func (r *router) buildDownlinkOptions(uplink *pb.UplinkMessage, isActivation bool, gateway *gateway.Gateway) (downlinkOptions []*pb_broker.DownlinkOption) {
var options []*pb_broker.DownlinkOption
gatewayStatus, _ := gateway.Status.Get() // This just returns empty if non-existing
lorawanMetadata := uplink.ProtocolMetadata.GetLorawan()
if lorawanMetadata == nil {
return // We can't handle any other protocols than LoRaWAN yet
}
region := gatewayStatus.Region
if region == "" {
region = band.Guess(uplink.GatewayMetadata.Frequency)
}
band, err := band.Get(region)
if err != nil {
return // We can't handle this region
}
if region == "EU_863_870" && isActivation {
band.RX2DataRate = 0
}
dataRate, err := lorawanMetadata.GetDataRate()
if err != nil {
return
}
// Configuration for RX2
buildRX2 := func() (*pb_broker.DownlinkOption, error) {
option := r.buildDownlinkOption(gateway.ID, band)
if region == "EU_863_870" {
option.GatewayConfig.Power = 27 // The EU RX2 frequency allows up to 27dBm
}
if isActivation {
option.GatewayConfig.Timestamp = uplink.GatewayMetadata.Timestamp + uint32(band.JoinAcceptDelay2/1000)
} else {
option.GatewayConfig.Timestamp = uplink.GatewayMetadata.Timestamp + uint32(band.ReceiveDelay2/1000)
}
option.ProtocolConfig.GetLorawan().CodingRate = lorawanMetadata.CodingRate
return option, nil
}
if option, err := buildRX2(); err == nil {
options = append(options, option)
}
// Configuration for RX1
buildRX1 := func() (*pb_broker.DownlinkOption, error) {
option := r.buildDownlinkOption(gateway.ID, band)
if isActivation {
option.GatewayConfig.Timestamp = uplink.GatewayMetadata.Timestamp + uint32(band.JoinAcceptDelay1/1000)
} else {
option.GatewayConfig.Timestamp = uplink.GatewayMetadata.Timestamp + uint32(band.ReceiveDelay1/1000)
}
option.ProtocolConfig.GetLorawan().CodingRate = lorawanMetadata.CodingRate
freq, err := band.GetRX1Frequency(int(uplink.GatewayMetadata.Frequency))
if err != nil {
return nil, err
}
option.GatewayConfig.Frequency = uint64(freq)
upDR, err := band.GetDataRate(dataRate)
if err != nil {
return nil, err
}
downDR, err := band.GetRX1DataRate(upDR, 0)
if err != nil {
return nil, err
}
if err := option.ProtocolConfig.GetLorawan().SetDataRate(band.DataRates[downDR]); err != nil {
return nil, err
}
option.GatewayConfig.FrequencyDeviation = uint32(option.ProtocolConfig.GetLorawan().BitRate / 2)
return option, nil
}
if option, err := buildRX1(); err == nil {
options = append(options, option)
}
computeDownlinkScores(gateway, uplink, options)
for _, option := range options {
// Add router ID to downlink option
if r.Component != nil && r.Component.Identity != nil {
option.Identifier = fmt.Sprintf("%s:%s", r.Component.Identity.Id, option.Identifier)
}
// Filter all illegal options
if option.Score < 1000 {
downlinkOptions = append(downlinkOptions, option)
}
}
return
}
func (r *router) HandleActivation(gatewayID string, activation *pb.DeviceActivationRequest) (res *pb.DeviceActivationResponse, err error) {
ctx := r.Ctx.WithFields(log.Fields{
"GatewayID": gatewayID,
"AppEUI": *activation.AppEui,
"DevEUI": *activation.DevEui,
})
start := time.Now()
defer func() {
if err != nil {
ctx.WithError(err).Warn("Could not handle activation")
} else {
ctx.WithField("Duration", time.Now().Sub(start)).Info("Handled activation")
}
}()
r.status.activations.Mark(1)
gateway := r.getGateway(gatewayID)
gateway.LastSeen = time.Now()
uplink := &pb.UplinkMessage{
Payload: activation.Payload,
ProtocolMetadata: activation.ProtocolMetadata,
GatewayMetadata: activation.GatewayMetadata,
}
if err = gateway.HandleUplink(uplink); err != nil {
return nil, err
}
if !gateway.Schedule.IsActive() {
return nil, errors.NewErrInternal(fmt.Sprintf("Gateway %s not available for downlink", gatewayID))
}
downlinkOptions := r.buildDownlinkOptions(uplink, true, gateway)
// Find Broker
brokers, err := r.Discovery.GetAll("broker")
if err != nil {
return nil, err
}
// Prepare request
request := &pb_broker.DeviceActivationRequest{
Payload: activation.Payload,
DevEui: activation.DevEui,
AppEui: activation.AppEui,
ProtocolMetadata: activation.ProtocolMetadata,
GatewayMetadata: activation.GatewayMetadata,
ActivationMetadata: &pb_protocol.ActivationMetadata{
Protocol: &pb_protocol.ActivationMetadata_Lorawan{
Lorawan: &pb_lorawan.ActivationMetadata{
AppEui: activation.AppEui,
DevEui: activation.DevEui,
},
},
},
DownlinkOptions: downlinkOptions,
}
// Prepare LoRaWAN activation
status, err := gateway.Status.Get()
if err != nil {
return nil, err
}
region := status.Region
if region == "" {
region = band.Guess(uplink.GatewayMetadata.Frequency)
}
band, err := band.Get(region)
if err != nil {
return nil, err
}
lorawan := request.ActivationMetadata.GetLorawan()
lorawan.Rx1DrOffset = 0
lorawan.Rx2Dr = uint32(band.RX2DataRate)
