diff --git a/README.md b/README.md
index d1de959..1f0ddc5 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,8 @@ connection but also supporting RPC (remote procedure call) like
 [JSON-RPC](https://de.wikipedia.org/wiki/JSON-RPC).
 
 OGRP is a protocol based on JSON [[RFC4627](#RFC4627)].
+Valid messages are defined using [[json-schema](#json-schema)]. The core
+protocol can be extended using an application specific schema, see [usage](#usage).
 
 For the use in RPC, zerorpc (<http://zerorpc.dotcloud.com/>) is recommended as a transport mechanism.
 Protocols that already provide message framing should use one JSON object per message.
@@ -105,35 +107,36 @@ Consider the following:
 Message specification
 =====================
 
-An OGRP message is composed of one JSON object. Two mandatory fields
-exist
+An OGRP message is composed of one JSON object. Required fields are:
+"$schema", "timestamp", "time_reference" and "protocol".
 
 ```
-msg = {
-    "protocol": protocol,
-    "id": id,
+{
+    "$schema": schema,
+    "protocol": "OGRP1_3",
+    "timestamp": 101,
+	"time_reference": "UTC",
     ...
 }
 
-protocol = "OGRP1"
-id = string ; lower-case, underscore separated id, e.g. "measurement", ...
+schema = "https://fraunhofer-iis.github.io/ogrp/draft-xx/measurement"
 ```
 
-The additional content in the message is dependant on the message id.
+The additional content in the message is dependent on the message schema.
 Optional fields are allowed and must be ignored by parsers if unknown
 (according to JSON).
 
 Example definitions
 -------------------
 
-A message of id 'measurement' for raw measurements of a GNSS receiver,
+A message of schema 'measurement' for raw measurements of a GNSS receiver,
 e.g. including pseudorange and carrier phase measurements for multiple
 satellites on different channels, can look like this:
 
 ```
 measurement = {
+    "$schema": "https://fraunhofer-iis.github.io/ogrp/next/schema#",
     "protocol": protocol,
-    "id": "measurement",
     "sw_version": int / hex,
     "timestamp": float / string, ; (see Representing time and date)
     "time_status": time_status,
@@ -172,6 +175,7 @@ title element in the schema.
 Usage
 =====
 
+The OGRP core schema can be extended by an application specific schema.
 Applications using OGRP for input or output should define the supported messages
 as JSON Schema [[json-schema](#json-schema)].
 
@@ -179,46 +183,39 @@ An example how to extend the OGRP core schema:
 
 ```JSON
 {
-    "id": "http://example.org/pvt-input-schema#",
-    "$schema": "http://json-schema.org/draft-04/schema#",
-    "description": "Minimum schema for a PVT application",
-    "type": "object",
-    "properties": {
-        "protocol": { "type": "string" },
-        "id": { "type": "string" },
-        "timestamp": { "$ref": "http://ogrp.org/definitions/timestamp" },
-        "channel_measurements": {
+    "$schema": "https://json-schema.org/draft-07/schema#",
+    "$id": "https://example.com/my/application",
+    "title": "My OGRP application",
+    "allOf": [ { "$ref": "https://fraunhofer-iis.github.io/ogrp/draft-xx/schema#" },
+               { "$ref": "#my_element" }
+             ],
+    "definitions": {
+        "my_element": {
+            "$id": "#my_element",
             "type": "object",
             "properties": {
-                "satellite_id": {
+                "my_integer": {
                     "type": "integer",
                     "minimum": 1
                 },
-                "pseudorange": {
-                    "type": "number"
-                }
-            }
-        },
-        "satellites": {
-            "type": "object",
-            "properties": {
-                "satellite_id": {
-                    "type": "integer",
-                    "minimum": 1
+                "my_string": {
+                    "type": "string"
                 },
-                "position": {
-                    "type": "object",
-                    "properties": {
-                        "x": { "type": "number" },
-                        "y": { "type": "number" },
-                        "z": { "type": "number" }
-                    }
+                "my_time": {
+                    "$ref": "https://fraunhofer-iis.github.io/ogrp/draft-xx/schema#gnss_time"
                 }
             }
         }
     }
 }
 ```
+
+The important line here is `"allOf": [ { "$ref": "https://fraunhofer-iis.github.io/ogrp/draft-xx/schema#" } ],`,
+as it imports all properties of the OGRP core schema. An application schema should not link to the "experimental"
+schema, as this might often change, but instead use a frozen draft as a baseline.
+
+See also [hyper-schema](http://json-schema.org/hyper-schema) as an example how to extend an existing schema.
