Transmission of data over a radio frequency channel

A data communications apparatus adapted for transferring data over a communication channel between a local system and a remote system, said data communications apparatus comprising:

• a DTE interface adapted for connecting said data communications apparatus to said local system so as to permit data to be transmitted to and received from said local system;
• an analog interface adapted for connecting said data communications apparatus to said communication channel and;
• a protocol and control processor adapted for enabling the local system to transfer data between said analog interface and said DTE interface, and to transmit and receive data over said communications channel according to a predefined data communication protocol, whereby data is transferred in packets;
• said protocol and control processor including credits determined as a function of a buffer size available at said remote system for receiving packets,
• wherein said protocol and control processor is adapted to enable the local system to repeat the transmission of all packets which have not been acknowledged if said credits indicate that new packets cannot be sent to said remote system.

A method of transmitting data over a data communications channel from a local system to a remote system, comprising the steps of:

• transmitting at least one data packet over said communications channel to said remote system;
• repeatedly transmitting said at least one data packet over said communications channel to said remote system until an acknowledgement for said data packet is received from said remote system or said communications channel becomes disconnected;
• providing credits and determining said credits as a function of a buffer size available at said remote system to receive packets;
• and
• repeating the transmission of all packets which have not been acknowledged if said credits indicate that new packets cannot be sent to said remote system.

A method of transmitting data over a data communications channel from a local system to a remote system whereby said remote system includes a receive buffer memory having a predetermined size, said method further comprising the steps of:

• providing credits and determining said credits as a function of said receive buffer memory available to receive data packets at said remote system;
• determining a quantity of data packets that can be transmitted to said remote system;
• transmitting said quantity of data packets to said remote system;
• and
• repeatedly transmitting all of said data packets until an (a) acknowledgment from said remote system that said data packets have been received or (b) said communications channel becomes disconnected if said credits indicate that new packets cannot be sent to said remote system.