RE: [WISPA] BPSK QAM16 DSSS interference
Tom, There are always several ways to skin that cat! Well the larger antenna would certainly allow you to decrease your back lobe and increase power and the size of your ear. If the problem is interference at your site, a lot of this is going to depend on how your site is built, length of the face of the tower, and direction of all of your equipment. While I haven't done any current work with the 2 foot Gabriel professional series I've been hearing enough good stuff about it that I ordered one to play with and see if it worth deploying. What I like to do in situations like this is break out the Anritsu spectrum analyzer and spend some time documenting the site. Knowing the ambient noise floor at the site is important before putting any additional equipment up as it's likely to interfere with other equipment. Dustin Jurman -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom DeReggi Sent: Wednesday, February 08, 2006 9:24 PM To: WISPA General List Subject: Re: [WISPA] BPSK QAM16 DSSS interference Thanks, Charles and Dustin, The challenge I'm working on is to determine if the degregation of my test link, is caused by A) Distortion on the transmitter, at full power? or B) Overload or lack of acuracy of the receiver. or C) Or Just plain interference creeping in. (tested at about -80db) note: multipath unlikely, as LOS link, 10 miles, parabolic antenna, o wall behind antennas, 100ft above other buildings. In my Trango test case, w/ 2ft antennas, QAM16, at -55 db I got worse signal Quality quality (packet loss) than at -65db. To me that would infer case A or B was happening. What was interesting, is my Mikrotik test link w/ range5s, actually got peak rssi (full power) of -47db apposed to Altas's peak signal of -55. (note: path analisys calculated -55 db appropriate, so not a negative for the Trango, but a Plus for the Range 5, exceeding expectations). With the Mikrotik, the higher the rssi radio power, the better the speed results, and lower the packet loss. So Mikrotik did not seem to be plagued with the same delimna. However, at a surprise, the Mikrotik performed at a slower speed, and had more packet loss, in its best link configuration, than Trango had. So the Trango at -65db QAM16, outperformed the Mikrotik at -47db. I attribute those results partially, to how the radios deal with interference. One side of the link (AP/MU) had significant noise, causing the Mikrotik to lower modulation more frequently. I proved this, by repeating speed tests with Trango using 5.3Ghz, which performed perfect links (no loss). However, the 10-11 miles was pushing the maxrange of 5.3, and I felt 5.3 was to risky, based on that. I actually had to turnup the Power a little over the legal limit to get the perfect link, but still lower rssi than the 5.8G link. But my point was, when noise wasn't there, the links worked much better. So the decission I am trying to decide on is, a) increase the gain (dbi) of the antennas and lower the gain (dbm) of the radio, to improve the link. For example, upgrade from 2 ft dished to 3 or 4 ft dished. or b) get a better 2 ft antenna with more isolation. For example, upgrade Gabriel cheap 2 ft para to the high performance 2 ft Gabriel Drum style antennas? Either one could have a possitive effect. Its likely that my noise is comming from my colocated antennas at the same site. The Drum style antenna will likely have much better isolation comming from the sides. Better F/B ratio is not jsut about an antenna behind me, but also beside me, and interference is not always cured by lowering the beamwidth, if the interference is comming from the side. So better isolation antenna could be the choice. However, if the packet loss was from self generated noise, larger antenna would keep my gain up, even after lowering power. However, I actually would still have a gain improvement, because the antenna increases gain in both directions, where as lowering he TX power only does it in one direction. Because most of my interference is at the AP/MU side my paln was possibly to Increase the antenna at the RU/Client, to a 3-4 ft dish. If packet loss at -55db was due to transmitting to high power, and loss was at MU/AP then it would be most importantto lower transmit power at the RU/Client side. Increasing dish size at RU would help this. Then on the MU/AP side, I would add the high performance 2ft antenna, with better isolation, taking that most of teh interference may be colocation interference. Increasing the antenna size may not block interference comming from the side. But then again, if interference comming from the front (I have another site 20 deg off to the left), its possible the larger dish and narrower beam may in fact also help isolate interference. Now to make it complicated, what if the cause is not interference at the radio receivers? But instead its all the RF in between
