Add join back-off

examples/compliance-otaa-halconfig/compliance-otaa-halconfig.ino

@@ -223,6 +223,8 @@ bool lastWasTxStart;
 uint32_t lastTxStartTime;
 
 void myEventCb(void *pUserData, ev_t ev) {
+    LMIC_complianceEvent(ev);
+
     eventQueue.putEvent(ev);
 
     if (ev == EV_TXSTART) {

src/lmic/lmic.c

@@ -597,6 +597,7 @@ static void stateJustJoined (void) {
     LMIC.rejoinCnt   = 0;
     LMIC.dnConf      = LMIC.lastDnConf  = LMIC.adrChanged = 0;
     LMIC.upRepeatCount = LMIC.upRepeat = 0;
+    LMIC.globalDutyRate = 0;
 #if !defined(DISABLE_MCMD_RXParamSetupReq)
     LMIC.dn2Ans      = 0;
 #endif
@@ -1719,6 +1720,21 @@ static bit_t processJoinAccept_nojoinframe(void) {
         LMIC.opmode &= ~OP_TXRXPEND;
         reportEventNoUpdate(EV_JOIN_TXCOMPLETE);
         int failed = LMICbandplan_nextJoinState();
+
+        if(LMIC.globalDutyRate != 0 && (LMIC.txend - LMIC.globalDutyAvail) < 0) {
+            LMIC.txend = LMIC.globalDutyAvail;
+            // Add random delay 10s is arbitrary
+            LMIC.txend += LMICcore_rndDelay(10);
+        }
+
+        // Adjust dutyrate to respect retransmissions back-off during join
+        // Duty rate of 2^14 is enought to respect the max 8.7s by 24h (5.7s / 24h)
+        // Divide the rate by 2 every 4000s respect the limit of 36s during hours 1 to 11
+        if (LMIC.globalDutyRate < 14 && os_getTime() - LMIC.lastDutyRateBackOff > sec2osticks(4000)) {
+            LMIC.globalDutyRate++;
+            LMIC.lastDutyRateBackOff = os_getTime();
+        }
+
         EV(devCond, DEBUG, (e_.reason = EV::devCond_t::NO_JACC,
                             e_.eui    = MAIN::CDEV->getEui(),
                             e_.info   = LMIC.datarate|DR_PAGE,
@@ -2164,8 +2180,12 @@ bit_t LMIC_startJoining (void) {
         // There should be no TX/RX going on
         // ASSERT((LMIC.opmode & (OP_POLL|OP_TXRXPEND)) == 0);
         LMIC.opmode &= ~OP_POLL;
-        // Lift any previous duty limitation
-        LMIC.globalDutyRate = 0;
+        // Reset Duty rate limitation to respect retransmission backoff
+        // (max 28s < 36s during first hour)
+        LMIC.globalDutyRate = 7;
+        LMIC.globalDutyAvail = os_getTime();
+        LMIC.lastDutyRateBackOff = os_getTime();
+
         // Cancel scanning
         LMIC.opmode &= ~(OP_SCAN|OP_UNJOIN|OP_REJOIN|OP_LINKDEAD|OP_NEXTCHNL);
         // Setup state

src/lmic/lmic.h

@@ -569,6 +569,7 @@ struct lmic_t {
 
     u1_t        txChnl;          // channel for next TX
     u1_t        globalDutyRate;  // max rate: 1/2^k
+    ostime_t    lastDutyRateBackOff;
 
     u1_t        upRepeat;     // configured up repeat
     s1_t        adrTxPow;     // ADR adjusted TX power
@@ -715,6 +716,7 @@ enum lmic_compliance_rx_action_e {
     LMIC_COMPLIANCE_RX_ACTION_END           // exit compliance mode, discard this message
 };
 
+void LMIC_complianceEvent(ev_t ev);
 lmic_compliance_rx_action_t LMIC_complianceRxMessage(u1_t port, const u1_t *pMessage, size_t nMessage);
 
 // Declare onEvent() function, to make sure any definition will have the

src/lmic/lmic_compliance.c

@@ -74,6 +74,47 @@ lmic_compliance_t LMIC_Compliance;
 
 /*
 
+Name:   LMIC_complianceEvent()
+
+Function:
+        Modify join state during compliance test.
+
+Definition:
+        void LMIC_complianceEvent(ev_t ev);
+
+Description:
+        Clients who want to handle the LoRaWAN compliance protocol on
+        port 224 should call this routine in the event callback.
+        This function will update the LMIC duty rate to allow the test
+        to run in a raisonnable time.
+
+Returns:
+        nothing.
+
+*/
+
+
+void LMIC_complianceEvent(ev_t ev) {
+    lmic_compliance_state_t const complianceState = LMIC_Compliance.state;
+
+    // only handle event during compliance test.
+    if(!lmic_compliance_state_IsActive(complianceState))
+        return;
+
+    switch (ev)
+    {
+        case EV_JOINING:
+        case EV_JOIN_TXCOMPLETE:
+            // Remove duty rate during join test.
+            LMIC.globalDutyRate = 0;
+            break;
+        default:
+            break;
+    }
+}
+
+/*
+
 Name:   LMIC_complianceRxMessage()
 
 Function: