20171208

Fork of LoRaWAN-lib by Semtech

Revision:
7:c16969e0f70f
Parent:
6:d7a34ded7c87
Child:
8:26002607de9c
--- a/LoRaMac.cpp	Wed May 18 11:19:24 2016 +0000
+++ b/LoRaMac.cpp	Tue Jul 05 13:24:54 2016 +0000
@@ -186,10 +186,20 @@
 static uint8_t MacCommandsBufferIndex = 0;
 
 /*!
+ * Contains the current MacCommandsBuffer index for MAC commands to repeat
+ */
+static uint8_t MacCommandsBufferToRepeatIndex = 0;
+
+/*!
  * Buffer containing the MAC layer commands
  */
 static uint8_t MacCommandsBuffer[LORA_MAC_COMMAND_MAX_LENGTH];
 
+/*!
+ * Buffer containing the MAC layer commands which must be repeated
+ */
+static uint8_t MacCommandsBufferToRepeat[LORA_MAC_COMMAND_MAX_LENGTH];
+
 #if defined( USE_BAND_433 )
 /*!
  * Data rates table definition
@@ -324,28 +334,17 @@
     { DR_12, DR_11, DR_10, DR_9  }, // DR_2
     { DR_13, DR_12, DR_11, DR_10 }, // DR_3
     { DR_13, DR_13, DR_12, DR_11 }, // DR_4
-    { 0xFF , 0xFF , 0xFF , 0xFF  },
-    { 0xFF , 0xFF , 0xFF , 0xFF  },
-    { 0xFF , 0xFF , 0xFF , 0xFF  },
-    { DR_8 , DR_8 , DR_8 , DR_8  },
-    { DR_9 , DR_8 , DR_8 , DR_8  },
-    { DR_10, DR_9 , DR_8 , DR_8  },
-    { DR_11, DR_10, DR_9 , DR_8  },
-    { DR_12, DR_11, DR_10, DR_9  },
-    { DR_13, DR_12, DR_11, DR_10 },
-    { 0xFF , 0xFF , 0xFF , 0xFF  },
-    { 0xFF , 0xFF , 0xFF , 0xFF  },
 };
 
 /*!
  * Maximum payload with respect to the datarate index. Cannot operate with repeater.
  */
-const uint8_t MaxPayloadOfDatarate[] = { 11, 53, 129, 242, 242, 0, 0, 0, 53, 129, 242, 242, 242, 242, 0, 0 };
+const uint8_t MaxPayloadOfDatarate[] = { 11, 53, 125, 242, 242, 0, 0, 0, 53, 129, 242, 242, 242, 242, 0, 0 };
 
 /*!
  * Maximum payload with respect to the datarate index. Can operate with repeater.
  */
-const uint8_t MaxPayloadOfDatarateRepeater[] = { 11, 53, 129, 242, 242, 0, 0, 0, 33, 103, 222, 222, 222, 222, 0, 0 };
+const uint8_t MaxPayloadOfDatarateRepeater[] = { 11, 53, 125, 242, 242, 0, 0, 0, 33, 109, 222, 222, 222, 222, 0, 0 };
 
 /*!
  * Tx output powers table definition
@@ -369,44 +368,35 @@
  * Contains the channels which remain to be applied.
  */
 static uint16_t ChannelsMaskRemaining[6];
+
+/*!
+ * Defines the first channel for RX window 2 for US band
+ */
+#define LORAMAC_FIRST_RX2_CHANNEL           ( (uint32_t) 923.3e6 )
+
+/*!
+ * Defines the last channel for RX window 2 for US band
+ */
+#define LORAMAC_LAST_RX2_CHANNEL            ( (uint32_t) 927.5e6 )
+
+/*!
+ * Defines the step width of the channels for RX window 2
+ */
+#define LORAMAC_STEPWIDTH_RX2_CHANNEL       ( (uint32_t) 600e3 )
+
 #else
     #error "Please define a frequency band in the compiler options."
 #endif
 
 /*!
- * LoRaMAC 2nd reception window settings
- */
-static Rx2ChannelParams_t Rx2Channel = RX_WND_2_CHANNEL;
-
-/*!
- * Datarate offset between uplink and downlink on first window
+ * LoRaMac parameters
  */
-static uint8_t Rx1DrOffset = 0;
-
-/*!
- * Mask indicating which channels are enabled
- */
-static uint16_t ChannelsMask[6];
+LoRaMacParams_t LoRaMacParams;
 
 /*!
- * Channels Tx output power
- */
-static int8_t ChannelsTxPower = LORAMAC_DEFAULT_TX_POWER;
-
-/*!
- * Channels datarate
+ * LoRaMac default parameters
  */
-static int8_t ChannelsDatarate = LORAMAC_DEFAULT_DATARATE;
-
-/*!
- * Channels default datarate
- */
-static int8_t ChannelsDefaultDatarate = LORAMAC_DEFAULT_DATARATE;
-
-/*!
- * Number of uplink messages repetitions [1:15] (unconfirmed messages only)
- */
-static uint8_t ChannelsNbRep = 1;
+LoRaMacParams_t LoRaMacParamsDefaults;
 
 /*!
  * Uplink messages repetitions counter
@@ -436,6 +426,9 @@
  */
 static uint8_t Channel;
 
+/*!
+ * Channel index of the last transmission
+ */
 static uint8_t LastTxChannel;
 
 /*!
@@ -490,14 +483,6 @@
 static TimerEvent_t RxWindowTimer2;
 
 /*!
- * LoRaMac reception windows delay from end of Tx
- */
-static uint32_t ReceiveDelay1;
-static uint32_t ReceiveDelay2;
-static uint32_t JoinAcceptDelay1;
-static uint32_t JoinAcceptDelay2;
-
-/*!
  * LoRaMac reception windows delay
  * \remark normal frame: RxWindowXDelay = ReceiveDelayX - RADIO_WAKEUP_TIME
  *         join frame  : RxWindowXDelay = JoinAcceptDelayX - RADIO_WAKEUP_TIME
@@ -506,11 +491,6 @@
 static uint32_t RxWindow2Delay;
 
 /*!
- * LoRaMac maximum time a reception window stays open
- */
-static uint32_t MaxRxWindow;
-
-/*!
  * Acknowledge timeout timer. Used for packet retransmissions.
  */
 static TimerEvent_t AckTimeoutTimer;
@@ -536,6 +516,11 @@
 TimerTime_t TxTimeOnAir = 0;
 
 /*!
+ * Number of trials for the Join Request
+ */
+static uint16_t JoinRequestTrials;
+
+/*!
  * Structure to hold an MCPS indication data.
  */
 static McpsIndication_t McpsIndication;
@@ -645,6 +630,15 @@
 static void RxWindowSetup( uint32_t freq, int8_t datarate, uint32_t bandwidth, uint16_t timeout, bool rxContinuous );
 
 /*!
+ * \brief Verifies if the RX window 2 frequency is in range
+ *
+ * \param [IN] freq window channel frequency
+ *
+ * \retval status  Function status [1: OK, 0: Frequency not applicable]
+ */
+static bool Rx2FreqInRange( uint32_t freq );
+
+/*!
  * \brief Adds a new MAC command to be sent.
  *
  * \Remark MAC layer internal function
@@ -664,6 +658,20 @@
 static LoRaMacStatus_t AddMacCommand( uint8_t cmd, uint8_t p1, uint8_t p2 );
 
 /*!
+ * \brief Parses the MAC commands which must be repeated.
+ *
+ * \Remark MAC layer internal function
+ *
+ * \param [IN] cmdBufIn  Buffer which stores the MAC commands to send
+ * \param [IN] length  Length of the input buffer to parse
+ * \param [OUT] cmdBufOut  Buffer which stores the MAC commands which must be
+ *                         repeated.
+ *
+ * \retval Size of the MAC commands to repeat.
+ */
+static uint8_t ParseMacCommandsToRepeat( uint8_t* cmdBufIn, uint8_t length, uint8_t* cmdBufOut );
+
+/*!
  * \brief Validates if the payload fits into the frame, taking the datarate
  *        into account.
  *
@@ -804,12 +812,27 @@
 static LoRaMacStatus_t ScheduleTx( void );
 
 /*
+ * \brief Sets the duty cycle for retransmissions
+ *
+ * \retval Duty cycle
+ */
+static uint16_t RetransmissionDutyCylce( void );
+
+/*
  * \brief Calculates the back-off time for the band of a channel.
  *
  * \param [IN] channel     The last Tx channel index
  */
 static void CalculateBackOff( uint8_t channel );
 
+/*
+ * \brief Alternates the datarate of the channel for the join request.
+ *
+ * \param [IN] nbTrials    Number of performed join requests.
+ * \retval Datarate to apply
+ */
+static int8_t AlternateDatarate( uint16_t nbTrials );
+
 /*!
  * \brief LoRaMAC layer prepared frame buffer transmission with channel specification
  *
@@ -821,7 +844,10 @@
  */
 LoRaMacStatus_t SendFrameOnChannel( ChannelParams_t channel );
 