+
 Security considerations
 =======================
 
diff --git a/draft-01/measurement.ogrp b/draft-01/measurement.ogrp
index 3c25619..676a039 100644
--- a/draft-01/measurement.ogrp
+++ b/draft-01/measurement.ogrp
@@ -1,10 +1,11 @@
 {
-	"$schema": "https://fraunhofer-iis.github.io/ogrp/draft-01/schema#",
+	"$schema": "https://fraunhofer-iis.github.io/ogrp/next/schema.json#",
 	"protocol": "OGRP1_3",
 	"timestamp": 101,
 	"time_status": "SYSTEM",
 	"time_reference": "UTC",
-	"channel_measurements": [{
+	"channel_measurements": [
+		{
 			"doppler": 1200,
 			"sw_channel_number": 0,
 			"hw_channel_number": 0,
@@ -16,7 +17,7 @@
 			"snr": 32,
 			"satellite_id": 1,
 			"pseudo_range": 20000000,
-                        "time_of_transmission" : 0.0
+			"time_of_transmission": 0.0
 		},
 		{
 			"doppler": -1100.3,
@@ -30,7 +31,7 @@
 			"snr": 45.5,
 			"satellite_id": 50,
 			"pseudo_range": 20340000,
-                        "time_of_transmission" : 0.0
+			"time_of_transmission": 0.0
 		}
 	],
 	"id": "measurement"
diff --git a/next/imu.json b/next/imu.json
new file mode 100644
index 0000000..f89c7e7
--- /dev/null
+++ b/next/imu.json
@@ -0,0 +1,144 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/imu.json",
+    "title": "OGRP IMU schema",
+    "description": "Measurements of an IMU",
+    "type": "object",
+    "additionalProperties": true,
+    "properties": {
+        "$schema": {
+            "const": "https://fraunhofer-iis.github.io/ogrp/next/imu.json"
+        },
+        "acceleration": {
+            "type": "object",
+            "properties": {
+                "x": {
+                    "type": "number",
+                    "description": "(m/s^2)"
+                },
+                "y": {
+                    "type": "number",
+                    "description": "(m/s^2)"
+                },
+                "z": {
+                    "type": "number",
+                    "description": "(m/s^2)"
+                }
+            },
+            "description": "The acceleration vector as reported from the IMU"
+        },
+        "angular_rate": {
+            "type": "object",
+            "properties": {
+                "x": {
+                    "type": "number",
+                    "description": "(rad/s)"
+                },
+                "y": {
+                    "type": "number",
+                    "description": "(rad/s)"
+                },
+                "z": {
+                    "type": "number",
+                    "description": "(rad/s)"
+                }
+            },
+            "description": "The angular rate as reported from the IMU"
+        },
+        "delta_theta": {
+            "type": "object",
+            "properties": {
+                "x": {
+                    "type": "number",
+                    "description": "(rad)"
+                },
+                "y": {
+                    "type": "number",
+                    "description": "(rad)"
+                },
+                "z": {
+                    "type": "number",
+                    "description": "(rad)"
+                }
+            },
+            "description": "Integral of angular rate over measurement interval"
+        },
+        "delta_velocity": {
+            "type": "object",
+            "properties": {
+                "x": {
+                    "type": "number",
+                    "description": "(m/s)"
+                },
+                "y": {
+                    "type": "number",
+                    "description": "(m/s)"
+                },
+                "z": {
+                    "type": "number",
+                    "description": "(m/s)"
+                }
+            },
+            "description": "Integral of acceleration over measurement interval"
+        },
+        "magnetic_field": {
+            "type": "object",
+            "properties": {
+                "x": {
+                    "type": "number",
+                    "description": "(Gs)"
+                },
+                "y": {
+                    "type": "number",
+                    "description": "(Gs)"
+                },
+                "z": {
+                    "type": "number",
+                    "description": "(Gs)"
+                }
+            },
+            "description": "The magnetic field as reported from the IMU"
+        },
+        "gps_correlation_timestamp": {
+            "type": "object",
+            "properties": {
+                "gps_tow": {
+                    "type": "number",
+                    "description": "GPS time of week (s)"
+                },
+                "gps_week_number": {
+                    "type": "number",
+                    "description": "GPS week number"
+                },
+                "pps_beacon_good": {
+                    "type": "boolean",
+                    "description": "If set, GNSS PPS is present"
+                },
+                "gps_time_refresh": {
+                    "type": "number",
+                    "description": "PPS pulse counter"
+                },
+                "gps_time_initialized": {
+                    "type": "boolean",
+                    "description": "Is set once upon the first valid GPS time record"
+                }
+            },
+            "required": [
+                "gnss_tow",
+                "gnss_week_number",
+                "pps_beacon_good",
+                "gps_time_refresh",
+                "gps_time_initialized"
+            ]
+        },
+        "pressure": {
+            "type": "number",
+            "description": "Pressure (hPa)"
+        },
+        "measurement_interval": {
+            "type": "number",
+            "title": "Time since last measurement",
+            "description": "(s)"
+        }
+    }
+}
diff --git a/next/measurement.json b/next/measurement.json
new file mode 100644
index 0000000..4fb21fe
--- /dev/null
+++ b/next/measurement.json
@@ -0,0 +1,98 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/measurement.json",
+    "title": "OGRP measurement schema",
+    "type": "object",
+    "properties": {
+        "gnss": {
+            "$ref": "types.json#gnss"
+        },
+        "satellite_id": {
+            "$ref": "types.json#satellite_id"
+        },
+        "frequency_number": {
+            "type": "integer",
+            "minimum": -7,
+            "description": "Only for GLONASS frequency slot number"
+        },
+        "signal_type": {
+            "$ref": "types.json#signal"
+        },
+        "carrier_phase": {
+            "type": "number",
+            "description": "(cycles)"
