Implement LR-FHSS modulation type.

Author: brocaar

go.mod

@@ -3,7 +3,7 @@ module github.com/brocaar/chirpstack-gateway-bridge
 go 1.16
 
 require (
-	github.com/brocaar/chirpstack-api/go/v3 v3.9.7
+	github.com/brocaar/chirpstack-api/go/v3 v3.10.1
 	github.com/brocaar/lorawan v0.0.0-20201030140234-f23da2d4a303
 	github.com/dgrijalva/jwt-go v3.2.0+incompatible
 	github.com/eclipse/paho.mqtt.golang v1.3.0

go.sum

@@ -51,8 +51,8 @@ github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kB
 github.com/bketelsen/crypt v0.0.3-0.20200106085610-5cbc8cc4026c/go.mod h1:MKsuJmJgSg28kpZDP6UIiPt0e0Oz0kqKNGyRaWEPv84=
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2 h1:oMCHnXa6CCCafdPDbMh/lWRhRByN0VFLvv+g+ayx1SI=
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2/go.mod h1:PkYb9DJNAwrSvRx5DYA+gUcOIgTGVMNkfSCbZM8cWpI=
-github.com/brocaar/chirpstack-api/go/v3 v3.9.7 h1:n5Zte6zIg+qbqtb4dwp3vGQwIXpXsk5nMR4WwMUcLgA=
-github.com/brocaar/chirpstack-api/go/v3 v3.9.7/go.mod h1:v8AWP19nOJK4rwJsr1+weDfpUc4UNLbRh8Eygn4Oh00=
+github.com/brocaar/chirpstack-api/go/v3 v3.10.1 h1:ijf3AKDw++aSPJE41lkiPxXtshxZF++cXzV2l9e7EYk=
+github.com/brocaar/chirpstack-api/go/v3 v3.10.1/go.mod h1:v8AWP19nOJK4rwJsr1+weDfpUc4UNLbRh8Eygn4Oh00=
 github.com/brocaar/lorawan v0.0.0-20201030140234-f23da2d4a303 h1:LkE19tFPfDaRh1HIKWLCZKSBZNonMu0rIOJPCLvEjC0=
 github.com/brocaar/lorawan v0.0.0-20201030140234-f23da2d4a303/go.mod h1:CciUmQHIpUYTHHMeICtyamM7d+47VV+WBZ5ReDozpoc=
 github.com/caarlos0/ctrlc v1.0.0 h1:2DtF8GSIcajgffDFJzyG15vO+1PuBWOMUdFut7NnXhw=

internal/backend/semtechudp/packets/packets.go

@@ -102,23 +102,34 @@ func (t *CompactTime) UnmarshalJSON(data []byte) error {
 // DatR implements the data rate which can be either a string (LoRa identifier)
 // or an unsigned integer in case of FSK (bits per second).
 type DatR struct {
-	LoRa string
-	FSK  uint32
+	LRFHSS string
+	LoRa   string
+	FSK    uint32
 }
 
 // MarshalJSON implements the json.Marshaler interface.
 func (d DatR) MarshalJSON() ([]byte, error) {
 	if d.LoRa != "" {
 		return []byte(`"` + d.LoRa + `"`), nil
 	}
+	if d.LRFHSS != "" {
+		return []byte(`"` + d.LRFHSS + `"`), nil
+	}
 	return []byte(strconv.FormatUint(uint64(d.FSK), 10)), nil
 }
 
 // UnmarshalJSON implements the json.Unmarshaler interface.
 func (d *DatR) UnmarshalJSON(data []byte) error {
 	i, err := strconv.ParseUint(string(data), 10, 32)
 	if err != nil {
-		d.LoRa = strings.Trim(string(data), `"`)
+		// remove the trailing and leading quotes
+		str := strings.Trim(string(data), `"`)
+
+		if strings.HasPrefix(str, "SF") {
+			d.LoRa = str
+		} else {
+			d.LRFHSS = str
+		}
 		return nil
 	}
 	d.FSK = uint32(i)

internal/backend/semtechudp/packets/push_data.go

@@ -16,9 +16,12 @@ import (
 	"github.com/brocaar/lorawan"
 )
 
-// loRaDataRateRegex contains a regexp for parsing the data-rate string.
+// loRaDataRateRegex contains a regexp for parsing the LoRa data-rate string.
 var loRaDataRateRegex = regexp.MustCompile(`SF(\d+)BW(\d+)`)
 
+// lrFHSSDataRateRegex contains the regexp for parsing the LR-FHSS data-rate string.
+var lrFHSSDataRateRegex = regexp.MustCompile(`M0CW(\d+)`)
+
 // PushDataPacket type is used by the gateway mainly to forward the RF packets
 // received, and associated metadata, to the server.
 type PushDataPacket struct {
@@ -203,8 +206,8 @@ func getUplinkFrame(gatewayID []byte, rxpk RXPK, FakeRxInfoTime bool) (gw.Uplink
 	if rxpk.DatR.LoRa != "" {
 		frame.TxInfo.Modulation = common.Modulation_LORA
 