-
+/*!
+ * \brief Resets MAC specific parameters to default
+ */
+static void ResetMacParameters( void );
 
 static void OnRadioTxDone( void )
 {
@@ -980,26 +1006,26 @@
                 LoRaMacDevAddr |= ( ( uint32_t )LoRaMacRxPayload[10] << 24 );
 
                 // DLSettings
-                Rx1DrOffset = ( LoRaMacRxPayload[11] >> 4 ) & 0x07;
-                Rx2Channel.Datarate = LoRaMacRxPayload[11] & 0x0F;
+                LoRaMacParams.Rx1DrOffset = ( LoRaMacRxPayload[11] >> 4 ) & 0x07;
+                LoRaMacParams.Rx2Channel.Datarate = LoRaMacRxPayload[11] & 0x0F;
 #if defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
                 /*
                  * WARNING: To be removed once Semtech server implementation
                  *          is corrected.
                  */
-                if( Rx2Channel.Datarate == DR_3 )
+                if( LoRaMacParams.Rx2Channel.Datarate == DR_3 )
                 {
-                    Rx2Channel.Datarate = DR_8;
+                    LoRaMacParams.Rx2Channel.Datarate = DR_8;
                 }
 #endif
                 // RxDelay
-                ReceiveDelay1 = ( LoRaMacRxPayload[12] & 0x0F );
-                if( ReceiveDelay1 == 0 )
+                LoRaMacParams.ReceiveDelay1 = ( LoRaMacRxPayload[12] & 0x0F );
+                if( LoRaMacParams.ReceiveDelay1 == 0 )
                 {
-                    ReceiveDelay1 = 1;
+                    LoRaMacParams.ReceiveDelay1 = 1;
                 }
-                ReceiveDelay1 *= 1e6;
-                ReceiveDelay2 = ReceiveDelay1 + 1e6;
+                LoRaMacParams.ReceiveDelay1 *= 1e6;
+                LoRaMacParams.ReceiveDelay2 = LoRaMacParams.ReceiveDelay1 + 1e6;
 
 #if !( defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID ) )
                 //CFList
@@ -1019,7 +1045,7 @@
 #endif
                 MlmeConfirm.Status = LORAMAC_EVENT_INFO_STATUS_OK;
                 IsLoRaMacNetworkJoined = true;
-                ChannelsDatarate = ChannelsDefaultDatarate;
+                LoRaMacParams.ChannelsDatarate = LoRaMacParamsDefaults.ChannelsDatarate;
             }
             else
             {
@@ -1122,6 +1148,7 @@
                     McpsConfirm.Status = LORAMAC_EVENT_INFO_STATUS_OK;
 
                     AdrAckCounter = 0;
+                    MacCommandsBufferToRepeatIndex = 0;
 
                     // Update 32 bits downlink counter
                     if( multicast == 1 )
@@ -1191,11 +1218,6 @@
                         }
                     }
 
-                    if( fCtrl.Bits.FOptsLen > 0 )
-                    {
-                        // Decode Options field MAC commands
-                        ProcessMacCommands( payload, 8, appPayloadStartIndex, snr );
-                    }
                     if( ( ( size - 4 ) - appPayloadStartIndex ) > 0 )
                     {
                         port = payload[appPayloadStartIndex++];
@@ -1205,19 +1227,32 @@
 
                         if( port == 0 )
                         {
-                            LoRaMacPayloadDecrypt( payload + appPayloadStartIndex,
-                                                   frameLen,
-                                                   nwkSKey,
-                                                   address,
-                                                   DOWN_LINK,
-                                                   downLinkCounter,
-                                                   LoRaMacRxPayload );
-
-                            // Decode frame payload MAC commands
-                            ProcessMacCommands( LoRaMacRxPayload, 0, frameLen, snr );
+                            if( fCtrl.Bits.FOptsLen == 0 )
+                            {
+                                LoRaMacPayloadDecrypt( payload + appPayloadStartIndex,
+                                                       frameLen,
+                                                       nwkSKey,
+                                                       address,
+                                                       DOWN_LINK,
+                                                       downLinkCounter,
+                                                       LoRaMacRxPayload );
+
+                                // Decode frame payload MAC commands
+                                ProcessMacCommands( LoRaMacRxPayload, 0, frameLen, snr );
+                            }
+                            else
+                            {
+                                skipIndication = true;
+                            }
                         }
                         else
                         {
+                            if( fCtrl.Bits.FOptsLen > 0 )
+                            {
+                                // Decode Options field MAC commands. Omit the fPort.
+                                ProcessMacCommands( payload, 8, appPayloadStartIndex - 1, snr );
+                            }
+
                             LoRaMacPayloadDecrypt( payload + appPayloadStartIndex,
                                                    frameLen,
                                                    appSKey,
@@ -1234,6 +1269,15 @@
                             }
                         }
                     }
+                    else
+                    {
+                        if( fCtrl.Bits.FOptsLen > 0 )
+                        {
+                            // Decode Options field MAC commands
+                            ProcessMacCommands( payload, 8, appPayloadStartIndex, snr );
+                        }
+                    }
+
                     if( skipIndication == false )
                     {
                         LoRaMacFlags.Bits.McpsInd = 1;
@@ -1370,17 +1414,20 @@
             {
                 if( MlmeConfirm.MlmeRequest == MLME_JOIN )
                 {
+                    // Retransmit only if the answer is not OK
+                    ChannelsNbRepCounter = 0;
+
                     if( MlmeConfirm.Status == LORAMAC_EVENT_INFO_STATUS_OK )
                     {
+                        // Stop retransmission
+                        ChannelsNbRepCounter = LoRaMacParams.ChannelsNbRep;
                         UpLinkCounter = 0;
                     }
-                    // Join messages aren't repeated automatically
-                    ChannelsNbRepCounter = ChannelsNbRep;
                 }
             }
             if( ( LoRaMacFlags.Bits.MlmeReq == 1 ) || ( ( LoRaMacFlags.Bits.McpsReq == 1 ) ) )
             {
-                if( ( ChannelsNbRepCounter >= ChannelsNbRep ) || ( LoRaMacFlags.Bits.McpsInd == 1 ) )
+                if( ( ChannelsNbRepCounter >= LoRaMacParams.ChannelsNbRep ) || ( LoRaMacFlags.Bits.McpsInd == 1 ) )
                 {
                     ChannelsNbRepCounter = 0;
 
@@ -1426,7 +1473,7 @@
 
                 if( ( AckTimeoutRetriesCounter % 2 ) == 1 )
                 {
-                    ChannelsDatarate = MAX( ChannelsDatarate - 1, LORAMAC_TX_MIN_DATARATE );
+                    LoRaMacParams.ChannelsDatarate = MAX( LoRaMacParams.ChannelsDatarate - 1, LORAMAC_TX_MIN_DATARATE );
                 }
                 LoRaMacFlags.Bits.MacDone = 0;
                 // Sends the same frame again
@@ -1436,18 +1483,18 @@
             {
 #if defined( USE_BAND_433 ) || defined( USE_BAND_780 ) || defined( USE_BAND_868 )
                 // Re-enable default channels LC1, LC2, LC3
-                ChannelsMask[0] = ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
+                LoRaMacParams.ChannelsMask[0] = LoRaMacParams.ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
 #elif defined( USE_BAND_915 )
                 // Re-enable default channels
-                ChannelsMask[0] = 0xFFFF;
-                ChannelsMask[1] = 0xFFFF;
-                ChannelsMask[2] = 0xFFFF;
-                ChannelsMask[3] = 0xFFFF;
-                ChannelsMask[4] = 0x00FF;
-                ChannelsMask[5] = 0x0000;
+                LoRaMacParams.ChannelsMask[0] = 0xFFFF;
+                LoRaMacParams.ChannelsMask[1] = 0xFFFF;
+                LoRaMacParams.ChannelsMask[2] = 0xFFFF;
+                LoRaMacParams.ChannelsMask[3] = 0xFFFF;
+                LoRaMacParams.ChannelsMask[4] = 0x00FF;
+                LoRaMacParams.ChannelsMask[5] = 0x0000;
 #elif defined( USE_BAND_915_HYBRID )
                 // Re-enable default channels
-                ReenableChannels( ChannelsMask[4], ChannelsMask );
+                ReenableChannels( LoRaMacParams.ChannelsMask[4], LoRaMacParams.ChannelsMask );
 #else
     #error "Please define a frequency band in the compiler options."
 #endif
@@ -1500,9 +1547,26 @@
 
 static void OnTxDelayedTimerEvent( void )
 {
+    LoRaMacHeader_t macHdr;
+    LoRaMacFrameCtrl_t fCtrl;
+
     TimerStop( &TxDelayedTimer );
     LoRaMacState &= ~MAC_TX_DELAYED;
 