+        },
+        "carrier_range": {
+            "type": "number",
+            "description": "(meter)"
+        },
+        "code_phase": {
+            "type": "number",
+            "description": "(chips)"
+        },
+        "channel_state": {
+            "enum": [
+                "IDLE",
+                "SEARCHING",
+                "PULL_IN",
+                "LOCKED",
+                "SYNCED"
+            ]
+        },
+        "sw_channel_number": {
+            "type": "integer",
+            "minimum": 0,
+            "description": "SW channel number"
+        },
+        "hw_channel_number": {
+            "type": "integer",
+            "minimum": 0,
+            "description": "HW channel number"
+        },
+        "doppler": {
+            "type": "number",
+            "description": "(Hz)"
+        },
+        "locktime": {
+            "type": "number",
+            "description": "(seconds)"
+        },
+        "frequency_lock": {
+            "type": "number",
+            "description": "frequency lock indicator"
+        },
+        "phase_lock": {
+            "type": "number",
+            "description": "phase lock indicator"
+        },
+        "snr": {
+            "title": "Signal to noise ratio",
+            "type": "number",
+            "description": "(dB)"
+        },
+        "cn0": {
+            "title": "Carrier to noise density",
+            "type": "number",
+            "description": "(dB-Hz)"
+        },
+        "pseudo_range": {
+            "title": "Pseudo range or code range",
+            "type": "number",
+            "description": "(meter)"
+        },
+        "corrected_pseudo_range": {
+            "type": "number",
+            "description": "Pseudorange after applying clock and atmospheric correction (in meter)"
+        },
+        "time_of_transmission": {
+            "$ref": "types.json#tow",
+            "description": "Estimated GNSS time of week of the signal transmission"
+        }
+    },
+    "required": [
+        "carrier_phase",
+        "pseudo_range",
+        "satellite_id",
+        "gnss"
+    ]
+}
diff --git a/next/measurement.ogrp b/next/measurement.ogrp
new file mode 100644
index 0000000..bcdd55d
--- /dev/null
+++ b/next/measurement.ogrp
@@ -0,0 +1,32 @@
+{
+	"$schema": "https://fraunhofer-iis.github.io/ogrp/next/schema#",
+	"protocol": "OGRP1_2",
+	"timestamp": 101,
+	"time_status": "SYSTEM",
+	"time_reference": "UTC",
+	"range_measurements": [{
+			"doppler": 1200,
+			"channel_number": 1,
+			"gnss": "GPS",
+			"locktime": 0,
+			"carrier_phase": 0,
+			"channel_state": "IDLE",
+			"signal_type": "L1CA",
+			"snr": 32,
+			"satellite_id": 1,
+			"pseudo_range": 20000000
+		},
+		{
+			"doppler": -1100.3,
+			"channel_number": 1,
+			"gnss": "Galileo",
+			"locktime": 0,
+			"carrier_phase": -123.4,
+			"channel_state": "SYNCED",
+			"signal_type": "E5aI",
+			"snr": 45.5,
+			"satellite_id": 50,
+			"pseudo_range": 20340000
+		}
+	]
+}
diff --git a/next/navigation-data.json b/next/navigation-data.json
new file mode 100644
index 0000000..589eb55
--- /dev/null
+++ b/next/navigation-data.json
@@ -0,0 +1,424 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/navigation-data.json",
+    "title": "OGRP navigation data schema",
+    "definitions": {
+        "glonass_ephemeris": {
+            "$id": "#glonass_ephemeris",
+            "type": "object",
+            "properties": {
+                "satellite_id": {
+                    "$ref": "types.json#satellite_id"
+                },
+                "freqnum": {
+                    "type": "integer",
+                    "description": "Frequency channel number (-7...24)"
+                },
+                "reference_time": {
+                    "type": "integer",
+                    "description": "Reference time of ephemeris (s)"
+                },
+                "reference_day": {
+                    "type": "integer",
+                    "description": "Day of reference time of ephemeris (day in 4 year block)"
+                },
+                "healthy": {
+                    "type": "boolean",
+                    "description": "True means satelitte is healthy, taken from signal"
+                },
+                "healthy1": {
+                    "type": "boolean",
+                    "description": "True means satelitte is healthy, taken from almanac"
+                },
+                "healthy2": {
+                    "type": "boolean",
+                    "description": "True means satelitte is healthy, own diagnostic"
+                },
+                "age": {
+                    "type": "number",
+                    "description": "Ephemeris, age of data (days)"
+                },
+                "coords": {
+                    "title": "Ephemeris coordinates (x, y, z)",
+                    "type": "array",
+                    "numItems": 3,
+                    "description": "(km)",
+                    "items": {
+                        "type": "number"
+                    }
+                },
+                "velocities": {
+                    "title": "Ephemeris velocities (vx, vy, vz)",
+                    "type": "array",
+                    "numItems": 3,
+                    "description": "(km/s)",
+                    "items": {
+                        "type": "number"
+                    }
+                },
+                "accelarations": {
+                    "title": "Ephemeris accelarations (ax, ay, az)",
+                    "type": "array",
+                    "numItems": 3,
+                    "description": "(km/s²)",
+                    "items": {
+                        "type": "number"
+                    }
+                },
+                "tau_sys": {
+                    "type": "number",
+                    "description": "Clock, time correction to glonass time scale (s)"
+                },
+                "tau": {
+                    "type": "number",
+                    "description": "Clock, time correction to sat-clock (s)"
+                },
+                "gamma": {
+                    "type": "number",
+                    "description": "Clock, sat-clock offset rate (s/s)"
+                }
+            },
+            "required": [
+                "satellite_id",
+                "reference_time",
+                "reference_day",
+                "coords",
+                "velocities",
+                "accelarations"
+            ]
+        },
+        "ephemeris": {
+            "$id": "#ephemeris",
+            "type": "object",
+            "properties": {