Re: [WISPA] BPSK QAM16 DSSS interference
Dustin, While I haven't done any current work with the 2 foot Gabriel professional series I've been hearing enough good stuff about it that I ordered one to play with and see if it worth deploying. So far I like the Gabriel antennas. However, I am starting to see a pattern where the various radios perform better on 5.3Ghz than on 5.8Ghz when using the Gabriel Dual Freq (5.3-5.8) antenna. (from a packet loss perspective not a RSSI perspective). I believe that this is totally coincidental, and a result that the 5.3G spectrum is VERY clean, and the 5.8Ghz spectrum is VERY noisy. However, how do I know that for sure? I can't just assume, that its the radios' fault or the noise floor. I have two sites using the Gabriels, both tested with Trango and Mikrotik. Next week, I am going to swap the antenna, with a PacWireless (5.8G only) 2 footer, just to confirm for sure, that the Gabriel (Dual Freq model) performs equivellently. It is a possibilty that the antenna feed is optimized for 5.3 and causing some issues at 5.8G. With Pack wireless they make seperate antennas for 5.8G and 5.3G, and if you mismatch them with the other Freq, you get a few percent packet loss, that can't be gotten rid of. I have no evidense, that the Gabriel is working anything but perfectly. But its worth proving since its a new product for me that I plan to use a lot more of. I'd be interested in what you find, and whether you find that it works optimally for 5.8Ghz. Tom DeReggi RapidDSL Wireless, Inc -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] BPSK QAM16 DSSS interference
Tom, I currently have several Pac Wireless 5.8ghz 2ft dishes running at 5.3ghz with no packet loss. Granted, the RSSI is 1-2db higher than it should be, but they do work. Travis Microserv Tom DeReggi wrote: Dustin, While I haven't done any current work with the 2 foot Gabriel professional series I've been hearing enough good stuff about it that I ordered one to play with and see if it worth deploying. So far I like the Gabriel antennas. However, I am starting to see a pattern where the various radios perform better on 5.3Ghz than on 5.8Ghz when using the Gabriel Dual Freq (5.3-5.8) antenna. (from a packet loss perspective not a RSSI perspective). I believe that this is totally coincidental, and a result that the 5.3G spectrum is VERY clean, and the 5.8Ghz spectrum is VERY noisy. However, how do I know that for sure? I can't just assume, that its the radios' fault or the noise floor. I have two sites using the Gabriels, both tested with Trango and Mikrotik. Next week, I am going to swap the antenna, with a PacWireless (5.8G only) 2 footer, just to confirm for sure, that the Gabriel (Dual Freq model) performs equivellently. It is a possibilty that the antenna feed is optimized for 5.3 and causing some issues at 5.8G. With Pack wireless they make seperate antennas for 5.8G and 5.3G, and if you mismatch them with the other Freq, you get a few percent packet loss, that can't be gotten rid of. I have no evidense, that the Gabriel is working anything but perfectly. But its worth proving since its a new product for me that I plan to use a lot more of. I'd be interested in what you find, and whether you find that it works optimally for 5.8Ghz. Tom DeReggi RapidDSL Wireless, Inc -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] BPSK QAM16 DSSS interference
If you are using 2.9.12, there should be a choice where it says 5ghz and 5ghz Turbo there should be a choice that says 5ghz 5mhz and 5ghz 10mhz. Travis Microserv Tom DeReggi wrote: How do you change channel width? Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Travis Johnson [EMAIL PROTECTED] To: WISPA General List wireless@wispa.org Sent: Wednesday, February 08, 2006 9:36 PM Subject: Re: [WISPA] BPSK QAM16 DSSS interference Tom, Can you try changing the MT to use only 5mhz or 10mhz of spectrum just to see what that does? Or even temporarily change to an unused band with the MT (5.9ghz) to see what happens? It may help isolate what's really going on. Travis Microserv Tom DeReggi wrote: Thanks, Charles and Dustin, The challenge I'm working on is to determine if the degregation of my test link, is caused by A) Distortion on the transmitter, at full power? or B) Overload or lack of acuracy of the receiver. or C) Or Just plain interference creeping in. (tested at about -80db) note: multipath unlikely, as LOS link, 10 miles, parabolic antenna, o wall behind antennas, 100ft above other buildings. In my Trango test case, w/ 2ft antennas, QAM16, at -55 db I