+    if( ( LoRaMacFlags.Bits.MlmeReq == 1 ) && ( MlmeConfirm.MlmeRequest == MLME_JOIN ) )
+    {
+        macHdr.Value = 0;
+        macHdr.Bits.MType = FRAME_TYPE_JOIN_REQ;
+
+        fCtrl.Value = 0;
+        fCtrl.Bits.Adr = AdrCtrlOn;
+
+        /* In case of a join request retransmission, the stack must prepare
+         * the frame again, because the network server keeps track of the random
+         * LoRaMacDevNonce values to prevent reply attacks. */
+        PrepareFrame( &macHdr, &fCtrl, 0, NULL, 0 );
+    }
+
     ScheduleTx( );
 }
 
@@ -1521,7 +1585,7 @@
     }
 
 #if defined( USE_BAND_433 ) || defined( USE_BAND_780 ) || defined( USE_BAND_868 )
-    datarate = ChannelsDatarate - Rx1DrOffset;
+    datarate = LoRaMacParams.ChannelsDatarate - LoRaMacParams.Rx1DrOffset;
     if( datarate < 0 )
     {
         datarate = DR_0;
@@ -1543,7 +1607,7 @@
     }
     RxWindowSetup( Channels[Channel].Frequency, datarate, bandwidth, symbTimeout, false );
 #elif ( defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID ) )
-    datarate = datarateOffsets[ChannelsDatarate][Rx1DrOffset];
+    datarate = datarateOffsets[LoRaMacParams.ChannelsDatarate][LoRaMacParams.Rx1DrOffset];
     if( datarate < 0 )
     {
         datarate = DR_0;
@@ -1583,7 +1647,7 @@
     {// LoRa 500 kHz
         bandwidth  = 2;
     }
-    RxWindowSetup( 923.3e6 + ( Channel % 8 ) * 600e3, datarate, bandwidth, symbTimeout, false );
+    RxWindowSetup( LORAMAC_FIRST_RX2_CHANNEL + ( Channel % 8 ) * LORAMAC_STEPWIDTH_RX2_CHANNEL, datarate, bandwidth, symbTimeout, false );
 #else
     #error "Please define a frequency band in the compiler options."
 #endif
@@ -1599,22 +1663,22 @@
 
 #if defined( USE_BAND_433 ) || defined( USE_BAND_780 ) || defined( USE_BAND_868 )
     // For higher datarates, we increase the number of symbols generating a Rx Timeout
-    if( ( Rx2Channel.Datarate == DR_3 ) || ( Rx2Channel.Datarate == DR_4 ) )
+    if( ( LoRaMacParams.Rx2Channel.Datarate == DR_3 ) || ( LoRaMacParams.Rx2Channel.Datarate == DR_4 ) )
     { // DR_4, DR_3
         symbTimeout = 8;
     }
-    else if( Rx2Channel.Datarate == DR_5 )
+    else if( LoRaMacParams.Rx2Channel.Datarate == DR_5 )
     {
         symbTimeout = 10;
     }
-    else if( Rx2Channel.Datarate == DR_6 )
+    else if( LoRaMacParams.Rx2Channel.Datarate == DR_6 )
     {// LoRa 250 kHz
         bandwidth  = 1;
         symbTimeout = 14;
     }
 #elif ( defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID ) )
     // For higher datarates, we increase the number of symbols generating a Rx Timeout
-    switch( Rx2Channel.Datarate )
+    switch( LoRaMacParams.Rx2Channel.Datarate )
     {
         case DR_0:       // SF10 - BW125
             symbTimeout = 5;
@@ -1644,7 +1708,7 @@
         default:
             break;
     }
-    if( Rx2Channel.Datarate >= DR_4 )
+    if( LoRaMacParams.Rx2Channel.Datarate >= DR_4 )
     {// LoRa 500 kHz
         bandwidth  = 2;
     }
@@ -1653,11 +1717,11 @@
 #endif
     if( LoRaMacDeviceClass != CLASS_C )
     {
-        RxWindowSetup( Rx2Channel.Frequency, Rx2Channel.Datarate, bandwidth, symbTimeout, false );
+        RxWindowSetup( LoRaMacParams.Rx2Channel.Frequency, LoRaMacParams.Rx2Channel.Datarate, bandwidth, symbTimeout, false );
     }
     else
     {
-        RxWindowSetup( Rx2Channel.Frequency, Rx2Channel.Datarate, bandwidth, symbTimeout, true );
+        RxWindowSetup( LoRaMacParams.Rx2Channel.Frequency, LoRaMacParams.Rx2Channel.Datarate, bandwidth, symbTimeout, true );
     }
 }
 
@@ -1688,17 +1752,17 @@
 #if defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
     if( CountNbEnabled125kHzChannels( ChannelsMaskRemaining ) == 0 )
     { // Restore default channels
-        memcpy1( ( uint8_t* ) ChannelsMaskRemaining, ( uint8_t* ) ChannelsMask, 8 );
+        memcpy1( ( uint8_t* ) ChannelsMaskRemaining, ( uint8_t* ) LoRaMacParams.ChannelsMask, 8 );
     }
-    if( ( ChannelsDatarate >= DR_4 ) && ( ( ChannelsMaskRemaining[4] & 0x00FF ) == 0 ) )
+    if( ( LoRaMacParams.ChannelsDatarate >= DR_4 ) && ( ( ChannelsMaskRemaining[4] & 0x00FF ) == 0 ) )
     { // Make sure, that the channels are activated
-        ChannelsMaskRemaining[4] = ChannelsMask[4];
+        ChannelsMaskRemaining[4] = LoRaMacParams.ChannelsMask[4];
     }
 #else
-    if( CountBits( ChannelsMask[0], 16 ) == 0 )
+    if( CountBits( LoRaMacParams.ChannelsMask[0], 16 ) == 0 )
     {
         // Re-enable default channels, if no channel is enabled
-        ChannelsMask[0] = ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
+        LoRaMacParams.ChannelsMask[0] = LoRaMacParams.ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
     }
 #endif
 
@@ -1738,7 +1802,7 @@
 #if defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
                 if( ( ChannelsMaskRemaining[k] & ( 1 << j ) ) != 0 )
 #else
-                if( ( ChannelsMask[k] & ( 1 << j ) ) != 0 )
+                if( ( LoRaMacParams.ChannelsMask[k] & ( 1 << j ) ) != 0 )
 #endif
                 {
                     if( Channels[i + j].Frequency == 0 )
@@ -1754,8 +1818,8 @@
                         }
                     }
 #endif
-                    if( ( ( Channels[i + j].DrRange.Fields.Min <= ChannelsDatarate ) &&
-                          ( ChannelsDatarate <= Channels[i + j].DrRange.Fields.Max ) ) == false )
+                    if( ( ( Channels[i + j].DrRange.Fields.Min <= LoRaMacParams.ChannelsDatarate ) &&
+                          ( LoRaMacParams.ChannelsDatarate <= Channels[i + j].DrRange.Fields.Max ) ) == false )
                     { // Check if the current channel selection supports the given datarate
                         continue;
                     }
@@ -1856,7 +1920,7 @@
 
         if( rxContinuous == false )
         {
-            Radio.Rx( MaxRxWindow );
+            Radio.Rx( LoRaMacParams.MaxRxWindow );
         }
         else
         {
@@ -1865,6 +1929,22 @@
     }
 }
 
+static bool Rx2FreqInRange( uint32_t freq )
+{
+#if defined( USE_BAND_433 ) || defined( USE_BAND_780 ) || defined( USE_BAND_868 )
+    if( Radio.CheckRfFrequency( freq ) == true )
+#elif ( defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID ) )
+    if( ( Radio.CheckRfFrequency( freq ) == true ) &&
+        ( freq >= LORAMAC_FIRST_RX2_CHANNEL ) &&
+        ( freq <= LORAMAC_LAST_RX2_CHANNEL ) &&
+        ( ( ( freq - ( uint32_t ) LORAMAC_FIRST_RX2_CHANNEL ) % ( uint32_t ) LORAMAC_STEPWIDTH_RX2_CHANNEL ) == 0 ) )
+#endif
+    {
+        return true;
+    }
+    return false;
+}
+
 static bool ValidatePayloadLength( uint8_t lenN, int8_t datarate, uint8_t fOptsLen )
 {
     uint16_t maxN = 0;
@@ -1987,14 +2067,14 @@
 {
     int8_t resultTxPower = txPower;
 #if defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
-    if( ( ChannelsDatarate == DR_4 ) ||
-        ( ( ChannelsDatarate >= DR_8 ) && ( ChannelsDatarate <= DR_13 ) ) )
+    if( ( LoRaMacParams.ChannelsDatarate == DR_4 ) ||
+        ( ( LoRaMacParams.ChannelsDatarate >= DR_8 ) && ( LoRaMacParams.ChannelsDatarate <= DR_13 ) ) )
     {// Limit tx power to max 26dBm
         resultTxPower =  MAX( txPower, TX_POWER_26_DBM );
     }
     else
     {
-        if( CountNbEnabled125kHzChannels( ChannelsMask ) < 50 )
+        if( CountNbEnabled125kHzChannels( LoRaMacParams.ChannelsMask ) < 50 )
         {// Limit tx power to max 21dBm
             resultTxPower = MAX( txPower, TX_POWER_20_DBM );
         }
@@ -2031,7 +2111,7 @@
 static bool AdrNextDr( bool adrEnabled, bool updateChannelMask, int8_t* datarateOut )
 {
     bool adrAckReq = false;
-    int8_t datarate = ChannelsDatarate;
+    int8_t datarate = LoRaMacParams.ChannelsDatarate;
 