+                "gnss": {
+                    "$ref": "types.json#gnss",
+                    "description": "All GNSS Systems with Kepler Data for ephemeris"
+                },
+                "satellite_id": {
+                    "$ref": "types.json#satellite_id"
+                },
+                "clock_issue": {
+                    "type": "integer",
+                    "description": "Subframe 1, issue of data, clock"
+                },
+                "satellite_health": {
+                    "type": "integer",
+                    "description": "Subframe 1, satellite health"
+                },
+                "clock_reference": {
+                    "$ref": "types.json#tow",
+                    "description": "GPS: Subframe 1, clock Data reference time; Galileo E1/E5b (s)"
+                },
+                "week_number": {
+                    "$ref": "types.json#week_number",
+                    "description": "Subframe 1, GPS week number"
+                },
+                "group_delay": {
+                    "type": "number",
+                    "description": "GPS: Subframe 1, estimated group delay differential; Galileo: Group delay E1/E5b (s)"
+                },
+                "af_2": {
+                    "type": "number",
+                    "description": "GPS: Subframe 1, polynomal coefficient; Galileo: E1/E5b (s/s*s)"
+                },
+                "af_1": {
+                    "type": "number",
+                    "description": "GPS: Subframe 1, polynomal coefficient; Galileo: E1/E5b (s/s)"
+                },
+                "af_0": {
+                    "type": "number",
+                    "description": "GPS: Subframe 1, polynomal coefficient; Galileo: E1/E5b (s)"
+                },
+                "clock_reference_e1e5a": {
+                    "type": "integer",
+                    "description": "Galileo clock Data reference time (s)"
+                },
+                "group_delay_e1e5a": {
+                    "type": "number",
+                    "description": "Galileo group delay E1/E5a (s)"
+                },
+                "af_2_e1e5a": {
+                    "type": "number",
+                    "description": "Galileo SV clock drift rate correction coefficient E1/E5a (s/(s*s))"
+                },
+                "af_1_e1e5a": {
+                    "type": "number",
+                    "description": "Galileo SV clock drift correction coefficient E1/E5a (s/s)"
+                },
+                "af_0_e1e5a": {
+                    "type": "number",
+                    "description": "Galileo SV clock bias correction coefficient E1/E5a (s)"
+                },
+                "ephemeris_reference": {
+                    "$ref": "types.json#tow",
+                    "description": "Subframe 2 and 3, ephemeris reference time (s)"
+                },
+                "ephemeris_issue": {
+                    "type": "integer",
+                    "description": "Subframe 2 and 3, issue of data, ephemeris"
+                },
+                "root_a": {
+                    "type": "number",
+                    "description": "Keplerian, root_a (m^1/2)"
+                },
+                "ecc": {
+                    "type": "number",
+                    "description": "Keplerian, ecc"
+                },
+                "m_0": {
+                    "type": "number",
+                    "description": "Keplerian, m_0 (radian)"
+                },
+                "omega_0": {
+                    "type": "number",
+                    "description": "Keplerian, omega_0 (radian)"
+                },
+                "inc_0": {
+                    "type": "number",
+                    "description": "Keplerian, inc_0 (radian)"
+                },
+                "arg_per": {
+                    "type": "number",
+                    "description": "Keplerian, arg_per (radian)"
+                },
+                "deln": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, deln (radian/s)"
+                },
+                "omega_dot": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, omega_dot (radian/s)"
+                },
+                "inc_dot": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, inc_dot (radian/s)"
+                },
+                "crc": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, crc (m)"
+                },
+                "crs": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, crs (m)"
+                },
+                "cuc": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, cuc (radian)"
+                },
+                "cus": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, cus (radian)"
+                },
+                "cic": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, cic (radian)"
+                },
+                "cis": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, cis (radian)"
+                }
+            },
+            "required": [
+                "satellite_id",
+                "ephemeris_reference",
+                "root_a",
+                "ecc",
+                "m_0",
+                "omega_0",
+                "inc_0",
+                "arg_per"
+            ]
+        },
+        "almanac": {
+            "$id": "#almanac",
+            "type": "object",
+            "properties": {
+                "gnss": {
+                    "$ref": "types.json#gnss",
+                    "description": "All GNSS Systems with Kepler Data for ephemeris"
+                },
+                "satellite_id": {
+                    "$ref": "types.json#satellite_id"
+                },
+                "almanac_issue": {
+                    "type": "integer",
+                    "description": "Issue of almanac data"
+                },
+                "satellite_health": {
+                    "type": "integer",
+                    "description": "Satellite health status"
+                },
+                "almanac_reference": {
+                    "$ref": "types.json#tow",
+                    "description": "Almanac reference time (s)"
+                },
+                "week_number": {
+                    "$ref": "types.json#week_number",
+                    "description": "Almanac reference week number"
+                },
+                "af_1": {
+                    "type": "number",
+                    "description": "Satellite clock correction linear (s/s)"
+                },
+                "af_0": {
+                    "type": "number",
+                    "description": "Satellite clock correction bias (s)"
