NV2 Disconnections

sricci · Thu Jul 28, 2011 1:19 pm

Hi,

we're experiencing an outstanding disconnection problem between AP and a client; the client dissociates roughly every 30 minutes. We already tried some modifications to the config (eg. increasing tdma period), but without any success at all.

This is the configuration:

AP: RB433AH with a sector

/interface wireless
set 0 adaptive-noise-immunity=none allow-sharedkey=no antenna-gain=0 area="" arp=enabled band=5ghz-onlyn basic-rates-a/g=6Mbps \
    basic-rates-b=1Mbps bridge-mode=enabled channel-width=20mhz compression=no country=italy default-ap-tx-limit=0 \
    default-authentication=no default-client-tx-limit=0 default-forwarding=yes dfs-mode=none disable-running-check=no disabled=no \
    disconnect-timeout=3s distance=dynamic frame-lifetime=0 frequency=5540 frequency-mode=manual-txpower frequency-offset=0 hide-ssid=\
    no ht-ampdu-priorities=0 ht-amsdu-limit=8192 ht-amsdu-threshold=8192 ht-basic-mcs=mcs-0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7 \
    ht-guard-interval=any ht-rxchains=0,1 ht-supported-mcs=\
    mcs-0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7,mcs-8,mcs-9,mcs-10,mcs-11,mcs-12,mcs-13,mcs-14,mcs-15 ht-txchains=0,1 \
    hw-fragmentation-threshold=disabled hw-protection-mode=none hw-protection-threshold=0 hw-retries=7 l2mtu=2290 mac-address=\
    00:14:6C:65:6F:15 max-station-count=2007 mode=ap-bridge mtu=1500 name=wlan1 noise-floor-threshold=default nv2-cell-radius=15 \
    nv2-noise-floor-offset=default nv2-qos=default nv2-queue-count=2 nv2-security=enabled on-fail-retry-time=100ms \
    periodic-calibration=default periodic-calibration-interval=60 preamble-mode=both proprietary-extensions=post-2.9.25 radio-name=\
    00146C656F15 rate-selection=legacy rate-set=default scan-list=default security-profile=default ssid=alpha station-bridge-clone-mac=\
    00:00:00:00:00:00 supported-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps,48Mbps,54Mbps supported-rates-b=\
    1Mbps,2Mbps,5.5Mbps,11Mbps tdma-period-size=3 tx-power-mode=default update-stats-interval=disabled wds-cost-range=50-150 \
    wds-default-bridge=bridge1 wds-default-cost=100 wds-ignore-ssid=no wds-mode=dynamic wireless-protocol=nv2 wmm-support=disabled

LOGS:

11:02:31 wireless,info 00:0C:42:88:D6:AB@wlan1: disconnected, not responding 
11:02:33 wireless,debug wlan1: 00:0C:42:88:D6:AB in local ACL, accept 
11:02:33 wireless,info 00:0C:42:88:D6:AB@wlan1: reconnecting 
11:02:33 wireless,debug wlan1: 00:0C:42:88:D6:AB in local ACL, accept 
11:02:34 wireless,info 00:0C:42:88:D6:AB@wlan1: connected 
11:36:29 wireless,info 00:0C:42:88:D6:AB@wlan1: disconnected, not responding 
11:36:31 wireless,debug wlan1: 00:0C:42:88:D6:AB in local ACL, accept 
11:36:31 wireless,info 00:0C:42:88:D6:AB@wlan1: connected 
11:57:42 wireless,info 00:0C:42:96:B8:96@wlan1: disconnected, not responding 
11:57:52 wireless,debug wlan1: 00:0C:42:96:B8:96 in local ACL, accept 
11:57:52 wireless,info 00:0C:42:96:B8:96@wlan1: connected 
11:59:45 wireless,info 00:0C:42:88:D6:AB@wlan1: disconnected, not responding 
11:59:45 wireless,debug wlan1: 00:0C:42:88:D6:AB in local ACL, accept 
11:59:45 wireless,info 00:0C:42:88:D6:AB@wlan1: connected

