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()

2025-09-30 17:47:25,474 gym                            INFO       Resetting environment with seed=3825668436
2025-09-30 17:47:25,476 scene.targets                  INFO       Generating 1000 targets
2025-09-30 17:47:25,616 sats.satellite.EO-1            INFO       <0.00> EO-1: Finding opportunity windows from 0.00 to 600.00 seconds
2025-09-30 17:47:25,657 sats.satellite.EO-2            INFO       <0.00> EO-2: Finding opportunity windows from 0.00 to 600.00 seconds
2025-09-30 17:47:25,701 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})

2025-09-30 17:47:25,706 gym                            INFO       <0.00> === STARTING STEP ===
2025-09-30 17:47:25,707 sats.satellite.EO-1            INFO       <0.00> EO-1: target index 3 tasked
2025-09-30 17:47:25,707 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-725) tasked for imaging
2025-09-30 17:47:25,709 sats.satellite.EO-1            INFO       <0.00> EO-1: Target(tgt-725) window enabled: 111.6 to 215.1
2025-09-30 17:47:25,709 sats.satellite.EO-1            INFO       <0.00> EO-1: setting timed terminal event at 215.1
2025-09-30 17:47:25,711 sats.satellite.EO-2            INFO       <0.00> EO-2: target index 2 tasked
2025-09-30 17:47:25,711 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-725) tasked for imaging
2025-09-30 17:47:25,713 sats.satellite.EO-2            INFO       <0.00> EO-2: Target(tgt-725) window enabled: 28.9 to 123.0
2025-09-30 17:47:25,713 sats.satellite.EO-2            INFO       <0.00> EO-2: setting timed terminal event at 123.0
2025-09-30 17:47:25,746 sats.satellite.EO-2            INFO       <74.00> EO-2: imaged Target(tgt-725)
2025-09-30 17:47:25,749 data.base                      INFO       <74.00> Total reward: {'EO-2': 0.4197384400981222}
2025-09-30 17:47:25,750 sats.satellite.EO-2            INFO       <74.00> EO-2: Satellite EO-2 requires retasking
2025-09-30 17:47:25,753 gym                            INFO       <74.00> Step reward: {'EO-2': 0.4197384400981222}

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})

2025-09-30 17:47:25,758 gym                            INFO       <74.00> === STARTING STEP ===
2025-09-30 17:47:25,759 sats.satellite.EO-1            INFO       <74.00> EO-1: setting timed terminal event at 89.0
2025-09-30 17:47:25,760 sats.satellite.EO-2            INFO       <74.00> EO-2: setting timed terminal event at 89.0
2025-09-30 17:47:25,768 sats.satellite.EO-1            INFO       <89.00> EO-1: timed termination at 89.0 for broadcast
2025-09-30 17:47:25,768 sats.satellite.EO-2            INFO       <89.00> EO-2: timed termination at 89.0 for broadcast
2025-09-30 17:47:25,771 data.base                      INFO       <89.00> Total reward: {}
2025-09-30 17:47:25,772 comm.communication             INFO       <89.00> Communicating data in 2 directions.
2025-09-30 17:47:25,773 comm.communication             INFO       <89.00> Optimizing data communication between all pairs of satellites
2025-09-30 17:47:25,775 sats.satellite.EO-1            INFO       <89.00> EO-1: Satellite EO-1 requires retasking
2025-09-30 17:47:25,775 sats.satellite.EO-2            INFO       <89.00> EO-2: Satellite EO-2 requires retasking
2025-09-30 17:47:25,778 gym                            INFO       <89.00> 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

2025-09-30 17:47:25,783 gym                            INFO       <89.00> === STARTING STEP ===
2025-09-30 17:47:25,784 sats.satellite.EO-1            INFO       <89.00> EO-1: target index 2 tasked
2025-09-30 17:47:25,785 sats.satellite.EO-1            INFO       <89.00> EO-1: Target(tgt-852) tasked for imaging
2025-09-30 17:47:25,786 sats.satellite.EO-1            INFO       <89.00> EO-1: Target(tgt-852) window enabled: 124.9 to 332.6
2025-09-30 17:47:25,787 sats.satellite.EO-1            INFO       <89.00> EO-1: setting timed terminal event at 332.6
2025-09-30 17:47:25,787 sats.satellite.EO-2            INFO       <89.00> EO-2: setting timed terminal event at 104.0
2025-09-30 17:47:25,796 sats.satellite.EO-2            INFO       <104.00> EO-2: timed termination at 104.0 for broadcast
2025-09-30 17:47:25,798 data.base                      INFO       <104.00> Total reward: {}
2025-09-30 17:47:25,799 comm.communication             INFO       <104.00> Communicating data in 1 direction.
2025-09-30 17:47:25,800 sats.satellite.EO-2            INFO       <104.00> EO-2: Satellite EO-2 requires retasking
2025-09-30 17:47:25,803 gym                            INFO       <104.00> Step reward: {}