got worse signal Quality quality (packet loss) than at -65db. To me that would infer case A or B was happening. What was interesting, is my Mikrotik test link w/ range5s, actually got peak rssi (full power) of -47db apposed to Altas's peak signal of -55. (note: path analisys calculated -55 db appropriate, so not a negative for the Trango, but a Plus for the Range 5, exceeding expectations). With the Mikrotik, the higher the rssi radio power, the better the speed results, and lower the packet loss. So Mikrotik did not seem to be plagued with the same delimna. However, at a surprise, the Mikrotik performed at a slower speed, and had more packet loss, in its best link configuration, than Trango had. So the Trango at -65db QAM16, outperformed the Mikrotik at -47db. I attribute those results partially, to how the radios deal with interference. One side of the link (AP/MU) had significant noise, causing the Mikrotik to lower modulation more frequently. I proved this, by repeating speed tests with Trango using 5.3Ghz, which performed perfect links (no loss). However, the 10-11 miles was pushing the maxrange of 5.3, and I felt 5.3 was to risky, based on that. I actually had to turnup the Power a little over the legal limit to get the perfect link, but still lower rssi than the 5.8G link. But my point was, when noise wasn't there, the links worked much better. So the decission I am trying to decide on is, a) increase the gain (dbi) of the antennas and lower the gain (dbm) of the radio, to improve the link. For example, upgrade from 2 ft dished to 3 or 4 ft dished. or b) get a better 2 ft antenna with more isolation. For example, upgrade Gabriel cheap 2 ft para to the high performance 2 ft Gabriel Drum style antennas? Either one could have a possitive effect. Its likely that my noise is comming from my colocated antennas at the same site. The Drum style antenna will likely have much better isolation comming from the sides. Better F/B ratio is not jsut about an antenna behind me, but also beside me, and interference is not always cured by lowering the beamwidth, if the interference is comming from the side. So better isolation antenna could be the choice. However, if the packet loss was from self generated noise, larger antenna would keep my gain up, even after lowering power. However, I actually would still have a gain improvement, because the antenna increases gain in both directions, where as lowering he TX power only does it in one direction. Because most of my interference is at the AP/MU side my paln was possibly to Increase the antenna at the RU/Client, to a 3-4 ft dish. If packet loss at -55db was due to transmitting to high power, and loss was at MU/AP then it would be most importantto lower transmit power at the RU/Client side. Increasing dish size at RU would help this. Then on the MU/AP side, I would add the high performance 2ft antenna, with better isolation, taking that most of teh interference may be colocation interference. Increasing the antenna size may not block interference comming from the side. But then again, if interference comming from the front (I have another site 20 deg off to the left), its possible the larger dish and narrower beam may in fact also help isolate interference. Now to make it complicated, what if the cause is not interference at the radio receivers? But instead its all the RF in between and reflections comming out of phase and distorting my signal before it gets to my radios? Now I could just add 4 ft high performance drum antennas on both sides, and call the problem done, but then that would be $4000 just in antennas :-( But also means upgrading mounting pole
RE: [WISPA] BPSK QAM16 DSSS interference
Tom, DSSS modulation is a single-carrier modulation scheme, BPSK operates much in the same way as DSSS which usually are much more robust then other forms of modulation because they seem to run like a single carrier modulation schema's. The neat thing about BPSK is its ability to take interference and still run because it sends multiple bits of the same data and then aggregates it into a single bit so it's not an all or nothing but more of a something. As you start to walk up the modulation line you definitely need more C/I, but you also start to loose the ability to use full power out of the radio. As you turn the power up on the radio, the more distortion you get so you can't achieve full modulation at full power where as you can run BPSK at full power. So dish size and quality becomes more important than radio power when you are gunning for full modulation. Dustin Jurman President Rapid Systems Corporation 1211 N. Westshore Blvd Tampa, FL 33607 [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Tom DeReggi Sent: Sunday, February 