+                },
+                "root_a": {
+                    "type": "number",
+                    "description": "Keplerian, root_a (m^1/2)"
+                },
+                "ecc": {
+                    "type": "number",
+                    "description": "Keplerian, ecc"
+                },
+                "m_0": {
+                    "type": "number",
+                    "description": "Keplerian, m_0 (radian)"
+                },
+                "omega_0": {
+                    "type": "number",
+                    "description": "Keplerian, omega_0 (radian)"
+                },
+                "arg_per": {
+                    "type": "number",
+                    "description": "Keplerian, arg_per (radian)"
+                },
+                "omega_dot": {
+                    "type": "number",
+                    "description": "Corrections to orbital E, omega_dot (radian/s)"
+                },
+                "delta_i": {
+                    "type": "number",
+                    "description": "Correction of inclination (radian)"
+                }
+            },
+            "required": [
+                "satellite_id"
+            ]
+        },
+        "ionosphere_klobuchar": {
+            "$id": "#ionosphere_klobuchar",
+            "type": "object",
+            "properties": {
+                "amplitude": {
+                    "type": "array",
+                    "numItems": 4,
+                    "description": "Coefficients of cubic equation, amplitude of vertical delay (s..s/semicircles³)",
+                    "items": {
+                        "type": "number"
+                    }
+                },
+                "period": {
+                    "type": "array",
+                    "numItems": 4,
+                    "description": "Coefficients of cubic equation, modelperiod (s..s/semicircles³)",
+                    "items": {
+                        "type": "number"
+                    }
+                }
+            },
+            "required": [
+                "amplitude",
+                "period"
+            ]
+        },
+        "ionosphere_nequick": {
+            "$id": "#ionosphere_nequick",
+            "type": "object",
+            "properties": {
+                "effective_ionisation_level": {
+                    "type": "array",
+                    "numItems": 3,
+                    "description": "Effective ionisation level 1st..3rd order of Nequick model (sfu..sfu/deg²)",
+                    "items": {
+                        "type": "number"
+                    }
+                },
+                "disturbance": {
+                    "type": "array",
+                    "numItems": 5,
+                    "description": "Disturbance flags of the 5 regions",
+                    "items": {
+                        "type": "boolean"
+                    }
+                }
+            },
+            "required": [
+                "effective_ionisation_level"
+            ]
+        },
+        "gnss_utc_parameter": {
+            "$id": "#gnss_utc_parameter",
+            "type": "object",
+            "properties": {
+                "gnss": {
+                    "$ref": "types.json#gnss"
+                },
+                "a_0": {
+                    "type": "number",
+                    "description": "Polynom constant value (s)"
+                },
+                "a_1": {
+                    "type": "number",
+                    "description": "Polynom linear value (s/s)"
+                },
+                "delta_ls": {
+                    "type": "integer",
+                    "description": "Leap second count before leap second adjustment (s)"
+                },
+                "reference_time": {
+                    "$ref": "types.json#time_reference"
+                },
+                "week_lsf": {
+                    "type": "integer",
+                    "description": "Week number of leap second adjustment (week)"
+                },
+                "day_number": {
+                    "type": "integer",
+                    "description": "Day number at the end of which a leap second adjustment becomes effective (day)"
+                },
+                "delta_lsf": {
+                    "type": "integer",
+                    "description": "Leap second count after leap second adjustment (s)"
+                }
+            },
+            "required": [
+                "gnss",
+                "a_0",
+                "a_1",
+                "delta_ls",
+                "reference_time",
+                "week_lsf",
+                "day_number",
+                "delta_lsf"
+            ],
+            "description": "GNSS-UTC conversion parameters"
+        },
+        "ggto_parameter": {
+            "$id": "#ggto_parameter",
+            "type": "object",
+            "properties": {
+                "a_0": {
+                    "type": "number",
+                    "description": "Polynom constant value (s)"
+                },
+                "a_1": {
+                    "type": "number",
+                    "description": "Polynom linear value (s/s)"
+                },
+                "reference_time": {
+                    "$ref": "types.json#time_reference"
+                }
+            },
+            "required": [
+                "a_0",
+                "a_1",
+                "reference_time"
+            ],
+            "additionalProperties": false,
+            "description": "GPS-Galileo system time conversion parameters"
+        }
+    }
+}
diff --git a/next/pvt.json b/next/pvt.json
new file mode 100644
index 0000000..ffb63ad
--- /dev/null
+++ b/next/pvt.json
@@ -0,0 +1,111 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/pvt.json",
+    "title": "OGRP PVT schema",
+    "properties": {
+        "number_of_satellites": {
+            "type": "number",
+            "description": "Number of satellites used in the PVT calculation"
+        },
+        "coordinate_system": {
+            "enum": [
+                "ECEF",
+                "WGS84"
+            ],
+            "description": "In case of WGS84 the coordinates are x:lat, y:lon in degree and z in meter"
+        },
+        "precision": {
+            "enum": [
+                "2D",
+                "3D",
+                "RTK_FIX",
+                "RTK_FLOAT",
+                "DGPS",
+                "SBAS",
+                "NO_FIX"
+            ],
+            "description": "Calculation precision "
+        },
+        "position": {
+            "type": "object",
