ATM-Based digital set top box

An ATM-based digital STB (Set Top Box) for on-demand multimedia services ov er the FTTB (Fiber to the Building) network has been developed. The STB int erfaces with the UTP (Unshield Twisted Pair) based VDSL (Very High-Speed Di gital Subscriber Line) and ATM25 local access networks through which fiber networks are accessed. The ATM layer and ATM adaptation layer are terminate d at the STB. The STB hardware comprises four basic modules and one optiona l module connected through the PCI bus. Changing the hardware module such a s network interface module or adding an optional hardware can be easily don e thanks to the modularized design around the PCI bus. The STB is equipped with a 32-bit RISC processor to deal with user interactions while handling communication protocols and real-time MPEG decoding. Hardware ATM SAR (Segm entation and Reassembly) and hardware MPEG decoders are employed to cone wi th time critical information streams. Three custom LSIs have been developed to enhance graphics operations, memory control, and I/O control. The softw are functions are implemented as independent modules. The service is built by aggregating required software modules. Changing or adding a service invo lves merely replacing or installing appropriate modules. The STB supports s tandard protocols to achieve interoperability. MPEG over ATM, classical IP over ATM, and UNI3.1 signaling are supported as a base of the upper layer p rotocols.