Client: SXT 5HnD

/interface wireless
set 0 adaptive-noise-immunity=none allow-sharedkey=no antenna-gain=0 area="" arp=enabled band=5ghz-onlyn basic-rates-a/g=6Mbps \
    bridge-mode=enabled channel-width=20mhz compression=no country=italy default-ap-tx-limit=0 default-authentication=yes \
    default-client-tx-limit=0 default-forwarding=yes dfs-mode=none disable-running-check=no disabled=no disconnect-timeout=3s distance=\
    dynamic frame-lifetime=0 frequency=5600 frequency-mode=manual-txpower frequency-offset=0 hide-ssid=no ht-ampdu-priorities=0 \
    ht-amsdu-limit=8192 ht-amsdu-threshold=8192 ht-basic-mcs=mcs-0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7 ht-guard-interval=any \
    ht-rxchains=0,1 ht-supported-mcs=\
    mcs-0,mcs-1,mcs-2,mcs-3,mcs-4,mcs-5,mcs-6,mcs-7,mcs-8,mcs-9,mcs-10,mcs-11,mcs-12,mcs-13,mcs-14,mcs-15 ht-txchains=0,1 \
    hw-fragmentation-threshold=disabled hw-protection-mode=none hw-protection-threshold=0 hw-retries=7 l2mtu=2290 mac-address=\
    00:0C:42:88:D6:AB max-station-count=2007 mode=station mtu=1500 name=wlan1 noise-floor-threshold=default nv2-cell-radius=30 \
    nv2-noise-floor-offset=default nv2-qos=default nv2-queue-count=2 nv2-security=enabled on-fail-retry-time=100ms \
    periodic-calibration=default periodic-calibration-interval=60 preamble-mode=both proprietary-extensions=post-2.9.25 radio-name=\
    000C4288D6AB rate-selection=legacy rate-set=default scan-list=default security-profile=default ssid=alpha station-bridge-clone-mac=\
    00:00:00:00:00:00 supported-rates-a/g=6Mbps,9Mbps,12Mbps,18Mbps,24Mbps,36Mbps,48Mbps,54Mbps tdma-period-size=2 tx-power-mode=\
    default update-stats-interval=disabled wds-cost-range=50-150 wds-default-bridge=none wds-default-cost=100 wds-ignore-ssid=no \
    wds-mode=disabled wireless-protocol=nv2 wmm-support=disabled

