Telecommunications protocol with PID control of data transmission rate

摘要

A computer data transmission system is provided with proportional-integral-derivative (PID) control over a data transmission rate so as to maximize use of available bandwidth of a datagram-based network. A data channel and a separate feedback channel are established between the sender and receiver units of the system. The sender unit coupled to the data and feedback channels sends datagrams over the data channel to the receiver continuously until a source of data is exhausted or paused by the receiver unit. The receiver unit sends acknowledgment messages over the feedback channel to the sender unit at predetermined intervals. A PID controller in the sender unit uses the information provided in the acknowledgment messages to track unsuccessfully transmitted datagrams and to adapt the data transmission rate to any changing network transfer conditions. In particular, the rate of datagram loss may be used as a PID process variable to control an inter-datagram delay of the sender. There may also be absolute speed and transmission rate acceleration/deceleration limits constraining the PID control. PID control may also be adapted for data compression control, datagram block sizes, and degree of redundancy in the datagrams sent.

主权项

1. A method integrated into a computer data transmission system of transferring data between a sender and a receiver in a datagram-based network, the method comprising:
establishing a data channel between a sender unit and a receiver unit; establishing a feedback channel separate from the data channel between the sender and receiver units; sending datagrams from the sender unit to the receiver unit over the data channel continuously until a source of data is exhausted or the sending is paused at the request of the receiver unit,
wherein the sender unit groups datagrams to be sent into chapters of datagrams and creates an output stream containing a controlled amount of redundancy that allows each chapter of datagrams to be recoverable from a subset of datagrams,proportional-integral-derivative (PID) control being applied by the sender unit over the amount of redundancy of the chapters of datagrams in the output stream and also over a data transmission rate of datagrams over the data channel so as to maximize use of available bandwidth in the established data channel independent of network latency,wherein application of PID control over the data transmission rate adjusts an inter-datagram delay establishing a time duration between the sending of consecutive datagrams; and sending acknowledgment messages from the receiver unit to the sender unit over the feedback channel at predetermined intervals and using the acknowledgement messages in the sender unit to track unsuccessfully transmitted datagrams, the PID control adapted to react to any changing network transfer conditions by changing the amount of redundancy and the data transmission rate,
wherein a process variable monitored by the PID control is a rate of datagram loss that is calculated as a ratio of number of datagrams lost or corrupted, as determined from the acknowledgement messages, to total number of datagrams sent by the sender unit,a PID error value thereby being the rate of datagram loss minus a user-specified loss rate,the process variable for the PID control having tuning factors Kp, Ki and Kd for component proportional, integral and derivative terms of that process variable selected such thatζ=Kp2⁢Ki⁢Kd≥1.