.odessaoffice.com/wireless
www.odessaoffice.com/marlon/cam



----- Original Message ----- 
From: "Marty Dougherty" <[EMAIL PROTECTED]>
To: "'WISPA General List'" <wireless@wispa.org>
Sent: Friday, December 22, 2006 6:47 AM
Subject: [WISPA] Alvarion Comnet Radios have arrived


> Well we got our 1st 100 pack of VL Su's under the Comnet program
> yesterday- Just wanted you all to know they are the EXACT same radios
as
> before the big price drop- Same high quality metal radio and still
> INCLUDES the mounting hardware AND the pre-made cat5 outdoor cable
(60ft
> long)- the cable is worth more then you can imagine- the RJ45 plug is
> already factory terminated and properly shielded so your installers
> don't have to do that up on the roof and you don't have to worry about
a
> bad connector later.
>
> We have deployed a LOT of these radios already and I can tell you this
> is a great price. I'm looking forward to Alvarion extending this
program
> to other products. (Patrick...)
>
> Marty
>
> ___________________________________
> Marty Dougherty
> CEO
> Roadstar Internet Inc.
> [EMAIL PROTECTED]
>
>
>
>
>
> -- 
> WISPA Wireless List: wireless@wispa.org
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