     if( adrEnabled == true )
     {
@@ -2052,7 +2132,7 @@
             }
             if( AdrAckCounter >= ( ADR_ACK_LIMIT + ADR_ACK_DELAY ) )
             {
-                if( ( ( AdrAckCounter - ADR_ACK_DELAY ) % ADR_ACK_LIMIT ) == 0 )
+                if( ( AdrAckCounter % ADR_ACK_DELAY ) == 0 )
                 {
 #if defined( USE_BAND_433 ) || defined( USE_BAND_780 ) || defined( USE_BAND_868 )
                     if( datarate > LORAMAC_TX_MIN_DATARATE )
@@ -2063,9 +2143,8 @@
                     {
                         if( updateChannelMask == true )
                         {
-
                             // Re-enable default channels LC1, LC2, LC3
-                            ChannelsMask[0] = ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
+                            LoRaMacParams.ChannelsMask[0] = LoRaMacParams.ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
                         }
                     }
 #elif defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
@@ -2083,15 +2162,15 @@
                         {
 #if defined( USE_BAND_915 )
                             // Re-enable default channels
-                            ChannelsMask[0] = 0xFFFF;
-                            ChannelsMask[1] = 0xFFFF;
-                            ChannelsMask[2] = 0xFFFF;
-                            ChannelsMask[3] = 0xFFFF;
-                            ChannelsMask[4] = 0x00FF;
-                            ChannelsMask[5] = 0x0000;
+                            LoRaMacParams.ChannelsMask[0] = 0xFFFF;
+                            LoRaMacParams.ChannelsMask[1] = 0xFFFF;
+                            LoRaMacParams.ChannelsMask[2] = 0xFFFF;
+                            LoRaMacParams.ChannelsMask[3] = 0xFFFF;
+                            LoRaMacParams.ChannelsMask[4] = 0x00FF;
+                            LoRaMacParams.ChannelsMask[5] = 0x0000;
 #else // defined( USE_BAND_915_HYBRID )
                             // Re-enable default channels
-                            ReenableChannels( ChannelsMask[4], ChannelsMask );
+                            ReenableChannels( LoRaMacParams.ChannelsMask[4], LoRaMacParams.ChannelsMask );
 #endif
                         }
                     }
@@ -2111,11 +2190,13 @@
 static LoRaMacStatus_t AddMacCommand( uint8_t cmd, uint8_t p1, uint8_t p2 )
 {
     LoRaMacStatus_t status = LORAMAC_STATUS_BUSY;
+    // The maximum buffer length must take MAC commands to re-send into account.
+    uint8_t bufLen = LORA_MAC_COMMAND_MAX_LENGTH - MacCommandsBufferToRepeatIndex;
 
     switch( cmd )
     {
         case MOTE_MAC_LINK_CHECK_REQ:
-            if( MacCommandsBufferIndex < LORA_MAC_COMMAND_MAX_LENGTH )
+            if( MacCommandsBufferIndex < bufLen )
             {
                 MacCommandsBuffer[MacCommandsBufferIndex++] = cmd;
                 // No payload for this command
@@ -2123,7 +2204,7 @@
             }
             break;
         case MOTE_MAC_LINK_ADR_ANS:
-            if( MacCommandsBufferIndex < ( LORA_MAC_COMMAND_MAX_LENGTH - 1 ) )
+            if( MacCommandsBufferIndex < ( bufLen - 1 ) )
             {
                 MacCommandsBuffer[MacCommandsBufferIndex++] = cmd;
                 // Margin
@@ -2132,7 +2213,7 @@
             }
             break;
         case MOTE_MAC_DUTY_CYCLE_ANS:
-            if( MacCommandsBufferIndex < LORA_MAC_COMMAND_MAX_LENGTH )
+            if( MacCommandsBufferIndex < bufLen )
             {
                 MacCommandsBuffer[MacCommandsBufferIndex++] = cmd;
                 // No payload for this answer
@@ -2140,7 +2221,7 @@
             }
             break;
         case MOTE_MAC_RX_PARAM_SETUP_ANS:
-            if( MacCommandsBufferIndex < ( LORA_MAC_COMMAND_MAX_LENGTH - 1 ) )
+            if( MacCommandsBufferIndex < ( bufLen - 1 ) )
             {
                 MacCommandsBuffer[MacCommandsBufferIndex++] = cmd;
                 // Status: Datarate ACK, Channel ACK
@@ -2149,7 +2230,7 @@
             }
             break;
         case MOTE_MAC_DEV_STATUS_ANS:
-            if( MacCommandsBufferIndex < ( LORA_MAC_COMMAND_MAX_LENGTH - 2 ) )
+            if( MacCommandsBufferIndex < ( bufLen - 2 ) )
             {
                 MacCommandsBuffer[MacCommandsBufferIndex++] = cmd;
                 // 1st byte Battery
@@ -2160,7 +2241,7 @@
             }
             break;
         case MOTE_MAC_NEW_CHANNEL_ANS:
-            if( MacCommandsBufferIndex < ( LORA_MAC_COMMAND_MAX_LENGTH - 1 ) )
+            if( MacCommandsBufferIndex < ( bufLen - 1 ) )
             {
                 MacCommandsBuffer[MacCommandsBufferIndex++] = cmd;
                 // Status: Datarate range OK, Channel frequency OK
@@ -2169,7 +2250,7 @@
             }
             break;
         case MOTE_MAC_RX_TIMING_SETUP_ANS:
-            if( MacCommandsBufferIndex < LORA_MAC_COMMAND_MAX_LENGTH )
+            if( MacCommandsBufferIndex < bufLen )
             {
                 MacCommandsBuffer[MacCommandsBufferIndex++] = cmd;
                 // No payload for this answer
@@ -2186,6 +2267,40 @@
     return status;
 }
 
+static uint8_t ParseMacCommandsToRepeat( uint8_t* cmdBufIn, uint8_t length, uint8_t* cmdBufOut )
+{
+    uint8_t i = 0;
+    uint8_t cmdCount = 0;
+
+    if( ( cmdBufIn == NULL ) || ( cmdBufOut == NULL ) )
+    {
+        return 0;
+    }
+
+    for( i = 0; i < length; i++ )
+    {
+        switch( cmdBufIn[i] )
+        {
+            case MOTE_MAC_RX_PARAM_SETUP_ANS:
+            {
+                cmdBufOut[cmdCount++] = cmdBufIn[i++];
+                cmdBufOut[cmdCount++] = cmdBufIn[i++];
+                cmdBufOut[cmdCount++] = cmdBufIn[i];
+                break;
+            }
+            case MOTE_MAC_RX_TIMING_SETUP_ANS:
+            {
+                cmdBufOut[cmdCount++] = cmdBufIn[i];
+                break;
+            }
+            default:
+                break;
+        }
+    }
+
+    return cmdCount;
+}
+
 static void ProcessMacCommands( uint8_t *payload, uint8_t macIndex, uint8_t commandsSize, uint8_t snr )
 {
     while( macIndex < commandsSize )
@@ -2212,14 +2327,14 @@
                     // Initialize local copy of the channels mask array
                     for( i = 0; i < 6; i++ )
                     {
-                        channelsMask[i] = ChannelsMask[i];
+                        channelsMask[i] = LoRaMacParams.ChannelsMask[i];
                     }
                     datarate = payload[macIndex++];
                     txPower = datarate & 0x0F;
                     datarate = ( datarate >> 4 ) & 0x0F;
 
