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()

2025-12-03 22:22:26,433 gym                            INFO       Resetting environment with seed=630312157
2025-12-03 22:22:26,435 scene.targets                  INFO       Generating 1000 targets
2025-12-03 22:22:26,567 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2025-12-03 22:22:26,605 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2025-12-03 22:22:26,638 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})

2025-12-03 22:22:26,644 gym                            INFO       <0.00> === STARTING STEP ===
2025-12-03 22:22:26,644 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2025-12-03 22:22:26,645 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-744) tasked for imaging
2025-12-03 22:22:26,645 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-744) window enabled: 113.1 to 238.9
2025-12-03 22:22:26,646 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 238.9
2025-12-03 22:22:26,647 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2025-12-03 22:22:26,647 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-91) tasked for imaging
2025-12-03 22:22:26,648 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-91) window enabled: 0.0 to 96.7
2025-12-03 22:22:26,649 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 96.7
2025-12-03 22:22:26,667 sats.satellite.EO-2            INFO       <97.00> EO-2: timed termination at 96.7 for Target(tgt-91) window
2025-12-03 22:22:26,668 data.base                      INFO       <97.00> Total reward: {}
2025-12-03 22:22:26,669 sats.satellite.EO-2            INFO       <97.00> EO-2: Satellite EO-2 requires retasking
2025-12-03 22:22:26,672 gym                            INFO       <97.00> Step reward: {}

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})

2025-12-03 22:22:26,677 gym                            INFO       <97.00> === STARTING STEP ===
2025-12-03 22:22:26,678 sats.satellite.EO-1            INFO       <97.00> EO-1: setting timed terminal event at 112.0
2025-12-03 22:22:26,679 sats.satellite.EO-2            INFO       <97.00> EO-2: setting timed terminal event at 112.0
2025-12-03 22:22:26,683 sats.satellite.EO-1            INFO       <112.00> EO-1: timed termination at 112.0 for broadcast
2025-12-03 22:22:26,683 sats.satellite.EO-2            INFO       <112.00> EO-2: timed termination at 112.0 for broadcast
2025-12-03 22:22:26,684 data.base                      INFO       <112.00> Total reward: {}
2025-12-03 22:22:26,685 comm.communication             INFO       <112.00> Communicating data in 2 directions.
2025-12-03 22:22:26,685 comm.communication             INFO       <112.00> Optimizing data communication between all pairs of satellites
2025-12-03 22:22:26,686 sats.satellite.EO-1            INFO       <112.00> EO-1: Satellite EO-1 requires retasking
2025-12-03 22:22:26,687 sats.satellite.EO-2            INFO       <112.00> EO-2: Satellite EO-2 requires retasking
2025-12-03 22:22:26,689 gym                            INFO       <112.00> 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

2025-12-03 22:22:26,695 gym                            INFO       <112.00> === STARTING STEP ===
2025-12-03 22:22:26,695 sats.satellite.EO-1            INFO       <112.00> EO-1: target index 2 tasked
2025-12-03 22:22:26,696 sats.satellite.EO-1            INFO       <112.00> EO-1: Target(tgt-744) tasked for imaging
2025-12-03 22:22:26,697 sats.satellite.EO-1            INFO       <112.00> EO-1: Target(tgt-744) window enabled: 113.1 to 238.9
2025-12-03 22:22:26,697 sats.satellite.EO-1            INFO       <112.00> EO-1: setting timed terminal event at 238.9
2025-12-03 22:22:26,698 sats.satellite.EO-2            INFO       <112.00> EO-2: setting timed terminal event at 127.0
2025-12-03 22:22:26,700 sats.satellite.EO-1            INFO       <116.00> EO-1: imaged Target(tgt-744)
2025-12-03 22:22:26,701 data.base                      INFO       <116.00> Total reward: {'EO-1': 0.8802964815306269}
2025-12-03 22:22:26,702 comm.communication             INFO       <116.00> Communicating data in 1 direction.
2025-12-03 22:22:26,702 sats.satellite.EO-1            INFO       <116.00> EO-1: Satellite EO-1 requires retasking
2025-12-03 22:22:26,704 gym                            INFO       <116.00> Step reward: {'EO-1': 0.8802964815306269}