RE: [WISPA] once again, several of the key...

2006-12-26 Thread Brad Belton
Hello Patrick,

With all due respect I don't think anyone here doubts the Alvarion VL is not
simply a plain vanilla CSMA product.  However, unfortunately the end result
is the same when deployed in a RF hostile environment.

All the items you list below while impressive are of little use in RF
hostile environments.  Believe me I wish this wasn't the case as I'd love to
make use of some of the many nifty VL features.  Unfortunately until VL
makes the turn and offers the tools required in today's unlicensed fixed
wireless world it is best suited for bursty, best effort applications.

The VL can scream in the right environment, but unfortunately the days of
friendly RF and clean unlicensed airways are long gone in many markets and
disappearing quickly in the rural markets as well.  As unlicensed users we
require greater flexibility out of the products we purchase not less
flexibility.

Best,


Brad


-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Patrick Leary
Sent: Tuesday, December 26, 2006 12:21 PM
To: WISPA General List
Subject: [WISPA] once again, several of the key...

...features that make VL NOT a basic CSMA/CA product.

- 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
maximum is 1023.

- 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.

- Low Priority Traffic Minimum Percent feature ensures a selectable
certain amount of the traffic 

Re: [WISPA] once again, several of the key...

2006-12-26 Thread Marlon K. Schafer (509) 982-2181



- Original Message - 
From: Patrick Leary [EMAIL PROTECTED]

To: WISPA General List wireless@wispa.org
Sent: Tuesday, December 26, 2006 10:20 AM
Subject: [WISPA] once again, several of the key...


...features that make VL NOT a basic CSMA/CA product.

- 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
maximum is 1023.

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there will 
NEVER be totally clear air.


- 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.

mks:  Some of my new wifi gear has the ability to tune for distances.  It's 
a great feature and it's amazing how much of a difference it can make.


- 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.

mks:  Cool.

- 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 

Re: [WISPA] once again, several of the key...

2006-12-26 Thread Mark Koskenmaki
Hopefully you understand all of those:)

Part of Marlon's issue with the basic 802.11 system is talked about below,
but of course, since it's there, the tuneability helps, but does not
resolve the issue.

I beleive Marlon's reference to CSMA / CA is two pronged.   While it's true
that recieved noise will block transmission, it also blocks reception of ACK
packets, meaning a double whammy.   During periods of high noise or
repetitive noise,  not only does the AP wait to transmit, it then fails to
beleive that the transmission was accepted.  After so many of thse failures,
it then renegotiates the rate at which it's connected and tries again.
While these are not the same process, they do link to each and occur in
cascade-type failure.

I have seen data on a nearly clear channel suddenly have a 200, 300 or more
ms interruption while this cascade occurs...  repettive noise, rate
renegotiations and contention window increases, and ack failures from weak
clients all cause all clients to have that momentary communication block.

I believe there have been quite a number of interesting means of addressing
this,  as I recall some products from Trango don't ack packets, but
instead allows the higher layer controls to ensure data integrity, while
some versions seem to have a mechanism to request retransmits.   There, of
course, are polling type systems, and so on.   Each has its perceived
strengths and weaknesses.

Overall, while what you post below is quite interesting, I doubt that most
of us (including me) fully grasp what tuning each of these parameters does
in real life and why you'd use them and under what circumstances.   Thus,
I really don't know what effect in real life all this ability to muck with
the works will have.   I have seen real world demonstrations of how
differring equipment using the exact same hardware, but different settings
for many of those settings performs dramatically different.   But not
understanding the full picture of what each does, I cannot estimate in my
mind their worth, nor how much they alleviate the various issues that are
part of the nature of 802.11 based systems.

I also don't see any mention of packet aggregation or hardware compression,
which would be wonderful things to have, and would improve the overall
life and performance of the system.

I believe what most of the respondents have at issue here is really the
reliance upon 802.11, which is simply NOT anywhere near great when it
comes to WISP use. Yes, it appears that you can raise the threshold for
ignoring noise, and you can tune the system to better cope with varioius
kind of situations - distance,  colocated small cells, etc.  And then the
high inefficiency that 802.11 introduces with it's ack mechanism and the
large amount of access point time spent doing nothing but passing time,
waiting for ACK packets.

