TFRCExpression

TFRCExpression is a domain-specific expression language and runtime library designed to model and evaluate mathematical expressions used in TFRC-based network rate control simulations and implementations. It provides a compact notation for describing how key variables influence throughput, congestion signals, and timing parameters within TFRC-enabled systems.

The language supports common arithmetic operators and a small set of mathematical functions, along with a simple variable namespace. Typical variables include p for packet loss probability, RTT for round-trip time, s for packet size, and t_RTO for retransmission timeout. Expressions can also incorporate conditional constructs, allowing policy decisions to be encoded as if-then-else expressions. The syntax is designed to be easily embedded in simulators or control loops, enabling researchers to specify, modify, and compare rate-control policies without rewriting core code.

A principal use of TFRCExpression is to encode TFRC-related throughput formulas and policy rules as evaluable expressions. For example, the TFRC-throughput relationship can be represented as an expression such as T = s / ( RTT * sqrt(2*p/3) + t_RTO * max(1, 3*sqrt(3*p/8)*p*(1-p)) ), with p, RTT, s, and t_RTO substituted at run time. Encodings like this allow dynamic evaluation as network conditions change, supporting rapid experimentation with alternative control strategies.

Implementation and interoperability vary by project, but TFRCExpression is commonly designed to be integrable with network simulators and TFRC implementations, including language bindings for C++ and Python. It emphasizes being lightweight, portable, and easy to extend with new functions or operators to suit specific TFRC variants or research needs.

See also: TFRC, rate control, domain-specific expression languages.