Hi Chris, What is the optimum SNR or aka the sweet spot.
Which actually leads to another question which I have... On my link, I had to manually reduce TX Power to 10dBm (lowest possible) in order to end up with a SNR of 35/37... Can we possible see this being done by TPC vs a manual power decrease ? Regards. Faisal Imtiaz Snappy Internet & Telecom 7266 SW 48 Street Miami, FL 33155 Tel: 305 663 5518 x 232 Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net > From: "Chris Trout" <ch...@mimosa.co> > To: af@afmug.com > Sent: Thursday, January 26, 2017 12:32:32 PM > Subject: Re: [AFMUG] B11, TDMA, and TCP > Great point, Tim. I have updated our documentation. > Transmit compression starts at 27 dBm Tx power on backhaul products. TPC backs > off from this value automatically if SNR allows. > Mimosa backhaul radios are capable of associating at relatively high Rx power > levels (between -30 and -20 dBm). However, higher power levels cause the > receivers to saturate, and this increases the error vector magnitude (EVM). > For > this reason, Mimosa recommends designing links with -30 dBm or lower received > power to avoid saturation. > To optimize RF performance, adjust Tx power on the AP while monitoring both Rx > power and EVM on the Station side of the link. Tx power should be set to a > value that results in the lowest EVM value. > The only reason why some compression or saturation may be acceptable is in the > case of low SNR, which has a larger effect on overall performance. > Chris Trout > Mimosa Networks, Inc. > From: Af <af-boun...@afmug.com> on behalf of "Hardy, Tim" > <tha...@comsearch.com> > Reply-To: "af@afmug.com" <af@afmug.com> > Date: Wednesday, January 25, 2017 at 6:47 PM > To: "af@afmug.com" <af@afmug.com> > Subject: Re: [AFMUG] B11, TDMA, and TCP > Chris, > It might help us design these properly if we knew what the saturation levels > were. We have these for most other radios. > Thanks, > Tim > From: Af <af-boun...@afmug.com> on behalf of Chris Trout <ch...@mimosa.co> > Sent: Wednesday, January 25, 2017 9:22:14 PM > To: af@afmug.com > Subject: Re: [AFMUG] B11, TDMA, and TCP > The PHY (Layer 1) is affected by EVM and PER which cause changes in > modulation. > The MAC (Layer 2), where TDMA lives, makes use of the PHY but does not change > it > directly. > Changes in the amount and direction of traffic across the link do affect EVM > and > PER, however. > It is likely that the PHY rate is more stable on your link at 1300 Mbps (MCS7) > than at 1560 Mbps (MCS8), and Auto TDMA is reacting faster to changing > conditions since it sends a shorter duration of packets for training the PHY > rate. > As others have recommended, reducing power will avoid saturating the receiver, > and reduce (improve) EVM. I think that is what we may be seeing here on a very > short link. > Chris Trout > Mimosa Networks, Inc. > From: Af <af-boun...@afmug.com> on behalf of Chris Wright > <ch...@velociter.net> > Reply-To: "af@afmug.com" <af@afmug.com> > Date: Wednesday, January 25, 2017 at 1:55 PM > To: "af@afmug.com" <af@afmug.com> > Subject: Re: [AFMUG] B11, TDMA, and TCP > Traffic Split set to Auto: > PHY 1300/1300 > Traffic Split set to 75/25, 8ms window: > PHY 1560/1300 > Anyone can see why one should prefer setting the Traffic Split to 75/25 – it > provides more bandwidth in one direction. > Chris Wright > Network Administrator > From: Faisal Imtiaz [mailto:fai...@snappytelecom.net] > Sent: Wednesday, January 25, 2017 12:35 PM > To: af@afmug.com > Cc: Chris Wright > Subject: Re: [AFMUG] B11, TDMA, and TCP > Hi Chris, > I want to compare something with my link... > Can you please share what's the listed PHY rates were on your PCN for the > link. > Regards. > Faisal Imtiaz > Snappy Internet & Telecom > 7266 SW 48 Street > Miami, FL 33155 > Tel: 305 663 5518 x 232 > Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net >> From: "Chris Wright" < ch...