                     if( ( AdrCtrlOn == false ) &&
-                        ( ( ChannelsDatarate != datarate ) || ( ChannelsTxPower != txPower ) ) )
+                        ( ( LoRaMacParams.ChannelsDatarate != datarate ) || ( LoRaMacParams.ChannelsTxPower != txPower ) ) )
                     { // ADR disabled don't handle ADR requests if server tries to change datarate or txpower
                         // Answer the server with fail status
                         // Power ACK     = 0
@@ -2341,17 +2456,17 @@
                     }
                     if( ( status & 0x07 ) == 0x07 )
                     {
-                        ChannelsDatarate = datarate;
-                        ChannelsTxPower = txPower;
-
-                        ChannelsMask[0] = channelsMask[0];
-                        ChannelsMask[1] = channelsMask[1];
-                        ChannelsMask[2] = channelsMask[2];
-                        ChannelsMask[3] = channelsMask[3];
-                        ChannelsMask[4] = channelsMask[4];
-                        ChannelsMask[5] = channelsMask[5];
-
-                        ChannelsNbRep = nbRep;
+                        LoRaMacParams.ChannelsDatarate = datarate;
+                        LoRaMacParams.ChannelsTxPower = txPower;
+
+                        LoRaMacParams.ChannelsMask[0] = channelsMask[0];
+                        LoRaMacParams.ChannelsMask[1] = channelsMask[1];
+                        LoRaMacParams.ChannelsMask[2] = channelsMask[2];
+                        LoRaMacParams.ChannelsMask[3] = channelsMask[3];
+                        LoRaMacParams.ChannelsMask[4] = channelsMask[4];
+                        LoRaMacParams.ChannelsMask[5] = channelsMask[5];
+
+                        LoRaMacParams.ChannelsNbRep = nbRep;
                     }
                     AddMacCommand( MOTE_MAC_LINK_ADR_ANS, status, 0 );
                 }
@@ -2377,7 +2492,7 @@
                     freq |= ( uint32_t )payload[macIndex++] << 16;
                     freq *= 100;
 
-                    if( Radio.CheckRfFrequency( freq ) == false )
+                    if( Rx2FreqInRange( freq ) == false )
                     {
                         status &= 0xFE; // Channel frequency KO
                     }
@@ -2400,9 +2515,9 @@
 
                     if( ( status & 0x07 ) == 0x07 )
                     {
-                        Rx2Channel.Datarate = datarate;
-                        Rx2Channel.Frequency = freq;
-                        Rx1DrOffset = drOffset;
+                        LoRaMacParams.Rx2Channel.Datarate = datarate;
+                        LoRaMacParams.Rx2Channel.Frequency = freq;
+                        LoRaMacParams.Rx1DrOffset = drOffset;
                     }
                     AddMacCommand( MOTE_MAC_RX_PARAM_SETUP_ANS, status, 0 );
                 }
@@ -2493,8 +2608,8 @@
                     {
                         delay++;
                     }
-                    ReceiveDelay1 = delay * 1e6;
-                    ReceiveDelay2 = ReceiveDelay1 + 1e6;
+                    LoRaMacParams.ReceiveDelay1 = delay * 1e6;
+                    LoRaMacParams.ReceiveDelay2 = LoRaMacParams.ReceiveDelay1 + 1e6;
                     AddMacCommand( MOTE_MAC_RX_TIMING_SETUP_ANS, 0, 0 );
                 }
                 break;
@@ -2556,11 +2671,11 @@
     while( SetNextChannel( &dutyCycleTimeOff ) == false )
     {
         // Set the default datarate
-        ChannelsDatarate = ChannelsDefaultDatarate;
+        LoRaMacParams.ChannelsDatarate = LoRaMacParamsDefaults.ChannelsDatarate;
 
 #if defined( USE_BAND_433 ) || defined( USE_BAND_780 ) || defined( USE_BAND_868 )
         // Re-enable default channels LC1, LC2, LC3
-        ChannelsMask[0] = ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
+        LoRaMacParams.ChannelsMask[0] = LoRaMacParams.ChannelsMask[0] | ( LC( 1 ) + LC( 2 ) + LC( 3 ) );
 #endif
     }
 
@@ -2581,15 +2696,45 @@
     }
 }
 
+static uint16_t RetransmissionDutyCylce( void )
+{
+    uint16_t dutyCycle = 0;
+
+#if defined( USE_BAND_868 ) || defined( USE_BAND_433 ) || defined( USE_BAND_780 )
+    TimerTime_t timeElapsed = TimerGetElapsedTime( 0 );
+
+    if( timeElapsed < 3600000000 )
+    {
+        dutyCycle = BACKOFF_DC_1_HOUR;
+    }
+    else if( timeElapsed < ( 3600000000 + 36000000000 ) )
+    {
+        dutyCycle = BACKOFF_DC_10_HOURS;
+    }
+    else
+    {
+        dutyCycle = BACKOFF_DC_24_HOURS;
+    }
+#endif
+    return dutyCycle;
+}
+
 static void CalculateBackOff( uint8_t channel )
 {
     uint16_t dutyCycle = Bands[Channels[channel].Band].DCycle;
+    uint16_t joinDutyCycle = 0;
+    bool rndTimeOff = false;
 
     if( IsLoRaMacNetworkJoined == false )
     {
-#if defined( USE_BAND_868 ) || defined( USE_BAND_433 ) || defined( USE_BAND_780 )
-        dutyCycle = JOIN_DC;
-#endif
+        joinDutyCycle = RetransmissionDutyCylce( );
+        dutyCycle = MAX( dutyCycle, joinDutyCycle );
+
+        // Make sure to not apply the random back-off to the first TX
+        if( TxTimeOnAir > 0 )
+        {
+            rndTimeOff = true;
+        }
     }
 
     // Update Band Time OFF
@@ -2601,10 +2746,126 @@
     {
         Bands[Channels[channel].Band].TimeOff = 0;
     }
+
+    if( rndTimeOff == true )
+    {
+        Bands[Channels[channel].Band].TimeOff = randr( Bands[Channels[channel].Band].TimeOff,
+                                                       Bands[Channels[channel].Band].TimeOff + BACKOFF_RND_OFFSET );
+    }
+
     // Update Aggregated Time OFF
     AggregatedTimeOff = AggregatedTimeOff + ( TxTimeOnAir * AggregatedDCycle - TxTimeOnAir );
 }
 
+static int8_t AlternateDatarate( uint16_t nbTrials )
+{
+    int8_t datarate = LORAMAC_TX_MIN_DATARATE;
+#if defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
+#if defined( USE_BAND_915 )
+    // Re-enable 500 kHz default channels
+    LoRaMacParams.ChannelsMask[4] = 0x00FF;
+#else // defined( USE_BAND_915_HYBRID )
+    // Re-enable 500 kHz default channels
+    ReenableChannels( LoRaMacParams.ChannelsMask[4], LoRaMacParams.ChannelsMask );
+#endif
+
+    if( ( nbTrials & 0x01 ) == 0x01 )
+    {
+        datarate = DR_4;
+    }
+    else
+    {
+        datarate = DR_1;
+    }
+#else
+    if( ( nbTrials % 48 ) == 0 )
+    {
+        datarate = DR_0;
+    }
+    else if( ( nbTrials % 32 ) == 0 )
+    {
+        datarate = DR_1;
+    }
+    else if( ( nbTrials % 24 ) == 0 )
+    {
+        datarate = DR_2;
+    }
+    else if( ( nbTrials % 16 ) == 0 )
+    {
+        datarate = DR_3;
+    }
+    else if( ( nbTrials % 8 ) == 0 )
+    {
+        datarate = DR_4;
+    }
+    else
+    {
+        datarate = DR_5;
+    }
+#endif
+    return datarate;
+}
+
+static void ResetMacParameters( void )
+{
+    IsLoRaMacNetworkJoined = false;
+
+    // Counters
+    UpLinkCounter = 1;
+    DownLinkCounter = 0;
+    AdrAckCounter = 0;
+
+    ChannelsNbRepCounter = 0;
+
+    AckTimeoutRetries = 1;
+    AckTimeoutRetriesCounter = 1;
+    AckTimeoutRetry = false;
+
+    MaxDCycle = 0;
+    AggregatedDCycle = 1;
+
+    MacCommandsBufferIndex = 0;
+    MacCommandsBufferToRepeatIndex = 0;
+
+    IsRxWindowsEnabled = true;
+
+    LoRaMacParams.ChannelsTxPower = LoRaMacParamsDefaults.ChannelsTxPower;
+    LoRaMacParams.ChannelsDatarate = LoRaMacParamsDefaults.ChannelsDatarate;
+
+    LoRaMacParams.MaxRxWindow = LoRaMacParamsDefaults.MaxRxWindow;
+    LoRaMacParams.ReceiveDelay1 = LoRaMacParamsDefaults.ReceiveDelay1;
+    LoRaMacParams.ReceiveDelay2 = LoRaMacParamsDefaults.ReceiveDelay2;
+    LoRaMacParams.JoinAcceptDelay1 = LoRaMacParamsDefaults.JoinAcceptDelay1;
+    LoRaMacParams.JoinAcceptDelay2 = LoRaMacParamsDefaults.JoinAcceptDelay2;
+
+    LoRaMacParams.Rx1DrOffset = LoRaMacParamsDefaults.Rx1DrOffset;
+    LoRaMacParams.ChannelsNbRep = LoRaMacParamsDefaults.ChannelsNbRep;
+
+    LoRaMacParams.Rx2Channel = LoRaMacParamsDefaults.Rx2Channel;
+
+    memcpy1( ( uint8_t* ) LoRaMacParams.ChannelsMask, ( uint8_t* ) LoRaMacParamsDefaults.ChannelsMask, sizeof( LoRaMacParams.ChannelsMask ) );
+
+#if defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
+    memcpy1( ( uint8_t* ) ChannelsMaskRemaining, ( uint8_t* ) LoRaMacParamsDefaults.ChannelsMask, sizeof( LoRaMacParams.ChannelsMask ) );
+#endif
+
+
+    NodeAckRequested = false;
+    SrvAckRequested = false;
+    MacCommandsInNextTx = false;
+
+    // Reset Multicast downlink counters
+    MulticastParams_t *cur = MulticastChannels;
+    while( cur != NULL )
+    {
+        cur->DownLinkCounter = 0;
+        cur = cur->Next;
+    }
+
+    // Initialize channel index.
+    Channel = LORA_MAX_NB_CHANNELS;
+}
+
 LoRaMacStatus_t PrepareFrame( LoRaMacHeader_t *macHdr, LoRaMacFrameCtrl_t *fCtrl, uint8_t fPort, void *fBuffer, uint16_t fBufferSize )
 {
     uint16_t i;
@@ -2628,8 +2889,8 @@
     switch( macHdr->Bits.MType )
     {
         case FRAME_TYPE_JOIN_REQ:
-            RxWindow1Delay = JoinAcceptDelay1 - RADIO_WAKEUP_TIME;
-            RxWindow2Delay = JoinAcceptDelay2 - RADIO_WAKEUP_TIME;
+            RxWindow1Delay = LoRaMacParams.JoinAcceptDelay1 - RADIO_WAKEUP_TIME;
+            RxWindow2Delay = LoRaMacParams.JoinAcceptDelay2 - RADIO_WAKEUP_TIME;
 