05, 2006 11:37 AM To: WISPA General List Subject: [WISPA] BPSK QAM16 DSSS interference I have a problem where BPSK modulation has packet loss due to interference greater than QAM16 at good RSSI levels. I am using tons of DSSS all around the troubled OFDM link. (16 PtMP links totalled from two cells, 2 miles apart). And my DSSS links most likely are the culprits causing some self interference with the OFDM PtP link. So is there anything about BPSK modulation that would make it more prone to interferrence from DSSS radios apposed to QAM16? RSSI at -65 when this occured most obviously. QPSK had similar characteristic/loss as BPSK, when comparing to QAM16. At -55 QAM modulations got worse/unusable, possibly because overloaded by self noise. At -75 QAM modulations got worse/unusable, possibly because to close to noise floor (-80). Testing at -65 was the sweet spot that QAM worked well, much better than BPSK and QPSK. QOS loss was relatively consistent for BPSK/QPSK at -55,-65, rssi, with a little more degregation at -75 for QPSK as getting close to noise. Note: 10 mile link. Rssi adjustments accomplished by reducing radio TX power on both ends, Antenna type remained constant. For the purpose of this discussion, I'm looking for theory pertaining to all radios, not a specific brand. Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
RE: [WISPA] BPSK QAM16 DSSS interference
As you start to walk up the modulation line you definitely need more C/I, but you also start to loose the ability to use full power out of the radio. A small bit of trivial regarding this issue With higher order modulation schemes, the EVM (Error Vector Magnitude) can be so high that even on a perfect link (no noise) the receive chip is incable of decoding the signal properly into the correct 64 dots of the QAM modulation plot. This QAM constellation interference can be represented by a grid of 8x8 dots that are being blurred by the transmitter not handling the signals with enough linearity (e.g., the radio power amp is turned to high). When too much blur occurs, the adjacent dots touch each other and the receiver will not be able to decipher the signal (it's blurred) -Charles --- WiNOG Austin, TX March 13-15, 2006 http://www.winog.com -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] BPSK QAM16 DSSS interference
what brand? dustin jurman wrote: Thank you Charles, We use radio's that use 256 dots of modulation. Dustin Jurman President Rapid Systems Corporation 1211 N. Westshore Blvd Tampa, FL 33607 [EMAIL PROTECTED] -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of Charles Wu Sent: Wednesday, February 08, 2006 9:29 AM To: 'WISPA General List' Subject: RE: [WISPA] BPSK QAM16 DSSS interference As you start to walk up the modulation line you definitely need more C/I, but you also start to loose the ability to use full power out of the radio. A small bit of trivial regarding this issue With higher order modulation schemes, the EVM (Error Vector Magnitude) can be so high that even on a perfect link (no noise) the receive chip is incable of decoding the signal properly into the correct 64 "dots" of the QAM modulation plot. This QAM constellation "interference" can be represented by a grid of 8x8 dots that are being blurred by the transmitter not handling the signals with enough linearity (e.g., the radio power amp is turned to high). When too much blur occurs, the adjacent dots touch each other and the receiver will not be able to decipher the signal (it's blurred) -Charles --- WiNOG Austin, TX March 13-15, 2006 http://www.winog.com -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
RE: [WISPA] BPSK QAM16 DSSS interference
Moto/Orthogon From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mario Pommier Sent: Wednesday, February 08, 2006 11:14 AM To: WISPA General List Subject: Re: [WISPA] BPSK QAM16 DSSS interference what brand? dustin jurman wrote: Thank you Charles, We use radio's that use 256 dots of modulation.Dustin JurmanPresidentRapid Systems Corporation1211 N. Westshore BlvdTampa, FL 33607[EMAIL PROTECTED]-Original Message-From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] OnBehalf Of Charles WuSent: Wednesday, February 08, 2006 9:29 AMTo: 'WISPA General List'Subject: RE: [WISPA] BPSK QAM16 DSSS interference As you start to walk up the modulation line you definitely need more C/I, but you also start to loose the ability to use full power out of the radio.A small bit of trivial regarding this issueWith higher order modulation schemes, the EVM (Error Vector Magnitude) canbe so high that even on a perfect link (no noise) the receive chip isincable of decoding the signal properly into the correct 64 dots of theQAM modulation plot.This QAM constellation interference can be represented by a grid of 8x8dots that are being blurred by the transmitter not handling the signals withenough linearity (e.g., the radio power amp is turned to high). When toomuch blur occurs, the adjacent dots touch each other and the receiver willnot be able to decipher the signal (it's blurred)-Charles---WiNOG Austin, TXMarch 13-15, 2006http://www.winog.com --WISPA Wireless List: wireless@wispa.orgSubscribe/Unsubscribe:http://lists.wispa.org/mailman/listinfo/wirelessArchives: http://lists.wispa.org/pipermail/wireless/ -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] BPSK QAM16 DSSS interference
