Broadcast Communication

By default, communication occurs between all satellites that are specified by the communication method. This tutorial shows how to use two classes to configure a broadcast action that must be taken for communication to occur:

  • Broadcast, which gives satellites an action that enables communication from them at the end of the current step.

  • BroadcastCommunication, which can be combined with another communication method to limit communication from broadcasters to those satellites satisfying the requirements of the other communication method.

Configuring the Environment

For this example, a multisatellite target imaging environment will be used. The goal is to maximize the value of unique images taken. This configuration is similar to the Multi-Agent Environments example.

[1]:
from bsk_rl import sats, act, obs, scene, data, comm
from bsk_rl.sim import dyn, fsw


class ImagingSatellite(sats.ImagingSatellite):
    observation_spec = [
        obs.OpportunityProperties(
            dict(prop="priority"),
            dict(prop="opportunity_open", norm=5700.0),
            n_ahead_observe=4,
        )
    ]
    action_spec = [act.Broadcast(duration=15.0), act.Image(n_ahead_image=4)]
    dyn_type = dyn.FullFeaturedDynModel
    fsw_type = fsw.SteeringImagerFSWModel


ACTION_BROADCAST = 0
ACTION_IMAGE_0 = 1
ACTION_IMAGE_1 = 2
ACTION_IMAGE_2 = 3
ACTION_IMAGE_3 = 4

Satellite properties are set to give the satellite near-unlimited power and storage resources. To randomize some parameters in a correlated manner across satellites, a sat_arg_randomizer is set and passed to the environment. In this case, the satellites are distributed in a trivial single-plane Walker-delta constellation.

[2]:
from bsk_rl.utils.orbital import walker_delta_args

N_AGENTS = 2
sat_args = dict(
    imageAttErrorRequirement=0.01,
    imageRateErrorRequirement=0.01,
    batteryStorageCapacity=1e9,
    storedCharge_Init=1e9,
    dataStorageCapacity=1e12,
    u_max=0.4,
    K1=0.25,
    K3=3.0,
    omega_max=0.087,
    servo_Ki=5.0,
    servo_P=150 / 5,
)
sat_arg_randomizer = walker_delta_args(
    altitude=800.0, inc=60.0, n_planes=1, clustersize=N_AGENTS, clusterspacing=5.0
)

A communication type is defined that uses multidegree line-of-sight communication with broadcasting.

[3]:
class BroadcastLOS(comm.BroadcastCommunication, comm.LOSMultiCommunication):
    pass

Finally, the environment can be instantiated.

[4]:
from bsk_rl import ConstellationTasking

env = ConstellationTasking(
    satellites=[ImagingSatellite(f"EO-{i + 1}", sat_args) for i in range(N_AGENTS)],
    scenario=scene.UniformTargets(1000),
    rewarder=data.UniqueImageReward(),
    communicator=BroadcastLOS(),
    sat_arg_randomizer=sat_arg_randomizer,
    log_level="INFO",
)
_ = env.reset()
2025-10-16 18:32:36,248 gym                            INFO       Resetting environment with seed=531235560
2025-10-16 18:32:36,250 scene.targets                  INFO       Generating 1000 targets
2025-10-16 18:32:36,471 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2025-10-16 18:32:36,510 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2025-10-16 18:32:36,566 gym                            INFO       <0.00> Environment reset

In the first step, both agents are tasked with an imaging action, and one successfully images a target.