             LoRaMacBufferPktLen = pktHeaderLen;
 
@@ -2660,15 +2921,15 @@
                 return LORAMAC_STATUS_NO_NETWORK_JOINED; // No network has been joined yet
             }
 
-            fCtrl->Bits.AdrAckReq = AdrNextDr( fCtrl->Bits.Adr, true, &ChannelsDatarate );
-
-            if( ValidatePayloadLength( fBufferSize, ChannelsDatarate, MacCommandsBufferIndex ) == false )
+            fCtrl->Bits.AdrAckReq = AdrNextDr( fCtrl->Bits.Adr, true, &LoRaMacParams.ChannelsDatarate );
+
+            if( ValidatePayloadLength( fBufferSize, LoRaMacParams.ChannelsDatarate, MacCommandsBufferIndex ) == false )
             {
                 return LORAMAC_STATUS_LENGTH_ERROR;
             }
 
-            RxWindow1Delay = ReceiveDelay1 - RADIO_WAKEUP_TIME;
-            RxWindow2Delay = ReceiveDelay2 - RADIO_WAKEUP_TIME;
+            RxWindow1Delay = LoRaMacParams.ReceiveDelay1 - RADIO_WAKEUP_TIME;
+            RxWindow2Delay = LoRaMacParams.ReceiveDelay2 - RADIO_WAKEUP_TIME;
 
             if( SrvAckRequested == true )
             {
@@ -2686,6 +2947,10 @@
             LoRaMacBuffer[pktHeaderLen++] = UpLinkCounter & 0xFF;
             LoRaMacBuffer[pktHeaderLen++] = ( UpLinkCounter >> 8 ) & 0xFF;
 
+            // Copy the MAC commands which must be re-send into the MAC command buffer
+            memcpy1( &MacCommandsBuffer[MacCommandsBufferIndex], MacCommandsBufferToRepeat, MacCommandsBufferToRepeatIndex );
+            MacCommandsBufferIndex += MacCommandsBufferToRepeatIndex;
+
             if( ( payload != NULL ) && ( payloadSize > 0 ) )
             {
                 if( ( MacCommandsBufferIndex <= LORA_MAC_COMMAND_MAX_LENGTH ) && ( MacCommandsInNextTx == true ) )
@@ -2710,6 +2975,12 @@
                 }
             }
             MacCommandsInNextTx = false;
+            // Store MAC commands which must be re-send in case the device does not receive a downlink anymore
+            MacCommandsBufferToRepeatIndex = ParseMacCommandsToRepeat( MacCommandsBuffer, MacCommandsBufferIndex, MacCommandsBufferToRepeat );
+            if( MacCommandsBufferToRepeatIndex > 0 )
+            {
+                MacCommandsInNextTx = true;
+            }
             MacCommandsBufferIndex = 0;
 
             if( ( payload != NULL ) && ( payloadSize > 0 ) )
@@ -2754,29 +3025,29 @@
 
 LoRaMacStatus_t SendFrameOnChannel( ChannelParams_t channel )
 {
-    int8_t datarate = Datarates[ChannelsDatarate];
+    int8_t datarate = Datarates[LoRaMacParams.ChannelsDatarate];
     int8_t txPowerIndex = 0;
     int8_t txPower = 0;
 
-    txPowerIndex = LimitTxPower( ChannelsTxPower );
+    txPowerIndex = LimitTxPower( LoRaMacParams.ChannelsTxPower );
     txPower = TxPowers[txPowerIndex];
 
     MlmeConfirm.Status = LORAMAC_EVENT_INFO_STATUS_ERROR;
     McpsConfirm.Status = LORAMAC_EVENT_INFO_STATUS_ERROR;
-    McpsConfirm.Datarate = ChannelsDatarate;
+    McpsConfirm.Datarate = LoRaMacParams.ChannelsDatarate;
     McpsConfirm.TxPower = txPowerIndex;
 
     Radio.SetChannel( channel.Frequency );
 
 #if defined( USE_BAND_433 ) || defined( USE_BAND_780 ) || defined( USE_BAND_868 )
-    if( ChannelsDatarate == DR_7 )
+    if( LoRaMacParams.ChannelsDatarate == DR_7 )
     { // High Speed FSK channel
         Radio.SetMaxPayloadLength( MODEM_FSK, LoRaMacBufferPktLen );
         Radio.SetTxConfig( MODEM_FSK, txPower, 25e3, 0, datarate * 1e3, 0, 5, false, true, 0, 0, false, 3e6 );
         TxTimeOnAir = Radio.TimeOnAir( MODEM_FSK, LoRaMacBufferPktLen );
 
     }
-    else if( ChannelsDatarate == DR_6 )
+    else if( LoRaMacParams.ChannelsDatarate == DR_6 )
     { // High speed LoRa channel
         Radio.SetMaxPayloadLength( MODEM_LORA, LoRaMacBufferPktLen );
         Radio.SetTxConfig( MODEM_LORA, txPower, 0, 1, datarate, 1, 8, false, true, 0, 0, false, 3e6 );
@@ -2790,7 +3061,7 @@
     }
 #elif defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
     Radio.SetMaxPayloadLength( MODEM_LORA, LoRaMacBufferPktLen );
-    if( ChannelsDatarate >= DR_4 )
+    if( LoRaMacParams.ChannelsDatarate >= DR_4 )
     { // High speed LoRa channel BW500 kHz
         Radio.SetTxConfig( MODEM_LORA, txPower, 0, 2, datarate, 1, 8, false, true, 0, 0, false, 3e6 );
         TxTimeOnAir = Radio.TimeOnAir( MODEM_LORA, LoRaMacBufferPktLen );
@@ -2840,40 +3111,64 @@
     LoRaMacFlags.Value = 0;
 
     LoRaMacDeviceClass = CLASS_A;
-
-    UpLinkCounter = 1;
-    DownLinkCounter = 0;
-    AdrAckCounter = 0;
-
+    LoRaMacState = MAC_IDLE;
+
+    JoinRequestTrials = 0;
     RepeaterSupport = false;
-    IsRxWindowsEnabled = true;
-    IsLoRaMacNetworkJoined = false;
-    LoRaMacState = MAC_IDLE;
-
+
+    // Reset duty cycle times
+    AggregatedLastTxDoneTime = 0;
+    AggregatedTimeOff = 0;
+
+    // Duty cycle
 #if defined( USE_BAND_433 )
-    ChannelsMask[0] = LC( 1 ) + LC( 2 ) + LC( 3 );
+    DutyCycleOn = false;
 #elif defined( USE_BAND_780 )
-    ChannelsMask[0] = LC( 1 ) + LC( 2 ) + LC( 3 );
+    DutyCycleOn = false;
 #elif defined( USE_BAND_868 )
-    ChannelsMask[0] = LC( 1 ) + LC( 2 ) + LC( 3 );
+    DutyCycleOn = true;
+#elif defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
+    DutyCycleOn = false;
+#else
+    #error "Please define a frequency band in the compiler options."
+#endif
+
+    // Reset to defaults
+    LoRaMacParamsDefaults.ChannelsTxPower = LORAMAC_DEFAULT_TX_POWER;
+    LoRaMacParamsDefaults.ChannelsDatarate = LORAMAC_DEFAULT_DATARATE;
+
+    LoRaMacParamsDefaults.MaxRxWindow = MAX_RX_WINDOW;
+    LoRaMacParamsDefaults.ReceiveDelay1 = RECEIVE_DELAY1;
+    LoRaMacParamsDefaults.ReceiveDelay2 = RECEIVE_DELAY2;
+    LoRaMacParamsDefaults.JoinAcceptDelay1 = JOIN_ACCEPT_DELAY1;
+    LoRaMacParamsDefaults.JoinAcceptDelay2 = JOIN_ACCEPT_DELAY2;
+
+    LoRaMacParamsDefaults.ChannelsNbRep = 1;
+    LoRaMacParamsDefaults.Rx1DrOffset = 0;
+
+    LoRaMacParamsDefaults.Rx2Channel = ( Rx2ChannelParams_t )RX_WND_2_CHANNEL;
+
+    // Channel mask
+#if defined( USE_BAND_433 )
+    LoRaMacParamsDefaults.ChannelsMask[0] = LC( 1 ) + LC( 2 ) + LC( 3 );
+#elif defined( USE_BAND_780 )
+    LoRaMacParamsDefaults.ChannelsMask[0] = LC( 1 ) + LC( 2 ) + LC( 3 );
+#elif defined( USE_BAND_868 )
+    LoRaMacParamsDefaults.ChannelsMask[0] = LC( 1 ) + LC( 2 ) + LC( 3 );
 #elif defined( USE_BAND_915 )
-    ChannelsMask[0] = 0xFFFF;
-    ChannelsMask[1] = 0xFFFF;
-    ChannelsMask[2] = 0xFFFF;
-    ChannelsMask[3] = 0xFFFF;
-    ChannelsMask[4] = 0x00FF;
-    ChannelsMask[5] = 0x0000;
-
-    memcpy1( ( uint8_t* ) ChannelsMaskRemaining, ( uint8_t* ) ChannelsMask, sizeof( ChannelsMask ) );
+    LoRaMacParamsDefaults.ChannelsMask[0] = 0xFFFF;
+    LoRaMacParamsDefaults.ChannelsMask[1] = 0xFFFF;
+    LoRaMacParamsDefaults.ChannelsMask[2] = 0xFFFF;
+    LoRaMacParamsDefaults.ChannelsMask[3] = 0xFFFF;
+    LoRaMacParamsDefaults.ChannelsMask[4] = 0x00FF;
+    LoRaMacParamsDefaults.ChannelsMask[5] = 0x0000;
 #elif defined( USE_BAND_915_HYBRID )
-    ChannelsMask[0] = 0x00FF;
-    ChannelsMask[1] = 0x0000;
-    ChannelsMask[2] = 0x0000;
-    ChannelsMask[3] = 0x0000;
-    ChannelsMask[4] = 0x0001;
-    ChannelsMask[5] = 0x0000;
-
-    memcpy1( ( uint8_t* ) ChannelsMaskRemaining, ( uint8_t* ) ChannelsMask, sizeof( ChannelsMask ) );
+    LoRaMacParamsDefaults.ChannelsMask[0] = 0x00FF;
+    LoRaMacParamsDefaults.ChannelsMask[1] = 0x0000;
+    LoRaMacParamsDefaults.ChannelsMask[2] = 0x0000;
+    LoRaMacParamsDefaults.ChannelsMask[3] = 0x0000;
+    LoRaMacParamsDefaults.ChannelsMask[4] = 0x0001;
+    LoRaMacParamsDefaults.ChannelsMask[5] = 0x0000;
 #else
     #error "Please define a frequency band in the compiler options."
 #endif
@@ -2895,34 +3190,9 @@
     }
 #endif
 
-    ChannelsTxPower = LORAMAC_DEFAULT_TX_POWER;
-    ChannelsDefaultDatarate = ChannelsDatarate = LORAMAC_DEFAULT_DATARATE;
-    ChannelsNbRep = 1;
-    ChannelsNbRepCounter = 0;
-
-    MaxDCycle = 0;
-    AggregatedDCycle = 1;
-    AggregatedLastTxDoneTime = 0;
-    AggregatedTimeOff = 0;
-
-#if defined( USE_BAND_433 )
-    DutyCycleOn = false;
-#elif defined( USE_BAND_780 )
-    DutyCycleOn = false;
-#elif defined( USE_BAND_868 )
-    DutyCycleOn = true;
-#elif defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
-    DutyCycleOn = false;
-#else
-    #error "Please define a frequency band in the compiler options."
-#endif
-
-    MaxRxWindow = MAX_RX_WINDOW;
-    ReceiveDelay1 = RECEIVE_DELAY1;
-    ReceiveDelay2 = RECEIVE_DELAY2;
-    JoinAcceptDelay1 = JOIN_ACCEPT_DELAY1;
-    JoinAcceptDelay2 = JOIN_ACCEPT_DELAY2;
-
+    ResetMacParameters( );
+
+    // Initialize timers
     TimerInit( &MacStateCheckTimer, OnMacStateCheckTimerEvent );
     TimerSetValue( &MacStateCheckTimer, MAC_STATE_CHECK_TIMEOUT );
 
@@ -2942,9 +3212,6 @@
     // Random seed initialization
     srand1( Radio.Random( ) );
 
-    // Initialize channel index.
-    Channel = LORA_MAX_NB_CHANNELS;
-
     PublicNetwork = true;
     SetPublicNetwork( PublicNetwork );
     Radio.Sleep( );
@@ -2954,7 +3221,8 @@
 
 LoRaMacStatus_t LoRaMacQueryTxPossible( uint8_t size, LoRaMacTxInfo_t* txInfo )
 {
-    int8_t datarate = ChannelsDefaultDatarate;
+    int8_t datarate = LoRaMacParamsDefaults.ChannelsDatarate;
+    uint8_t fOptLen = MacCommandsBufferIndex + MacCommandsBufferToRepeatIndex;
 
     if( txInfo == NULL )
     {
@@ -2972,9 +3240,9 @@
         txInfo->CurrentPayloadSize = MaxPayloadOfDatarate[datarate];
     }
 
-    if( txInfo->CurrentPayloadSize >= MacCommandsBufferIndex )
+    if( txInfo->CurrentPayloadSize >= fOptLen )
     {
-        txInfo->MaxPossiblePayload = txInfo->CurrentPayloadSize - MacCommandsBufferIndex;
+        txInfo->MaxPossiblePayload = txInfo->CurrentPayloadSize - fOptLen;
     }
     else
     {
@@ -2986,7 +3254,7 @@
         return LORAMAC_STATUS_LENGTH_ERROR;
     }
 
