Ieee 802.11 ac throughput very low

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anas

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Aug 10, 2020, 9:20:25 AM8/10/20
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Hello everyone,

I have seen multiple questions regarding 802.11ac throughput here. And most of the answers those questions got are that there are multiple factors that affect the throughput of 802.11ac. But can anybody mention that what are the optimal parameters for 802.11ac test simulation?
I have copied and modified the exact same Ieee 802.11 ac example given in Inet 4.0 (using omnet 5.5.1). I have removed ping app and placed 1 udp basic app in wireless node. This wireless node sends data to a wired node via access point. This way there is only 1 wireless node in the simulation and it generates data at 100Mbps.

scenario is like this: wireless node --wifi-- accesspoint --ethernet-- wired node.
Even with 5ghz 40mhz channel, and qam 64, i cant get more than 50Mbps.

My full scenario files are attached.

If anyone can tell what im doing wrong, it will be great help. And if anyone has managed to get 802.11ac simulation working properly, can you please share the wireless config?

80211ac_test.ned
omnetpp.ini

Khalid Hussain Mohammadani

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Aug 12, 2020, 9:50:04 AM8/12/20
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see the following discussion and also some examples in inet.4.2 like . inet.showcases.wireless.throughput. ..

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Khalid Mohammadani

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Aug 12, 2020, 9:51:11 AM8/12/20
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see the following discussion and also some examples in inet.4.2 like . inet.showcases.wireless.throughput. ..


anas

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Aug 13, 2020, 10:41:05 AM8/13/20
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Thanks for the reply.

I have seen those discussions before posting the question. Those points although valid still doesnt solve the problem. You mentioned that you eventually got 130+Mbps throughput but by varying the size of TXOP. I think that 802.11ac should be able to go way above that throughput without EDCA manipulation. Afterall EDCA reduces the effective throughput that applications get.
I know that 802.11ac can get advertised datarates when only 2 devices are connected and only 1 is transmitting with block ack and aggregation enabled. I have tried this with Wireless aggregation showcase example but without any success. All of the wireless examples/showcases just use 802.11g .. It would have been better and way easier to understand if there was a 802.11n/ac 5ghz throughout example other than basic ping example which is there for 802.11ac.

Khalid Mohammadani

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Aug 14, 2020, 4:13:48 AM8/14/20
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Dear Anas,

Yes, I got 130+Mbps when I changed some basic parameters like TXOP in EDCA because I wanted to use the QoS applications and in EDCA priority queues are used for each traffic class. But I do not know about your scenario. Do you use EDCA? 

I think you can change something like in showcase example as 
*.sourceHost.app[*].messageLength = ${packetLength = 100, 1000, 2268}byte
*.sourceHost.app[*].sendInterval = ${packetLength} * 8 / ${bitrate} * 1us

messageLength and sendInterval are also effecting on throughput. You can use this formula for sendInterval in your .ini file, by varying your bitrates and message lengths.

anas

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Aug 14, 2020, 9:33:04 AM8/14/20
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For just testing 802.11ac im not using EDCA because EDCA reduces the trhoughput. I am trying to just get high throughput with 802.11ac.

*.sourceHost.app[*].messageLength = ${packetLength = 100, 1000, 2268}byte
*.sourceHost.app[*].sendInterval = ${packetLength} * 8 / ${bitrate} * 1us
I know that here send interval is calculated so that applications generate data with same bit rate that is specified in the showcase.

I am trying to just use 802.11ac with blockack in aggregation showcase so i can see how much is the effective throughput but even with 802.11ac, i still only get 802.11g speeds.

Here is my ini file:
#traffic
*.host1.numApps = 1
*.host1.app[0].typename = "UdpBasicApp"
*.host1.app[0].destAddresses = "host2"
*.host1.app[0].destPort = 80
*.host1.app[0].messageLength = ${packetLength = 2268}byte
*.host1.app[0].startTime = 0s
*.host1.app[0].sendInterval = ${packetLength} * 8 / ${bitrate} * 1us
*.host2.numApps = 1
*.host2.app[0].typename = "UdpSink"
*.host2.app[0].localPort = 80

#802.11
**.bandName = "5 GHz (40 MHz)"
**.opMode = "ac"
**.bitrate = ${bitrate = 1440}Mbps
**.bandwidth = 40MHz
**.radio.antenna.numAntennas = 8
**.ignorePartialInterference = true
**.centerFrequency = 5GHz
**.radio.receiver.modulation = "QAM-64"
**.wlan[*].mac.qosStation = false

#arp
*.host*.ipv4.arp.typename = "GlobalArp"

# turn off fragmentation
**.mtu = 20000Byte   # turn off IP fragmentation
**.fragmentationThreshold = 20000Byte    # turn off 802.11 fragmentation
**.pendingQueue.packetCapacity = 2000

[Config Aggregation]
*.*.wlan[*].mac.hcf.originatorMacDataService.msduAggregationPolicy.maxAMsduSize = 10000

With this i am getting below 100Mbps at application layer.
If there is something wrong with the configuration, please let me know. Thanks.

Khalid Mohammadani

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Aug 14, 2020, 4:48:38 PM8/14/20
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Try this  
*.host1.app[0].sendInterval =  exponential(${packetLength} * 8 / ${bitrate} * 1us)  OR you can calculate value in excel according to the formula then put in exponential() .
You can vary this 1us value according to your load.
I would like to suggest if you do not use EDCA then go to simply non-QoS parameters for 802.11ac.  
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