lorawan.RxDelay = uint32(band.ReceiveDelay1.Seconds())
if band.CFList != nil {
lorawan.CfList = new(pb_lorawan.CFList)
for _, freq := range band.CFList {
lorawan.CfList.Freq = append(lorawan.CfList.Freq, freq)
}
}
ctx = ctx.WithField("NumBrokers", len(brokers))
// Forward to all brokers and collect responses
var wg sync.WaitGroup
responses := make(chan *pb_broker.DeviceActivationResponse, len(brokers))
for _, broker := range brokers {
broker, err := r.getBroker(broker)
if err != nil {
continue
}
// Do async request
wg.Add(1)
go func() {
res, err := broker.client.Activate(r.Component.GetContext(""), request)
if err == nil && res != nil {
responses <- res
}
wg.Done()
}()
}
// Make sure to close channel when all requests are done
go func() {
wg.Wait()
close(responses)
}()
var gotFirst bool
for res := range responses {
if gotFirst {
ctx.Warn("Duplicate Activation Response")
} else {
gotFirst = true
downlink := &pb_broker.DownlinkMessage{
Payload: res.Payload,
Message: res.Message,
DownlinkOption: res.DownlinkOption,
}
err := r.HandleDownlink(downlink)
if err != nil {
ctx.Warn("Could not send downlink for Activation")
gotFirst = false // try again
}
}
}
// Activation not accepted by any broker
if !gotFirst {
ctx.Debug("Activation not accepted at this gateway")
return nil, errors.New("Activation not accepted at this Gateway")
}
// Activation accepted by (at least one) broker
ctx.Debug("Activation accepted")
return &pb.DeviceActivationResponse{}, nil
}
// Calculating the score for each downlink option; lower is better, 0 is best
// If a score is over 1000, it may should not be used as feasible option.
// TODO: The weights of these parameters should be optimized. I'm sure someone
// can do some computer simulations to find the right values.
func computeDownlinkScores(gateway *gateway.Gateway, uplink *pb.UplinkMessage, options []*pb_broker.DownlinkOption) {
gatewayStatus, _ := gateway.Status.Get() // This just returns empty if non-existing
region := gatewayStatus.Region
if region == "" {
region = band.Guess(uplink.GatewayMetadata.Frequency)
}
gatewayRx, _ := gateway.Utilization.Get()
for _, option := range options {
// Invalid if no LoRaWAN
lorawan := option.GetProtocolConfig().GetLorawan()
if lorawan == nil {
option.Score = 1000
continue
}
var time time.Duration
if lorawan.Modulation == pb_lorawan.Modulation_LORA {
// Calculate max ToA
time, _ = toa.ComputeLoRa(
51+13, // Max MACPayload plus LoRaWAN header, TODO: What is the length we should use?
lorawan.DataRate,
lorawan.CodingRate,
)
}
if lorawan.Modulation == pb_lorawan.Modulation_FSK {
// Calculate max ToA
time, _ = toa.ComputeFSK(
51+13, // Max MACPayload plus LoRaWAN header, TODO: What is the length we should use?
int(lorawan.BitRate),
)
}
// Invalid if time is zero
if time == 0 {
option.Score = 1000
continue
}
timeScore := math.Min(time.Seconds()*5, 10) // 2 seconds will be 10 (max)
signalScore := 0.0 // Between 0 and 20 (lower is better)
{
// Prefer high SNR
if uplink.GatewayMetadata.Snr < 5 {
signalScore += 10
}
// Prefer good RSSI
signalScore += math.Min(float64(uplink.GatewayMetadata.Rssi*-0.1), 10)
}
utilizationScore := 0.0 // Between 0 and 40 (lower is better) will be over 100 if forbidden
{
// Avoid gateways that do more Rx
utilizationScore += math.Min(gatewayRx*50, 20) / 2 // 40% utilization = 10 (max)
// Avoid busy channels
freq := option.GatewayConfig.Frequency
channelRx, channelTx := gateway.Utilization.GetChannel(freq)
utilizationScore += math.Min((channelTx+channelRx)*200, 20) / 2 // 10% utilization = 10 (max)
// European Duty Cycle
if region == "EU_863_870" {
var duty float64
switch {
case freq >= 863000000 && freq < 868000000:
duty = 0.01 // g 863.0 – 868.0 MHz 1%
case freq >= 868000000 && freq < 868600000:
duty = 0.01 // g1 868.0 – 868.6 MHz 1%
case freq >= 868700000 && freq < 869200000:
duty = 0.001 // g2 868.7 – 869.2 MHz 0.1%
case freq >= 869400000 && freq < 869650000:
duty = 0.1 // g3 869.4 – 869.65 MHz 10%
case freq >= 869700000 && freq < 870000000:
duty = 0.01 // g4 869.7 – 870.0 MHz 1%
default:
utilizationScore += 100 // Transmissions on this frequency are forbidden
}
if channelTx > duty {
utilizationScore += 100 // Transmissions on this frequency are forbidden
}
if duty > 0 {
utilizationScore += math.Min(time.Seconds()/duty/100, 20) // Impact on duty-cycle (in order to prefer RX2 for SF9BW125)
}
}
}
scheduleScore := 0.0 // Between 0 and 30 (lower is better) will be over 100 if forbidden
{
id, conflicts := gateway.Schedule.GetOption(option.GatewayConfig.Timestamp, uint32(time/1000))
option.Identifier = id
if conflicts >= 100 {
scheduleScore += 100
} else {
scheduleScore += math.Min(float64(conflicts*10), 30) // max 30
}
}
option.Score = uint32((timeScore + signalScore + utilizationScore + scheduleScore) * 10)
}
}