[5]:
_ = env.step({"EO-1": ACTION_IMAGE_3, "EO-2": ACTION_IMAGE_2})
2025-10-16 18:32:36,571 gym                            INFO       <0.00> === STARTING STEP ===
2025-10-16 18:32:36,572 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2025-10-16 18:32:36,572 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-611) tasked for imaging
2025-10-16 18:32:36,573 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-611) window enabled: 20.1 to 223.8
2025-10-16 18:32:36,574 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 223.8
2025-10-16 18:32:36,575 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2025-10-16 18:32:36,575 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-611) tasked for imaging
2025-10-16 18:32:36,576 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-611) window enabled: 0.0 to 135.8
2025-10-16 18:32:36,576 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 135.8
2025-10-16 18:32:36,590 sats.satellite.EO-2            INFO       <72.00> EO-2: imaged Target(tgt-611)
2025-10-16 18:32:36,591 data.base                      INFO       <72.00> Total reward: {'EO-2': 0.43128026715251633}
2025-10-16 18:32:36,592 sats.satellite.EO-2            INFO       <72.00> EO-2: Satellite EO-2 requires retasking
2025-10-16 18:32:36,595 gym                            INFO       <72.00> Step reward: {'EO-2': 0.43128026715251633}

When both select the broadcast action, data is shared in both directions. This is subject to line-of-sight availability as well as selecting the correct action.

[6]:
_ = env.step({"EO-1": ACTION_BROADCAST, "EO-2": ACTION_BROADCAST})
2025-10-16 18:32:36,599 gym                            INFO       <72.00> === STARTING STEP ===
2025-10-16 18:32:36,600 sats.satellite.EO-1            INFO       <72.00> EO-1: setting timed terminal event at 87.0
2025-10-16 18:32:36,601 sats.satellite.EO-2            INFO       <72.00> EO-2: setting timed terminal event at 87.0
2025-10-16 18:32:36,605 sats.satellite.EO-1            INFO       <87.00> EO-1: timed termination at 87.0 for broadcast
2025-10-16 18:32:36,606 sats.satellite.EO-2            INFO       <87.00> EO-2: timed termination at 87.0 for broadcast
2025-10-16 18:32:36,607 data.base                      INFO       <87.00> Total reward: {}
2025-10-16 18:32:36,607 comm.communication             INFO       <87.00> Communicating data in 2 directions.
2025-10-16 18:32:36,608 comm.communication             INFO       <87.00> Optimizing data communication between all pairs of satellites
2025-10-16 18:32:36,608 sats.satellite.EO-1            INFO       <87.00> EO-1: Satellite EO-1 requires retasking
2025-10-16 18:32:36,609 sats.satellite.EO-2            INFO       <87.00> EO-2: Satellite EO-2 requires retasking
2025-10-16 18:32:36,611 gym                            INFO       <87.00> Step reward: {}

One agent can broadcast while the others are completing a different task.

[7]:
_ = env.step({"EO-1": ACTION_IMAGE_2, "EO-2": ACTION_BROADCAST})  # Agent 1 broadcasts
2025-10-16 18:32:36,616 gym                            INFO       <87.00> === STARTING STEP ===
2025-10-16 18:32:36,617 sats.satellite.EO-1            INFO       <87.00> EO-1: target index 2 tasked
2025-10-16 18:32:36,618 sats.satellite.EO-1            INFO       <87.00> EO-1: Target(tgt-974) tasked for imaging
2025-10-16 18:32:36,619 sats.satellite.EO-1            INFO       <87.00> EO-1: Target(tgt-974) window enabled: 56.5 to 255.5
2025-10-16 18:32:36,619 sats.satellite.EO-1            INFO       <87.00> EO-1: setting timed terminal event at 255.5
2025-10-16 18:32:36,620 sats.satellite.EO-2            INFO       <87.00> EO-2: setting timed terminal event at 102.0
2025-10-16 18:32:36,623 sats.satellite.EO-2            INFO       <102.00> EO-2: timed termination at 102.0 for broadcast
2025-10-16 18:32:36,624 data.base                      INFO       <102.00> Total reward: {}
2025-10-16 18:32:36,625 comm.communication             INFO       <102.00> Communicating data in 1 direction.
2025-10-16 18:32:36,626 sats.satellite.EO-2            INFO       <102.00> EO-2: Satellite EO-2 requires retasking
2025-10-16 18:32:36,628 gym                            INFO       <102.00> Step reward: {}