Compatible metropolitan area gateways for integrated broadband cable systems

Abstract

In the near future, integrated voice/data services will be introduced and provided by the Integrated Services Digital Network [1]. To ease the transition to these new types of services, gateways may be provided which allow for existing high-speed data networks to support the integrated traffic types. In the paper, novel gateway designs are presented for integrating the flow of voice streams with existing broadband cable systems. The interface between the integrated voice subnetwork and the cable system is realised by a metropolitan area gateway (MAG) which is implemented at the broadband cable headend. Both fixed-frame (with realignment) and dynamic movable boundary designs are proposed. In both systems, an intelligent scheduling algorithm in the MAG dynamically allocates channel bandwidth using a variation of the data switch filtering (SWIFT) technique introduced in Reference 2. The MAG accomplishes this by coordinating the transmission of inbound and outbound voice packets in an upwardly compatible fashion with respect to the existing CSMA/CD data stations. This means that previously installed stations require no hardware or software modification. Also, the systems are suitable for use with standard ISDN voice streams. Results are presented which indicate that the new designs perform significantly better than previous compatible voice/data integration methods.