Please understand, I am neither criticizing nor praising, it just appears to
me that people are talking past each other, and that neither I nor at least
some of the readers, really understand what real life value these things
have.


+++
neofast.net - fast internet for North East Oregon and South East Washington
email me at mark at neofast dot net
541-969-8200
Direct commercial inquiries to purchasing at neofast dot net

- Original Message - 
From: Patrick Leary [EMAIL PROTECTED]
To: WISPA General List wireless@wispa.org
Sent: Tuesday, December 26, 2006 10:20 AM
Subject: [WISPA] once again, several of the key...


 ...features that make VL NOT a basic CSMA/CA product.

 - 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
 maximum is 1023.

 - 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 

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Patrick Leary
mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

PL: Marlon, 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... So one could set the value to 0 and that essentially tuns off
the contention mechanism.

BTW, regarding ATPC, I think we can all expect ATPC to be mandatory for
any new UL frequency. Like it will be for 3650MHz (it was required in
the initial RO).


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

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

- 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.

mks:  Some of my new wifi gear has the ability to tune for distances.
It's 
a great feature and it's amazing how much of a difference it can make.

- 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.

mks:  Cool.

- 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%)

mks:  That's good.  As long as we have clear air for the transmit 
cycle..

- Auto or 

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Patrick Leary
Mark, yes that is true with basic CSMA/CA, but VL, again, allows
adjustments of parameters to prevent what you fear. For example, the ack
time is first based on the Max Cell Distance setting you set, so the
radio knows to expect, so to speak, an ack from each station within a
very specific time and it knows the ack from each station will be
different (it 'learns' that info). So if the ack does not come when
expected, the radio will attempt a retrans, but it will not cascade as
you fear. Why, because you are able to set the maximum number of
retries. Not only can you do that, but you can set different values for
that retry number for high priority versus low priority traffic.

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 Mark Koskenmaki
Sent: Tuesday, December 26, 2006 10:57 AM
To: WISPA General List
Subject: Re: [WISPA] once again, several of the key...

Hopefully you understand all of those:)

Part of Marlon's issue with the basic 802.11 system is talked about
below,
but of course, since it's there, the tuneability helps, but does not
resolve the issue.

I beleive Marlon's reference to CSMA / CA is two pronged.   While it's
true
that recieved noise will block transmission, it also blocks reception of
ACK
packets, meaning a double whammy.   During periods of high noise or
repetitive noise,  not only does the AP wait to transmit, it then fails
to
beleive that the transmission was accepted.  After so many of thse
failures,
it then renegotiates the rate at which it's connected and tries again.
While these are not the same process, they do link to each and occur in
cascade-type failure.

I have seen data on a nearly clear channel suddenly have a 200, 300 or
more
ms interruption while this cascade occurs...  repettive noise, rate
renegotiations and contention window increases, and ack failures from
weak
clients all cause all clients to have that momentary communication
block.

I believe there have been quite a number of interesting means of
addressing
this,  as I recall some products from Trango don't ack packets, but
instead allows the higher layer controls to ensure data integrity, while
some versions seem to have a mechanism to request retransmits.   There,
of
course, are polling type systems, and so on.   Each has its perceived
strengths and weaknesses.

Overall, while what you post below is quite interesting, I doubt that
most
of us (including me) fully grasp what tuning each of these parameters
does
in real life and why you'd use them and under what circumstances.
Thus,
I really don't know what effect in real life all this ability to muck
with
the works will have.   I have seen real world demonstrations of how
differring equipment using the exact same hardware, but different
settings
for many of those settings performs dramatically different.   But not
understanding the full picture of what each does, I cannot estimate in
my
mind their worth, nor how much they alleviate the various issues that
are
part of the nature of 802.11 based systems.

I also don't see any mention of packet aggregation or hardware
compression,
which would be wonderful things to have, and would improve the overall
life and performance of the system.

