Changes between Version 15 and Version 16 of Tutorials/g0WmLTE/Tutorial4-OAI


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Timestamp:
Mar 5, 2015, 4:17:57 PM (9 years ago)
Author:
seskar
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  • Tutorials/g0WmLTE/Tutorial4-OAI

    v15 v16  
    55This tutorial also assumes basic familiarity with [http://en.wikipedia.org/wiki/LTE_%28telecommunication%29 LTE standard]. It uses [http://www.openairinterface.org/ OpenAirInterface] open source software implementation of LTE basestation (eNodeB or eNB) and modem (user equipment or UE) developed at [http://www.eurecom.fr/en Eurecom]. The tutorial given here is based on the [https://twiki.eurecom.fr/twiki/bin/view/OpenAirInterface/OpenAirLXRT OAI_real-time_LTEsoftmodem] tutorial.
    66
    7 The image used for this experiment is oai-trunk-full.ndz. Image uses Ubunutu 14.04 and has low-latency 3.17 kernel install and UHD drivers needed for B210/X310 USRPs (UHD 3.8.2)) as well as the !OpenAirInteface source code installed in /root/trunk (svn tag 668).
     7The image used for this experiment is oai-trunk-full.ndz. Image uses Ubunutu 14.04 and has low-latency 3.17 kernel install and UHD drivers needed for B210/X310 USRPs (UHD 3.8.2)) as well as the !OpenAirInteface source code installed in /root/trunk (svn tag 668). The code was compiled with USRP support i.e. with:
     8{{{
     9cd trunk/targets/bin; build_oai.bash -l ENB -c -w USRP
     10}}}
     11More details on various build options are available on [https://twiki.eurecom.fr/twiki/bin/view/OpenAirInterface/AutoBuild OpenAirInterface build page].
    812
    9 In this tutorial we will use nodes with b310 and have the basestation on node9-1 and modem on node6-20.
     13In this tutorial we will use nodes with USRP b310 and have the basestation on node9-1 and modem on node6-20.
    1014
    1115=== Prepare the nodes ===
    … …  
    1721
    1822Primary objective is to establish the LTE connection between the UE and eNB. In order to that we need to prepare configuration files on two nodes: node9-1 and node6-20.
    19 1. In oai.conf file, make sure to have correct IP address configuration for parameters "ENB_IPV4_ADDRESS_FOR_S1_MME" and "ENB_IPV4_ADDRESS_FOR_S1U" to match node numbers. For example, for nodeX-Y, these IP address parameters become as "10.10.X.Y/16". So for our basestation node the relevant sections in the oai.conf file in /root directory on the nodes we should look like (we don't want MME support and have to adjust the ip addresses to match what we have on the control interface of the node):
     23  1. Open the two ssh sessions from the console to the two nodes:
     24|| [[Image(node9-1.png, width=200)]] || [[Image(node6-20.png, width=200)]] ||
     25  2. '''Prepare configuration files:''' In oai.conf file roots home directory on the node (/root), make sure to have correct IP address configuration for parameters "ENB_IPV4_ADDRESS_FOR_S1_MME" and "ENB_IPV4_ADDRESS_FOR_S1U" to match node numbers. For example, for nodeX-Y, these IP address parameters become as "10.10.X.Y/16". So for our basestation node the relevant sections in the oai.conf file in /root directory on the nodes we should look like (we don't want MME support and have to adjust the ip addresses to match what we have on the control interface of the node):
    2026{{{
    2127    ////////// MME parameters:
    … …  
    3743    };
    3844}}}
    39 
    40 1. Execute commands as
     45  1. '''Run the lte-softmodem:''' Depending on wheather you want to run it with or without mme, execute lte-softmodem on corresponding nodes:
    4146
    4247 || || On the eNB node (node9-1) || On the UE node (node6-20)  ||
    43  || w/o MME ||  lte-softmodem -Ooai.conf -V  || lte-softmodem -U -V -Ooai.conf ||
    44  || w MME ||  lte-softmodem-nomme -Ooai.conf || lte-softmodem-nomme -U -Ooai.conf ||
     48 || w/o MME ||  {{{ lte-softmodem -Ooai.conf }}}  || {{{ lte-softmodem -U -Ooai.conf }}} ||
     49 || w MME ||  {{{ lte-softmodem-nomme -Ooai.conf }}} || {{{ lte-softmodem -U -Ooai.conf  }}} ||
    4550
    46 
    47  || Add "-d" flag if you have enabled X11 forwarding and want to see the signal tracer (requires relatively high bandwidth). || [[Image(Scope.png, width=300)]] ||
     51If the above commands are executed with the "-d" flag and if X11 forwarding is enabled for the current ssh session, the signal tracer will pop out as shown in Figure 1 (not that this requires relatively high bandwidth).
     52[[Image(Scope.png, width=300)]] ||
    4853
    4954[[CollapsibleStart(The output on both consoles should look something like this:)]]
    … …  
    135140
    136141=== The command line parameters of lte-softmodem ===
    137 1. -O file: eNB configuration file (this is the preferred way to pass basic parameters and there are several examples in $OPENAIR_TARGETS/PROJECTS/GENERIC-LTE_EPC/CONF/
    138 1. -g LEVEL: set the level of debug for the log generation (-g7 is quite high and useful to trace bugs in the procedures/protocols, -g9 even dumps packets at all levels of the protocol stack)
    139 1. -d: enables xforms signal tracer
    140 1. -U: start as UE (default: eNB)
    141 1. -C freq: set carrier frequency to f0 for all chains (extension to independent frequencies trivial)
    142 1. -V: enables the VCD debugging tool (this is a temporal event tracer, which is useful for real-time debugging using GTKWave)
    143 1. -K file: ITTI logfile. ITTI is an intertask tracing utility which helps debugging with an EPC. It can traces all exchanges between RRC<->S1AP, RRC<->PDCP, PDCP<->S1
    144 1. -S: do not exit for the missing slots, instead increment the counter.
    145 1. --debug-ue-prach: only send prach but do not connect
    146 1. --no-L2-connect: only runs rx, does not send prach
     142Relevant (i.e. for USRP command line parameters for the lte-softmodem command are:
     143 * -O file: eNB configuration file (this is the preferred way to pass basic parameters and there are several examples in $OPENAIR_TARGETS/PROJECTS/GENERIC-LTE_EPC/CONF/
     144 * -g LEVEL: set the level of debug for the log generation (-g7 is quite high and useful to trace bugs in the procedures/protocols, -g9 even dumps packets at all levels of the protocol stack)
     145 * -d: enables xforms signal tracer
     146 * -U: start as UE (default: eNB)
     147 * -C freq: set carrier frequency to f0 for all chains (extension to independent frequencies trivial)
     148 * -V: enables the VCD debugging tool (this is a temporal event tracer, which is useful for real-time debugging using GTKWave)
     149 * -K file: ITTI logfile. ITTI is an intertask tracing utility which helps debugging with an EPC. It can traces all exchanges between RRC<->S1AP, RRC<->PDCP, PDCP<->S1
     150 * -S: do not exit for the missing slots, instead increment the counter.
     151 * --debug-ue-prach: only send prach but do not connect
     152 * --no-L2-connect: only runs rx, does not send prach
     153
     154More details on running lte-softmodem are available on [https://twiki.eurecom.fr/twiki/bin/view/OpenAirInterface/OpenAirLXRT OpenAirInterface real-time LTE softmodem page].