Bad signal level but good SNR....

cgreen · Wed Oct 09, 2013 11:26 pm

we have started switching over from HP M110 AP's on campus to the mikrotik groove 2.4 AP (the metal one @ 1.6W) i have noticed a issue today and am looking for an answer.

when i login to see the registered clients it shows a few clients connected with what i consider poor signal strength (between -80 to around -89) but the SNR is 35-40.
when i check on the client side with something like inSSIDer it shows the signal to be around -67.

should there be concern or is it just looking at the signal at the client and ap independently.
i know some are going to ask what the config is so ill go ahead and dump a compact.

  MMM      MMM       KKK                          TTTTTTTTTTT      KKK
  MMMM    MMMM       KKK                          TTTTTTTTTTT      KKK
  MMM MMMM MMM  III  KKK  KKK  RRRRRR     OOOOOO      TTT     III  KKK  KKK
  MMM  MM  MMM  III  KKKKK     RRR  RRR  OOO  OOO     TTT     III  KKKKK
  MMM      MMM  III  KKK KKK   RRRRRR    OOO  OOO     TTT     III  KKK KKK
  MMM      MMM  III  KKK  KKK  RRR  RRR   OOOOOO      TTT     III  KKK  KKK

  MikroTik RouterOS 6.1 (c) 1999-2013       http://www.mikrotik.com/

[?]             Gives the list of available commands
command [?]     Gives help on the command and list of arguments

[Tab]           Completes the command/word. If the input is ambigous,
                a second [Tab] gives possible options

/               Move up to base level
..              Move up one level
/command        Use command at the base level
[admin@FM Tower AP] > /export compact 
# oct/09/2013 15:22:19 by RouterOS 6.1
# software id = 799M-DW3T
#
/interface bridge
add l2mtu=1594 name="bcf wireless bridge"
add l2mtu=1594 name="bcf wireless secured bridge"
/interface wireless
set 2 adaptive-noise-immunity=ap-and-client-mode antenna-gain=15 band=\
    2ghz-b/g/n country="united states" disabled=no l2mtu=2290 mode=ap-bridge \
    radio-name=TowerAP ssid="" wireless-protocol=802.11
/ip neighbor discovery
set "bcf wireless VLAN" discover=no
set "bcf_wrls sec VLAN14" discover=no
/interface vlan
add interface=ether1-local l2mtu=1594 name="bcf wireless VLAN" vlan-id=12
add interface=ether1-local l2mtu=1594 name="bcf_wrls sec VLAN14" vlan-id=14
/interface wireless
add default-forwarding=no disabled=no l2mtu=2290 mac-address=\
    D4:CA:6D:7B:0E:9E master-interface=wlan1 name="bcf wireless" ssid=\
    "bcf wireless" wds-cost-range=0 wds-default-cost=0
/ip neighbor discovery
set "bcf wireless" discover=no
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
add authentication-types=wpa2-eap group-ciphers=tkip mode=dynamic-keys name=\
    "bcf secured sec prof" radius-mac-mode=as-username-and-password \
    supplicant-identity="bcf wireless secured" unicast-ciphers=tkip
/interface wireless
add default-forwarding=no disabled=no l2mtu=2290 mac-address=\
    D4:CA:6D:7B:0E:9F master-interface=wlan1 name="bcf wireless secured" \
    security-profile="bcf secured sec prof" ssid="bcf wireless secured" \
    wds-cost-range=0 wds-default-cost=0
/ip neighbor discovery
set "bcf wireless secured" discover=no
/ip hotspot user profile
set [ find default=yes ] idle-timeout=none keepalive-timeout=2m \
    mac-cookie-timeout=3d
/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/system logging action
set 0 memory-lines=1000
set 1 disk-file-count=4 disk-lines-per-file=500
add name=kiwisyslog remote=10.1.35.66 src-address=10.1.35.50 syslog-facility=\
    local1 target=remote
add disk-file-count=4 disk-lines-per-file=1000 name=file target=disk
/tool user-manager customer
add backup-allowed=yes disabled=no login=admin password="" \
    paypal-accept-pending=no paypal-allowed=no paypal-secure-response=no \
    permissions=owner signup-allowed=no time-zone=-00:00
/interface bridge port
add bridge="bcf wireless bridge" interface="bcf wireless VLAN"
add bridge="bcf wireless bridge" interface="bcf wireless"
add bridge="bcf wireless secured bridge" interface="bcf wireless secured"
add bridge="bcf wireless secured bridge" interface="bcf_wrls sec VLAN14"
/ip address
add address=192.168.88.1/24 comment="default configuration" disabled=yes \
    interface=ether1-local network=192.168.88.0
add address=10.1.35.50/24 interface=ether1-local network=10.1.35.0
/ip dhcp-client
add comment="default configuration" dhcp-options=hostname,clientid disabled=\
    no
/ip dhcp-relay
add dhcp-server=10.1.36.1 disabled=no interface=ether1-local name=relay1
/ip dns
set allow-remote-requests=yes max-udp-packet-size=512
/ip dns static
add address=192.168.88.1 name=router
/ip firewall filter
add chain=input comment="default configuration" disabled=yes protocol=icmp
add chain=input comment="default configuration" connection-state=established \
    disabled=yes
add chain=input comment="default configuration" connection-state=related \
    disabled=yes
add action=drop chain=input comment="default configuration" disabled=yes \
    in-interface="(unknown)"
/ip firewall nat
add action=masquerade chain=srcnat comment="default configuration" disabled=\
    yes out-interface="(unknown)" to-addresses=0.0.0.0
/ip service
set telnet disabled=yes
set ftp disabled=yes
set api disabled=yes
/radius
add address=10.1.35.66 secret=******* service=wireless
/system clock
set time-zone-name=America/Chicago
/system identity
set name="FM Tower AP"
/system lcd
set contrast=0 enabled=no port=parallel type=24x4
/system lcd page
set time disabled=yes display-time=5s
set resources disabled=yes display-time=5s
set uptime disabled=yes display-time=5s
set packets disabled=yes display-time=5s
set bits disabled=yes display-time=5s
set version disabled=yes display-time=5s
set identity disabled=yes display-time=5s
set "bcf_wrls sec VLAN14" disabled=yes display-time=5s
set "bcf wireless VLAN" disabled=yes display-time=5s
set "bcf wireless" disabled=yes display-time=5s
set "bcf wireless bridge" disabled=yes display-time=5s
set "bcf wireless secured bridge" disabled=yes display-time=5s
set "bcf wireless secured" disabled=yes display-time=5s
set wlan1 disabled=yes display-time=5s
set ether1-local disabled=yes display-time=5s
/system leds
set 1 interface=ether1-local
/system logging
set 0 topics=warning
set 1 topics=critical
set 2 topics=error
set 3 topics=system
add action=kiwisyslog topics=critical
add action=kiwisyslog topics=error
add action=kiwisyslog topics=event
add action=kiwisyslog topics=info
add action=kiwisyslog topics=system
add action=kiwisyslog topics=warning
add action=file topics=critical
add action=file topics=error
add action=file topics=event
add action=file topics=system
add action=file topics=warning
/system ntp client
set enabled=yes primary-ntp=10.1.35.66
/tool graphing interface
add
/tool graphing resource
add
/tool mac-server
add interface=ether1-local
/tool mac-server mac-winbox
set [ find default=yes ] disabled=yes
add interface=ether1-local
[admin@FM Tower AP] >