I believe what most of the respondents have at issue here is really the
reliance upon 802.11, which is simply NOT anywhere near great when it
comes to WISP use. Yes, it appears that you can raise the threshold
for
ignoring noise, and you can tune the system to better cope with varioius
kind of situations - distance,  colocated small cells, etc.  And then
the
high inefficiency that 802.11 introduces with it's ack mechanism and
the
large amount of access point time spent doing nothing but passing time,
waiting for ACK packets.

Please understand, I am neither criticizing nor praising, it just
appears to
me that people are talking past each other, and that neither I nor at
least
some of the readers, really understand what real life value these things
have.


+++
neofast.net - fast internet for North East Oregon and South East
Washington
email me at mark at neofast dot net
541-969-8200
Direct commercial inquiries to purchasing at neofast dot net

- Original Message - 
From: Patrick Leary [EMAIL PROTECTED]
To: WISPA General List wireless@wispa.org
Sent: Tuesday, December 26, 2006 10:20 AM
Subject: [WISPA] once again, several of the key...


 ...features that make VL NOT a basic CSMA/CA product.

 - 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

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Patrick Leary
Mark,
...also, in terms of your question about packet aggregation,
BreezeACCESS VL employs very aggressive concatenation. That is why it
delivers over 40,000 packets per second performance of small packets
(such as 64k frames). The radio also allows setting the Maximum
Concatenated Frame Size, as well as disabling the concatenation
feature. Frame sizes (in software version 4.0 and hardware rev. C or
higher) can be aggregated 4032 bytes. As well, you can configure the max
number of concatenated frames. Finally, the concatenation process is
performed separately by the AU for each subscriber radio. 

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 Mark Koskenmaki
Sent: Tuesday, December 26, 2006 10:57 AM
To: WISPA General List
Subject: Re: [WISPA] once again, several of the key...

Hopefully you understand all of those:)

Part of Marlon's issue with the basic 802.11 system is talked about
below,
but of course, since it's there, the tuneability helps, but does not
resolve the issue.

I beleive Marlon's reference to CSMA / CA is two pronged.   While it's
true
that recieved noise will block transmission, it also blocks reception of
ACK
packets, meaning a double whammy.   During periods of high noise or
repetitive noise,  not only does the AP wait to transmit, it then fails
to
beleive that the transmission was accepted.  After so many of thse
failures,
it then renegotiates the rate at which it's connected and tries again.
While these are not the same process, they do link to each and occur in
cascade-type failure.

I have seen data on a nearly clear channel suddenly have a 200, 300 or
more
ms interruption while this cascade occurs...  repettive noise, rate
renegotiations and contention window increases, and ack failures from
weak
clients all cause all clients to have that momentary communication
block.

I believe there have been quite a number of interesting means of
addressing
this,  as I recall some products from Trango don't ack packets, but
instead allows the higher layer controls to ensure data integrity, while
some versions seem to have a mechanism to request retransmits.   There,
of
course, are polling type systems, and so on.   Each has its perceived
strengths and weaknesses.

Overall, while what you post below is quite interesting, I doubt that
most
of us (including me) fully grasp what tuning each of these parameters
does
in real life and why you'd use them and under what circumstances.
Thus,
I really don't know what effect in real life all this ability to muck
with
the works will have.   I have seen real world demonstrations of how
differring equipment using the exact same hardware, but different
settings
for many of those settings performs dramatically different.   But not
understanding the full picture of what each does, I cannot estimate in
my
mind their worth, nor how much they alleviate the various issues that
are
part of the nature of 802.11 based systems.

I also don't see any mention of packet aggregation or hardware
compression,
which would be wonderful things to have, and would improve the overall
life and performance of the system.

I believe what most of the respondents have at issue here is really the
reliance upon 802.11, which is simply NOT anywhere near great when it
comes to WISP use. Yes, it appears that you can raise the threshold
for
ignoring noise, and you can tune the system to better cope with varioius
kind of situations - distance,  colocated small cells, etc.  And then
the
high inefficiency that 802.11 introduces with it's ack mechanism and
the
large amount of access point time spent doing nothing but passing time,
waiting for ACK packets.

Please understand, I am neither criticizing nor praising, it just
appears to
me that people are talking past each other, and that neither I nor at
least
some of the readers, really understand what real life value these things
have.