IntAirNet- Fixed Wireless Broadband - Original Message - From: Charles Wu [EMAIL PROTECTED] To: 'WISPA General List' wireless@wispa.org Sent: Wednesday, February 08, 2006 9:29 AM Subject: RE: [WISPA] BPSK QAM16 DSSS interference As you start to walk up the modulation line you definitely need more C/I, but you also start to loose the ability to use full power out of the radio. A small bit of trivial regarding this issue With higher order modulation schemes, the EVM (Error Vector Magnitude) can be so high that even on a perfect link (no noise) the receive chip is incable of decoding the signal properly into the correct 64 dots of the QAM modulation plot. This QAM constellation interference can be represented by a grid of 8x8 dots that are being blurred by the transmitter not handling the signals with enough linearity (e.g., the radio power amp is turned to high). When too much blur occurs, the adjacent dots touch each other and the receiver will not be able to decipher the signal (it's blurred) -Charles --- WiNOG Austin, TX March 13-15, 2006 http://www.winog.com -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/ -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] BPSK QAM16 DSSS interference
the best radio, its what tool do you need to solve each unique problem. The hard part of this business is conclusively identifying what problem exists, to know the most cost effective way to solve it. Decissions, decissions, decissions. Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Charles Wu [EMAIL PROTECTED] To: 'WISPA General List' wireless@wispa.org Sent: Wednesday, February 08, 2006 9:29 AM Subject: RE: [WISPA] BPSK QAM16 DSSS interference As you start to walk up the modulation line you definitely need more C/I, but you also start to loose the ability to use full power out of the radio. A small bit of trivial regarding this issue With higher order modulation schemes, the EVM (Error Vector Magnitude) can be so high that even on a perfect link (no noise) the receive chip is incable of decoding the signal properly into the correct 64 dots of the QAM modulation plot. This QAM constellation interference can be represented by a grid of 8x8 dots that are being blurred by the transmitter not handling the signals with enough linearity (e.g., the radio power amp is turned to high). When too much blur occurs, the adjacent dots touch each other and the receiver will not be able to decipher the signal (it's blurred) -Charles --- WiNOG Austin, TX March 13-15, 2006 http://www.winog.com -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
Re: [WISPA] BPSK QAM16 DSSS interference
How do you change channel width? Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband - Original Message - From: Travis Johnson [EMAIL PROTECTED] To: WISPA General List wireless@wispa.org Sent: Wednesday, February 08, 2006 9:36 PM Subject: Re: [WISPA] BPSK QAM16 DSSS interference Tom, Can you try changing the MT to use only 5mhz or 10mhz of spectrum just to see what that does? Or even temporarily change to an unused band with the MT (5.9ghz) to see what happens? It may help isolate what's really going on. Travis Microserv Tom DeReggi wrote: Thanks, Charles and Dustin, The challenge I'm working on is to determine if the degregation of my test link, is caused by A) Distortion on the transmitter, at full power? or B) Overload or lack of acuracy of the receiver. or C) Or Just plain interference creeping in. (tested at about -80db) note: multipath unlikely, as LOS link, 10 miles, parabolic antenna, o wall behind antennas, 100ft above other buildings. In my Trango test case, w/ 2ft antennas, QAM16, at -55 db I got worse signal Quality quality (packet loss) than at -65db. To me that would infer case A or B was happening. What was interesting, is my Mikrotik test link w/ range5s, actually got peak rssi (full power) of -47db apposed to Altas's peak signal of -55. (note: path analisys calculated -55 db appropriate, so not a negative for the Trango, but a Plus for the Range 5, exceeding expectations). With the Mikrotik, the higher the rssi radio power, the better the speed