11:02:28 wireless,info 00:14:6C:65:6F:15@wlan1: lost connection, synchronization timeout 
11:02:33 wireless,debug wlan1: must select network 
11:02:33 wireless,debug 00:80:48:XX:XX:XX: on 5300 AP: yes SSID xxxxxxx caps 0x431 rates 0xff00 basic 0x100 MT: yes 
11:02:33 wireless,debug 00:0C:42:XX:XX:XX: on 5500 AP: no SSID xxxxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:02:33 wireless,debug 00:10:E7:XX:XX:XX: on 5520 AP: yes SSID xxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:02:33 wireless,debug 00:10:E7:XX:XX:XX: on 5520 AP: yes SSID xxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:02:33 wireless,debug 00:11:22:XX:XX:XX: on 5700 AP: no SSID xxxxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:02:33 wireless,debug 00:80:48:XX:XX:XX: on 5540 AP: yes SSID xxxxxxx caps 0x431 rates 0xff00 basic 0x100 MT: yes 
11:02:33 wireless,debug 00:14:6C:65:6F:15: on 5540 AP: no SSID alpha caps 0x0 rates 0x0 basic 0x0 MT: no 
11:02:33 wireless,debug 00:0C:42:XX:XX:XX: on 5500 AP: no SSID xxxxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:02:34 wireless,info 00:14:6C:65:6F:15@wlan1 established connection on 5540, SSID alpha 
11:36:26 wireless,info 00:14:6C:65:6F:15@wlan1: lost connection, synchronization timeout 
11:36:31 wireless,debug wlan1: must select network 
11:36:31 wireless,debug 00:80:48:XX:XX:XX: on 5300 AP: yes SSID xxxxxx caps 0x431 rates 0xff00 basic 0x100 MT: yes 
11:36:31 wireless,debug 00:0C:42:XX:XX:XX: on 5500 AP: no SSID xxxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:36:31 wireless,debug 00:10:E7:XX:XX:XX: on 5520 AP: yes SSID xxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:36:31 wireless,debug 00:10:E7:XX:XX:XX: on 5520 AP: yes SSID xxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:36:31 wireless,debug 00:11:22:XX:XX:XX: on 5700 AP: no SSID xxxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:36:31 wireless,debug 00:14:6C:65:6F:15: on 5540 AP: no SSID alpha caps 0x0 rates 0x0 basic 0x0 MT: no 
11:36:31 wireless,debug 00:0C:42:XX:XX:XX: on 5500 AP: no SSID xxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:36:31 wireless,debug 00:10:E7:XX:XX:XX: on 5500 AP: yes SSID xxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:36:31 wireless,debug 00:15:6D:XX:XX:XX: on 5640 AP: yes SSID xxxxxxx caps 0x431 rates 0x3f00 basic 0x100 MT: yes 
11:36:31 wireless,debug 00:10:E7:XX:XX:XX: on 5700 AP: yes SSID xxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:36:31 wireless,debug 00:10:E7:XX:XX:XX: on 5700 AP: yes SSID xxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:36:31 wireless,info 00:14:6C:65:6F:15@wlan1 established connection on 5540, SSID alpha 
11:59:40 wireless,info 00:14:6C:65:6F:15@wlan1: lost connection, synchronization timeout 
11:59:45 wireless,debug wlan1: must select network 
11:59:45 wireless,debug 00:80:48:XX:XX:XX: on 5300 AP: yes SSID xxxxxxx caps 0x431 rates 0xff00 basic 0x100 MT: yes 
11:59:45 wireless,debug 00:0C:42:XX:XX:XX: on 5500 AP: no SSID xxxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:59:45 wireless,debug 00:10:E7:XX:XX:XX: on 5520 AP: yes SSID xxxxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:59:45 wireless,debug 00:10:E7:XX:XX:XX: on 5520 AP: yes SSID xxxxxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:59:45 wireless,debug 00:11:22:XX:XX:XX: on 5700 AP: no SSID xxxxxxx caps 0x0 rates 0x0 basic 0x0 MT: no 
11:59:45 wireless,debug 00:14:6C:65:6F:15: on 5540 AP: no SSID alpha caps 0x0 rates 0x0 basic 0x0 MT: no 
11:59:45 wireless,debug 00:10:E7:XX:XX:XX: on 5700 AP: yes SSID xxxxxxxx caps 0x1 rates 0xff00 basic 0x100 MT: no 
11:59:45 wireless,debug 00:80:48:XX:XX:XX: on 5540 AP: yes SSID xxxxxxx caps 0x431 rates 0xff00 basic 0x100 MT: yes 
11:59:45 wireless,debug 00:80:48:XX:XX:XX: on 5580 AP: yes SSID xxxxxxxx caps 0x431 rates 0xff00 basic 0x100 MT: yes 
11:59:45 wireless,info 00:14:6C:65:6F:15@wlan1 established connection on 5540, SSID alpha

nv2-security is enabled (we tried without it, too), and access point has been added to client's connect list.

Any hints?

Regards,
Simone

n21roadie · Thu Jul 28, 2011 1:40 pm

With NV2 disconnects your next option is to contact MT support and they may give you a pre-release v5.6 to test on your network

Thu Jul 28, 2011 1:44 pm

With NV2 disconnects your next option is to contact MT support and they may give you a pre-release v5.6 to test on your network

Read the logs, it's not even Nv2 related.

sricci - can you post the registration table? what are the signals on both sides?

Thu Jul 28, 2011 3:43 pm

you can also email support to get the v5.6 pre-release which has better wireless debug logs, so we can see what causes the disconnects

sricci · Thu Jul 28, 2011 3:54 pm

sricci - can you post the registration table? what are the signals on both sides?