+++
neofast.net - fast internet for North East Oregon and South East
Washington
email me at mark at neofast dot net
541-969-8200
Direct commercial inquiries to purchasing at neofast dot net

- Original Message - 
From: Patrick Leary [EMAIL PROTECTED]
To: WISPA General List wireless@wispa.org
Sent: Tuesday, December 26, 2006 10:20 AM
Subject: [WISPA] once again, several of the key...


 ...features that make VL NOT a basic CSMA/CA product.

 - 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

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Patrick Leary
I should also note our support of jumbo packets of 1600 bytes +
4 bytes of CRC. If VLAN is used the length is the same 1600 + 4 bytes.
This applies to version 4.0.23 or higher.

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 Patrick Leary
Sent: Tuesday, December 26, 2006 11:48 AM
To: WISPA General List
Subject: RE: [WISPA] once again, several of the key...

Mark,
...also, in terms of your question about packet aggregation,
BreezeACCESS VL employs very aggressive concatenation. That is why it
delivers over 40,000 packets per second performance of small packets
(such as 64k frames). The radio also allows setting the Maximum
Concatenated Frame Size, as well as disabling the concatenation
feature. Frame sizes (in software version 4.0 and hardware rev. C or
higher) can be aggregated 4032 bytes. As well, you can configure the max
number of concatenated frames. Finally, the concatenation process is
performed separately by the AU for each subscriber radio. 

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 Mark Koskenmaki
Sent: Tuesday, December 26, 2006 10:57 AM
To: WISPA General List
Subject: Re: [WISPA] once again, several of the key...

Hopefully you understand all of those:)

Part of Marlon's issue with the basic 802.11 system is talked about
below,
but of course, since it's there, the tuneability helps, but does not
resolve the issue.

I beleive Marlon's reference to CSMA / CA is two pronged.   While it's
true
that recieved noise will block transmission, it also blocks reception of
ACK
packets, meaning a double whammy.   During periods of high noise or
repetitive noise,  not only does the AP wait to transmit, it then fails
to
beleive that the transmission was accepted.  After so many of thse
failures,
it then renegotiates the rate at which it's connected and tries again.
While these are not the same process, they do link to each and occur in
cascade-type failure.

I have seen data on a nearly clear channel suddenly have a 200, 300 or
more
ms interruption while this cascade occurs...  repettive noise, rate
renegotiations and contention window increases, and ack failures from
weak
clients all cause all clients to have that momentary communication
block.

I believe there have been quite a number of interesting means of
addressing
this,  as I recall some products from Trango don't ack packets, but
instead allows the higher layer controls to ensure data integrity, while
some versions seem to have a mechanism to request retransmits.   There,
of
course, are polling type systems, and so on.   Each has its perceived
strengths and weaknesses.

Overall, while what you post below is quite interesting, I doubt that
most
of us (including me) fully grasp what tuning each of these parameters
does
in real life and why you'd use them and under what circumstances.
Thus,
I really don't know what effect in real life all this ability to muck
with
the works will have.   I have seen real world demonstrations of how
differring equipment using the exact same hardware, but different
settings
for many of those settings performs dramatically different.   But not
understanding the full picture of what each does, I cannot estimate in
my
mind their worth, nor how much they alleviate the various issues that
are
part of the nature of 802.11 based systems.

I also don't see any mention of packet aggregation or hardware
compression,
which would be wonderful things to have, and would improve the overall
life and performance of the system.

I believe what most of the respondents have at issue here is really the
reliance upon 802.11, which is simply NOT anywhere near great when it
comes to WISP use. Yes, it appears that you can raise the threshold
for
ignoring noise, and you can tune the system to better cope with varioius
kind of situations - distance,  colocated small cells, etc.  And then
the
high inefficiency that 802.11 introduces with it's ack mechanism and
the
large amount of access point time spent doing nothing but passing time,
waiting for ACK packets.

Please understand, I am neither criticizing nor praising, it just
appears to
me that people are talking past each other, and that neither I nor at
least
some of the readers, really understand what real life value these things
have.


