Effective data transfer rate

Abstract: In one embodiment a system is provided for multirate communications allowing for different data rates for each data unit on a channel, including both data units from different mobile units and from the same mobile unit. A sending unit (102) preferably begins by determining the rate at which to start communications, and monitors, for example by use of an RSSI detector (106), for an indication that the rate should be changed. A rate adjustor (105) implements the change, and can make changes as frequently as every data unit. The encoder (104) applies the appropriate rate and inserts a rate indicator (202) indicative of the data or encoding rate, and sends the data unit (107). On receiving data units, the receiving unit (110) first determines the rate for each data unit or group of units, then appropriately decodes the data unit(s). As a result, the actual data throughput can be adjusted to permit optimized throughput.

Abstract: The present invention, generally speaking, provides for transmission and flow control of real-time data streams over computer networks. A real-time data stream is transmitted in data packets from a data source in accordance with a predetermined protocol over a shared network, for example. Data packets of said real-time data stream are received at a data destination connected to the local area network. The data destination determines a suggested data rate for the data source based in part on a number of data packets lost during a preceding interval of time and transmits the suggested data rate to the data source. The suggested data rate is received at the data source, which adjusts its data rate in accordance with the suggested data rate. The rate adjustment mechanism is designed such that a network segment will not be overloaded with a single isochronous data stream connection and that a disproportionate shared of the network bandwidth is not consumed by the isochronous data stream connection.

Abstract: A method of managing, in a network system having at least two end systems, at least two networks respectively connected to the at least two end systems and at least one transfer device for connecting the networks and transferring data between the networks, a maximum transfer unit of one unit of data transferred at time on a transfer route connected between the two end systems and including the networks and the transfer device. A table is provided having information about the transfer route in each of the end systems and the transfer device, and an optimum value of maximum data lengths of the one unit of data which are transferable on the transfer route is registered, as the maximum transfer unit for the transfer device, in each of the tables. In particular, the optimum value is a minimum value of maximum data lengths of the one unit of data which are transferable through each of the networks on the transfer route.

Abstract: A data communication system, such as a local area network, is provided with a capability of transmitting isochronous data. Preferably the system conveys both isochronous data and non-isochronous data by time-multiplexing the data into a recurring frame structure on a four-bit nibble basis. Bandwidth available for a particular isochronous source/sink is selectable and sustainable with a predefined granularity. Data rates can be adjusted by using "rate adjustment" time slots which can transmit data in some frames and "no data" in other frames. A particular time frame or template is provided which accommodates isochronous data, non-isochronous data, D channel data, maintenance data and frame synchronization signals. Non-isochronous operation and bandwidth allocation is independent and transparent to the isochronous data activity. Frame timing can be coordinated with one or more reference clock signals, e.g., from a public telephone or wide area network. A buffer can convert between the source/sink or hub circuitry data rates and the data rates for transmission over the physical media which, for a given type of data, is discontinuous on a small time scale.