What is ST Secondary transmitter

Secondary Transmitter (ST) Explained Technically

The term "Secondary Transmitter" (ST) can have different meanings depending on the context. Here are two common interpretations:

1. Cognitive Radio Networks (CRNs):

In the context of Cognitive Radio Networks (CRNs), a Secondary Transmitter (ST) refers to a device that can opportunistically access unused portions of the radio spectrum licensed to primary users (PUs).

Here's a breakdown of the technical details in CRNs:

• Spectrum Sharing: CRNs allow unlicensed users (secondary users) to utilize spectrum bands that are not actively being used by licensed primary users.
• Spectrum Sensing: The ST plays a crucial role by continuously monitoring the spectrum to identify unoccupied channels (spectrum holes) that can be temporarily used for secondary communication.
• Spectrum Access: Once a spectrum hole is detected, the ST can initiate transmission within the available bandwidth, adhering to specific rules to avoid interference with primary users.
• Spectrum Sharing Techniques: Different techniques can be employed in CRNs, including:
  • Overlays: Secondary users transmit over unused portions of the primary user's signal bandwidth.
  • Underlays: Secondary users transmit at a lower power level to avoid causing interference to primary users.

Benefits of ST in CRNs:

• Improved spectrum utilization by enabling secondary users to access unused portions of the spectrum.
• Increased network capacity by allowing more devices to share the available spectrum.
• Flexibility for secondary users to adapt their communication based on spectrum availability.

Challenges of ST in CRNs:

• Maintaining fair access and avoiding interference with primary users is crucial.
• Efficient spectrum sensing and dynamic spectrum access algorithms are required.
• Regulatory considerations and standards need to be addressed for widespread adoption of CRNs.

2. Specific Network Implementations:

In some specific network implementations, "Secondary Transmitter" might refer to a device that transmits supplementary information alongside a primary signal. This could be relevant in:

• Cooperative Communication Systems: An ST might be used to relay or retransmit data packets to enhance coverage or reliability.
• Multi-Antenna Systems: In certain configurations, additional antennas might be designated as "secondary transmitters" to support beamforming or spatial diversity techniques.

Understanding the Context:

To determine the exact meaning of ST in a specific case, it's essential to consider the context in which the term is used. Look for additional information about the system or application where you encountered "Secondary Transmitter."

Additional Considerations:

• The concept of ST has also been explored in other areas like radar systems, but these usages are less common.
• When referring to CRNs, ST is often used interchangeably with terms like "Secondary User (SU)" or "Cognitive Radio User (CRU)."