Here's it:

CLIENT:

 0 interface=wlan1 radio-name="00146C656F15" mac-address=00:14:6C:65:6F:15 ap=yes wds=no bridge=no rx-rate="78.0Mbps" tx-rate="117.0Mbps" 
   packets=190213,131459 bytes=249273882,19492483 frames=173267,34349 frame-bytes=249384038,6891240 uptime=33m35s last-activity=0ms 
   signal-strength=-64dBm signal-to-noise=48dB signal-strength-ch0=-67dBm signal-strength-ch1=-68dBm tx-signal-strength-ch0=-66dBm 
   tx-signal-strength-ch1=-68dBm strength-at-rates=-64dBm@6Mbps 0ms,-108dBm@48Mbps 20m10s910ms,-66dBm@HT20-0 32m48s800ms,-67dBm@HT20-1 
                  32m48s460ms,-67dBm@HT20-2 33m12s90ms,-68dBm@HT20-3 33m10s900ms,-70dBm@HT20-4 30ms,-70dBm@HT20-5 10ms,-71dBm@HT20-6 2s610ms,-
                  71dBm@HT20-7 1s150ms 
   tx-signal-strength=-64dBm tx-ccq=97% rx-ccq=62% distance=4 routeros-version="5.5" last-ip=x.x.x.x encryption=aes-ccm 
   group-encryption=aes-ccm tdma-timing-offset=25 tdma-tx-size=3056 tdma-rx-size=2544 tdma-retx=8 tdma-winfull=19

AP:

 1 interface=wlan1 radio-name="000C4288D6AB" mac-address=00:0C:42:88:D6:AB ap=no wds=no bridge=yes rx-rate="130.0Mbps" tx-rate="78.0Mbps" 
   packets=333807,510076 bytes=56790958,647942760 frames=105678,458642 frame-bytes=57829091,597210602 uptime=35m48s last-activity=0ms 
   signal-strength=-65dBm signal-to-noise=41dB signal-strength-ch0=-67dBm signal-strength-ch1=-69dBm tx-signal-strength-ch0=-67dBm 
   tx-signal-strength-ch1=-68dBm strength-at-rates=-65dBm@6Mbps 0ms,-69dBm@54Mbps 30ms,-64dBm@HT20-0 35m13s800ms,-62dBm@HT20-1 35m13s610ms,-
                  67dBm@HT20-2 35m20s740ms,-67dBm@HT20-3 35m19s890ms,-66dBm@HT20-4 2m20s850ms,-69dBm@HT20-5 2s800ms,-70dBm@HT20-6 40ms,-
                  62dBm@HT20-7 10ms 
   tx-signal-strength=-64dBm tx-ccq=62% rx-ccq=77% distance=6 routeros-version="5.4" last-ip=172.31.1.5 encryption=aes-ccm 
   group-encryption=aes-ccm tdma-timing-offset=35 tdma-tx-size=2544 tdma-rx-size=3056 tdma-retx=46 tdma-winfull=0

Thank you for your prompt reply !

Regards,
Simone.

n21roadie · Thu Jul 28, 2011 4:14 pm

Can you post frequency scan both ends so we can see what other devices and at what signal levels the 433+SXT are picking up.

sricci · Thu Jul 28, 2011 4:35 pm

Can you post frequency scan both ends so we can see what other devices and at what signal levels the 433+SXT are picking up.

That's the scan executed from the AP (RB433)

Flags: A - active, B - bss, P - privacy, R - routeros-network, N - nstreme, T - tdma 
      ADDRESS           SSID                                   BAND   CHANNEL-WIDTH FREQ SIG   NF SNR RADIO-NAME                                  
AB RN 00:15:6D:XX:XX:XX xxxx                                   5ghz-n 20mhz         5180 -89 -115  26                               
ABPRN 00:80:48:XX:XX:XX xxxxx                                  5ghz-n 20mhz         5200 -88 -115  27                             
ABPR  00:15:6D:XX:XX:XX xxxxxxxx                               5ghz-n 20mhz         5260 -80 -115  35                                       
ABPR  00:15:6D:XX:XX:XX xxxxxx                                 5ghz-n 20mhz         5280 -89 -115  26                                    
AB    00:12:9E:XX:XX:XX xxxxxxx                                5ghz-n 20mhz         5500 -89 -110  21
ABPR  00:80:48:XX:XX:XX xxxxxxxxx                              5ghz-n 20mhz         5500 -86 -110  24                                 
A  RT 00:0C:42:XX:XX:XX xxxxxx                                 5ghz-n 20mhz         5500 -77 -110  33                                
A  RT 00:0C:42:XX:XX:XX xxxx                                   5ghz-n 20mhz         5500 -86 -110  24                                             
AB    00:10:E7:XX:XX:XX xxxxxxxxx                              5ghz-n 20mhz         5500 -88 -110  22
AB R  00:15:6D:XX:XX:XX xxxxxxxxxxxx                           5ghz-n 20mhz         5560 -80 -110  30                             
AB R  00:80:48:XX:XX:XX xxxxxxxxxx                             5ghz-n 20mhz         5560 -86 -110  24                                
ABPR  00:80:48:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5600 -90 -102  12                             
ABPR  00:80:48:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5600 -89 -102  13                            
ABPR  00:80:48:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5620 -82 -108  26                         
AB RN 00:15:6D:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5640 -87 -102  15                                
A PRT 00:0C:42:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5680 -57 -102  45                                
ABPRN 00:0C:42:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5680 -88 -102  14                                   
AB RN 00:0B:6B:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5700 -87 -107  20                                      
A  RT 00:11:22:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5700 -80 -107  27                                
A PRT 10:0B:6B:XX:XX:XX xxxxxxxxxxx                            5ghz-n 20mhz         5620 -75 -108  33

