LEO Satellite Relay Uplink Timing Control for IoT Collision Avoidance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In IoT systems, the reliability of communication is compromised due to data collisions and congestion, especially when a large number of IoT terminals transmit data, as existing methods do not effectively control transmission schedules based on the occupancy state of the base station, leading to fluctuations in communication congestion and decreased reliability.
Innovation Solution
A wireless communication system that includes a relay device mountable on a moving body, such as a LEO satellite, which generates a transmission permission signal and transmits it to communication devices, allowing them to determine their transmission timing based on the elevation angle of the relay device, thereby controlling the transmission schedule to prevent data collisions and congestion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If autonomous and distributed transmission schedule control is implemented to avoid data collision, then data collision is reduced, but transmission timing cannot be optimized based on relay device occupancy state, leading to fluctuating communication congestion
Solution Approach 1:
The relay device transmits occupancy state information back to IoT terminals, creating a feedback loop that enables terminals to adjust their transmission schedules based on real-time relay availability. This resolves the contradiction by allowing distributed control (maintaining reliability) while incorporating occupancy-based optimization (improving productivity).
Solution Approach 2:
The transmission schedule is made dynamic rather than static. Terminals continuously adjust their transmission timing based on the current occupancy state of the relay device, transitioning from fixed autonomous scheduling to adaptive scheduling that responds to real-time conditions, thereby optimizing both collision avoidance and transmission efficiency.
2Reliability
If LEO satellite is used as relay station to achieve low delay and low propagation loss, then communication quality is improved, but the visible time per orbit is limited and direction changes continuously
Solution Approach 1:
The relay device transmits occupancy state information in advance to IoT terminals before the actual transmission occurs. This preliminary action allows terminals to prepare their transmission schedules ahead of time, optimizing the utilization of the limited visible time window and continuous direction changes of the LEO satellite.
3Use of energy by moving object
If LPWA is used for wide-area communication at low power, then power consumption is reduced, but data rate is low and transmission time becomes relatively long
Solution Approach 1:
The system implements periodic transmission opportunities based on the orbital period of the LEO satellite. By structuring transmissions around these natural periodic cycles and using occupancy state information to identify optimal windows, the system maximizes the utilization of each transmission opportunity, reducing overall transmission time while maintaining low power consumption characteristics of LPWA.
Data Source
AI summary
A wireless communication system includes one or more communication devices located in a communication target area, and a relay device mountable on a moving body, in which the relay device includes a timing control unit that generates a transmission permission signal that is a signal representing transmission permission of an uplink signal, and a first transmission unit that transmits the transmission permission signal to the communication target area by a beam. The communication device includes a reception unit that obtains the transmission permission signal from the relay device, a transmission control unit that determines an earlier transmission timing as an elevation angle of the relay device viewed from the communication device is larger on a basis of the transmission permission signal, and a second transmission unit that transmits the uplink signal to the relay device at the transmission timing.