-		match := loRaDataRateRegex.FindStringSubmatch(rxpk.DatR.LoRa)
 		// parse e.g. SF12BW250 into separate variables
+		match := loRaDataRateRegex.FindStringSubmatch(rxpk.DatR.LoRa)
 		if len(match) != 3 {
 			return frame, errors.New("backend/semtechudp/packets: could not parse LoRa data-rate")
 		}
@@ -229,6 +232,31 @@ func getUplinkFrame(gatewayID []byte, rxpk RXPK, FakeRxInfoTime bool) (gw.Uplink
 		}
 	}
 
+	// LR-FHSS data-rate
+	if rxpk.DatR.LRFHSS != "" {
+		frame.TxInfo.Modulation = common.Modulation_LR_FHSS
+
+		// parse M0CW137 into CW (OCW) variable
+		match := lrFHSSDataRateRegex.FindStringSubmatch(rxpk.DatR.LRFHSS)
+		if len(match) != 2 {
+			return frame, errors.New("backend/semtechudp/packets: could not parse LR-FHSS data-rate")
+		}
+
+		// cast variable to int
+		ocw, err := strconv.Atoi(match[1])
+		if err != nil {
+			return frame, errors.Wrap(err, "backend/semtechudp/packets: could not convert cw to int")
+		}
+
+		frame.TxInfo.ModulationInfo = &gw.UplinkTXInfo_LrFhssModulationInfo{
+			LrFhssModulationInfo: &gw.LRFHSSModulationInfo{
+				OperatingChannelWidth: uint32(ocw) * 1000, // kHz -> Hz
+				CodeRate:              rxpk.CodR,
+				GridSteps:             uint32(rxpk.HPW),
+			},
+		}
+	}
+
 	// FSK data-rate
 	if rxpk.DatR.FSK != 0 {
 		frame.TxInfo.Modulation = common.Modulation_FSK
@@ -302,6 +330,7 @@ type RXPK struct {
 	Modu string       `json:"modu"` // Modulation identifier "LORA" or "FSK"
 	CodR string       `json:"codr"` // LoRa ECC coding rate identifier
 	LSNR float64      `json:"lsnr"` // Lora SNR ratio in dB (signed float, 0.1 dB precision)
+	HPW  uint8        `json:"hpw"`  // LR-FHSS hopping grid number of steps.
 	Data []byte       `json:"data"` // Base64 encoded RF packet payload, padded
 	RSig []RSig       `json:"rsig"` // Received signal information, per antenna (Optional)
 }

internal/backend/semtechudp/packets/push_data_test.go

@@ -417,6 +417,55 @@ func TestGetUplinkFrame(t *testing.T) {
 				},
 			},
 		},
+		{
+			Name: "LR-FHSS modulation",
+			PushDataPacket: PushDataPacket{
+				GatewayMAC:      lorawan.EUI64{1, 2, 3, 4, 5, 6, 7, 8},
+				ProtocolVersion: ProtocolVersion2,
+				Payload: PushDataPayload{
+					RXPK: []RXPK{
+						{
+							Tmst: 1000000,
+							Freq: 868.3,
+							Stat: 1,
+							Modu: "LR-FHSS",
+							DatR: DatR{LRFHSS: "M0CW137"},
+							CodR: "4/6",
+							HPW:  8,
+							Size: 5,
+							Data: []byte{1, 2, 3, 4, 5},
+							RSig: []RSig{
+								{
+									RSSIC: -74,
+								},
+							},
+						},
+					},
+				},
+			},
+			UplinkFrames: []gw.UplinkFrame{
+				{
+					PhyPayload: []byte{1, 2, 3, 4, 5},
+					TxInfo: &gw.UplinkTXInfo{
+						Frequency:  868300000,
+						Modulation: common.Modulation_LR_FHSS,
+						ModulationInfo: &gw.UplinkTXInfo_LrFhssModulationInfo{
+							LrFhssModulationInfo: &gw.LRFHSSModulationInfo{
+								OperatingChannelWidth: 137000,
+								CodeRate:              "4/6",
+								GridSteps:             8,
+							},
+						},
+					},
+					RxInfo: &gw.UplinkRXInfo{
+						GatewayId: []byte{1, 2, 3, 4, 5, 6, 7, 8},
+						Rssi:      -74,
+						Context:   []byte{0x00, 0x0f, 0x42, 0x40},
+						CrcStatus: gw.CRCStatus_CRC_OK,
+					},
+				},
+			},
+		},
 	}
 
 	for _, test := range testTable {