+            "properties": {
+                "x": {
+                    "type": "number",
+                    "description": "Depending on coordinate_systems"
+                },
+                "y": {
+                    "type": "number",
+                    "description": "Depending on coordinate_systems"
+                },
+                "z": {
+                    "type": "number",
+                    "description": "Depending on coordinate_systems"
+                }
+            },
+            "description": "The calculated position"
+        },
+        "velocity": {
+            "type": "object",
+            "properties": {
+                "x": {
+                    "type": "number",
+                    "description": "ECEF"
+                },
+                "y": {
+                    "type": "number",
+                    "description": "ECEF"
+                },
+                "z": {
+                    "type": "number",
+                    "description": "ECEF"
+                }
+            },
+            "description": "The calculated velocity"
+        },
+        "clock_bias": {
+            "type": "number",
+            "description": "The calculated clock error (s)"
+        },
+        "clock_drift": {
+            "type": "number",
+            "description": "The variation of the clock error in the last PVT interval (s/s)"
+        },
+        "vdop": {
+            "type": "number",
+            "description": "The vertical dilution of precision"
+        },
+        "hdop": {
+            "type": "number",
+            "description": "The horizontal dilution of precision"
+        },
+        "pdop": {
+            "type": "number",
+            "description": "The positional dilution of precision"
+        },
+        "tdop": {
+            "type": "number",
+            "description": "The time dilution of precision"
+        },
+        "gdop": {
+            "type": "number",
+            "description": "The geometric dilution of precision"
+        },
+        "frequency_band": {
+            "enum": [
+                "L1",
+                "S",
+                "L2",
+                "E5c",
+                "E6",
+                "L5E5a",
+                "E5 AltBOC"
+            ],
+            "description": "Frequency band or signal components used for PVT"
+        }
+    },
+    "required": [
+        "coordinate_system",
+        "precision",
+        "position"
+    ]
+}
diff --git a/next/satellite-info.json b/next/satellite-info.json
new file mode 100644
index 0000000..018b0fb
--- /dev/null
+++ b/next/satellite-info.json
@@ -0,0 +1,76 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/satellite-info.json",
+    "title": "OGRP satellite info schema",
+    "properties": {
+        "satellite_id": {
+            "$ref": "types.json#satellite_id"
+        },
+        "gnss": {
+            "$ref": "types.json#gnss"
+        },
+        "direction": {
+            "type": "array",
+            "description": "Normalized direction vector receiver-satellite in ECEF frame",
+            "minItems": 3,
+            "maxItems": 3,
+            "items": {
+                "type": "number"
+            }
+        },
+        "expected_pseudorange": {
+            "type": "number",
+            "description": "Expected range between receiver and satellite from PVT with errors (m)"
+        },
+        "expected_range": {
+            "type": "number",
+            "description": "Expected range between receiver and satellite from PVT (m)"
+        },
+        "expected_range_rate": {
+            "type": "number",
+            "description": "Expected range rate between receiver and satellite from PVT (m/s)"
+        },
+        "azimuth": {
+            "type": "number",
+            "description": "Azimuth of the satellite 0..360 (degree)"
+        },
+        "elevation": {
+            "type": "number",
+            "description": "Elevation of the satellite 0..90 (degree)"
+        },
+        "authentication_status_osnma": {
+            "type": "number",
+            "description": "Galileo OSNMA authentication status (-3: Not available, -2: Internal error, -1: Authentication failure, 0: Initializing, 1: Authenticated)"
+        },
+        "range_authenticated_signals": {
+            "type": "array",
+            "minItems": 0,
+            "maxItems": 3,
+            "items": {
+                "enum": [
+                    "E1",
+                    "E5a",
+                    "E6"
+                ],
+                "description": "List of authenticated signal components"
+            }
+        },
+        "spoofed_signals": {
+            "type": "array",
+            "minItems": 0,
+            "maxItems": 3,
+            "items": {
+                "enum": [
+                    "E1",
+                    "E5a",
+                    "E6"
+                ],
+                "description": "List of spoofed signal components"
+            }
+        }
+    },
+    "required": [
+        "satellite_id",
+        "gnss"
+    ]
+}
diff --git a/next/schema b/next/schema
new file mode 100644
index 0000000..5812e7e
--- /dev/null
+++ b/next/schema
@@ -0,0 +1,105 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/schema#",
+    "title": "OGRP core schema draft",
+    "type": "object",
+    "required": [
+        "$schema",
+        "timestamp",
+        "time_reference",
+        "protocol"
+    ],
+    "properties": {
+        "$schema": {
+            "const": "https://fraunhofer-iis.github.io/ogrp/next/schema#"
+        },
+        "protocol": {
+            "enum": [
+                "OGRP1_2"
+            ],
+            "description": "OGRP version"
+        },
+        "time_status": {
+            "enum": [
+                "SYSTEM",
+                "EXTERNAL",
+                "FREE_RUNNING",
+                "FINESTEERING",
+                "GPS_SYNCED",
+                "GALILEO_SYNCED"
+            ],
+            "description": "Timestamp source"
+        },
+        "timestamp": {
+            "$ref": "types.json#unix_time"
+        },
+        "time_reference": {
+            "$ref": "types.json#time_reference"
+        },
+        "hw_timestamp": {
+            "type": "integer",
+            "description": "Hardware timestamp, which is required for external tracking (clock ticks, overflow at 2^32)"
+        },
+        "sw_version": {
+            "type": "string"
+        },
+        "module": {
+            "type": "string",
+            "description": "Name of associated module"
+        },
+        "settings": {