+++
neofast.net - fast internet for North East Oregon and South East
Washington
email me at mark at neofast dot net
541-969-8200
Direct commercial inquiries to purchasing at neofast dot net

- Original Message - 
From: Patrick Leary [EMAIL PROTECTED]
To: WISPA General List wireless@wispa.org
Sent: Tuesday, December 26, 2006 10:20 AM
Subject: [WISPA] once again, several of the key...


 ...features

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Patrick Leary
Marlon,

I also just realized you asked what the Lost Beacon Threshold setting
is about. In standard CSMA/CA radios, the APs will reset if their
beacons are not received within a certain window, which can cause havoc
on the network. This can happen in high interference environments.

With BreezeACCESS VL an operator can set the time value for the Lost
Beacon Threshold. 

From the manual:
When [an AU] is unable to send beacon frames for a predetermined period
of time, such as in the case of interference, 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.

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







This footnote confirms that this email message has been scanned by
PineApp Mail-SeCure for the presence of malicious code, vandals  computer 
viruses.




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Re: [WISPA] once again, several of the key...

2006-12-26 Thread Marlon K. Schafer (509) 982-2181
OK, so when we set the value to 0, how does the ap decide who it's going to 
listen to and when it'll talk?


Is this the same as turning the radio into a polling mechanism?

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: Patrick Leary [EMAIL PROTECTED]

To: WISPA General List wireless@wispa.org
Sent: Tuesday, December 26, 2006 11:19 AM
Subject: RE: [WISPA] once again, several of the key...


mks:  And what happens when we have someone light up a Wmux type system
that's ALWAYS on?  The time value won't make a difference since there
will
NEVER be totally clear air.

PL: Marlon, 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... So one could set the value to 0 and that essentially tuns off
the contention mechanism.

BTW, regarding ATPC, I think we can all expect ATPC to be mandatory for
any new UL frequency. Like it will be for 3650MHz (it was required in
the initial RO).


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

mks:  And what happens when we have someone light up a Wmux type system
that's ALWAYS on?  The time value won't make a difference since there
will
NEVER be totally clear air.

- 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.

mks:  Some of my new wifi gear has the ability to tune for distances.
It's
a great feature and it's amazing how much of a difference it can make.

- 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

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Brad Belton
This is a bit misleading and doesn't answer Marlon's question.  

Entering a 0 value in the VL contention window algorithm setting will
indeed turn off the VL contention mechanism, but it will do little for the
client behind the VL radio trying to pass data.  

Glossy advertisement buzz words like contention window algorithm will not
solve the problem Marlon describes.  Relocating to a new channel, band
and/or polarity is a good start to getting your client back up and running
in such an event.  Throw in a RX threshold and you'll even have a better
chance at keeping that client!

Best,


Brad



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Patrick Leary
Sent: Tuesday, December 26, 2006 1:20 PM
To: WISPA General List
Subject: RE: [WISPA] once again, several of the key...

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

PL: Marlon, 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... So one could set the value to 0 and that essentially tuns off
the contention mechanism.

BTW, regarding ATPC, I think we can all expect ATPC to be mandatory for
any new UL frequency. Like it will be for 3650MHz (it was required in
the initial RO).


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

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

- 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.

mks:  Some of my new wifi gear has the ability to tune for distances.
It's 
a great feature and it's amazing how much of a difference it can make.

- Low

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Brad Belton
grin



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Marlon K. Schafer (509) 982-2181
Sent: Tuesday, December 26, 2006 2:33 PM
To: WISPA General List
Subject: Re: [WISPA] once again, several of the key...

OK, so when we set the value to 0, how does the ap decide who it's going to 
listen to and when it'll talk?

Is this the same as turning the radio into a polling mechanism?

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: Patrick Leary [EMAIL PROTECTED]
To: WISPA General List wireless@wispa.org
Sent: Tuesday, December 26, 2006 11:19 AM
Subject: RE: [WISPA] once again, several of the key...


mks:  And what happens when we have someone light up a Wmux type system
that's ALWAYS on?  The time value won't make a difference since there
will
NEVER be totally clear air.

PL: Marlon, 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... So one could set the value to 0 and that essentially tuns off
the contention mechanism.