results, and lower the packet loss. So Mikrotik did not seem to be plagued with the same delimna. However, at a surprise, the Mikrotik performed at a slower speed, and had more packet loss, in its best link configuration, than Trango had. So the Trango at -65db QAM16, outperformed the Mikrotik at -47db. I attribute those results partially, to how the radios deal with interference. One side of the link (AP/MU) had significant noise, causing the Mikrotik to lower modulation more frequently. I proved this, by repeating speed tests with Trango using 5.3Ghz, which performed perfect links (no loss). However, the 10-11 miles was pushing the maxrange of 5.3, and I felt 5.3 was to risky, based on that. I actually had to turnup the Power a little over the legal limit to get the perfect link, but still lower rssi than the 5.8G link. But my point was, when noise wasn't there, the links worked much better. So the decission I am trying to decide on is, a) increase the gain (dbi) of the antennas and lower the gain (dbm) of the radio, to improve the link. For example, upgrade from 2 ft dished to 3 or 4 ft dished. or b) get a better 2 ft antenna with more isolation. For example, upgrade Gabriel cheap 2 ft para to the high performance 2 ft Gabriel Drum style antennas? Either one could have a possitive effect. Its likely that my noise is comming from my colocated antennas at the same site. The Drum style antenna will likely have much better isolation comming from the sides. Better F/B ratio is not jsut about an antenna behind me, but also beside me, and interference is not always cured by lowering the beamwidth, if the interference is comming from the side. So better isolation antenna could be the choice. However, if the packet loss was from self generated noise, larger antenna would keep my gain up, even after lowering power. However, I actually would still have a gain improvement, because the antenna increases gain in both directions, where as lowering he TX power only does it in one direction. Because most of my interference is at the AP/MU side my paln was possibly to Increase the antenna at the RU/Client, to a 3-4 ft dish. If packet loss at -55db was due to transmitting to high power, and loss was at MU/AP then it would be most importantto lower transmit power at the RU/Client side. Increasing dish size at RU would help this. Then on the MU/AP side, I would add the high performance 2ft antenna, with better isolation, taking that most of teh interference may be colocation interference. Increasing the antenna size may not block interference comming from the side. But then again, if interference comming from the front (I have another site 20 deg off to the left), its possible the larger dish and narrower beam may in fact also help isolate interference. Now to make it complicated, what if the cause is not interference at the radio receivers? But instead its all the RF in between and reflections comming out of phase and distorting my signal before it gets to my radios? Now I could just add 4 ft high performance drum antennas on both sides, and call the problem done, but then that would be $4000 just in antennas :-( But also means upgrading mounting pole and ballast hardware. Which brings me back to my original post, is it just cheaper to buy better radios, and which have better C/Is and SNR threshholds? The orthogon has more power
[WISPA] BPSK QAM16 DSSS interference
I have a problem where BPSK modulation has packet loss due to interference greater than QAM16 at good RSSI levels. I am using tons of DSSS all around the troubled OFDM link. (16 PtMP links totalled from two cells, 2 miles apart). And my DSSS links most likely are the culprits causing some self interference with the OFDM PtP link. So is there anything about BPSK modulation that would make it more prone to interferrence from DSSS radios apposed to QAM16? RSSI at -65 when this occured most obviously. QPSK had similar characteristic/loss as BPSK, when comparing to QAM16. At -55 QAM modulations got worse/unusable, possibly because overloaded by self noise. At -75 QAM modulations got worse/unusable, possibly because to close to noise floor (-80). Testing at -65 was the sweet spot that QAM worked well, much better than BPSK and QPSK. QOS loss was relatively consistent for BPSK/QPSK at -55,-65, rssi, with a little more degregation at -75 for QPSK as getting close to noise. Note: 10 mile link. Rssi adjustments accomplished by reducing radio TX power on both ends, Antenna type remained constant. For the purpose of this discussion, I'm looking for theory pertaining to all radios, not a specific brand. Tom DeReggi RapidDSL Wireless, Inc IntAirNet- Fixed Wireless Broadband -- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