samsung172 · Thu Oct 10, 2013 3:31 am

here you could make a calculation of signal. If your AP sends at 1,6W and client have 40mw (as many laptop have) the result could be -80to-89 and -67 in the other side

make a connect list rule, and don't allow clients with bad signal.

Mikrotik is a nice hardware/software in 99% of all systems. But it's bad for large internal hotspot. MT is nice, if you have 100% control of clients. At once as your control of a client don't exist, mikrotik is not the best HW/SW platform. Ita better to use a 20$ Linksys device.

visalink · Thu Oct 10, 2013 5:42 am

here you could make a calculation of signal. If your AP sends at 1,6W and client have 40mw (as many laptop have) the result could be -80to-89 and -67 in the other side

make a connect list rule, and don't allow clients with bad signal.

Mikrotik is a nice hardware/software in 99% of all systems. But it's bad for large internal hotspot. MT is nice, if you have 100% control of clients. At once as your control of a client don't exist, mikrotik is not the best HW/SW platform. Ita better to use a 20$ Linksys device.

I agree with you.
I also have many problems using mikrotik wireless, highly sensitive to interference, many disconnections, low throughput, hight jitter, etc ...

0ldman · Thu Oct 10, 2013 5:21 pm

I've had the exact opposite experience.

I've got several APs on the ground and a couple of hotels running MT. The only issues I've had were power and bad capacitors.

On the original topic, high tx power is wasted when using laptops for clients. I'll run a R52H at default transmit power so the clients have better rx signal for better download speeds, but once you more than 25dB transmit power it seems to cause more problems than it fixes.

A few dB difference between tx and rx is fine, but if you are transmitting 1.6W + antenna gain you are completely blowing away the laptops which tend to max out at 20dB + 2dBi. More than 1W EIRP is overkill.

cgreen · Thu Oct 10, 2013 5:26 pm

does it make more sense to use high gain antennas and turn the tx power down to keep it in the legal limits or is it better to use max tx power with a matched antenna to keep it in the legal limits.

im covering 2 different types of areas.
the first is inside of dorms where there are dorms with 16 or so rooms in it with the AP in the attic with an 7.5 dbi omni.

the second is an outside area where there are apartments. i have a 60' tower with a metal groove ap and a 15dbi panel @ 45 degrees. today im replacing the panel antenna with a 16dbi 90 degree sector antenna.
there is also a pavilion area close by (about 600' away) that has a metal groove ap with a 12dbi omni.

any recommendations on ap/antenna matching with this setup. ill post a pix below. the line measures about 400' in the photo

here is another factor also.... about 30' away from the pavilion ap there is a licensed low power FM broadcast tower for the college.

samsung172 · Fri Oct 11, 2013 3:10 am

Its better to use high gain antennas, and low power cards. But remember for Omni antennas, high gain, make the opening angle shorter. The more power you have to the radio card, the more noise you will get. ITs amplifying noise just as good as the signal you want.

Due to the hotspot MT setup, Off course, it works, but its the last 5% in a big setup, that have bad clients, that will have problem to connect to MT. Encryption is on main big issue here. I have also seen some problem in random dhcp client's connecting to mikrotik etc. Also new power saving devices, with low power and week signal, can mess up the MT device. Also the old standard "ack timeout" ""problem"". Its possible to have mikrotik in all wireless environment, but to use mikrotik 100% you need control. Control of all devices. In a public hotspot setup, you have no control at all so client devices.

cgreen · Fri Oct 11, 2013 9:59 pm

have you ever heard of a low power (i think 100W) FM broadcast tower causing interference with 2.4GHz AP's.

it seem like if i kill power to the transmitter the wifi starts working more reliable and clients get better signals.

like i said earlier the tower is within a few feet of one AP and withing a few hundred feet of the other AP
it is also in the middle of the area im trying to provide coverage for.

cgreen · Fri Oct 11, 2013 10:23 pm

here is one more questions for the wireless guru's out there

is it better to run the AP in b/g mode or b only or g only

i dont care about the throughput so much as i do coverage and penetration into homes.
is one of the modes better than the others in that aspect

samsung172 · Fri Oct 11, 2013 11:43 pm

Old good fashion B mode is best, if speed and performance is no issue.

samsung172 · Fri Oct 11, 2013 11:45 pm

have you ever heard of a low power (i think 100W) FM broadcast tower causing interference with 2.4GHz AP's.

it seem like if i kill power to the transmitter the wifi starts working more reliable and clients get better signals.

like i said earlier the tower is within a few feet of one AP and withing a few hundred feet of the other AP
it is also in the middle of the area im trying to provide coverage for.

I have seen a lot of sources to interference, but the FM signal them self, is not the problem. But a bad cable, in the tower etc, can make strange signals. Try to run a spectral scan.

samsung172 · Fri Oct 11, 2013 11:49 pm

But. if I look into your setup, a outside AP, to make cover inside all your building, is not a easy good idea. If you want to have cover in all house, have a 5ghz omnitik or something, and connect a SXT at each house. Connect a low cost 2,4ghz AP inside, and have the same ssid to all inside AP's. Connect Sxt to lan port, and remove dhcp etc from the lowcost AP's. Make all SXT in station bridge mode, and omnitik as AP bridge, dynamic wds. Put all interface to a bridge, and connect ethenet to a gateway (both tower to the same). Then all building have their own senders, and all clients (inside, outside) will roame between all the clients inside. I have made some setup like this, and its always rock solid.

cgreen · Fri Oct 11, 2013 11:56 pm

that would be nice if funding will allow for it.
it is going to be a slow process to replace all of the low power HP access points with the Tik's.

samsung172 · Sat Oct 12, 2013 1:14 am

2 omnitik and 20 building inside your area. This should all be mounted by 2 guys/girls in 2 days of working. Cost? 445 for sxt sixpack. 89 for a omitik and 20 for TPlink. (routerboard.com, my local distributor have even cheeper sxt's and omnitk's) Total about 2000$ -2500$. To cover 20 CPE 100% for a cost about 100$ each is not to bad.

I don't know about your billing etc, but even in a 10$ per cpe each month, you will make money after less than 1 year. to have 100$ in setup fee, is not that bad either, and you will make money the first day of use. (I don't know to much about your setup/plans, so I cannot tell that this will be a nice way to do stuff, just how I would have done this)

dannyboy · Wed Mar 19, 2014 6:44 am

Ok, I just got three Grooves a-52HPn and they really suck. Atleast with the default config and the 6dbi antenna they are selling it with. I just changed from 5ghz to 2ghz and nothing else. I get 30m away and ccq its no more then 60%, if I go more then 40m I loose connection. This is a really bad radio unless that config is not the best config. I was planning on using MT equipment for a large hotspot but from reading above looks like MT is not the solution for this. What do you guys recommend? I could go back to the nanos or get some opemmesh. I really wanted to work with MT and have my whole network as a MT network. If anyone know of a good groove config that its working for them, please send to me.

Daniboy

Bad signal level but good SNR....

Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

Re: Bad signal level but good SNR....

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