-    if( ValidatePayloadLength( size, datarate, MacCommandsBufferIndex ) == false )
+    if( ValidatePayloadLength( size, datarate, fOptLen ) == false )
     {
         return LORAMAC_STATUS_MAC_CMD_LENGTH_ERROR;
     }
@@ -3057,57 +3325,57 @@
         }
         case MIB_RX2_CHANNEL:
         {
-            mibGet->Param.Rx2Channel = Rx2Channel;
+            mibGet->Param.Rx2Channel = LoRaMacParams.Rx2Channel;
             break;
         }
         case MIB_CHANNELS_MASK:
         {
-            mibGet->Param.ChannelsMask = ChannelsMask;
+            mibGet->Param.ChannelsMask = LoRaMacParams.ChannelsMask;
             break;
         }
         case MIB_CHANNELS_NB_REP:
         {
-            mibGet->Param.ChannelNbRep = ChannelsNbRep;
+            mibGet->Param.ChannelNbRep = LoRaMacParams.ChannelsNbRep;
             break;
         }
         case MIB_MAX_RX_WINDOW_DURATION:
         {
-            mibGet->Param.MaxRxWindow = MaxRxWindow;
+            mibGet->Param.MaxRxWindow = LoRaMacParams.MaxRxWindow;
             break;
         }
         case MIB_RECEIVE_DELAY_1:
         {
-            mibGet->Param.ReceiveDelay1 = ReceiveDelay1;
+            mibGet->Param.ReceiveDelay1 = LoRaMacParams.ReceiveDelay1;
             break;
         }
         case MIB_RECEIVE_DELAY_2:
         {
-            mibGet->Param.ReceiveDelay2 = ReceiveDelay2;
+            mibGet->Param.ReceiveDelay2 = LoRaMacParams.ReceiveDelay2;
             break;
         }
         case MIB_JOIN_ACCEPT_DELAY_1:
         {
-            mibGet->Param.JoinAcceptDelay1 = JoinAcceptDelay1;
+            mibGet->Param.JoinAcceptDelay1 = LoRaMacParams.JoinAcceptDelay1;
             break;
         }
         case MIB_JOIN_ACCEPT_DELAY_2:
         {
-            mibGet->Param.JoinAcceptDelay2 = JoinAcceptDelay2;
+            mibGet->Param.JoinAcceptDelay2 = LoRaMacParams.JoinAcceptDelay2;
             break;
         }
         case MIB_CHANNELS_DEFAULT_DATARATE:
         {
-            mibGet->Param.ChannelsDefaultDatarate = ChannelsDefaultDatarate;
+            mibGet->Param.ChannelsDefaultDatarate = LoRaMacParamsDefaults.ChannelsDatarate;
             break;
         }
         case MIB_CHANNELS_DATARATE:
         {
-            mibGet->Param.ChannelsDatarate = ChannelsDatarate;
+            mibGet->Param.ChannelsDatarate = LoRaMacParams.ChannelsDatarate;
             break;
         }
         case MIB_CHANNELS_TX_POWER:
         {
-            mibGet->Param.ChannelsTxPower = ChannelsTxPower;
+            mibGet->Param.ChannelsTxPower = LoRaMacParams.ChannelsTxPower;
             break;
         }
         case MIB_UPLINK_COUNTER:
@@ -3231,7 +3499,7 @@
         }
         case MIB_RX2_CHANNEL:
         {
-            Rx2Channel = mibSet->Param.Rx2Channel;
+            LoRaMacParams.Rx2Channel = mibSet->Param.Rx2Channel;
             break;
         }
         case MIB_CHANNELS_MASK:
@@ -3253,12 +3521,12 @@
                     }
                     else
                     {
-                        memcpy1( ( uint8_t* ) ChannelsMask,
-                                 ( uint8_t* ) mibSet->Param.ChannelsMask, sizeof( ChannelsMask ) );
-                        for ( uint8_t i = 0; i < sizeof( ChannelsMask ) / 2; i++ )
+                        memcpy1( ( uint8_t* ) LoRaMacParams.ChannelsMask,
+                                 ( uint8_t* ) mibSet->Param.ChannelsMask, sizeof( LoRaMacParams.ChannelsMask ) );
+                        for ( uint8_t i = 0; i < sizeof( LoRaMacParams.ChannelsMask ) / 2; i++ )
                         {
                             // Disable channels which are no longer available
-                            ChannelsMaskRemaining[i] &= ChannelsMask[i];
+                            ChannelsMaskRemaining[i] &= LoRaMacParams.ChannelsMask[i];
                         }
                     }
                 }
@@ -3267,7 +3535,7 @@
                     status = LORAMAC_STATUS_PARAMETER_INVALID;
                 }
 #else
-                memcpy1( ( uint8_t* ) ChannelsMask,
+                memcpy1( ( uint8_t* ) LoRaMacParams.ChannelsMask,
                          ( uint8_t* ) mibSet->Param.ChannelsMask, 2 );
 #endif
             }
@@ -3282,7 +3550,7 @@
             if( ( mibSet->Param.ChannelNbRep >= 1 ) &&
                 ( mibSet->Param.ChannelNbRep <= 15 ) )
             {
-                ChannelsNbRep = mibSet->Param.ChannelNbRep;
+                LoRaMacParams.ChannelsNbRep = mibSet->Param.ChannelNbRep;
             }
             else
             {
@@ -3292,27 +3560,27 @@
         }
         case MIB_MAX_RX_WINDOW_DURATION:
         {
-            MaxRxWindow = mibSet->Param.MaxRxWindow;
+            LoRaMacParams.MaxRxWindow = mibSet->Param.MaxRxWindow;
             break;
         }
         case MIB_RECEIVE_DELAY_1:
         {
-            ReceiveDelay1 = mibSet->Param.ReceiveDelay1;
+            LoRaMacParams.ReceiveDelay1 = mibSet->Param.ReceiveDelay1;
             break;
         }
         case MIB_RECEIVE_DELAY_2:
         {
-            ReceiveDelay2 = mibSet->Param.ReceiveDelay2;
+            LoRaMacParams.ReceiveDelay2 = mibSet->Param.ReceiveDelay2;
             break;
         }
         case MIB_JOIN_ACCEPT_DELAY_1:
         {
-            JoinAcceptDelay1 = mibSet->Param.JoinAcceptDelay1;
+            LoRaMacParams.JoinAcceptDelay1 = mibSet->Param.JoinAcceptDelay1;
             break;
         }
         case MIB_JOIN_ACCEPT_DELAY_2:
         {
-            JoinAcceptDelay2 = mibSet->Param.JoinAcceptDelay2;
+            LoRaMacParams.JoinAcceptDelay2 = mibSet->Param.JoinAcceptDelay2;
             break;
         }
         case MIB_CHANNELS_DEFAULT_DATARATE:
@@ -3320,7 +3588,7 @@
             if( ValueInRange( mibSet->Param.ChannelsDefaultDatarate,
                               LORAMAC_TX_MIN_DATARATE, LORAMAC_TX_MAX_DATARATE ) )
             {
-                ChannelsDefaultDatarate = mibSet->Param.ChannelsDefaultDatarate;
+                LoRaMacParamsDefaults.ChannelsDatarate = mibSet->Param.ChannelsDefaultDatarate;
             }
             else
             {
@@ -3333,7 +3601,7 @@
             if( ValueInRange( mibSet->Param.ChannelsDatarate,
                               LORAMAC_TX_MIN_DATARATE, LORAMAC_TX_MAX_DATARATE ) )
             {
-                ChannelsDatarate = mibSet->Param.ChannelsDatarate;
+                LoRaMacParams.ChannelsDatarate = mibSet->Param.ChannelsDatarate;
             }
             else
             {
@@ -3346,7 +3614,7 @@
             if( ValueInRange( mibSet->Param.ChannelsTxPower,
                               LORAMAC_MAX_TX_POWER, LORAMAC_MIN_TX_POWER ) )
             {
-                ChannelsTxPower = mibSet->Param.ChannelsTxPower;
+                LoRaMacParams.ChannelsTxPower = mibSet->Param.ChannelsTxPower;
             }
             else
             {
@@ -3412,7 +3680,7 @@
             frequencyInvalid = true;
         }
 
-        if( params.DrRange.Fields.Min > ChannelsDefaultDatarate )
+        if( params.DrRange.Fields.Min > LoRaMacParamsDefaults.ChannelsDatarate )
         {
             datarateInvalid = true;
         }
@@ -3474,7 +3742,7 @@
     // Every parameter is valid, activate the channel
     Channels[id] = params;
     Channels[id].Band = band;
-    ChannelsMask[0] |= ( 1 << id );
+    LoRaMacParams.ChannelsMask[0] |= ( 1 << id );
 
     return LORAMAC_STATUS_OK;
 #endif
@@ -3501,7 +3769,7 @@
         Channels[id] = ( ChannelParams_t ){ 0, { 0 }, 0 };
 
         // Disable the channel as it doesn't exist anymore
-        if( DisableChannelInMask( id, ChannelsMask ) == false )
+        if( DisableChannelInMask( id, LoRaMacParams.ChannelsMask ) == false )
         {
             return LORAMAC_STATUS_PARAMETER_INVALID;
         }
@@ -3631,28 +3899,10 @@
             macHdr.Value = 0;
             macHdr.Bits.MType  = FRAME_TYPE_JOIN_REQ;
 
-            IsLoRaMacNetworkJoined = false;
-
-#if defined( USE_BAND_915 ) || defined( USE_BAND_915_HYBRID )
-#if defined( USE_BAND_915 )
-            // Re-enable 500 kHz default channels
-            ChannelsMask[4] = 0x00FF;
-#else // defined( USE_BAND_915_HYBRID )
-            // Re-enable 500 kHz default channels
-            ChannelsMask[4] = 0x0001;
-#endif
-
-            static uint8_t drSwitch = 0;
-
-            if( ( ++drSwitch & 0x01 ) == 0x01 )
-            {
-                ChannelsDatarate = DR_0;
-            }
-            else
-            {
-                ChannelsDatarate = DR_4;
-            }
-#endif
+            ResetMacParameters( );
+
+            JoinRequestTrials++;
+            LoRaMacParams.ChannelsDatarate = AlternateDatarate( JoinRequestTrials );
 
             status = Send( &macHdr, 0, NULL, 0 );
             break;
@@ -3751,7 +4001,7 @@
         {
             if( ValueInRange( datarate, LORAMAC_TX_MIN_DATARATE, LORAMAC_TX_MAX_DATARATE ) == true )
             {
-                ChannelsDatarate = datarate;
+                LoRaMacParams.ChannelsDatarate = datarate;
             }
             else
             {