BTW, regarding ATPC, I think we can all expect ATPC to be mandatory for
any new UL frequency. Like it will be for 3650MHz (it was required in
the initial RO).


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

mks:  And what happens when we have someone light up a Wmux type system
that's ALWAYS on?  The time value won't make a difference since there
will
NEVER be totally clear air.

- 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.

mks:  Some of my new wifi gear has the ability to tune

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Patrick Leary
So contention window algorithm is a glossy advertisement buzz word?
Yeah, I'm sure thems some hot and sexy buzzwords there. Looks to me like
that's about as dry and technically desciptive -- i.e. the ANTITHESIS of
hype -- as well could do. Brad, if that's a BS glossy buzz word, then
exactly WHAT, pray tell, should we call such an algorithm?

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 Brad Belton
Sent: Tuesday, December 26, 2006 12:36 PM
To: 'WISPA General List'
Subject: RE: [WISPA] once again, several of the key...

This is a bit misleading and doesn't answer Marlon's question.  

Entering a 0 value in the VL contention window algorithm setting
will
indeed turn off the VL contention mechanism, but it will do little for
the
client behind the VL radio trying to pass data.  

Glossy advertisement buzz words like contention window algorithm will
not
solve the problem Marlon describes.  Relocating to a new channel, band
and/or polarity is a good start to getting your client back up and
running
in such an event.  Throw in a RX threshold and you'll even have a better
chance at keeping that client!

Best,


Brad



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Patrick Leary
Sent: Tuesday, December 26, 2006 1:20 PM
To: WISPA General List
Subject: RE: [WISPA] once again, several of the key...

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

PL: Marlon, 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... So one could set the value to 0 and that essentially tuns off
the contention mechanism.

BTW, regarding ATPC, I think we can all expect ATPC to be mandatory for
any new UL frequency. Like it will be for 3650MHz (it was required in
the initial RO).


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

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

- 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

RE: [WISPA] once again, several of the key...

2006-12-26 Thread Brad Belton
lol...rather than trying to change the subject Patrick, why not answer
Marlon's question?

Here it is to refresh your memory.  Try to stay on topic.

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will NEVER be totally clear air.

Your answer was to change a setting in the VL radio and to imply problem
solved!  Yah, right!


BTW, I'm not the only one scoffing at your Alvarion manual regurgitation.
Twice today alone!  Instead focus on the questions being presented.

Best,


Brad



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Patrick Leary
Sent: Tuesday, December 26, 2006 3:07 PM
To: WISPA General List
Subject: RE: [WISPA] once again, several of the key...

So contention window algorithm is a glossy advertisement buzz word?
Yeah, I'm sure thems some hot and sexy buzzwords there. Looks to me like
that's about as dry and technically desciptive -- i.e. the ANTITHESIS of
hype -- as well could do. Brad, if that's a BS glossy buzz word, then
exactly WHAT, pray tell, should we call such an algorithm?

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 Brad Belton
Sent: Tuesday, December 26, 2006 12:36 PM
To: 'WISPA General List'
Subject: RE: [WISPA] once again, several of the key...

This is a bit misleading and doesn't answer Marlon's question.  

Entering a 0 value in the VL contention window algorithm setting
will
indeed turn off the VL contention mechanism, but it will do little for
the
client behind the VL radio trying to pass data.  

Glossy advertisement buzz words like contention window algorithm will
not
solve the problem Marlon describes.  Relocating to a new channel, band
and/or polarity is a good start to getting your client back up and
running
in such an event.  Throw in a RX threshold and you'll even have a better
chance at keeping that client!

Best,


Brad



-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
Behalf Of Patrick Leary
Sent: Tuesday, December 26, 2006 1:20 PM
To: WISPA General List
Subject: RE: [WISPA] once again, several of the key...

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

PL: Marlon, 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... So one could set the value to 0 and that essentially tuns off
the contention mechanism.

BTW, regarding ATPC, I think we can all expect ATPC to be mandatory for
any new UL frequency. Like it will be for 3650MHz (it was required in
the initial RO).


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

mks:  And what happens when we have someone light up a Wmux type system 
that's ALWAYS on?  The time value won't make a difference since there
will 
NEVER be totally clear air.

- 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