A point-to-point duplex communication link is known in the prior art to include a bus with multiple transmitters that operate on a non-concurrent basis. Specifically, only one of the transmitters communicates at any given time on the bus, typically by managing transmissions of each transmitter to avoid collisions.
Such a point-to-point duplex communications link has an inherent latency since only one transmitter communicates at any one time; one transmitter must therefore wait while the other transmits data on the bus. Another delay adds to the latency since a bus turnaround time is needed before the waiting transmitter can transmit, for example to avoid reflections on the bus. A further delay is added to the latency because a separate control device is needed to manage the non-concurrent transmissions, and that control device too has an inherent delay. Yet another latency typically occurs on the afore-mentioned communications link since additional logic may be used to ensure that data packets are received and complete at the intended bus receiver. The control device and/or the additional logic add architectural complexity to systems incorporating the link.
Another prior art point-to-point duplex communications link has multiple transmitters that concurrently communicate on the bus. Each of the transmitters has an associated receiver. Each receiver operates to subtract the signal from its respective transmitter to obtain the underlying signal.
Among other reasons, this duplex communications link is difficult to implement because of the complexity associated with subtraction at the receiver. By way of example, the subtraction must be extremely linear to avoid data corruption. Moreover, the desired data and the unwanted data must be entirely synchronous or else additional errors occur during subtraction. The bus also affects how synchronous the bus signals are, adding further complexity due to reflections, attenuation and/or residual noise. By way of example, bus attenuation degrades and/or delays the incoming signal as compared to the outgoing signal of a transmitter; the associated receiver must therefore perform the subtraction relative to bus characteristics.