OpenAirUsage.md

-# Tutorials (OpenAirInterface Usage)
+<table style="border-collapse: collapse; border: none;">
+  <tr style="border-collapse: collapse; border: none;">
+    <td style="border-collapse: collapse; border: none;">
+      <a href="http://www.openairinterface.org/">
+         <img src="images/oai_final_logo.png" alt="" border=3 height=50 width=150>
+         </img>
+      </a>
+    </td>
+    <td style="border-collapse: collapse; border: none; vertical-align: center;">
+      <b><font size = "5">Open Air Interface Tutorials</font></b>
+    </td>
+  </tr>
+</table>
 
-##  eNB, EPC tutorial
+# :construction: **WORK IN PROGRESS** :exclamation:
+
+We are in the midst of reworking the tutorials page:
+
+- updating the still valid ones
+- removing the obsolete ones.
+
+## Table of Contents ##
+
+1.   [Recently Updated Tutorials](#1-recently-updated-tutorials)
+2.   [Obsolete, not-to-date, to-be-checked tutorials](#2-obsolete-not-to-date-to-be-checked-tutorials)
+3.   [Community Managed Tutorials](#3-community-managed-tutorials)
+
+# 1. Recently Updated Tutorials #
+
+The following tutorials have been reviewed and updated if needed.
+
+##  eNB, EPC tutorials
 
 * [User-space PHY Simulation for LTE](OpenAirLTEPhySimul)
 * [OpenAirInterface System Emulation (previously known as oaisim)](OpenAirLTEEmulationNEW)
+* [L2 nFAPI simulator](l2-nfapi-simulator/l2-nfapi-simulator)
+* [Multiple PLMNs/S1-flex/NNSF](s1-flex-conf-nnsf)
+* [The F1 CU-DU split](f1-interface)
+
+# 2. Obsolete, not-to-date, to-be-checked tutorials #
+
+The following tutorials are subject to check/update/removal.
+
+##  eNB, EPC tutorials
+
 * [How to connect OAI eNB (USRP B210) with COTS UE](HowToConnectCOTSUEwithOAIeNBNew) (**```START HERE FOR FIRST TIME USER!!``` works best with tag 0.5.0 of openair-cn, and master branch of openairinterface5g**)
 * [How to connect OAI eNB (USRP B210) with COTS UE](HowToConnectCOTSUEwithOAIeNB) (**only valid for older version of openair-cn (tag v0.3.2)**)
 * [How to connect OAISIM with OAI EPC (on different machines)](https://gitlab.eurecom.fr/oai/openairinterface5g/wikis/T/howtoconnectoaisimwithoaiepc) (**Valid for version of openair-cn(tag >= v0.4.0, openairinterface5g (tag v0.1)**)
@@ -24,10 +63,8 @@
 * [How to setup 2 RRUs on C-RAN](how-to-connect-cots-ue-to-oai-enb-via-ngfi-2rru)
 * [How to setup OAI with Lime SDR](how-to-setup-oai-with-lmsdr)
 * [nFAPI introduction and HowTo](nFAPI-howto)
-* [Multiple PLMNs/S1-flex/NNSF](s1-flex-conf-nnsf)
-* [The F1 CU-DU split](f1-interface)
 
-## UE tutorial
+## UE tutorials
 
 * [UE Project Tracking](https://gitlab.eurecom.fr/oai1B/openairinterface5g/wikis/home)
 * [UE user start here](uestartup)
@@ -39,8 +76,10 @@
 * [High performance : thread to CPU execution](setup-for-real-time-performance)
 * [How to Offload Turbo Decode to FPGA](how-to-offload-turbo-decode-to-fpga)
 
-## Community Managed Tutorials
+# 3. Community Managed Tutorials #
+
 These tutorials are managed directly by the community.
+
 * [Quick Open Air Interface- Beginner Guide](https://docs.google.com/document/d/1dAAWkaa-aLmXS9jXRpFbBHVFU3hJvBhLwcOQ-7ZhVHs/edit?usp=sharing) (external document)(**only valid for older version of openair-cn (tag v0.3.2)**)
 * [How to connect OAI eNB with COTS UE via OAI RRH GW](HowtoconnectCOTSUEtoOAIeNBviaRRHGW)(**only valid for older version of openair-cn (tag v0.3.2, openairinterface5g(tag v0.1)**) -> Older version of RRH-GW
 * [Deploy openair-cn on OpenStack by Heat template] (DeployOpenStackHeat)