LTE peak data rate

[Vlatko]

Hello guys :)

I am doing a simulation on LTE mobility and the effects it produces on LTE performance. So far, I've come upon an interesting issue. How can I reproduce the maximum data rate on the UE ? I've been using only one BulkSendApplication and it results to 16Mbit/s. I've tried putting another one on the same Remote Host but it only does a slight increase in the data rate. Also, tried changing the bearer, still no change.  So, how can I get (near) the speed of 300 Mbit/s, or at least anything significantly higher than 16 Mbit/s ?

[Marco Miozzo]

Hi,

it depends on the configuration settings (bandwidth, scheduler), let's
have a look to the LENA manual (user section should help you on this
matter):
http://iptechwiki.cttc.es/LTE-EPC_Network_Simulator_%28LENA%29

Regards,
Marco.

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[Vlatko]

Hi Marco,

First of all, thanks for the reply. I was able to find the defining of the bandwidth (25 = 25 resource blocks, that was bothering me a while :D). Upon further testing I realized that in fact the application was producing a low data rate. I switched the application to UDP echo and tried testing with a 1500 Byte payload on a 1 microsecond interval, thus resulting in a 12Gbit/s UDP flow (or 8Gbit/s with 1024B). I figure the scheduler doesn't have a big role in the data rate because my simulation uses only one UE. The tests resulted in ~17Mbit/s for 25 RB and ~74 Mbit/s for 100 RB both for uplink and downlink. I would be grateful if someone can confirm that these are the maximum data rates one can achieve in ns-3 without the use of MIMO spatial multiplexing.

On that note, can someone tell me whether ns-3 supports LTE MIMO spatial multiplexing? I did a little googling and everything pointed to the fact that it doesn't.

Thanks,

Vlatko 

On Friday, August 3, 2012 9:42:09 AM UTC+2, Marco wrote:

Hi,

it depends on the configuration settings (bandwidth, scheduler), let's
have a look to the LENA manual (user section should help you on this
matter):
http://iptechwiki.cttc.es/LTE-EPC_Network_Simulator_%28LENA%29

Regards,
Marco.

[Leticia]

Hi Vlatko ,

I have the following question: How did  you get the data rate ? I am using flowmonitor in an LTE+EPC scenario and to get the throughput Im using the formula that I found in the group: Throughput: " << iter->second.rxBytes * 8.0 / (iter->second.timeLastRxPacket.GetSeconds()-iter->second.timeFirstTxPacket.GetSeconds()) / 1024 << " Kbps");

With this formula I got values of less than 1Mbps, I dont know what Im doing wrong.

Thank you very much!

Regards 

Leticia

[Vlatko]

Hi Leticia,

I am using the information gathered from the RLC/PDCP traces. I simply add the received bytes, convert them to bits and divide all that with the length of the simulation. So the formula is as follows: (Rx*8)/(Simulation time) = bit/s. Unfortunately, this results in the average data rate of the radio link, it does not display the change in data rate as time goes by, so I cannot get a graph which shows the change in data rate as the simulation progresses. Does your method solve this issue? I would be grateful if you would tell me more about it, or give me the link where you saw this.

As far as your issue goes, I would first check the data rate that your application uses. For example, if you are using UDP echo client/server, if you are sending 1024 bytes on an interval of 0.001 second, that would result in around 8Mbit/s. You can also check the data rate of your application using pcap traces, by using Wireshark to view them (check the tab Statistics>> Summary, it shows the average data rate). The problem is that ns-3 doesn't support  LTE pcap tracing, so use Wireshark only for checking your application data rate.

Hope that this helps :) 

Regards,

Vlatko

[Leticia]

Dear all,

I have a LTE scenario with only 1 UE and 1 eNB, I am generating UDP traffic at 100Mbps, the network is configured with 100RB   as I said in my last comment I installed FlowMonitor  in the RH and in the UE to measure throughput,with this configuration  I have a maximum throughput (at IP layer due to the measure is performed with FlowMonitor tool) of 71Mbps for downlink and 70Mbps in uplink. Despite I changed the Transmission Mode  I always get the same value of throughput, with Transmission Mode 0 (SISO), 1 (Tx diversity) and 2 (Spatial Multiplexing) ! Could anybody explain me this behaviour?

 I dont know the reason for this values for throughput, I think that Downlink must be near 100Mbps for transmission mode 2,  and is strange that the maximum value in both cases (dl and ul) are very close.

On the other hand, I saw that for a distance of 1000Km I still have downlink and until 2km the UE have an uplink throughput different of zero!

I would really appreciate any help or comments about this matter! Thank you very much!

[Leticia]

I just solve my problem, the configuration of MIMO must be at the begining of the script. With Mode Transmission 2 I obtain 142Mbps in downlink between RH and UE!.

Regards!

[Na]

Ηι Leticia,

with this code you change transmission mode?
Config::SetDefault ("ns3::LteEnbRrc::DefaultTransmissionMode", UintegerValue (1));

And what do you mean it must be at the begining of the script?

Thanks!

[Jerome Antonyraj]

Hi Leticia,

May I kindly know what changes you did overall to get the datarate of more than 100Mbps. I have checked application side and there is sufficient buffers. But the below two configurations at the beginning of my script are not making any changes to the ~17Mbps that I am getting for a single UE and single ENB:
    Config::SetDefault ("ns3::LteEnbRrc::DefaultTransmissionMode", UintegerValue (2));
    Config::SetDefault ("ns3::RadioEnvironmentMapHelper::Bandwidth", UintegerValue (100));

Would appreciate your comments.

Thanks.

[Jerome Antonyraj]

So, I have figured out the issues with my uplink not giving higher datarates. That is, when the packet length at the application is > 2017 Bytes, the packet gets fragmented at the RLC layer and added to the end of the RLC data field, resulting only one packet fragment per RLC packet. (RLC 3GPP exception is 2047 bytes, and upper layer header account for 30 bytes. lte-ue-um.cc has also added comments regarding this). So maximum packet size that can give a higher than 17Mbps uplink/downlink data rate in LTE is (2047-30) = 2017 bytes. Pls correct me if this is wrong..!!!

In the uplink however I was only able to achieve a datarate of 68.7 Mbps (I believe this was referred to as 70Mbps by Leticia in her reply above), with all other settings (other than MIMO and RB size) kept default. Has anyone been able to achieve a higher datarate in uplink?

-Jerome