I can't scan the client right now because it's single-homed ad I loose the connectivity.

Regards,
Simone.

n21roadie · Thu Jul 28, 2011 4:56 pm

I notice you have a strong signal at 5680, is that yours or someone else, what is your AP frequency

A PRT 00:0C:42:XX:XX:XX xxxxxxxxxxx 5ghz-n 20mhz 5680 -57 -102 45

It will be interesting to see the scan from CPE end?
And if possible can you scan at 5Mhz + 10Mhz only post if you find anything

sricci · Fri Jul 29, 2011 4:09 am

Hi guys,

thank you all for the prompt support, in the meantime we discovered the problem.
We had another AP on another tower (few meters away) @5500, after changing that one's frequency (gaining +20 mhz in spacing) all issues went away. At the present, we can confirm that TDMA needs 80-100 mhz spacing to work well (maybe because radio framing splatters a bit?).
Link began rock solid, 90 mbit/s in UDP (which - IMHO - is good, for a 20mhz channel )

Mikrotik, keep on your nice work !

Regards,
Simone.

Fri Jul 29, 2011 8:17 am

Hi guys,

thank you all for the prompt support, in the meantime we discovered the problem.
We had another AP on another tower (few meters away) @5500, after changing that one's frequency (gaining +20 mhz in spacing) all issues went away. At the present, we can confirm that TDMA needs 80-100 mhz spacing to work well (maybe because radio framing splatters a bit?).
Link began rock solid, 90 mbit/s in UDP (which - IMHO - is good, for a 20mhz channel )

Mikrotik, keep on your nice work !

Regards,
Simone.

This makes NV2 useless in a multisector setup. With >2 sectors in 5GHz we cant
get 100MHz spacing. So we need some better cards with a narrow band filter or
a sync solution to make it work.

n21roadie · Fri Jul 29, 2011 11:41 am

This makes NV2 useless in a multisector setup. With >2 sectors in 5GHz we cant
get 100MHz spacing. So we need some better cards with a narrow band filter or
a sync solution to make it work.

This is a question to date I cannot get information on, the receive bandwidth is not in any data sheets I have seen so far?

server8 · Fri Jul 29, 2011 11:46 am

Just a question in this scenario Ubiquiti SR71-15 is better than RouterBoard R52Hn? Any experience?

Giuseppe

Fri Jul 29, 2011 12:00 pm

This makes NV2 useless in a multisector setup. With >2 sectors in 5GHz we cant
get 100MHz spacing. So we need some better cards with a narrow band filter or
a sync solution to make it work.
This is a question to date I cannot get information on, the receive bandwidth is not in any data sheets I have seen so far?