+            "type": "array",
+            "minItems": 0,
+            "items": {
+                "$ref": "setting.json"
+            }
+        },
+        "glonass_ephemeris": {
+            "$ref": "navigation-data.json#glonass_ephemeris"
+        },
+        "ephemeris": {
+            "$ref": "navigation-data.json#ephemeris"
+        },
+        "almanac": {
+            "$ref": "navigation-data.json#almanac"
+        },
+        "ionosphere_klobuchar": {
+            "$ref": "navigation-data.json#ionosphere_klobuchar"
+        },
+        "ionosphere_nequick": {
+            "$ref": "navigation-data.json#ionosphere_nequick"
+        },
+        "pvt_calculation": {
+            "$ref": "pvt.json"
+        },
+        "satellite_info": {
+            "$ref": "satellite-info.json"
+        },
+        "gnss_utc_parameter": {
+            "$ref": "navigation-data.json#gnss_utc_parameter"
+        },
+        "ggto_parameter": {
+            "$ref": "navigation-data.json#ggto_parameter"
+        },
+        "channel_measurements": {
+            "type": "array",
+            "minItems": 1,
+            "items": {
+                "$ref": "measurement.json"
+            },
+            "uniqueItems": true
+        },
+        "tracking_init": {
+            "$ref": "tracking-loop.json#tracking_init"
+        },
+        "correlation_values": {
+            "$ref": "tracking-loop.json#correlation_values"
+        },
+        "control_values": {
+            "$ref": "tracking-loop.json#control_values"
+        },
+        "imu_measurements": {
+            "$ref": "imu.json"
+        }
+    }
+}
diff --git a/next/setting.json b/next/setting.json
new file mode 100644
index 0000000..ee25848
--- /dev/null
+++ b/next/setting.json
@@ -0,0 +1,30 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/setting.json#",
+    "title": "OGRP core types",
+
+    "type": "object",
+    "properties": {
+        "name": {
+            "type": "string",
+            "description": "Name of setting"
+        },
+        "value": {
+            "type": "string",
+            "description": "Value of data as string"
+        },
+        "type": {
+            "type": "string",
+            "description": "String with typename or array with enumvalues as string"
+        },
+        "remark": {
+            "type": "string",
+            "description": "It is a description but description is a reserved word when using schema"
+        }
+    },
+    "required": [
+        "name",
+        "value",
+        "type"
+    ]
+}
diff --git a/next/tracking-loop.json b/next/tracking-loop.json
new file mode 100644
index 0000000..397e562
--- /dev/null
+++ b/next/tracking-loop.json
@@ -0,0 +1,186 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/tracking-loop.json",
+    "title": "OGRP tracking loop schema",
+    "definitions": {
+        "hw_channel": {
+            "$id": "#hw_channel",
+            "type": "integer",
+            "description": "Unique ID of the hardware channel, which sent the IQ values"
+        },
+        "correlation": {
+            "$id": "#correlation",
+            "type": "object",
+            "description": "Correlation value",
+            "properties": {
+                "i": {
+                    "type": "number",
+                    "description": "Real part of the correlation"
+                },
+                "q": {
+                    "type": "number",
+                    "description": "Imaginary part of the correlation"
+                }
+            },
+            "required": [
+                "i",
+                "q"
+            ]
+        },
+        "clock_ticks": {
+            "type": "integer",
+            "minimum": 0,
+            "maximum": 4294967295,
+            "description": "Hardware timestamp, which is required for external tracking (clock ticks, overflow at 2^32)"
+        },
+        "tracking_init": {
+            "$id": "#tracking_init",
+            "type": "object",
+            "description": "Information about configuration of the hardware channel for external tracking loops",
+            "properties": {
+                "hw_channel_id": {
+                    "$ref": "#hw_channel"
+                },
+                "carrier_frequency": {
+                    "type": "number",
+                    "description": "Carrier frequency of acquired signal (Hz)"
+                },
+                "carrier_doppler": {
+                    "type": "number",
+                    "description": "Carrier doppler from acquisition (Hz)"
+                },
+                "code_doppler": {
+                    "type": "number",
+                    "description": "Code doppler from acquisition (chips/s)"
+                },
+                "early_late_spacing": {
+                    "type": "number",
+                    "description": "Early late spacing of the hardware channel (chips)"
+                },
+                "integration_time": {
+                    "type": "number",
+                    "description": "Integration time of the correlators (s)"
+                },
+                "acf_slope": {
+                    "type": "number",
+                    "description": "Slope of the autocorrelation function (chip/chip)"
+                },
+                "dll_hard_limiter": {
+                    "type": "number",
+                    "description": "Recommended hard limitation for DLL discriminator output (chips)"
+                }
+            },
+            "required": [
+                "hw_channel_id",
+                "carrier_doppler",
+                "code_doppler",
+                "early_late_spacing",
+                "integration_time",
+                "acf_slope"
+            ]
+        },
+        "correlation_values": {
+            "$id": "#correlation_values",
+            "type": "object",
+            "description": "I&D values of a hardware channel",
+            "properties": {
+                "hw_channel_id": {
+                    "$ref": "#hw_channel"
+                },
+                "epoch": {
+                    "type": "number",
+                    "minimum": 0,
+                    "description": "Epochs since hardware channel start (epochs)"
+                },
+                "integrated_epochs": {
+                    "type": "number",
+                    "description": "Integrated time in epochs"
+                },
+                "tow": {
+                    "$ref": "types.json#tow",
+                    "description": "Transmission time of the correlation values in seconds related to the beginning of the current week"
