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()

2025-11-05 22:47:52,066 gym                            INFO       Resetting environment with seed=2009381660
2025-11-05 22:47:52,069 scene.targets                  INFO       Generating 1000 targets
2025-11-05 22:47:52,200 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2025-11-05 22:47:52,240 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2025-11-05 22:47:52,280 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})

2025-11-05 22:47:52,285 gym                            INFO       <0.00> === STARTING STEP ===
2025-11-05 22:47:52,286 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2025-11-05 22:47:52,287 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-249) tasked for imaging
2025-11-05 22:47:52,288 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-249) window enabled: 0.0 to 165.4
2025-11-05 22:47:52,288 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 165.4
2025-11-05 22:47:52,289 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2025-11-05 22:47:52,290 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-249) tasked for imaging
2025-11-05 22:47:52,291 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-249) window enabled: 0.0 to 74.9
2025-11-05 22:47:52,292 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 74.9
2025-11-05 22:47:52,304 sats.satellite.EO-2            INFO       <55.00> EO-2: imaged Target(tgt-249)
2025-11-05 22:47:52,305 data.base                      INFO       <55.00> Total reward: {'EO-2': 0.7832178237991035}
2025-11-05 22:47:52,306 sats.satellite.EO-2            INFO       <55.00> EO-2: Satellite EO-2 requires retasking
2025-11-05 22:47:52,309 gym                            INFO       <55.00> Step reward: {'EO-2': 0.7832178237991035}

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})

2025-11-05 22:47:52,314 gym                            INFO       <55.00> === STARTING STEP ===
2025-11-05 22:47:52,315 sats.satellite.EO-1            INFO       <55.00> EO-1: setting timed terminal event at 70.0
2025-11-05 22:47:52,316 sats.satellite.EO-2            INFO       <55.00> EO-2: setting timed terminal event at 70.0
2025-11-05 22:47:52,318 sats.satellite.EO-1            INFO       <61.00> EO-1: imaged Target(tgt-249)
2025-11-05 22:47:52,319 data.base                      INFO       <61.00> Total reward: {}
2025-11-05 22:47:52,320 comm.communication             INFO       <61.00> Communicating data in 2 directions.
2025-11-05 22:47:52,321 comm.communication             INFO       <61.00> Optimizing data communication between all pairs of satellites
2025-11-05 22:47:52,322 sats.satellite.EO-1            INFO       <61.00> EO-1: Satellite EO-1 requires retasking
2025-11-05 22:47:52,324 gym                            INFO       <61.00> 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

2025-11-05 22:47:52,329 gym                            INFO       <61.00> === STARTING STEP ===
2025-11-05 22:47:52,330 sats.satellite.EO-1            INFO       <61.00> EO-1: target index 2 tasked
2025-11-05 22:47:52,331 sats.satellite.EO-1            INFO       <61.00> EO-1: Target(tgt-628) tasked for imaging
2025-11-05 22:47:52,331 sats.satellite.EO-1            INFO       <61.00> EO-1: Target(tgt-628) window enabled: 37.2 to 230.3
2025-11-05 22:47:52,332 sats.satellite.EO-1            INFO       <61.00> EO-1: setting timed terminal event at 230.3
2025-11-05 22:47:52,333 sats.satellite.EO-2            INFO       <61.00> EO-2: setting timed terminal event at 76.0
2025-11-05 22:47:52,336 sats.satellite.EO-2            INFO       <76.00> EO-2: timed termination at 76.0 for broadcast
2025-11-05 22:47:52,337 data.base                      INFO       <76.00> Total reward: {}
2025-11-05 22:47:52,338 comm.communication             INFO       <76.00> Communicating data in 1 direction.
2025-11-05 22:47:52,338 sats.satellite.EO-2            INFO       <76.00> EO-2: Satellite EO-2 requires retasking
2025-11-05 22:47:52,340 gym                            INFO       <76.00> Step reward: {}