LTE Module User Documentation (translator 6)--Physical error model, MIMO model, antenna model

LTE user documentation(if there are inappropriate places, please correct me!) )9 PHY Error ModelThe physical error model consists of a data error model and a downlink control error model, both of which are activated by default. You can use the Ns-3 property system to activate, specifically: 

Config::setdefault ("ns3::ltespectrumphy::ctrlerrormodelenabled", Booleanvalue (  False)); Config::setdefault ("ns3::ltespectrumphy::D ataerrormodelenabled", Booleanvalue ( false));

Ten MIMO Modelin this section, we will explain how to configure MIMO parameters. LTE defines 7 types of transmission modes:

• transmission Mode 1:siso.
• transmission Mode 2:mimo Tx Diversity .
• transmission Mode 3:mimo Spatial Multiplexity Open Loop.
• transmission Mode 4:mimo Spatial Multiplexity Closed Loop.
• transmission Mode 5:mimo multi-user.
• transmission Mode 6:closer Loop Single layer precoding.
• transmission Mode 7:single Antenna Port 5.

 based on the implemented model, the emulator contains 3 types of transmission modes, the default being transmission mode 1 (SISO). In order to modify the default transport mode used, you can use the LTEENBRRC property Defaulttransmissionmode, as shown here:

Config::setdefault ("NS3::LTEENBRRC::D efaulttransmissionmode", Uintegervalue (0));//SISOConfig::setdefault ("NS3::LTEENBRRC::D efaulttransmissionmode", Uintegervalue (1));//MIMO Tx diversity (1 layer)Config::setdefault ("NS3::LTEENBRRC::D efaulttransmissionmode", Uintegervalue (2));//MIMO Spatial multiplexity (2 layers)

to change the transfer mode of a particular user during simulation, a specific interface has been implemented in the standard scheduler:

void Transmissionmodeconfigurationupdate (uint16_t rnti, uint8_t txmode);

This method can be used to develop the transport Mode decision engine (for example, optimize the transfer mode based on channel conditions/user requirements) and manually switch the emulation script. For the latter, the switchover is implemented as follows:

ptr<lteenbnetdevice> Lteenbdev = Enbdevs.get (0)->getobject<lteenbnetdevice> (); Pointervalue Ptrval;enbnetdev->getattribute ("ffmacscheduler", Ptrval); Ptr<RrFfMacScheduler> rrsched = ptrval. Get<rrffmacscheduler> (); Simulator::schedule (Seconds (0.21

Finally, the implemented model can update the gain value according to different MIMO models (the only limitation is that the gain must be constant during the entire simulation run and is common to layers. ) to reconfigure. The gain for each transfer mode can be modified by the standard NS3 property system, where the properties are: Txmode1gain, Txmode2gain, Txmode3gain, Txmode4gain, Txmode5gain, Txmode6gain, and Txmode7gain. By default, only Txmode1gain, Txmode2gain, and Txmode3gain have a meaningful value, which is deduced by _[catreuxmimo] (for example, 0.0, 4.2, and -2.8 DB, respectively).   One use of Antennamodel We now show how to correlate a specific antenna model and a base station device to create a macro base station sector model. For this purpose, it is very convenient to use the Cosineantennamodel provided by the ns-3 antenna model. The base station is configured by Ltehelperinstance (before creating Enbnetdevice), as follows:

Ltehelper->setenbantennamodeltype ("ns3::cosineantennamodel"); Ltehelper- >setenbantennamodelattribute ("Orientation", Doublevalue (0)); Ltehelper->setenbantennamodelattribute ("beamwidth",   Doublevalue (  - ); Ltehelper->setenbantennamodelattribute ("maxgain",     Doublevalue (0.0));

The code above generates an antenna model with a 60-degree beam width along the X-axis. The direction is measured at an X-axis angle, for example, a direction of 90 degrees points to the y-axis, and a direction of 90 degrees points to the opposite direction of the y-axis. The beam width is 3 db beam width, for example, a 60-degree angle of the beam width, the angle of the antenna in the direction of the gain of 3 db.  in order to create a multi-sector site, you need to create different ns-3 nodes, place them in the same location, and configure separate enbnetdevice with different antenna orientations(installed on each node).      

Reference documents

Https://www.nsnam.org/docs/models/html/lte-user.html

LTE Module User Documentation (translator 6)--Physical error model, MIMO model, antenna model