Cable modems are neither required nor recommended for PC 98. The recommendations provided in this section are for informational purposes only.
Cable modems connected to a PC are one component in a system that cable-television operators use to deliver high-speed cable data services (HSCDS) to customers. HSCDS provides two-way services: Data flows downstream from the cable operator’s head end and upstream from the customer’s PC.
Ideally, two-way HSCDS is delivered over 450-MHz and 550-MHz hybrid fiber-coax (HFC) cable-television distribution networks. Most current cable-television distribution networks in the United States are 300-MHz, 350-MHz, and 400-MHz coax branch and tree networks.
Currently, the typical cable modems used on customer premises are external to the PC, with their own power supply. These cable modems are essentially IP routers. The cable modem’s upstream connection is either a standard F-coax interface or an ATM interface. The cable modem connection to the PC uses a 10BaseT interface (RJ45) to connect a twisted pair to a standard Ethernet network adapter. For the next several years, it is expected that external cable modems will be included as part of the HSCDS service by the cable operator, much like set-top boxes. In light of that, along with the absence of standards for cable modems, few PC vendors are expected to bundle cable-modem hardware with their systems.
PC platform vendors can build PCs that are capable of using external cable modems by including a standard Ethernet network adapter in their PC systems. The PC platform should also have pre-installed Microsoft TCP/IP software.
HSCDS upstream data flow can be implemented on the predominant 300-MHz, 350-MHz, and 400-MHz coax branch and tree cable-television distribution networks by using telephone circuits for the upstream channel. This is a design alternative used today to accomplish HSCDS field trials with existing cable-television networks until more HFC networks are built.
There are a great number of design issues for cable operators as they upgrade their cable-television distribution networks to HFC and begin to deliver HSCDS. Even operators who have existing HFC networks must add equipment to that network in order to begin offering HSCDS. The speed at which cable-television operators resolve these issues will determine the requirements for cable modems in homes and businesses in the next two years. Although HSCDS is only in trials today, a majority of the cable operators in the United States are working on business plans for delivering HSCDS within the next two years.
PC platform makers must track the rate at which cable-television operators are resolving these issues and must track the best methods. The key cable-modem design issues for PC platform makers are cost and standards.
Some cable-modem vendors plan to implement the new IEEE 802.14 protocol when it becomes available. It should be well-suited to the distances, data rates, and physical-plant scenarios for HSCDS on cable-television distribution networks.
If implemented under Windows or Windows NT, a cable modem should support PC 98 network adapter requirements, including Plug and Play, power management, and driver support.
The following recommendations should be considered for cable modems implemented in PC 98 systems: