From 2ede362cb3ab05fd064bd2cb275c020e2a5c233b Mon Sep 17 00:00:00 2001
From: Mark Qvist <mark@unsigned.io>
Date: Thu, 10 Oct 2024 23:26:12 +0200
Subject: [PATCH] Adjusted CSMA parameters and P-curve. Added dynamic CSMA slot
 time.

---
 Config.h           | 8 +++++---
 RNode_Firmware.ino | 4 ++--
 Utilities.h        | 4 +++-
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/Config.h b/Config.h
index d10cc60..b7871d8 100644
--- a/Config.h
+++ b/Config.h
@@ -20,7 +20,7 @@
 	#define CONFIG_H
 
 	#define MAJ_VERS  0x01
-	#define MIN_VERS  0x4d
+	#define MIN_VERS  0x4e
 
 	#define MODE_HOST 0x11
 	#define MODE_TNC  0x12
@@ -74,9 +74,11 @@
 	#define LORA_PREAMBLE_SYMBOLS_MIN 18
 	#define LORA_PREAMBLE_TARGET_MS   15
 	#define LORA_CAD_SYMBOLS 3
+	#define CSMA_SLOT_MAX_MS 100
+	#define CSMA_SLOT_MIN_MS 24
 	int csma_slot_ms = 50;
-	float csma_p_min = 0.08;
-	float csma_p_max = 0.75;
+	float csma_p_min = 0.15;
+	float csma_p_max = 0.333;
 	float csma_b_speed = 0.15;
 	uint8_t csma_p = 85;
 
diff --git a/RNode_Firmware.ino b/RNode_Firmware.ino
index 3e6b09f..089e82f 100644
--- a/RNode_Firmware.ino
+++ b/RNode_Firmware.ino
@@ -1298,10 +1298,10 @@ void validate_status() {
 
 #if MCU_VARIANT == MCU_ESP32 || MCU_VARIANT == MCU_NRF52
   #define _e 2.71828183
-  #define _S 10.0
+  #define _S 12.5
   float csma_slope(float u) { return (pow(_e,_S*u-_S/2.0))/(pow(_e,_S*u-_S/2.0)+1.0); }
   void update_csma_p() {
-    csma_p = (uint8_t)((1.0-(csma_p_min+(csma_p_max-csma_p_min)*csma_slope(airtime)))*255.0);
+    csma_p = (uint8_t)((1.0-(csma_p_min+(csma_p_max-csma_p_min)*csma_slope(airtime+csma_b_speed)))*255.0);
   }
 #endif
 
diff --git a/Utilities.h b/Utilities.h
index 0a3fffb..f0fccd0 100644
--- a/Utilities.h
+++ b/Utilities.h
@@ -1047,7 +1047,9 @@ void updateBitrate() {
 			lora_symbol_time_ms = (1.0/lora_symbol_rate)*1000.0;
 			lora_bitrate = (uint32_t)(lora_sf * ( (4.0/(float)lora_cr) / ((float)(pow(2, lora_sf))/((float)lora_bw/1000.0)) ) * 1000.0);
 			lora_us_per_byte = 1000000.0/((float)lora_bitrate/8.0);
-			// csma_slot_ms = lora_symbol_time_ms*10;
+			csma_slot_ms = lora_symbol_time_ms*12;
+			if (csma_slot_ms > CSMA_SLOT_MAX_MS) { csma_slot_ms = CSMA_SLOT_MAX_MS; }
+			if (csma_slot_ms < CSMA_SLOT_MIN_MS) { csma_slot_ms = CSMA_SLOT_MIN_MS; }
 			float target_preamble_symbols = (LORA_PREAMBLE_TARGET_MS/lora_symbol_time_ms)-LORA_PREAMBLE_SYMBOLS_HW;
 			if (target_preamble_symbols < LORA_PREAMBLE_SYMBOLS_MIN) {
 				target_preamble_symbols = LORA_PREAMBLE_SYMBOLS_MIN;