Www.planet.com.tw Application Guide For Mesh AP – MAP-3120 How to optimize the backhaul performance? F/W: 3.1.4.

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Application Guide For Mesh AP – MAP-3120

How to optimize the backhaul performance?

F/W: 3.1.4

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Preface

This guide help to configure the MAP-3120 to have the optimal setting from Web

The concepts also can apply to MAP-3100 and the previous model MAP-2000/MAP-2100


Topics

Network Hypothesis Backhaul Concepts How to check the connections How to maintain the

connections


Network Hypothesis

Assumes the network is as the topology right-hand side

Three Nodes, two @ 1st Floor, one @ 2nd floor

1F: GW253 & Relay252

2F: Relay251MESH

GW

MESH Relay

MESH Relay

Internet Router

Ethernet Switch

192.168.0.251@ 2F

192.168.0.252@ 1F 192.168.0.253

@ 1F

2.4GHz 802.11b/g Wireless Coverage

5.8GHz 802.11a Wireless Backhaul Link

5.8GHz 802.11a Wireless Backhaul Indirect Link

Note: Please also refer to MAP3K_AppGuide1 for some more information about this example.


Wireless Ad-Hoc Network Each nodes’ wireless coverage

should at least reach one of the Mesh other nodesLine-of-Sight

For non Line-of-Sight, there will need to have field test for the signal strength

That is, shouldhear other Mesh nodes!

MESH GW

MESH Relay

MESH Relay

Internet Router

Ethernet Switch

Backhaul Concepts

192.168.0.251@ 2F

192.168.0.253@ 1F

2.4GHz 802.11b/g Wireless Coverage



5.8GHz 802.11a Wireless Backhaul wireless coverage

應用程式

MESH GW

MESH Relay

MESH Relay

Internet Router

Ethernet Switch

應用

程式

MESH GW

MESH Relay

MESH Relay

Internet Router

Ethernet Switch


The Backhaul use the same ESSID Channels Security

This Backhaul use the same bandwidth IEEE802.11a/g: 54Mbps IEEE802.11b: 11Mbps TurboA/TurboG available automatically only at certain channels

Turbo A: channel 42, 50, 58, 152, 160 Turbo G: channel 6

Backhaul Concepts



MESH GW

MESH Relay

MESH Relay

Internet Router

Ethernet Switch

The same Backhaul Ad-Hoc domain


Check the Connections

A Good Link is both ends can hear each other clearly instead of one with powerful output power yet weak at listening to its link partner

A Good Clear Link is

At least RSSI can be at range 30 ~ 50dbm

Or receive sensitivity -35 ~-65dbm

Or the SOM (System Operation Margin) > 20dbm

RSSI below 20dbm or SOM below 10dbm, the link will not stable

RSSI above 60dbm, the voice could too loud to hear clearly

Note: 1. To check the SOM, please also refer to the URL page: http://huizen.deds.nl/~pa0hoo/helix_wifi/linkbudgetcalc/wlan_budgetcalc.html2. A simple way to convert RSSI to sensitivity is roughly:(RSSI value) - 95 = (Receive Sensitivity)



You can check the connectivity in advanced through the URL link

http://huizen.deds.nl/~pa0hoo/helix_wifi/linkbudgetcalc/wlan_budgetcalc.html



From Web page, click on Status -> Neighboor Example on Gateway 253 Gateway hear itselfGateway hear Relay252

19

Too Weak!!Unstable Link.60

Too Strong!!Too loud to transmit data

48

30~50OK!

Note: This RSSI value could change. It could be changed due to the environment factors, say, other wireless radio frequency in the air or reflections, dust, humidity changes or there could be walking people, objects moving around etc.



MESH

GW

MESH Relay

Internet Router

Ethernet Switch

Gateway 253 Web page

192.168.0.252@ 1F

192.168.0.253@ 1F

Relay 252 Web page

48dbm

Relay 252 Receive Signal Strength Indication

Gateway 253 RSSI

45dbm

Good Links toward Gateway and Relay

Example Reference Table:IEEE802.11a, Channel:160TX: 20dbmRX: -67dbm @ 54MbpsAntenna: 10dbiSpace loss: 50m =81dbm; Cable loss 0.3m = 0.1dbm

20+10-81 – 0.2 = -51.8dbm > - 67dbm (SOM >16dbm)

Ceiling mount, no objects / fence / wall in between


Maintain the Connections

Physically Check the angle of the Antenna

Both ends

Empower the Antenna

Could be one end or both ends

Check if there is loosen cable/connector that cause cable loss

Could be one end or both ends

Check if there is objects that cause the space loss

Logically Fix the data rate, say, manual set

to lower rate to gain more sensitivities

One end

MESH

GW

MESH Relay

Internet Router

Ethernet Switch

192.168.0.252@ 1F

192.168.0.253@ 1F

48dbm

20dbm

Hint:Check the spec. of the antenna. Wrong antenna say, 11g 2.4G antenna can not be applied to 11a frequency and without doubt will get a weak connection. In this example, could need to check GW’s antenna!!