As I've seen increasing interference problems with 11n I guess these newer cards do less
RF filtering. Marketing would let us know if something is better now

n21roadie · Fri Jul 29, 2011 12:24 pm

As I've seen increasing interference problems with 11n I guess these newer cards do less
RF filtering. Marketing would let us know if something is better now

My guess is the current build of radio cards are constructed with the domestic customer in mind, where I suspect the receive bandwidth is not critical and can reduce component count (?) on the card by not having a tight if any receive bandwidth but to make the card compliant with regulations the transmit section has bandwidth mask by this they can have very low receive performance which would be reduced if using a band pass filter, am I totally incorrect – strange no card manufacturer has replied to my request for an answer to this question,
Maybe we will see a special build of a radio card for WISP’s and suitable for propriety wireless protocols in the near future to help resolve the issues .

sricci · Fri Jul 29, 2011 3:18 pm

This makes NV2 useless in a multisector setup. With >2 sectors in 5GHz we cant
get 100MHz spacing. So we need some better cards with a narrow band filter or
a sync solution to make it work.

YES a sync solution may do the trick. IMHO the issues we faced are caused by TDMA framing...its continuos bursting tends to splatter a lot (someone with a spectrum analyzer can confirm that?) and two neighboring BSS will jam themselves. Just syncing the framing - assuming the same tdma period size is used on all base stations - may easily do the trick...and that can be done in software (easily, with some cpu overhead).

I honestly hope mikrotik will give us a good solution ASAP, optimal spectrum utilization is a must these days...

Regards,
Simone.

Ciambot · Fri Jul 29, 2011 3:22 pm

Just a question in this scenario Ubiquiti SR71-15 is better than RouterBoard R52Hn? Any experience?

Giuseppe

I've a mimo link with ubiqutiSR71+mikrotikRB, but it has a too many problems: disconnection, low modulation, low ccq (just disconnect manually and modulation goes back high).

Ciambot · Fri Jul 29, 2011 3:37 pm

Thinking well, months ago I saw, through a Infinet spectrum analyzer, that NV2 link adjacent trespass its channel very much.

n21roadie · Fri Jul 29, 2011 3:43 pm

YES a sync solution may do the trick. IMHO the issues we faced are caused by TDMA framing...its continuos bursting tends to splatter a lot (someone with a spectrum analyzer can confirm that?) and two neighboring BSS will jam themselves. Just syncing the framing - assuming the same tdma period size is used on all base stations - may easily do the trick...and that can be done in software (easily, with some cpu overhead).

I honestly hope mikrotik will give us a good solution ASAP, optimal spectrum utilization is a must these days...

Regards,
Simone.

Sync is a good idea but we must remember that for sync to be really effective it must sync all components at a base station AP's + Ptp's and not just the Ap's, in my case on one mast 5 Ap's and 4 Ptp's and increasing.

Fri Jul 29, 2011 8:58 pm

YES a sync solution may do the trick. IMHO the issues we faced are caused by TDMA framing...its continuos bursting tends to splatter a lot (someone with a spectrum analyzer can confirm that?) and two neighboring BSS will jam themselves. Just syncing the framing - assuming the same tdma period size is used on all base stations - may easily do the trick...and that can be done in software (easily, with some cpu overhead).

I honestly hope mikrotik will give us a good solution ASAP, optimal spectrum utilization is a must these days...

Regards,
Simone.
Sync is a good idea but we must remember that for sync to be really effective it must sync all components at a base station AP's + Ptp's and not just the Ap's, in my case on one mast 5 Ap's and 4 Ptp's and increasing.

We use different band for backhaul and APs where possible.

n21roadie · Sat Jul 30, 2011 12:00 am

We use different band for backhaul and APs where possible.

If the frequency for backhaul is below 2.4/5.8 Ap's then monitoring harmonics of the fundamental backhaul frequency is important, we all seen 3rd harmonics driving rf equipment crazy?

Ciambot · Fri Aug 05, 2011 5:40 pm

Just a question in this scenario Ubiquiti SR71-15 is better than RouterBoard R52Hn? Any experience?

Giuseppe
I've a mimo link with ubiqutiSR71+mikrotikRB, but it has a too many problems: disconnection, low modulation, low ccq (just disconnect manually and modulation goes back high).

I tried pair R52Hn: very much worse than SR71! 20-45 Mb vs 60-90 Mb in hard noise environment.
Same enclosures, same antennas, routerboards, pigtales, cables, configurations and RoS.
5.5 RouterOS is much better 5.2.

NV2 Disconnections

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