From 5bbb3d60013307669ef9140474e6ce1937511914 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mat=C3=ADas=20Richart?= <matis18@gmail.com>
Date: Wed, 9 Mar 2016 20:41:21 +0100
Subject: [PATCH] wifi: (fixes #2317) Add method to convert a HT MCS to a
 non-HT rate

---
 RELEASE_NOTES               |  1 +
 src/wifi/model/wifi-mode.cc | 94 +++++++++++++++++++++++++++++++++++++
 src/wifi/model/wifi-mode.h  | 11 ++++-
 3 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/RELEASE_NOTES b/RELEASE_NOTES
index e735eb07a..aac00e651 100644
--- a/RELEASE_NOTES
+++ b/RELEASE_NOTES
@@ -120,6 +120,7 @@ Bugs fixed
 - Bug 2313 - Assert failed when using aggregation and RTS/CTS
 - Bug 2315 - Problem when BACK Request is part of an A-MPDU
 - Bug 2316 - MacLow shall use a single TXVECTOR for all MPDUs belonging to a same A-MPDU
+- Bug 2317 - Get the non-HT reference rate of a HT MCS
 - Bug 2318 - MPDU Aggregation fails with TCP
 - Bug 2319 - BlockAckTimeout value is too low for 802.11n operating at 2.4 GHz
 - Bug 2320 - Add method to check whether a WifiTxVector contains a valid combination of WifiMode, number of spatial streams and channel width
diff --git a/src/wifi/model/wifi-mode.cc b/src/wifi/model/wifi-mode.cc
index 5525a6a69..efe904e8b 100644
--- a/src/wifi/model/wifi-mode.cc
+++ b/src/wifi/model/wifi-mode.cc
@@ -390,6 +390,100 @@ WifiMode::GetModulationClass () const
   return item->modClass;
 }
 
+WifiMode
+WifiMode::GetNonHtReferenceRate (uint8_t nss) const
+{
+  WifiMode mode;
+  struct WifiModeFactory::WifiModeItem *item = WifiModeFactory::GetFactory ()->Get (m_uid);
+  if (item->modClass == WIFI_MOD_CLASS_HT || item->modClass == WIFI_MOD_CLASS_VHT)
+    {
+      WifiCodeRate codeRate = GetCodeRate(nss);
+      switch(GetConstellationSize(nss))
+        {
+        case 2:
+          if (codeRate == WIFI_CODE_RATE_1_2)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate6Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    true,
+                                                    WIFI_CODE_RATE_1_2,
+                                                    2);
+          else if (codeRate == WIFI_CODE_RATE_3_4)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate9Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    false,
+                                                    WIFI_CODE_RATE_3_4,
+                                                    2);
+          else
+            NS_FATAL_ERROR ("Trying to get reference rate for a MCS with wrong combination of coding rate and modulation");
+          break;
+        case 4:
+          if (codeRate == WIFI_CODE_RATE_1_2)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate12Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    true,
+                                                    WIFI_CODE_RATE_1_2,
+                                                    4);
+          else if (codeRate == WIFI_CODE_RATE_3_4)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate18Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    false,
+                                                    WIFI_CODE_RATE_3_4,
+                                                    4);
+          else
+            NS_FATAL_ERROR ("Trying to get reference rate for a MCS with wrong combination of coding rate and modulation");
+          break;
+        case 16:
+          if (codeRate == WIFI_CODE_RATE_1_2)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate24Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    true,
+                                                    WIFI_CODE_RATE_1_2,
+                                                    16);
+          else if (codeRate == WIFI_CODE_RATE_3_4)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate36Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    false,
+                                                    WIFI_CODE_RATE_3_4,
+                                                    16);
+          else
+            NS_FATAL_ERROR ("Trying to get reference rate for a MCS with wrong combination of coding rate and modulation");
+          break;
+        case 64:
+          if (codeRate == WIFI_CODE_RATE_1_2 || codeRate == WIFI_CODE_RATE_2_3)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate48Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    false,
+                                                    WIFI_CODE_RATE_2_3,
+                                                    64);
+          else if (codeRate == WIFI_CODE_RATE_3_4 || codeRate == WIFI_CODE_RATE_5_6)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate54Mbps",
+                                                    WIFI_MOD_CLASS_OFDM,
+                                                    false,
+                                                    WIFI_CODE_RATE_3_4,
+                                                    64);
+          else
+            NS_FATAL_ERROR ("Trying to get reference rate for a MCS with wrong combination of coding rate and modulation");
+          break;
+        case 256:
+          if (codeRate == WIFI_CODE_RATE_3_4 || codeRate == WIFI_CODE_RATE_5_6)
+            mode = WifiModeFactory::CreateWifiMode ("OfdmRate54Mbps",
+                                               WIFI_MOD_CLASS_OFDM,
+                                               false,
+                                               WIFI_CODE_RATE_3_4,
+                                               64);
+          else
+            NS_FATAL_ERROR ("Trying to get reference rate for a MCS with wrong combination of coding rate and modulation");
+          break;
+        default:
+            NS_FATAL_ERROR ("Wrong constellation size");
+        }
+    }
+  else
+    mode = *this;
+
+  return mode;
+}
+
 WifiMode::WifiMode ()
   : m_uid (0)
 {
diff --git a/src/wifi/model/wifi-mode.h b/src/wifi/model/wifi-mode.h
index db49a26b0..e37b469ce 100644
--- a/src/wifi/model/wifi-mode.h
+++ b/src/wifi/model/wifi-mode.h
@@ -176,7 +176,16 @@ public:
    * \returns the Modulation Class (Section 9.7.8 "Modulation classes"; IEEE 802.11-2012)
    * to which this WifiMode belongs.
    */
-  enum WifiModulationClass GetModulationClass () const;
+  enum WifiModulationClass GetModulationClass () const;  
+  /**
+   * \returns the WifiMode which represents the non-HT Reference Rate
+   * which corresponds to the HT MCS of this WifiMode.
+   *
+   * To convert an HT MCS to is corresponding non-HT Reference Rate
+   * use the modulation and coding rate determined by the HT MCS
+   * and get the non-HT reference rate by lookup into Table 9-5 of IEEE 802.11-2012.
+   */
+  WifiMode GetNonHtReferenceRate (uint8_t nss) const;
 
   /**
    * Create an invalid WifiMode. Calling any method on the