@velociter.net > >> To: af@afmug.com >> Sent: Wednesday, January 25, 2017 11:21:12 AM >> Subject: Re: [AFMUG] B11, TDMA, and TCP >> Power is already at the minimum (10dBm) on both sides. 2.2km link. >> Chris Wright >> Network Administrator >> From: Af [ mailto:af-boun...@afmug.com ] On Behalf Of Faisal Imtiaz >> Sent: Tuesday, January 24, 2017 9:56 PM >> To: af@afmug.com >> Subject: Re: [AFMUG] B11, TDMA, and TCP >> > SNR 41, 42, 41, 41 >> Turn down your power, and bring the SNR in the 30-35 range... >> it will improve thruput and allow for the higher modulation. >> Regards. >> Faisal Imtiaz >> Snappy Internet & Telecom >> 7266 SW 48 Street >> Miami, FL 33155 >> Tel: 305 663 5518 x 232 >> Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net >>> From: "Chris Wright" < ch...@velociter.net > >>> To: af@afmug.com >>> Sent: Wednesday, January 25, 2017 12:41:37 AM >>> Subject: Re: [AFMUG] B11, TDMA, and TCP >>> Firmware 1.4.4 >>> SNR 41, 42, 41, 41 >>> Flow Control had no effect so it remains disabled for now. >>> Sent via mobile phone. >>> On Jan 24, 2017, at 9:05 PM, Faisal Imtiaz < fai...@snappytelecom.net > >>> wrote: >>>> What version for firmware is on the radio ? >>>> and What your SNR on the two chains (both directions, i.e. 4 readings). >>>> I can tell you that we do not see the behavior you are describing below... >>>> But I can also tell you that we had to do some 'tuning' on settings >>>> including >>>> flow control .. >>>> our B11's plug into netonix Switches.... >>>> Regards. >>>> Faisal Imtiaz >>>> Snappy Internet & Telecom >>>> 7266 SW 48 Street >>>> Miami, FL 33155 >>>> Tel: 305 663 5518 x 232 >>>> Help-desk: (305)663-5518 Option 2 or Email: supp...@snappytelecom.net >>>>> From: "Chris Wright" < ch...@velociter.net > >>>>> To: af@afmug.com >>>>> Sent: Tuesday, January 24, 2017 8:02:58 PM >>>>> Subject: [AFMUG] B11, TDMA, and TCP >>>>> According to Mimosa, I should be telling my customers that if they’re >>>>> using the >>>>> most popular metric in the world for testing internet speeds, they’re >>>>> doing it >>>>> wrong (I concede that while this may be technically correct, my customers >>>>> – and >>>>> yours too – don’t do technically correct very well.” >>>>> When TDMA is set to 75/25, 8ms window, MAC Tx/Rx is 980/290. This gives >>>>> me as >>>>> much Tx bandwidth as I require for peak times, but no one client IP can >>>>> download more than 20mbps of TCP traffic (from my speedtest.net at the >>>>> edge, >>>>> nor anyone else’s beyond my edge). >>>>> When TDMA is Auto, MAC Tx/Rx is 780/780 (lower Tx, which is undesirable >>>>> as it’s >>>>> 100mbps shy of what I need during peak hours), but TCP throughput per >>>>> client is >>>>> greatly increased (150+mbps). >>>>> So I’m in a pickle. Either my scrupulous customers can get those coveted >>>>> speedtest.net results they love seeing as they run them every thirty >>>>> seconds >>>>> ad-nauseum at the cost of overall Tx capacity of the link. Or I give >>>>> myself >>>>> some headroom in link capacity but the fastest speeds my 100mbps clients >>>>> can >>>>> see is 20mbps. >>>>> What’s even stranger is that client upload seems unaffected. I can upload >>>>> 150+mbps from my test on the link no matter what TDMA is configured. I >>>>> hit up >>>>> Mimosa’s chat support was as chipper as they were unyielding in their >>>>> idea that >>>>> I should test in a way that caters to the B11’s shortcomings. I’ve been a >>>>> Mimosa fanboy for a while now but boy am I feeling burned right now. >>>>> Chris Wright >>>>> Network Administrator
