A wide variety of computer networking and telecommunications standards and protocols continues to evolve on both fronts even as telecommunication and computer networks converge. At the physical level, twisted pair, coax and other copper conductors are giving way to fiber optics, broadband wireless and other technologies. Over these various media and networks data is carried using a host of different protocols, from serial sampled streams to packets, cells, frames, etc. Some of the common protocols and access standards in use presently include SONET, ATM, Frame Relay and many others. Encapsulation further complicates the matter: we see, for example, encapsulation of LAN protocols over AAL5, classical IP over ATM, Frame Relay over ATM, etc. The promise of “VOIP” is becoming a practical reality at least over managed networks.
Transmitting and receiving digital “content” (fundamentally bits) carried in a particular data format and using a specified protocol over a selected type of link or connection, to another node where the corresponding stack is implemented is relatively straightforward, at least over a network or connection where delay can be controlled. Transitioning to different formats, protocols or physical links along the way is somewhat more complicated but bridges and gateways to accomplish such tasks are known. These transitions often require special synchronization, segmentation, buffering, packetizing, encapsulating, etc. (and generally undoing all of that at the destination node—stripping headers, etc.). “Bridging” thus imposes costs, both for equipment, and in the sense of processing overhead and delay. For some applications, especially voice applications, delay must be carefully controlled.
According to the ITU's voice delay guidelines, delays below 150 milliseconds (msec) are considered acceptable for most applications provided that echo cancellation is implemented. A total (one-way) delay of 35 msec is the maximum tolerable delay for acceptable quality of service (QOS) without echo cancellation. A significant part of the total delay is packetization. Packetization delay is caused by holding digital voice samples for placement in the payload until enough samples are collected to fill the packet or cell payload. In other words, it is the time necessary to accumulate enough data to build the packet payload. Echo cancellation is well known and can be implemented using DSP (digital signal processors) but such solutions add considerably to system cost and complexity. The need remains for a way to bridge various formats and protocols while minimizing delay and cost.
A related problem is that the growing variety of services and capabilities brings more communications requirements—to move voice, data, video, etc. at various (and ever increasing) speeds. Each new application requires a new hardware/software solution, meaning more equipment to design or buy, spares to stock, more potential points of failure, and more training for technicians on multiple pieces of equipment, all of which adds to the total cost of acquisition and ownership, particularly for makers and users of telecom equipment. Costs can be reduced by a single, versatile solution that accommodates a wide variety of protocols and applications. The need remains for a multi-access platform that consolidates most or all communications onto a single network backbone, leaving only one set of equipment to maintain, and one network management system to operate. The present invention can be used, for example, to seamlessly integrate voice, data, and video communications over fiber-optic, hybrid fiber/copper or microwave or other paths.
Density is another important consideration. Higher density—in terms of channels or calls per board or slot—translates to fewer circuit boards, hence fewer backplane slots, and smaller power supplies etc. in network/telecom equipment such a bridges, gateways and routers, be they customer premises or CO applications. All of these factors affect cost, performance and reliability. What is needed is a single board or SOC product that not only implements a substantial number of channels, for example 4k simultaneous voice channels; but also supports a variety of protocols and interfaces, fully provisionable under software control.