Weak Connections



Physically

Reduce the antenna power Logically

Reduce the TX power

MESH

GW

MESH Relay

Internet Router

Ethernet Switch

192.168.0.252@ 1F

192.168.0.253@ 1F

60dbm

45dbm

Strong Connections



The Neighbor Listing

All the RSSI are in the range of 30 ~ 50dbm

If there are some links too weak, consider to remove it from the list (refer to App Guide 4)

Compare both ends

Due to backhaul is using the same CSMA/CA domain, to have an optimal performance, make sure both ends’ RSSI is close to each other, say in 10db difference

MESH

GW

MESH Relay

Internet Router

Ethernet Switch

192.168.0.252@ 1F

192.168.0.253@ 1F

48dbm

45dbm


Example Reference Table:IEEE802.11a, Channel:160TX: 20dbmRX: -67dbm @ 54MbpsAntenna: 10dbiSpace loss: 50m =81dbm; Cable loss 0.3m = 0.1dbm

20+10-81 – 0.2 = -51.8dbm > - 67dbm (SOM >16dbm)

Ceiling mount, no objects / fence / wall in between

Good Connections

30~ 50dbm

A dbm

B dbm

(A –B) < +/-10


Summary

To have the optimized backhaul performance

Check the RSSI from Web page -> Status -> Neighbor

The RSSI should not exceed 60

The RSSI should not below 20, at least above 30

A fair connection should be in the range 30 ~50dbm

The RSSI subtract between one nodes and its link partner should with in 10db, no more then 20db

MESH

GW

MESH Relay

Internet Router

Ethernet Switch

192.168.0.252@ 1F

192.168.0.253@ 1F

48dbm

45dbm



Summary

Overall backhaul bridging throughput 50Mbps @ 1024byte on this example Tested via IXIA1600, total 128 MAC address


One more Questions

Question: IF the three nodes got an average RSSI level to 30dbm, can I still

have a good connection? Answer:

Yes, if ALL the RSSI level is close to each other (in at least below 10db), the link should be fine.

BUT, if one of the node got a strong RSSI or TX power, that raise the RSSI to, say, 50dbm and the other end is 29 (50-29 > 30db), then the performance could be unstable.

Suggestions: Please consider to increase the power to make it better, like TX

power (from web page) or powerful antenna. Each nodes, in average up to 35 or 40dbm could much more better.

Also can consider to fix the data rate to make the link more stable. For example, due to the RSSI is stable in this example, we can set it to fixed 54Mbps. And if the RSSI is not so high, then, can fixed at 24Mbps or 36Mbps.


MESH GW

MESH Relay

MESH Relay

Internet Router

Ethernet Switch

Appendix

Performance Result on this example

SNMP Statistic Packet size: 1024byte

Simulate 128 nodes / MAC

Simulate 25Mbps injects to backhaul from gateway and 12.5Mbps to backhaul from relay

Backhaul Output Performance

0

10

20

30

40

50

60

04/23/20

08 18:1

7:54

04/23/20

08 18:2

0:54

04/23/20

08 18:2

3:54

04/23/20

08 18:2

6:54

04/23/20

08 18:2

9:54

04/23/20

08 18:3

2:54

04/23/20

08 18:3

5:54

04/23/20

08 18:3

8:54

04/23/20

08 18:4

3:54

04/23/20

08 18:4

8:24

04/23/20

08 18:5

2:55

04/23/20

08 18:5

7:27

04/23/20

08 19:0

1:57

04/23/20

08 19:0

6:27

04/23/20

08 19:1

0:57

04/23/20

08 19:1

5:27

04/23/20

08 19:1

9:57

04/23/20

08 19:2

4:27

04/23/20

08 19:2

8:57

04/23/20

08 19:3

3:28

04/23/20

08 19:3

7:58

04/23/20

08 19:4

2:30

04/23/20

08 19:4

7:00

Time

Mbp

s

Gatew ay Out

Relay252 Out

Relay251 Out

Total (bps)

25Mbps

12.5Mbps

12.5Mbps

Castle Rock SNMPc Monitor Point

Www.planet.com.tw Application Guide For Mesh AP – MAP-3120 How to optimize the backhaul performance? F/W: 3.1.4.

Documents

wireless ad

nodes wireless coverage

good link

connections slide

unstable link

bg wireless coverage

dbm rssi

url page