+                },
+                "carrier_doppler": {
+                    "type": "number",
+                    "description": "Last carrier doppler (Hz)"
+                },
+                "code_doppler": {
+                    "type": "number",
+                    "description": "Last code doppler (chips/s)"
+                },
+                "very_early": {
+                    "$ref": "#correlation",
+                    "description": "Correlation value at very early correlation point"
+                },
+                "early": {
+                    "$ref": "#correlation",
+                    "description": "Correlation value at early correlation point"
+                },
+                "prompt": {
+                    "$ref": "#correlation",
+                    "description": "Correlation value at prompt correlation point"
+                },
+                "late": {
+                    "$ref": "#correlation",
+                    "description": "Correlation value at late correlation point"
+                },
+                "very_late": {
+                    "$ref": "#correlation",
+                    "description": "Correlation value at very late correlation point"
+                }
+            },
+            "required": [
+                "hw_channel_id",
+                "epoch",
+                "early",
+                "prompt",
+                "late"
+            ]
+        },
+        "control_values": {
+            "$id": "#control_values",
+            "type": "object",
+            "description": "Code and carrier values to control a hardware channel",
+            "properties": {
+                "hw_channel_id": {
+                    "$ref": "#hw_channel"
+                },
+                "lock_lost": {
+                    "type": "boolean",
+                    "description": "True if tracking of the satellite is lost for the hardware channel, which sent the IQ values"
+                },
+                "value_list": {
+                    "type": "array",
+                    "minItems": 0,
+                    "description": "List of control values for multiple channels",
+                    "items": {
+                        "type": "object",
+                        "properties": {
+                            "hw_channel_id": {
+                                "$ref": "#hw_channel"
+                            },
+                            "carrier_doppler": {
+                                "type": "integer",
+                                "description": "Carrier doppler from tracking (Hz)"
+                            },
+                            "code_doppler": {
+                                "type": "integer",
+                                "description": "Code doppler from tracking (chips/s)"
+                            }
+                        },
+                        "required": [
+                            "hw_channel_id",
+                            "carrier_doppler",
+                            "code_doppler"
+                        ]
+                    }
+                }
+            },
+            "required": [
+                "hw_channel_id",
+                "value_list",
+                "lock_lost"
+            ]
+        }
+    }
+}
diff --git a/next/types.json b/next/types.json
new file mode 100644
index 0000000..f915d37
--- /dev/null
+++ b/next/types.json
@@ -0,0 +1,108 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "$id": "https://fraunhofer-iis.github.io/ogrp/next/types.json#",
+    "title": "OGRP core types",
+    "definitions": {
+        "gnss": {
+            "$id": "#gnss",
+            "title": "Global Navigation Satellite System",
+            "description": "Identifier for a satellite navigation system",
+            "enum": [
+                "GPS",
+                "Galileo",
+                "Glonass",
+                "Beidou",
+                "QZSS",
+                "SBAS",
+                "NavIC"
+            ]
+        },
+        "gnss_time": {
+            "$id": "#gnss_time",
+            "title": "Time in GNSS typical format",
+            "type": "object",
+            "properties": {
+                "tow": {
+                    "$ref": "#tow"
+                },
+                "week": {
+                    "$ref": "#week_number"
+                }
+            },
+            "required": [
+                "tow",
+                "week"
+            ]
+        },
+        "signal": {
+            "$id": "#signal",
+            "title": "GNSS signal that can be tracked",
+            "enum": [
+                "L1CA",
+                "L2CA",
+                "L2P_codeless",
+                "L2CM",
+                "L2CL",
+                "L2C",
+                "L5",
+                "L5I",
+                "L5Q",
+                "E1",
+                "E1B",
+                "E1C",
+                "E5",
+                "E5a",
+                "E5aI",
+                "E5aQ",
+                "E5b",
+                "E5bI",
+                "E5bQ",
+                "E6",
+                "P1",
+                "P2",
+                "P5"
+            ]
+        },
+        "satellite_id": {
+            "$id": "#satellite_id",
+            "title": "Satellite Identifier",
+            "type": "integer",
+            "minimum": 1,
+            "description": "Corresponds to a specific PRN (GPS) or SVID (Galileo). It is not bound to a specific satellite.",
+            "$comment": "TODO: Galileo frequency number"
+        },
+        "tow": {
+            "$id": "#tow",
+            "title": "Time of Week",
+            "type": "number",
+            "minimum": 0,
+            "exclusiveMaximum": 604800,
+            "description": "Seconds in current week (s)"
+        },
+        "unix_time": {
+            "$id": "#unix_time",
+            "title": "Unix Time",
+            "type": "number",
+            "minimum": 0,
+            "description": "Seconds since 1.1.1970 0:00 (UTC) (s)"
+        },
+        "week_number": {
+            "$id": "#week_number",
+            "title": "Week Number",
+            "type": "integer",
+            "minimum": 0,
+            "description": "Full weeks since 1980-01-06T00:00:00Z UTC (midnight), no overflow"
+        },
+        "time_reference": {
+            "$id": "#time_reference",
+            "enum": [
+                "UTC",
+                "GPST",
+                "GST",
+                "GLONASST",
+                "BDT"
+            ],
+            "description": "Time reference of timestamp"
+        }
+    }
+}