Question: What is the nature of the algorithm responsible for link-rate estimation in Transparent end-to-end Packet-switched Streaming Service (PSS) as per 3GPP specifications?
Option 1: It is strictly defined by 3GPP standards to ensure uniformity across implementations.
Option 2: It is partially specified, with key parameters open to vendor discretion.
Option 3: It must adhere to a set of predefined rules but allows for flexibility in its core design.
Option 4: It is entirely implementation-specific, with no standardized guidelines provided.
Explanation: The correct answer reflects the specification's acknowledgment that the actual link-rate estimation algorithm is left to the discretion of the implementer, indicating a lack of standardization on this specific aspect. This approach allows for innovation and optimization based on individual implementation requirements, highlighting the balance between standardization and flexibility in telecom protocols.